Each and every day we receive a phenomenal number of emails asking all matter of questions pertaining to audio / visual related issues. The more frequently we get asked something, the more likely that the question will end up here on our frequently asked questions page. This page is updated regularly and is forever growing, so check back regularly for updates. These are the questions we're most commonly asked, starting with questions about us all the way through to system design, product choice and how to do articles.
A frightening portion of our work comes from fixing other stores work; us bearing witness to a near endless stream of people being burned by shoddy workmanship and corner cutting. This is conducive to many walking away from car audio simply assuming no one does high quality work anymore. Starting out decades ago; Fhrx Studios set out to change this attitude, striving to produce the best install possible for any desired vehicle and budget. For info about us, our methodologies and reasons why you should come see us for your next install click here.
Yes we certainly do! We're always more than happy to take orders for most products via email and phone. Payment can be made by all the usual payment methods and upon clearance and receipt of payment you're issued with a receipt. Items are shipped via Australia Post and are registered and insured.
We are also more than happy to ship to New Zealand. Note; due to some of our agreements with certain distributors and companies we are forbidden to ship certain brands overseas. If in doubt, please ask as these conditions constantly change.
There are also some brands that we have interstate agreements with meaning that if you want to order a product from them we'll refer you to a reseller located in your state.
We certainly do. If you're stuck for ideas on what present to give a friend or relative how about giving them a Fhrx Studio's gift voucher? We can supply gift vouchers for any value and can even post them fully wrapped to people if that suits you better.
The short answer is nothing really; it's just Marty's nickname. Expanding upon this; when Marty was young there were no mobile phones or internet, ergo everyone was on CB radio and had call signs for identification. In those very early days Marty had aspirations for a career in pyrotechnics, therefore he went by the call sign ‘Firex’. Fast forward to the teenage years and with him now working within the aircraft industry, he was required to have a four letter code to sign off upon various things. Hence this moniker was shortened to Fhrx, pronounced ‘fikes’.
When the time came to start the audio store he didn’t want anything cheesy such as ‘Marty’s Audio’. Nor did he want the terms ‘car’ or ‘audio’ in the name either, simply because the business covered far more than just those two aspects. So having a musical background and therefore knowing a thing or two about professional sound studios; the name ‘Fhrx Studios’ was born henceforth. For Marty felt it sounded far more professional then those aforementioned.
The Acoustic Garage concept is basically a discussion, education and tuning session; on steroids. Whereby we first run through the mathematics and physics of sound in great depth, similar to what's taught within our seminars. From there we then set out to tailor your sound meticulously until it's just right dependant on your individual preferences. This has evolved over the years because a sizable portion of our workload, aside from the mandatory installation work of course; has focused specifically on system tuning. For not only do we employ digital sound processing in nearly every system we install here; we also tune said processors found within systems that're either self-installed by their owners, else installed by other stores. Both locally and interstate based.
Rather than have customers sit around endlessly whilst we tune their system 'for' them, we instead tune the car 'with' them. In doing this it also affords us opportunity to learn things from customers too because reality and wisdom dictate that no one knows everything; us included. How it works is we bring the customer’s car in and park it before a line of chairs containing our numerous testers, auditioners and tuners. At this point the customer also takes a seat amongst us and over the ensuing hours we all not only chat incessantly about all things audio but also take turns listening, measuring, testing, tuning and throwing around recommendations and ideas pertaining to their car. During this time the customer also has the opportunity to listen to our numerous demo cars too, in order to offer us their thoughts and feedback on each’s sound. This feedback also aids us in tailoring their sound perfectly for them.
Overall we’ve found this tuning methodology to present a far more casual atmosphere for both us and the customer. Us because we're unapologetically slow and like to take our time getting the tune just right, and them because they get to chat, learn and have a real hands on approach with their own system tuning; exactly how tuning ought to be done.
Without doubt the most common question we field here pertains to what system is best for any specific budget. Whilst there’s no absolute answer to this we find that during testing, reviewing and most importantly installing certain components constantly outperform most; especially those from the specialist boutique manufacturers. Now before we run through our favoured components there’re a few important things to remember:
When asked how one can destroy speakers we reply by explaining there is only three real ways. The first is thermally and this is the most commonly occurring. Breaking the equation down further there are only two ways to thermally destroy a speaker (and crossover in the case of split systems); over powering and under powering. Over powering the speaker with way too much power will cause the voice coil wire (which is receiving more current through it than its rated too) to melt and short on the magnet. This is simple enough to understand so if you have a 200 watt subwoofer then you don't feed it 2000 watts. However much more dangerous is under powering the speaker because the end result will be the same but it happens in a slightly slower and sneakier way.
In audio systems where you hear speakers 'distorting', it's not the speaker that is causing the struggle, it's the amplifier. Speakers are quite simple devices and don't discriminate. They cannot tell the difference between harmonic sound and rough distorted noise and simply reproduce whatever wave signal is given to them regardless of what it may sound like. When you ask the amplifier to do its job (by turning the volume up) it takes a comparatively small sound wave and amplifies it before sending this bigger signal to the speakers. If you ask your amplifier to produce more than it's capable of it will attempt to achieve this request but the output sound wave becomes rough and distorted as the amplifier reaches its power output threshold. Pushing it beyond this point causes the amplifier to begin clipping. When a woofer is driven hard by a high power amplifier there is a significant amount of current flowing through the voice coil. The voice coil has resistance and therefore a voltage drop across it occurs. This means that there may be a great amount of power being dissipated in the form of heat within the voice coil. When a speaker is driven with clean power the cone moves back and forth a great deal. You'll notice many speakers have perimeter vents in the basket and pole vents in the back. The speakers movement forces air to flow in through these perimeter vents and into the magnetic gap (the area where the voice coil lives and moves) before flowing out the pole vent (and hopefully taking the heat with it). When the cone moves forward out of the basket, the area that's under the dust cap and around the voice coil increases in volume. This pulls cool air into the magnetic gap. When the woofer moves the other direction, the chamber size is reduced and the hot air is forced out of the pole vent. This air flow cools the voice coil.
When a relatively low powered amplifier is driven into clipping (to the point of full square wave sometimes) the voltage delivered to the voice coil no longer resembles a sine wave because the amplifier clips the top and bottom of the wave off (because it's beyond what it can do). While this output is clipped (the flat spot on the top of the wave) the voice coil in your speaker is not moving but instead remains almost stationary at this time with high current still running through it. Because the voice coil is not moving it is not being cooled sufficiently (remember the coil is driven by a linear motor therefore the more voltage applied to the voice coil, the further it moves). In the image above you see that at points A, B, D, E, F and H the voltage is changing causing the voice coil to move in the gap and therefore pull in fresh cool air. At points C and G, the voice coil is still moving a little but this is only due to momentum. This is not enough to cool efficiently and there is still full current flowing through the voice coil. Since the displacement of the voice coil (and the relating airflow around it) is no longer proportional to the heat being generated, the voice coil will overheat. This excess heat (just as with overpowering) causes the voice coil to melt its insulation and the former to physically distort. Basically the whole motor burns apart as adhesives start to fail. However before you stress too much it should be noted that many reputable manufacturers underrate speakers so generally slight clipping isn't a problem. Severe clipping is more likely to cause a problem.
The second way to destroy a speaker is physically and this can also be broken down into two facets. The first physical facet is what we call bell mouthing. This is where the voice coil and former are driven so hard they actually extend beyond their normal range of motion and impact the back plate on the bottom of the speaker. This continual impacting causes the bottom of the voice coil to bend out like the bottom of a bell and this eventually cause the coil and corner to become so physically disfigured that it rubs on the magnet surrounding it and eventually comes to a complete halt. This isn't just restricted to subwoofers either. Tweeters playing frequencies that are too low tend to suffer from this phenomenon too because they're not designed for high excursion. The second facet of physically destroying a speaker is to punch way too much power into it fast and this causes what us engineering types like to call critical structure failure. That is a technical way of saying you'll simply tear the surround and/or spider(s) and pop the cone and motor assembly right off the frame. To 'blow the guts out of the speaker' is the more Aussie way of saying it. This is commonly witnessed during sound pressure level competition because the drivers are being pushed to their absolute limits.
The third and final way to destroy a speaker is an age old enemy of technology; sunlight. Nothing breaks down and erodes foam surrounds faster than sunlight (well except bugs like moths but you shouldn't have them living in your car). After only a few months of direct sunlight your speaker surrounds will be significantly weakened and may eventually begin cracking or simply tear all together. Butyl rubber surrounds are more resistant to sunlight but eventually all materials succumb to the mighty sun. The best thing to do with shelf speakers is place some grille cloth over the factory grilles. This helps in resisting ultra-violet rays from the sun penetrating through to the speaker.
These are the three main causes of most damaged speakers. The end result is the same with all three methods but you tend to get a lot more warning with thermal or sunlight damage. Physically speaking though; if you're pushing your speaker way beyond what its rating dictates you'll get very little warning before your speakers starts to smoke or literally explodes.
Now that you know about clipping (see above) we move to severe clipping (a.k.a square wave). It always amazes me when I hear some idiot driving down the road and the audio is clearly distorted (you know what I mean). Many people drive their amplifiers into what could be called a square wave output (white line below). When an amplifier is pushed that hard, it is actually possible to drive the speaker with twice as much power as the amplifier can cleanly produce into the speaker. As you can see below, the yellow sine wave is the maximum 'clean' output that the amp can produce. When an amplifier is pushed way too hard, the signal will eventually look like the white line. The effective voltage of the white line is ~1.414 x the yellow line. This means the total power driven into the speaker by the clipped (square wave) signal is double the power delivered by the 'clean' signal (yellow line). This means that the power is double but the cooling of the voice coil will not increase in proportion with the power increase (since the voice coil isn't moving as much as it needs to be for the given power dissipation). This will lead to the voice coil overheating. If we compared the output of a 100 watt amp (the one that's clipping) to a 200 watt amp, the 200 watt amplifier would be able to push the speaker as much as 40% farther than the 100 watt amp (depending on the frequency of the signal). This extra travel (in each direction from its point of rest) would result in added airflow around the voice coil.
Note: The RMS voltage of a pure sine wave is equal to the peak voltage multiplied by 0.707. The RMS voltage of a pure square wave it equal to the peak voltage. For 2 waveforms with equal amplitude (as shown above), the RMS voltage of the square wave is 1.414 times the voltage of the sine wave. If we use the example of the 100 watt amp which can produce a sine wave of 20 volts RMS, we can see that the output power at hard clipping is double the power it can produce cleanly.
Well, to get a little more complicated, distortion is any departure from a true and accurate reproduction of the original waveform. It can include Noise, Clipping Distortion, Harmonic, and Intermodulation Distortion. These last two forms are fairly common in loudspeaker reproduction and can be reduced but not entirely eliminated in the existing technology. It would be fair to say that modern amplifier design fairly eliminates nearly all forms of inherent perceived distortion, leaving only that caused by inappropriate user settings and overloading.
Distortion is the name given to anything that alters a pure input signal in any way other than changing its size. The most common forms of distortion are unwanted components or artifacts added to the original signal, including random and hum-related noise. Distortion measures a system's linearity - or nonlinearity. Anything unwanted added to the input signal changes its shape (skews, flattens, spikes, alters symmetry or asymmetry). A spectral analysis of the output shows these unwanted components. If a circuit is perfect, it does not add distortion of any kind. The spectrum of the output shows only the original signal - nothing else - no added components, no added noise - nothing but the original signal.
It's rather amusing to see amplifier manufacturers making great claims about the advantage of the extra .001 % Distortion they've wrung out of their products, while most speakers are considered very good if they can keep such distortions below 5 %. It's true that the reduction of any distortion anywhere is a positive contribution to the goal of high fidelity, but the disparity between the two technologies in this regard points up the largely subjective nature of many such claimed advantages.
Here are some of the definitions:
When talking speaker power ratings you need to exercise a little caution because whilst they hold significant meaning to us speaker designers, to you the end user these ratings can often border on being useless. Here’s why. Speakers possess two primary power ratings; continuous and maximum. The trouble is neither of these have much to do with music, but actually pertain to the thermal and physical limitations of the speaker's motor structure.
So how much power then?
Just because a speaker requires 1000 watts to move doesn't mean it's loud. It could possess a very heavy motor structure or very stiff suspension. Open cut mining trucks possess around 7000hp but you'd hardly call them fast and nimble. The opposite can also be said, in that just because a speaker only requires 35 watts doesn't mean it's quiet; it may have suspension that's extremely soft and nimble. Continuing the aforesaid horsepower analogy you'll find a Hayabusa only has 250hp; yet it's far from slow or sluggish. Smaller power requirements could also be conducive to the motor possessing advance lightweight materials too; such as Kapton rather than alloys and neodymium instead of strontium just to name a couple. Again, this doesn't mean its feeble. You can lift the front end of a top fuel dragster off the ground with your bare hands; that doesn't mean it's got a weak chassis. Or to cite a more dramatic example; a sizeable portion of a Boeing 787 or Airbus A350 wing is synthetic fibre, whereas a standard car chassis is mild steel. Which do you suspect is the stronger?
When it comes to speakers; understand that midranges are not designed to play subsonic frequencies whereas tweeters cannot even play midrange frequencies - lest they die a horrible death from over excursion (where the voice coil begins bottoming out). Therefore you should cross your speakers over at an acceptable frequency wherein they're capable of playing loudly but with minimal risk to their wellbeing. When building both high-pass and low-pass crossovers the technique is the same but the components change places. Simple 1st order (6dB) crossovers are created by using a single capacitor or coil in the positive wire of your speaker connection like this. If you want 2nd order (12dB) slopes then you'll need one component in the positive wire and the other bridged across the two speaker wires like this. 3rd order (18dB) and steeper slopes can also be achieved by wiring in a network of capacitors and coils like this. If you wish create more complex crossovers that incorporate such elements as phase control, shunts, attenuation and the like; you might want to consult your local car audio store as crossovers can become quite complex.
The answer to this question depends on factors such as how loud you like to listen, what speakers you're using and what your budget is. Remember we always say that the bigger the amplifier the better because the larger the amplifier, the less work it must perform to successfully drive the speakers. Larger amps keep their THD low, their efficiency and control level high and they stay cooler. It's better to have a larger amplifier doing minimal work than to wring the neck out of your smaller one. Remember though that too much power can also damage speakers so the gains MUST be set correctly.
Look up the sensitivity rating of the speaker, which is expressed in dB/watt/meter. For example a speaker with a 89dB sensitivity will produce 89dB of sound 1 meter (39") from the speaker with a 1 watt input. For every doubling of power input the SPL (volume) increases by 3dB. So in this case, assuming a 100 watt power handling spec:
Power input (watts = xdB @ 1 meter)
So, theoretically, the SPL limit of this speaker would be somewhere between 107dB and 110dB.
There are literally thousands of amplifiers to choose from out there. This is where an installers experience comes in handy. Serious installers will listen to your demands and then recommend an amplifier that best suits your desires.
Beware of "bargain" amps though as cheap amplifiers are exactly that and you'll often have problems not too long down the track. Too much power for too little money generally means that corners have been cut somewhere in quality of construction or service back-up. Aim for about $2-$3 per watt for quality.
Inspecting the manual included with your new subwoofer will reveal recommended enclosure types and volumes. However the manufacturer cannot possibly know what type of car you own, let alone what volume or order it's interior is. Therefore these suggestions are exactly that; mere suggestions, and they often feature a safely buffer as well. Whereby the manufacturer deliberately understates sealed enclosure volumes because it equates to higher compression, which is conducive to fewer bottom outs and ultimately less warranty returns. Ergo because manufacturers cannot accurately select an enclosure, many also include the subwoofers' Thiele / Small parameters. Specialised installers take these specifications, and utilising powerful modelling and simulation software design an enclosure to perfectly suit your application. Now make no mistake; even working with these fundamentals can soon result in a virtual minefield, as the laws of physics have a nasty habit of making simple things very complex. Then throw into the mix isobaric loading, whereby the subwoofers are coupled together in pairs to work together; you can get some absolutely amazing looking enclosures. However before we get too carried away let's canvas the fundamentals design types.
Bandpass enclosures can be divided into two basic types; single and dual reflex. In a single reflex design, or 4th order; the rear chamber is sealed and the front chamber is ported.
In a dual reflex design, or 6th order; both the front and rear chambers are ported into the listening area whilst the subwoofer resides in the middle.
There's also a more complex variation of the dual reflex design called a series-tuned or 8th order. This has a port which connects the rear and front chambers as well.
The differences between single reflex and dual reflex designs are similar to the differences between sealed and ported enclosures. A single reflex typically exhibits a shallower low-frequency roll off rate (e.g. 12dB/octave) and better transient response. A dual reflex is more efficient and controls cone motion over a wider range but typically has a sharper (e.g 18-24dB/octave) low frequency roll off. Because of the difference in low-frequency roll off rates, a dual reflex usually has to be larger in size to produce the same low frequency extension as a single reflex design.
Now it's important to note here that there're many variations of bandpassing, and compared to conventional sealed and ported enclosure designs bandpass enclosures are inherently more complex to design far less forgiving; the rules governing the performance of bandpass enclosures leave little room for error. Slight volume miscalculations or sloppy construction can turn a good design into a poor performing box. Integrating the proper size port or ports can be extremely challenging and often renders designs that looked great on paper completely impractical. No matter what type of enclosure you eventually chose to settle on, the design of these boxes should definitely be left to people with extensive enclosure experience.
Note; images above have been borrowed from the12volt.com website, permission pending.
The debate on whether to use sound deadening material, diffuser panels and fibrefill inside an enclosure has been around for a long time. However, this debate needs to be broken down into two areas because you're actually addressing two separate issues when asking about these materials. The first issue is regarding standing waves and the second is regarding the delaying of sound waves and the smoothing of resonance. Well start with standing wave issue first.
Sound delaying and resonance smoothing
Assuming your 3" / 4" / 5.25" / 6" / 6.5" speakers are midrange drivers and not subwoofers (Focal make a 5.25" subwoofer for example), you shouldn't need to make a sealed enclosure for it. In most cases (but not all) there is no need to build sealed enclosures for these midrange drivers because their suspension (the spider and surround) is designed to operate in an infinate baffle situation such as a door or rear deck of a car. In other words, most midranges are free-air drivers. However, it's always best to consult the manual for your new speakers if you're not sure.
There's no quick and easy answer to this question, It all depends on the car and the overall design of the system. Generally speaking you don't want your subwoofers to go much higher than 80-100Hz. Typically when you set your subwoofer crossover point you will use that as a starting point for your high-pass on your mid/bass drivers. Sometimes you will need to increase the crossover frequency and sometimes you will need to lower it. It is basically all a matter of personal preference and the acoustics of your car. Electronic crossovers make it very easy to try a variety of crossover frequencies to see what works best for you and your car.
Passive networks or crossovers are designed to take a full range signal and split it; sending higher frequencies to the smaller speakers and the lower frequencies to the larger drivers. Sounds easy enough until you introduce real world conditions into the equation; for the car interior is an absolutely horrible locale to attempt good sound in acoustically. Hence the need for customization, because even two identical cars side by side will have completely different sonic characteristics. To deal with the aforesaid idiosyncrasies we need to control two main aspects. The first aspect is the roll-off slope and the second aspect is the roll-off logarithm. Below we're just going to delve into what the different slopes and logarithms basically entail, rather than going into which ones to use where. Your installer will be able to select both these based on numerous criteria including speaker size, location, axis as well as other more technical parameters.
As you can see from the above graph what order slope you select basically dictates how steep the frequencies will be rolled off. For example, a second order slope means that the sound will change by 12dB for each octave of sound spanned.
These logarithms are basically concerned with how you deal with the perceived valley between the roll-offs of two sonically adjoining speakers. I say 'perceived' because although when plotted individually there is a valley, in actuality when both speakers are playing together there is in fact a gain (or summation) at the cross point where the two slopes meet because both speakers are in essence playing the same frequency. So as follows:
The graphs above demonstrate, from left to right; the summation of the Chebychev, Butterworth, Bessel and Linkwitz logarithms. The yellow line is the actual summation level.
Once you have these selected you can go about building a crossover to handle the splitting of your systems frequencies. Getting these aspects correct can mean the difference between your stereo sounding astonishing as opposed to just okay.
Okay, stop and think about a concert for a second. You don't sit with your back towards the band right? Rather, you want the sound in front of you. Likewise you want to be in the first row, be dead center of the band on stage and depending on your personal preference you might like to be slightly below the sound (as is an audience member) or slightly above the sound (as a conductor is). This is the image we try and capture inside cars today and tweeter positioning plays a large role in achieving this phenomenon. You cannot just simply slap tweeters in anywhere. To get a decent stage you need good width, height and depth - preferably mirror-tip to mirror-tip, floor to roof and as far down the bonnet as possible.
Where to mount them then? Kick panels, sails or elsewhere?
If you place the tweeters down in the kick panels then the right speaker distance is about three feet and the left speaker is about four feet away. The problem is not utterly eradicated but it becomes a lot less noticeable as the distance separation is reduced (by up to half sometimes). However using the kick panel method can result in the stage being a tad low (the kicks are often used on cars with no factory tweeter location to avoid the cost of custom A-pillars or sails too). Remember tweeters cannot be placed anywhere where they fire straight into ones feet so you have to be more careful about their placement on both sides and more often than not this results in them being mounted very high up in the kick panel, quite often well out of sight and well up under the dash - this is also good for security too.
The final mounting place of your tweeters depends what you desire from your system and what your budget is. As mentioned above; when choosing a tweeter mount in order to achieve a great sound stage you're always faced with various issues. Put the tweeters up high and forward and you'll get good depth and height but the stage width can sometimes suffer. If you put them deep in the kick panels you tend to get good width and depth but the height can sometimes suffer. Seems you cannot win sometimes, especially when you factor other things on like reflection issues. Generally speaking though, mounting the tweeters in the a-pillars right at the front corner of the dash will result in the best unmanipulated (i.e. no time alignment) sound stage. If that is not an option, then experimentation is the best strategy. Remember too that tweeter location can also play a role in ambience too. If the tweeters are positioned correctly (whether in the kick panels, A-pillars or even behind the review mirrors) they will help the whole component set fill the car with high frequency sound - not just way off in front of you.
There are two other issues to consider when choosing where your tweeters will go too. Cost is one because to mount the tweeters successfully in the A-pillars there is a good chance you're going to require some custom work done and hence the price goes up. Then there is also the security issue too because people can now see your tweeters. Factor all these issues in when you are deciding.
What about time alignment?
So how does one get the stage right in real world terms?
Advanced staging and imaging techniques
It seems there are few debates in the known world larger than the one concerning the humble 6x9" speaker. Now depending on which side you're on (as there seems to be no middle ground these days), 6x9's are either a little nuisance that you'd rather have sitting far in the rear of the car or better still, on the road behind the car, or you cannot even contemplate a life without them.
Lets begin with some basics. 6x9's are oval shaped speakers aptly named because they measure 6 inches by 9 inches. There are slightly different versions measuring 7x10, 4x6 and 6x8 on the market but let us concentrate on the daddy of the group. 6x9's are more often than not three or four way drivers (that is; three or four speakers in one unit) and comprise of a 6x9 woofer, smaller mid-bass (or two) woofer and a tweeter mounted on a bridge over the main woofer. They are commonplace in many different factory audio systems right over the world.
But I have heard so many conflicting opinions…
Lets look at the cons first.
But they must have some pro's?
Expense. Time. Space. Money. Say it how you will, 6x9's are a hell of a lot cheaper than lashing out on a large external amplifier, sub enclosure, subwoofer and splits. And they will take up a lot less room too incidentally. At the end of the day 6x9's make an excellent addition to budget systems and make terrific factory upgrades because they do a little of everything quite acceptably. They are very good drivers for beginners and people looking for a little more of everything but lets be realistic, they won't keep the staunch audio buffs satisfied for long.
Headlight dimming is caused by a voltage drop in your car's electrical system. Contrary to popular belief this isn't simply because the amplifiers are powerful per se, but rather the problem pertains to inferior earthing. Modern batteries usually possess between 500 and 1000 cranking amperes available for instant discharge. Therefore unless your amplifiers' have something approaching this by way of fusing on their side then obviously power 'availability' isn't the issue but rather power 'supply'. Fix the flow and remove the bottleneck via way of a earthing upgrade and you'll solve your issue. From here you need to have a read of how batteries and direct current works and then upgrade your car's earthing.
Of all the issues we regularly deal with this would be one of the more contentious; as it not only perplexes customers but also throws many a store owner too. In that we're not keen on demo walls. See sadly there's very little value in listening to speakers within a store, for they'll sound absolutely nothing like your car; as in not even close. That’s why many high end stores don't rely primarily upon endless demo walls full of speakers, as it often ends up offending serious audiophiles rather than assisting them. There're two primary factors for this phenomenon.
Intrinsic speaker design.
So how does one choose?
Realistically somewhere along the line you'll have to rely on someone else's advice. Now that doesn't mean old mate on the internet who once read the loudspeaker cookbook years back, but rather someone who not only installs speakers incessantly but also designs, develops, tests and reviews them too. That's where we come in. See we first invite you to sit through an Acoustic Garage session, during which we'll get you to listen to various cars and whilst peppering you with endless questions. Thenceforth we'll make an educated recommendation based on your answers.
We often get asked what speaker pods and door trims are available for different budgets. Below are some of the more common speaker pods and door trims we make here at Fhrx Studios. Remember many of these pods are colour matched then dyed or painted as opposed to using off-the-shelf trim. Many are also vacuum formed rather than hand formed. This often incurs extra costs.
If your speakers are out of phase, imaging will be vague and bass output will be reduced. To ensure that your speakers are hooked up in phase, check to make sure that the positive and negative leads are connected the same way to both your speakers and your receiver or amp. Make sure red is connected to red, black to black, etc. Check for correct phasing... With a 9-volt battery. Disconnect the speaker wire from the amp. Touch the wire you think is negative to the negative battery terminal (the big one). Touch the positive wire to the positive battery terminal (the other one). If your speakers are wired in phase, the speaker cone will move "out" and stay there. If they are out of phase, the driver cone will move "in" and stay there. (This won't help you for tweeters, only midranges and woofers. So when you're wiring your tweeters, be careful. Do it right the first time.) Phasing is never absolute in car audio situations, since speakers are rarely facing the same directions. Phasing differences mostly affect bass. Is your system lacking bass? Try changing the phase on your sub system. 90% of the time, that's the key to more bass!
Proper setting of your front-to-rear fader and left/right balance controls is important for optimum staging and imaging in your system. Too much sound in the rear of the car (sometimes called "rear fill") will often eliminate staging altogether, forcing sound away from the front of the car, while too little rear fill will sound dull. Too much sound on one side of the car or the other will add an unrealistic element to the imaging. To adjust fade and balance, play a tape or CD you are familiar with and turn the rear speakers on full with the fade control. Listen to the rear speakers, and then slowly turn the fade up in the front speakers just until you can't tell the rear speakers are playing anymore, then ease off a tad. You're probably close to optimum setting when the front staging is such that the rear speakers provide little more than ambiance and space to the sound. Test it by going full on the front speakers (without losing the position you just attained). You'll hear an immediate loss of spaciousness in the sound with the rear speakers faded all the way down. Return to your optimum setting. Setting the balance is more difficult, so it's always a good idea to leave the balance fader at the "12 o'clock" position. That's as close to equal as you're going to be able to hear with your own ears.
It most certainly can. Prolonged exposure to sound pressure levels above 85dB will cause permanent hearing damage. Professional audio competitions specify the use of hearing protection devices for their contests, especially at higher volume levels. You can test the dB level of your car stereo with a Sound Pressure Level Meter (available at electronics stores). If you're disoriented and your hearing is sort of muffled after you've been listening to your car stereo, or you hear ringing in your ears, then turn it down! If you have to shout at the person in the passenger seat, and you're not angry with them, then it's a good bet that your stereo is too loud. For the sake of your hearing, turn it down.
Sure is. The gang and Marty, along with literally thousands of other car audio nuts can be found on various forums around the country, by far the largest of them being Mobile Electronics Australia.
When it comes to achieving sonic bliss in your ride and getting the most from your audio system, most people simply focus on the speakers themselves and nothing else. They'll canvas just about every aspect of them from build quality and the materials employed through the power handling, size and weight. Then there's the home in which the speakers will live. Much consideration is given to deadening, enclosing, porting, filling, loading and all matter of other aspects - even the speaker cable gets a look in. What about the component driving the speaker though? That simple heat sink covered metal box with a few gold terminals on the end? You don't really need to worry about the amplifier so long as it's powerful enough right? Just like when you're considering the purchase of a new car the only thing you need to look at is the power output of the engine alone right? Well actually; wrong.
The amplifier is a most important element in your system however when choosing one there is more than just power output you need to consider, lest you splash out a couple of grand on one that could potentially sound terrible. Speakers are pretty simple and indiscriminate devices - sure their names and materials can certainly get quite exotic but that still doesn't detract from the fact that at the end of the day they're just pushing and pulling air around in the form of compression and rarefaction waves. Yes friends that's pretty much all they do; move their cones forward and backwards. It's actually the device driving them that dictates how controlled your music sounds, how much hiss it has, how distorted or clear the midrange and treble is, how defined the bass notes are and so on - these attributes are all controlled by the amplifier. So don't let's concentrate on the speakers so much but the driving force behind the music. After all you don't just concentrate solely on your tires when you're trying to go faster do you?
Before we get down to discussing the various performance attributes you'll see commonly associated with amplifiers let us first have a look at the various modes or operation, or classes. Analogue amplifiers are classed according to how much current is flowing during each wave cycle (or Hz) and this is measured in degrees, where 360º means the current is flowing during the entire cycle. There are many different classes of amplification but most are derivatives of either class A, B, AB or D so let's take a closer look at these four.
Now that we have that out of the way we can have a look at what makes the switching design so efficient. In the class D design the output transistors are either completely switched on or completely switched off. When a transistor is conducting (that is; switched on) there is virtually no voltage across it. When the transistor is switched off, there is no current flowing through it. This means the design is inherently efficient - usually to the tune of over 90%. The reason class D amplifiers are usually called digital is because these transistors are usually digitally switched on and off rather than via analogue voltage - there is no such thing as a true digital amplifier because sending 0's and 1's to a speaker will get you nowhere. The output stage still needs to send AC current down the speaker wires to the voice coil.
We now have a basic understanding of the main amplification classes. It gets a little more complicated when you start factoring in additional classes such as class G voltage following / switching amplifiers and class T tri-path designs but let's just stick with the main four for now. From here we'll move onto the main function of the amplifier which is raw power output.
As opposed to how much power you 'want', when looking at how much you 'need' you might be surprised to learn that bigger doesn't always mean louder. Open cut mining trucks have over 7000 horsepower whereas a Hayabusa only has a couple of hundred - therefore which is faster? Speakers are the same; just because a subwoofer has a power rating of 1000 watts doesn't mean it's necessarily loud - it might have extremely stiff suspension, possess a very heavy motor, have a steel cone reinforcement retainer or it might simply just have a large diameter voice coil because the magnet is located in the middle on the pole. Furthermore; higher level speakers tend to employ lighter and more exotic space age elemental materials which are extremely strong but lightweight so they only need a fraction of the power to produce maximum output. The crux of the matter is that while you should buy the largest amplifier you can afford, don't go overboard chasing titanic power figures at the expense of attributes such as damping factor, slew rate, total harmonic distortion, signal to noise ratio and channel separation.
Total Harmonic Distortion
When looking at amplifier specs you'll often find that they're followed by the term 'A-weighted'. Put very simply, 'weighting' scales are part of a compensation system that accounts for various factors such as the human ears' natural hearing curve. Be careful with heavily weighted figures though because sadly some companies are guilty of using these weighting scales to make inferior amplifier figures appear more attractive. Also take care with the amplifiers presented electrical load. While most amplifiers are stable at lower impedances, this doesn't mean they're overly efficient or happy when loaded down. Your car's engine is 8000rpm stable but it's unwise to hold it there for too long. By the same token many amplifiers are two, one, half and even quarter ohm stable but this is built into their design more for intermittent spikes as the music (which is dynamic) causes the speakers resistance to continuously change during playback. It's not for just strangling your amplifier with twenty 15" subwoofers. If you need more power then buy a larger amplifier - don't just squeeze the life out of your existing one.
These are some of the more important things to consider when looking too purchase to new amplifier. It's not simply just a matter of buying which ever unit outputs the most power. It's a matter of taking all the figures into consideration and ultimately choosing which amplifier best suits your application.
Well lets see? Put simply, Ohms is the measurement of electrical resistance and system impedance. It is a measure of the degree to which electrons are limited in both velocity and quantity in passing through a circuit. In Impedance measurements, this takes into account, the mechanical resistance inherent in the motion of transducers. The standard is usually 4 ohms for car audio and 8 ohms for home and commercial audio. Some specialty woofers may be rated at 2, 6, 12 or even 16 ohms. You would have seen the 12 ohm JL's before no doubt.
Ohm's Law is the he mathematical relationship between voltage, current, and resistance. It is named after George Ohm, it's discoverer. Ohm's law states that current volume in a conductor is directly proportional to the voltage flow across it and inversely proportional to its resistance (assuming the temp remains constant). In general, this means that more voltage will produce more current, if resistance stays the same, but higher resistance will cause current to decrease if voltage stays the same. In mathmatical terms, V = I x R, where V is voltage, I is current, and R is resistance. Ohm's law is a description of electron behavior upon which virtually all understanding of electronics is based.
Just for further background information, you might have heard all this called resistance of impedance so I'll give you a little more info on those two things as well.
Regarding resistance, almost all conductors of electrons exhibit a property called resistance. Resistance impedes the flow of current. It is measured in units called Ohms. With a water hose, resistance could be regarded as friction between the water and the hose. A larger hose would create less friction and have a lower resistance than a smaller hose. It could also be a finger over the hose end. In electrical circuits, small round cylinders with wires on either end are called resistors. These typically reduce the flow of electrons to serve the specific requirements of the circuit elements, such as amplification or switching functions.
Finally, Impedance. The totality measured in Ohms of all electrical opposition to current flow: resistance, reactance, capacitance, as well as all mechanical factors inhibiting the completion of energy transfer in a contained system. In practical terms, this means that most Drivers are assigned a certain nominal impedance based on their DC voice coil resistance and mechanical stiffness. For car audio this is usually 4 ohms; for home stereo, 8 ohms is the standard. Put simply, your voice coil has a certain amount of copper winds in the voice coil(s). If you want a high resistance, triple the amount of winds and the current suddenly has to do X amount more work to travel past the coil.
The aiming of subwoofers has been quite a topic of speculation for years now in car audio. Through experimenting many people have found that their subwoofers sound much better when aimed backwards. Many people realise that there seems to be much more bass with the boot open than with the boot closed. We've heard a great deal of strange and utterly incorrect theories to explain this phenomenon.
The main reason this phenomenon occurs is all about sound waves (direct and reflected) and more importantly the cancellation of these waves. The diagrams below assist in showing the sine waves and their phase relationships between the direct sound wave entering the car and the reflected wave that hits the back of the boot and reflects forward. Since the reflection is bounced into the listening area one can treat them much the same as having two sources.
In the above picture the vertical black line at the left of the picture is the boot rear panel (the beaver panel the tail lights are mounted on). This picture is an illustration of what happens when sound comes out of the front side of the subwoofer enclosure. Sound travels forward into the car (the purple wave) and also backwards to reflect off of the back of the boot (the red wave). Both the direct wave and reflected wave get to the listener but they are slightly out of phase causing a variable amount of cancellation in the listening area. At this stage if you opened the boot the reflected wave would disappear and not reflect back into the car, thus resulting in no cancellation.
In the picture above picture the speaker box has been aimed at the boot instead of the rear seat and you can clearly see the direct and reflected waves are not nearly as much out of phase as in the first example. This resulting in much better bass reproduction.
This picture above represents the subwoofer enclosure being moved to the rear of the trunk with the subwoofer aiming forward. The waves are a little closer to being in phase with each other.
In this picture (above) we're aiming the rear mounted subwoofer enclosure at the rear so the direct and reflected wave are very close to being in perfect phase from the start and hence they reinforcing each other quite well.
Note; these pictures are simulated using a 60Hz note with the rear of the box mounted approximately 3 feet from the back of the boot. Keep in mind we're only discussing the direct and rear reflected sound in an effort to try to simplify this. The reflecting sound waves in a car are much more complex than these drawings indicate but we must start simple before getting too carried away. For example, remember that placing the subwoofer cone face too close to any panel can load it (resulting in a similar effect to that achieved by a bandpass enclosure) but we'll worry about that another day. This explanation should be a nice foundation for those of you who wish to study this phenomenon further. One other thing we should mention is that before people comment that this cannot be true because the interior of cars being small in relation to bass wavelengths, the full wavelength does not have to completely develop to be in or out of phase with its own reflected sound. The pictures above are showing a 60Hz wavelength and the bounce distance to reflect back out of phase a complete 180 degrees is just over 4 foot. At higher frequencies the distance is less (120Hz is 2.3ft for example). Remember, the key is to experiment and see what works best for you and your vehicle.
Ever wondered just how loud or soft sound pressure can get? Or have you got no idea what all those dB readings you keep hearing about actually compare too? Well click here to find out.
Contrary to popular belief; your amplifier's gain control is not simply a volume knob that determines the maximum volume that your amplifier can squeeze out during a pink fit. Rather it's a device for matching the full undistorted output range of your head unit to the full output range of your amplifier. It is also used to level match the other amplifiers in the system in the case of a multi-amp setups. Not all head units have the same maximum preamp output voltage - some head units are capable of producing eight volts on their preouts while others are only capable of one volt. This is why the gains are variable.
As an important post script to the paragraph above; please note we said 'maximum undistorted power' of the head unit - not simply 'maximum volume'. This is because there is a big difference between the two. Most aftermarket head units will hit maximum undistorted power around 90% of their volume range (say 36 out of 40 for example). However many factory units will start distorting as little as half way. Sorry Holden and VW owners but those Blaupunkt and RNS510 head units are famous for it.
If your amplifier's power is similar to your speakers the procedure of setting the gains is not overly difficult. Grab yourself a CD that is normalised at nominal 80dB. Turn all amplifier gains right down and all head unit boosters (such as the loudness button) should be off. Then turn your deck up full volume and then back it off to about 85-90% (e.g. if your Alpine deck goes to 35, bring it up and then back off to 31-33). Moving to the amplifier, slowly bring the gain up until the distorting becomes audible. Once it's audible, turn it back ever so slightly and that is your gain set for that amplifier. That means as you turn the head unit up to full true volume range, the amplifier goes with it. If you have an Alpine deck you shouldn't be hitting maximum volume and distortion at 10 out of 35 on the volume dial. If you are then the gains (which is sensitivity) is too high. The single main issue with the gains being too high is that because the sensitivity being through the roof, you'll not only get a lot of hissing but you might also even hear the engine whining through the system too. This is why sound quality buffs use massive amplifiers; they turn the gain all the way down and that 90% of power that the amplifier will never be asked to output is called head room - more head room means less ambient noise. See both a 50 watt and a 5000 watt amplifier can run a 50 watt component set. However the former will need its sensitivity turned all the way up whereas the later uses much less effort - this means far less ambient noise. The larger amplifier will also run cooler and happier too.
Now seeing as we're looking for this extra head room, you might be wondering how the gains are then set with these titanic sized amplifiers - because the obvious problem is that if your amplifier's output is much higher than your speakers rating (e.g. running 50 watt speakers with the aforementioned 5000 watt amplifier) it'll destroy the speakers through bottoming them out long before it begins to output any distortion at all. For this reason we strongly recommend that you have a pro set the gains - as they use such tools as oscilloscopes and the like to measure distortion and clipping output rather than just relying on their ears.
Note; this listing and explanation is from the the12volt.com website.
Ever visited a cinema with no carpet on the walls? Ever wondered why most home theatre walls have curtains? Maybe you've seen a car or jet test cell without diffusers on the walls? What about a radio studio or sound recording booth without diffusers? No? Starting to notice a pattern? Sound deadening and diffusers are fundamental cornerstones (and arguably one of the most important aspects) of any sound system. They're so important in fact, that they should be budgeted for long before the speakers themselves are. However before we delve into the wonderful world of what sound deadening and diffusers actually do, let's first take a step back and look at what sound actually is.
Simply put; sound is differing frequencies of pressure waves. Expanding that concept a little; when sound is created in a medium (i.e. it cannot travel through a vacuum) it's in the form of a mechanical wave. This wave is the result of back and forth vibration of the particles that make up this medium. As sound waves move through air the particles are displaced both right and left as the energy of the sound wave passes through it. The motion of these particles is parallel to the direction of the energy origin and this phenomenon is why we characterize sound waves in air as longitudinal waves. A speaker cone is designed to create such a longitudinal wave. As the cone moves back and forth it pushes on neighbouring air particles. The forward motion of the cone pushes air molecules horizontally to the left while the backward retraction of the cone creates a low pressure area allowing the air particles to move back to the right. This movement creates regions in the air where the air particles are compressed together and other regions where the air particles are spread apart. The high pressure regions are known as compressions and the low pressure regions are known as rarefactions (note; not refractions - that's to do with light waves).
Wavelength (also known as path length or soundwave length) are common terms when talking speakers and physical sound. Wavelength is the distance the aforementioned disturbance travels along the medium in one complete wave cycle. However at this stage there is a small differentiating factor that should be explained and that's the difference between transverse and longitudinal waves. For traverse waves this pattern occurs once every wave cycle and is commonly measured from one wave peak to the next adjacent wave peak (or from one wave valley to the next adjacent wave valley). Since longitudinal waves do not contain peaks and troughs, their wavelengths must be measured differently. A longitudinal wave consists of a repeating pattern of compressions and rarefactions. Therefore the wavelength is commonly measured as the distance from one compression to the next adjacent compression or the distance from one rarefaction to the next adjacent rarefaction.
When speakers move backwards and forwards they do so many times a second. Each time the cone does one complete movement forward then backwards then back to the zero point it's known as a cycle or one hertz (a.k.a. 1Hz). If the speaker undertakes one thousand of these cycles per second it is known to be playing 1000 hertz or 1 kilohertz (a.k.a. 1000Hz or 1kHz respectively). Music is the repeating pattern of these high and low pressure regions in various frequency orders and certain patterns of frequencies our ears interpret as harmonious. This harmony is simply the music you're listening too. The Pinna (the outer ear skin section) catches these waves and directs them into our ear canal which houses our ear drum. The ear drum then mimics these varying pressure waves and lets your brain know what its hearing.
Now you understand the basics of how sound physically works so let us move to the sound deadening itself. As speakers move in alternating directions the sound emanates from both the front and rear of the cone. The front wave is heard by you while the rear wave is what the sound deadening and diffusers deals with. With all due respect; your cars doors are glorified metal cans. They echo and reverberate inside and the skins flex easily, causing bass to become blurred and muddy and even to cancel itself out all together. I usually explain it by using the following analogy. Imagine you're seated in a boat in the middle of a crystal clear flat lake. One hundred meters away there is another boat floating idle. If you start gently rocking you boat, waves emanate from it. Pretty soon these waves reach the second boat and it also begins bobbing to mimic these waves. The problem is that as this second boat rocks it not only reflects your waves back but also creates its own. Your doors are the same in that the metal skins flex and create all matter of sound effects. These waves are only minutes or seconds out of phase (i.e. not even whole degrees) to the active wave and the result is that your ears get bombarded by literally hundreds of sound waves that are not supposed to be there. This creates an echoic effect and the end result is that the music sounds hollow and tinny. By adding sound deadening you're adding mass to the doors skins (like swapping the second boat for a cement pier in our analogy). This combats flexing its effects on internal sound waves.
Diffusers are absorbent pads that resemble foam or tiny egg cartons. These fight wave reflections and are placed directly behind the speaker. Remembering back to our boat analogy with the cement pier (deadening) now in place; while extra waves are not being created any more, the main waves will still be reflected. This is where the diffusers come in. We know from above that sound waves have a certain lengths at any given frequency. Somewhere within these frequencies is the perfect distance for sound emanating from the rear of the speaker cone to travel to the doors outer skin. This will then reflect and come flying back to impact the cone and cancel the next cycle. The diffusers catch these sound waves and trap them much the same way that the paint on stealth aircraft catches radar waves or submarines rubber skin traps sonar waves. The reason you need diffusers on top of the deadening is that most sound deadening has a smooth skin and hence still reflects sound waves.
Another vitally important aspect of achieving good midbass is to seal the speaker into the door. In nature all elements take the easiest path from origin to destination. Water is a good example of this phenomenon; you pour it out and it will run wherever the easiest path is. Air is the same. When your speaker cone moves forward, it creates a high pressure cell right in front of the speaker cone. If there is a high pressure cell in front of the cone then there will be a low pressure cell on the rear side of the speaker cone. If the door is fully sound deadened and the speaker is sealed on using sealant of foam gasket, the high pressure air will move out towards you with the end result being incredibly punchy and tight midbass from your doors. If there is no sealing (say the speaker is simply screwed down to the metal) and contains air leaks everywhere, the high pressure air simply takes the easiest path and moves around the edge of the speaker frame to behind the speaker where the low pressure cell is. In simple terms, you get no bass.
Many cars come with deadening from the factory but it is usually an insufficient amount, often only being a few inches here and there to minimise rattles during transit. Car manufacturers limit this deadening in order to keep production costs down. How much deadening you end up installing depends on your budget but both the inner and outer skin of your front doors should be fully deadened at least. You can always add more to the boot, floor and roof down the track.
In conclusion; for the serious sound enthusiast sound deadening is an absolute must. If you have a close look you'll notice the cars that sound the best in every continent (especially the ones that win the sound offs) are chock full of deadening. Sound deadening even helps factory speakers so get your self some today.
Note; wavelength image taken from A Review of the Universe - Structures, Evolutions, Observations, and Theories.
Absorption, reflection, refraction, standing waves, azimuth, dispersion and the list goes on; these and all matter of other phenomena associated with soundwaves often receive mentions aplenty, especially pertaining to subwoofer enclosure design and tweeter aiming. However if you've ever wondered what the actual wavelength of a particular frequency is; use this wavelength calculator. Just enter in the frequency you're interested in and this'll return it's physical peak to peak cycle length.
Think about a concert, opera or other similar performance; you don't sit with your back to the band or performance do you? It's the same for your car, in that seeing as you're seated at the front and your ears face forwards we recommend you concentrate on getting the front stage and image perfect and leave the rear speakers alone. Therefore the short answer to the aforesaid question is 'no' if you're serious about sound quality, specifically regarding staging and imaging. Expanding upon this though requires us breaking the answer down into three parts.
The human ear The Pinna, also called the auricle; is the visible part of the outer ear. This membrane collects various frequencies of sound waves from front-on before redirecting them into the outer ear canal. It's important to remember that each pinna individually is responsible for determining height whilst the two work together to determine width. Because they face forwards; sound coming from behind the pinna will not be collected accurately unless the frequency or volume fluctuations are significant.
Laws of physics This intrinsically leads to the three main laws you're going to encounter in Newton's, Archimedes' and Pauli's. There's a very finite amount of air within your car's interior. Archimedes laws of displacement says that as you begin to agitate any one portion of this air you'll start influencing other portions of it too. With that in mind let's move to Newton's laws of motion. With it we can predict the first few bounces of a sound wave. Think of your car interior as a bucket of water. When you put two fingers in (i.e. your front speakers) and begin motioning them you can easily make out the neat waves that emanate henceforth. However put another two fingers (i.e. your rear speakers) into that finite amount of water and suddenly your surface turns into a choppy mess. About now is where you'll then encounter Pauli's princlple, that states two things cannot occupy the same space at the same time. Though not a problem in a large home theater room; sadly if you have a heap of speakers all playing the same thing within the finite confines of a car interior they're going to start affecting one another, thus resulting in some nasty cancellations and dead zones.
These are the reasons many demo and competition cars either have their rear speakers turned down or simply don't have them at all. Indeed it's why when talking sound quality we have front 'stage' but only rear 'fill'. One thing that should be mentioned though is that even when you're only running front speakers you should still have an ambience that fills the entire car, when the system is tuned correctly with a quality sound processor.
Cables quality and the difference it makes within audio is one subject bound to start an argument at any audio gathering, for everybody it seems has a different opinion. To us cables are not just cables; the reason we recommend high quality cables is two fold.
Current flow The first and primary reason pertains to the cable's current carrying ability. Not only do better quality cables tend to have a lot more strands, these strands are usually constructed from superior conductive materials such as gold, silver and copper. As opposed to aluminium, tin and zinc commonly found in the cheaper alternatives. A comparison of the two is pictured below. This means that for any given gauge of cable the superior ones will flow a lot more current whilst at the same time converting less of this energy into heat.
Build quality The other reason we advocate the better quality cable is because they tend to have a much more uniformly extruded jacket. If you get a meter of cheap cable and compare it to a meter of more expensive cable and chop it at 25mm intervals you'll find the cheap cable comes dangerously close to breaking out of the jacket every so often due to poor extrusion dies. See image above. Again not important if you plan on having your system for three months but if those cables have to withstand literally years of abuse under carpet (water / dirt / feet impacting them) then this might be of concern.
If you'd like to read more about the intrinsic intricacies of cable design then be sure to canvas two in-depth papers by cable virtuoso QED known as "The Genesis reports". These reports delve deeply into the realm of high end cable philosophy, thenceforth lending themselves to plenty of good old fashion polarised discussion. Read them and more by visiting the QED academy.
When running more than one subwoofer in an enclosure, you'll need to decide between using a common chamber (where all subwoofers run in the same airspace) or a separate chamber enclosure (where each subwoofer has its own airspace). Common chamber enclosures have no dividers between the subwoofers and the airspace inside the box is the internal volume for one subwoofer multiplied by the number of subwoofers in the enclosure. Separate chamber enclosures are built in a way that sees every subwoofer isolated inside the enclosure in its own chamber.
Generally speaking, it's usually better to have each subwoofer running in its own isolated enclosure, especially in a sealed box. We say this because if one of the subwoofers ceases working for any reason in a common chamber enclosure, it could cause the other subwoofer(s) to unload and you could end up ruining the subwoofers that are still working. For example, if your subwoofer can only handle a 1cf sealed enclosure and is running flat stick when it's brother dies, then all of a sudden that remaining subwoofer is in a 2cf sealed enclosure which may lend itself to a catastrophic suspension failure.
Ported and bandpass enclosures are the only type of enclosures that we tend to recommend running with a common chamber. This is because it allows you to have a single port (either slot, round or otherwise) acting as the port for all subwoofers in the box. This will generally require less space than having separate ports in separate chambers for each subwoofers. The possibility of a good subwoofer unloading when another fails is less likely in a ported box as well.
In conclusion; if you're running with a sealed box then we suggest it should have separate chambers for each subwoofer. If you're running a ported subwoofer enclosure then it is quite okay to have either separate or common chambered enclosure. However, if you have the space it is always best to design a multi-chambered enclosure so each subwoofer is isolated in its own airspace.
When it comes to protecting your new subwoofer there are grilles of every shape size and type. From simple bars to completely exotic custom machined numbers; we have your subwoofer covered - literally. To this end; we get asked so often about what grilles are available that we actually decided to add it to the frequently asked questions page! Below are some of the more common types and flavours of grilles we employ here at Fhrx Studios to protect your subwoofer.
Ever wondered what instruments play which frequncies? Or wondered what the difference is between an alto singer and a soprano? Well look no further, below are two frequency charts that will help clear things up a little.
These types of charts are what we more commonly use to demostrate where each frequency lies. These will also aid you in tuning your system, especially if you're using a multi-band equalizer.
Just like the petrol tank at the back of your car holds the fuel for your engine, your battery holds the fuel for the electrical components within your car. A standard battery is okay for standard electrical demands but once you start adding electrical components (such as amplifiers) you'll need to bring the power storage system up to speed too by either adding a capacitor or upgrading your battery. Lets look a little further into what a battery actually is.
Batteries differ to stiffening capacitors in that they create electricity via a chemical reaction whereas caps simply store energy. Your standard run-of-the-mill lead-acid cell (i.e. factory car battery) is created using a large number of thin plates that are mounted tightly side by side (or in spiral / circular cells as is the case with Optima batteries). The material these plates are made from alternates as they sit side by side (i.e. plates 1, 3, 5, 7 and 9 are one material while plates 2, 4, 6, 8 and 10 are the other). The most commonly used of these materials are Lead Dioxide (PbO2 / the positive plates) and Sponge lead (Pb / the negative plates). These plates are immersed in electrolyte which is most commonly diluted Sulphuric Acid (H2SO4). The types of metals and the electrolyte used will determine the output of a cell. A typical fully charged lead-acid battery produces approximately 2.11 volts per cell so when you couple six of these cells together you get your twelve volt car battery. The chemical action between the metals and the electrolyte (battery acid) creates the electrical energy. Energy flows from the battery as soon as there is an electrical load (e.g. a starter motor, an amplifier, a pair of headlights, a heater and so on) that completes a circuit between the positive terminal (connected to the positive plates) and the negative terminal which is connected to the negative plates. Electrical current flows as charged portions of acid (ions) between the battery plates and as electrons through the external circuit from negative to positive. Just re-read that last sentence again too; the power flows from the negative to the positive - this is why we put so much emphasis on earthing kits and other earth upgrades when installing systems. The action of the lead-acid battery is determined by many factors, some of which include the chemicals used, state-of-charge, temperature, porosity, diffusion, and of course; load. As a side note I should also mention that while many batteries (such as Optima and Odyssey) are called dry cells, they're actually gel-cells. The electrolyte is actually a jelly like substance rather than a true dry substance.
Moving to the actual life and home of batteries, what most people don't realize is that car batteries operate in a constant process of charge and discharge. When a battery is connected to a load that needs electricity (such as the starter motor) current flows from the battery and it begins to discharge. In the reverse process a battery becomes charged when current flows back into it. This process restores the chemical difference between the plates. This happens constantly while you're driving because the alternator puts current back into the battery. Expanding this concept and getting a little more technical; as a battery discharges the lead plates become more chemically alike. The acid becomes weaker and the voltage drops. Eventually the battery is so discharged that it can no longer deliver electricity at a useful voltage. You can recharge a discharged battery by feeding electrical current back into it. A full charge restores the chemical difference between the plates and leaves the battery ready to deliver its full power again. This unique process of discharge and charge in the lead-acid battery means that energy can be discharged and restored over and over again. This is what's known as the cycling ability in a battery. More about battery cycles later.
When the battery won't start your car people usual refer to it as "dead". However that is not technically correct. A battery that's merely discharged (from leaving your headlights on for example) can be jump-started from another fully charged battery and recharged to its full capacity. About thirty minutes of driving around should allow the alternator to fully charge the battery. However if the alternator (or another part of the cars electrical system) is damaged the battery will not recharge. So if your battery keeps discharging, have someone check the electrical system before changing the battery. Recharging can only be undertaken a certain number of times for any given battery and when once it reaches the end of its service life (when the active material in the plates can no longer sustain a discharge current) it must be replaced. Car batteries age as the active positive plate material sheds (or flakes off) due to the normal expansion and contraction that occurs during the discharge and charge cycles. This causes a loss of plate capacity and muddy sediment to build up in the bottom of the case. This can eventually lead to short between the plates of a cell and is a shore fire way to kill off the battery. In hot climates there are additional causes of failure such as positive grid growth, positive grid metal corrosion, negative grid shrinkage, buckling of plates or loss of water. The list doesn't end there though. Deep discharges, heat, vibration, fast charging, and overcharging all accelerate the "aging" process. Scarily though; approximately fifty percent of premature car battery failures are caused by water loss during normal recharging and charging (in other words; a lack of maintenance). The water simply evaporates under high temperature (either internally or under bonnet) and many people simply don't bother to top it up. And for heavens sake purchase a battery that is of the right size for the job at hand. Many intercooler kits (such as the one for the 200SX) come with Odyssey 650 battery to allow the intercooler tube to go through the battery tray. These batteries are designed for jet skis and are literally murdered when you start placing big demands on them.
Battery cycle is another important aspect to consider and if you're an audio nut you no doubt will have heard of deep-cycle batteries. A cycle is defined as one discharge and one recharge of the battery. Most normal and deep-cycle batteries are lead-acid cells and use exactly the same chemistry for their operation. The difference is in the way that the batteries optimize their design. Normal shallow cycle car batteries are designed to provide a very large amount of current for a short period of time. This surge of current is needed to turn the engine over during starting. Once the engine starts the alternator provides all the power that the car needs so a car battery may go through its entire life without ever being drained more than 20 percent of its total capacity. Used in this way a normal car battery can last a number of years. To achieve a large amount of current a normal car battery uses thin plates in order to increase its surface area.
Deep cycle batteries are designed differently. They're designed to provide a steady amount of current over a long period of time. They can still provide a surge when needed but not quite as powerful as a normal car battery can. A deep-cycle battery is also designed to be deeply discharged over and over again (such as when you're playing your stereo for long periods of time without the engine running). This is something that would ruin a car battery very quickly. To accomplish this feat, a deep-cycle battery uses thicker plates. The deep-cycle battery can withstand several thousand total discharge/recharge cycles, while a normal car battery is not designed to be totally discharged.
You would be ill-advised to purchase a battery without understanding some specs and two of the more important ones for a car battery are CCA and RC. Cold cranking amps (CCA) refers to the number of amperes the battery can produce at 0 degrees C for 30 seconds. Reserve Capacity (RC) is the number of minutes that the battery can deliver 25 amperes while keeping its voltage above 10.5 volts. Typically a deep-cycle battery will have two or three times the RC of a normal car battery but will deliver less CCA. For this reason you'll usually find deep-cycle batteries in sound quality cars and normal car batteries in sound pressure level cars. It's very important in SPL competition cars that massive amounts of current remains on tap for instant usage. The help this cause capacitors are also often employed right next to the amplifiers.
Capacitors (also known as stiffening or power capacitors) are similar to batteries but have one main difference in that they do not generate electricity. Rather; they only store it and discharge it - fast. They have a similar mechanical built to a battery, utilizing two rolled up plates of electrically conductive material separated by a dielectric insulator. Within this frame an electrical field charge is stored. The quantum (quantity) of this charge is the capacitor's value, measured in farads. It is determined via a few factors including the surface area of the plates, the effective distance between the plates and the chemical composition of the dielectric material. Audio capacitors (the ones the size of coke cans) are fast discharging energy reservoirs that store the necessary power your amplifier will need to punch those big bass notes while limiting clipping. They store power during intervals when it is not required (which is most of the time) and release it when a short term transient demand exceeds what is available from the car's power system.
If you wish to keep your factory car battery, generally you'll use a stiffening capacitor to keep your energy levels topped up. From the smallest 0.5 farad to monsters like the 35 farad one available from Stinger, you're guaranteed to find a capacitor suitable for your installation. When selecting what size cap you need there is a very general rule of thumb that states you require around 0.5 farad (500,000 microfarads) per 500 watts of continuous power output. Using more will not cause any problems other than damage to your bank account balance.
Like batteries, caps have many different specs but one important one (besides farads) is named the Equivalent Series Resistance. All caps are rated for ESR and in a perfect world they would only have one figure. However all conductors have resistance and in a cap there are many conductors such as terminal leads, foil and even the dielectric electrolyte and the resistance of these conductors all contribute to the capacitors series resistance. It's essentially the same as having a resistor in series with an ideal capacitor. Capacitors with relatively high ESR will have less ability to pass current from its plates to the load (the amplifier) so consider this aspect before purchasing.
In conclusion; aftermarket capacitors and batteries are NOT substitutes for a poor charging system. Even with an after market battery you may have to install a stronger alternator if your charging system is struggling. Remember too that while not all audio systems need a cap but they are nice if you can budget for one. In much the same way a car will stop with the factory brakes but if you can afford Brembo six pots you'll stop a lot faster!
Note; image above is taken from How Stuff Works.
The short answer is; yes there sure is. It is called Mobile audio and it can be found by clicking this link.
You most certainly should. However before we canvas this topic you might first want to read about how batteries work. For once you have a clear understanding of batteries and direct current we can then move onto to how to go about getting it efficiently moving around the car.
With engineering technology in modern cars getting more and more advanced one aspect that tends to get overlooked by many a manufacturer is an adequate grounding system dedicated specifically to assist the engine electrical and ignition systems. Upgrading existing earths in addition to adding numerous new key earth cables may not seem like much but when you do it the difference is certainly noticeable. Not only will you see small improvements in power and torque figures, your motor will run smoother, it will rev cleaner, your lights will be brighter and although hardly likely to impact you, earthing kits actually assist in fighting engine water corrosion caused through electrolysis. The big winner though is your sound system though, because like everything else in life; your amplifiers need fuel too.
So why add additional earthing? As you know; direct current flows in a circuit from the negative battery terminal, through the car and it's electrical devices then returned to the battery via the positive terminal. Everything is fine and dandy from the factory with current happily flowing through all the various electrical devices and back to the battery. However then you install yourself a titanic new amplifier. This is usually where the problems start, and it's not what many people assume either. See when it comes to inadequate earthing systems it's usually not the cable itself that is the problem but rather where those cables are anchored. Earthing cables are regularly attached to the side of the engine bay via a small screw often located on sheet metal. Here is where the first bottleneck is created, as you're trying to flow enormous amounts of current across one or two bolt threads. It's for this reason we install multiple earths on cars. These additional cables runs from the battery negative terminal to various points over the car such as shock towers, head, plenum chamber etc. Thenceforth this allows current to flow much more readily.
A quick disclaimer to the nitpickers; these earthing upgrades will ONLY assist if your cars existing earthing system is inadequate for the current you're attempting to flow. If your car already has a titanic earthing system capable of handling hundreds of amperes of current flow then you'll garner little value in adding additional earthing cables.
We're frequently asked what subwoofer enclosures are available for different budgets. Below are some of the more common enclosures designs we construct here at Fhrx Studios. All our enclosures are designed not only to suit your desired type of bass, but are also specifically to match your car and your particular subwoofer.
Construction material varies depending on the application however we typically start out using materials such as builders plywood, marine plywood and reinforced multi-panel as our most common ones. However we don't just stop there; in the past in order to achieve serious resistance against more severe tension and compression moments we've employed various metals such as aluminium and steel right through to inconel and even titanium. Besides the practical and extreme there is also the plain exotic - this has seen us make them from such materials as carbon fibre, marble, granite and even porcelain.
When it comes to finishing your enclosure the most common two methods are carpet and vinyl or a combination of both. However provided the surface is correctly prepared you can have anything from two-pac paint through to plasma spraying or plating.
When people are discussing sealed enclosures, you'll often hear the Qtc of the enclosure / subwoofer combination mentioned during the discussion. Qtc is the total resonance of the speaker system and basically is the relationship the enclosure will cause the subwoofer to have between smooth roll off and peaking at a particular frequency. An enclosure with a Qtc of 0.707 will give you the best of both worlds. In other words; the best peaking in conjunction with the lowest and smoothest possible roll off (also known or F3) point for your subwoofer.
If you look through the Thiele / Small specs which should come with your new subwoofer, you'll find Qts, Vas, and Fs. These are the main three electro-mechanical parameters that influence the Qtc. Using a calculator and various formulae, experienced shops can calculate your required enclosure volume.
In the chart above, the relative efficiency of the example subwoofer is set at 90dB. So when we look at the F3 point we need to start with a realistic sound pressure level (for example 90dB - 3dB = 87 dB). These coloured lines show how the different Qtc's look when plotted.
Now getting back to the Qtc of 0.707. While in theory this is best compromise for many a subbass requirement, sound quality inclined buffs often look for what is called a critically damped enclosure. These have a Qtc lower than 0.707 and hence have the smoothest and lowest rolloff. However this can also work against you because the lower the Qtc goes the more issues you can run into such as control loss or over run. Customers wanting louder subwoofer enclosures at the expense of a lower roll off (without resorting to porting for achieveing this phenomenon) tend to construct enclosures that have a higher Qtc than 0.707. In real world terms though; if you're not too sure then it's wise to trial a few different sized enclosures in your ride before you settle on the final design.
Note; image above is taken from CarStereo.com.
This discussion originated as a thread on MEA but we've had so many people converse with us about it that we've now transferred it here for preservation. Before we start I’ll offer a apology and disclaimer up front. The apology is for the length while the disclaimer is that this discussion is not an angry tirade, is not a whining grovel nor is it intended as fear mongering or attempted sensationalising. It’s simply a point of view put up for consideration. I could be totally off the mark here so considered feedback on my comments below is always appreciated. Without further ado; onto the discussion point:
For years we've been publically avoiding a discussion regarding the elephant in the corner of the room although we seem more than happy to grumble about it in private - the issue of why you (the consumer) should be buying local rather than taking your business overseas, especially when asking stores for unrealistic install pricing. I'll break this discussion into four separate parts. The first part will concentrate on what local stores require from you. The second part will concentrate on what stores are actually offering you, the third part concentrates on the possible negative consequences for yourself while the fourth part concentrates on the negative consequences for us (the industry) when you take your business overseas.
Part one - What your local stores require from you.
Part two - What your local stores are offering you.
So after reading through those lists you’ll hopefully appreciate that it can get a little despairing when people bring us boot full’s of equipment they’ve bought off online eBay stores and then ask us to put it in cheap or for free, all whilst expecting us to maintain a high standard.
Part three - What are the negative consequences for you if you’re not supporting the local industry?
Part four - What are the negative consequences for the industry itself if you’re not supporting it?
We’re constantly asked here by small car, sports car and ute owners if there is a solutions that can be implemented to provide decent bottom octave subbass without eating up a ton of space and costing a fortune. The short answer is yes - using components such as the Focal iBus20 and iBus2.1:
Delving a little deeper; we’re not talking about cracking 90-200Hz lower midbass frequencies like most slim-line subwoofers tend to output, but real deep impacting 30-80Hz bass that feels like you have a bass instrument thumping away right behind you. Double bass, cello, pipe organ, tuba, bass guitar, timpani, bassoon and the list goes on; these instruments simply cannot come to life with a lame slim-line subwoofer setup. So what makes the iBus units so different? Well the secret is in the design in that it doesn’t use a port to try and boost frequencies way below the F3 of the driver, nor does it utilise an adapted subwoofer with a minute excursion that cannot really handle any serious movement. Instead the driver is designed specifically to work with this strong alloy enclosure, from its edge wound voice coil design to it’s rather complex suspension system. Focal has really taken care to get the Qtc of the enclosure just right (it is around 0.71-0.73). This means it doesn’t boom at a certain higher frequency but rather rolls off smoothly and quite deep into subsonic territory. I won’t carry on too much about enclosure ‘Q’ here either suffice to say that it’s an important aspect to take into account when designing an enclosure. For those of you interested in more information regarding this topic, click here.
Getting back on topic; below we show you how we actually implement these units into small cars, sports car and utes. These are the most common applications they find themselves in and to undertake this task we simply make up a new stronger false floor to which the iBus can be bolted to upside down. You then just provide its amplifier (it’s an active enclosure) with power and signal and off you go. It comes with power cable, bass remote control and also has high level inputs so you can plug your existing speaker wires straight into it for signal.
Starting with boot installations, this is what they look like when installed in boots. We tend to make a new floor that allows the units to sit upside down within the factory tire. That way it doesn't impact any of the vehicles functionality at all.
Then there are the under seat installation. This scenario is most common is utes and in cars where maximum space required and it won't fit inside the spare tire (Japanese cars for example). Most of the time they simply sit under the seat but if extra bass energy is required we make a plate that can bolt down to the factory bolts, allowing the unit to transmit more kinetic energy to the passengers.
Next up is behind the seats. If you own a ute with low seats or two seat sports car such as a Lotus or Lamboghini, then one or two of these units can easily be mounted either behind or under the seats. We usually make up alloy brackets and a mounting plate to hold them in place.
Don't let's be limited though for if there is space, then we'll jam a subwoofer in there. With this mindset we've mounted them in even stranger places; everywhere from behind footwells where long sports cars tend to have a lot of feet space due to their length, to down behind boot side panels. If it will fit then why not?
Of course the important thing is the price; they're actually not that expensive at all. Click here for the information sheet from Focal or feel free to email us for more information and pricing.
So you've just installed all your new audio gear only to discover that whilst your system sounds wonderful, you cannot help but notice it looks just like everyone else's. Now you're faced with an interesting conundrum; with one option being that you could spend a titanic amount of money glassing, painting and chrome plating everything in sight. A more effective and professional looking option however is to instead add some personalised touches to your install using our CNC machine. Utilising this methodology you have the option of engraving or cutting various shapes, logos and other decorative pieces to suit your particular install. This'll not only render it highly individualised but in the process also allow you to highlight the various elements you wish to show off. Although the most common items we're asked to manufacture are metallic battery clamps and text plates, the reality is that if you can draw it we can CAD it and henceforth machine it for you.
Because the examples above are living in engine bays you'll find that the majority of these battery clamps, text plates and so on are nearly always constructed from metallic materials such as steel, alloy, stainless and even more exotic materials. However leaving the engine bay behind to travel to other areas of the vehicle; there are plenty of other objects and items you can make to give those larger boring panels a little decorative touch. Riser plates and logos are quite common:
In addition to the parts within the engine bay and decorations on flat surfaces, you'll actually find there are many areas of the car just screaming for a little more detail. Windows are one item which stand out and look a million bucks with just the addition of a simple (or complex) logo of image. The engraving is not just limited to text either - graphics and even LED back-lit three dimensional holographic-type engraving is also possible thanks to the mill's superbly accurate vertical axis.
Hell these parts don't even have to relate to your stereo. As stated above; realistically we can manufacture just about anything you want to customise. Be it a deck plaque, a bling'esq trinket, a drink holder or a set of wheel centre caps and inserts, if you can draw it we can manufacture it. So if you're keen to customise your car with a profession touch that isn't over the top, sitting there screaming 'somebody give me some more attention' then why not shoot us an email?
For those amongst you who are more the nuts and bolts engineering types, or if you're simply just interested in what the Fennec CNC machine looks like and how it manages to punch out all those complex and intricate shapes, we've prepared a small video clip of it knocking out a plaque for one of our jobs here recently.
When we install lighter crossovers, we don’t screw them down for a couple of reasons. The first of course is that it would be conducive to drilling holes in the car, which we refuse to do. Secondly; time and time again we find crossover PCB’s bent and broken because of being screwed down. Whilst some crossovers possess seriously robust cases; the reality is that most have flimsy cases, which love to bend and flex when screwed down. This in turn often lends itself to bending the PCB within and intermittent shorting henceforth as a result.
The foam liner shown above secures the crossover in position then we use a mat on the door trim itself to gently resist against the crossover when it’s in situ; thus stopping it from moving. This works every time for the aforesaid lighter crossovers. Now for the heavier units; we either weld up metal brackets to hold them in place else we install them elsewhere such as under a seat etc.
People sometimes seem perplexed when we recommend against using shallow subwoofers unless absolutely necessary, despite the fact we’re a dealer for many of them. Our reasoning has zero to do with build quality, nor does it pertain to the accuracy of the sound. Rather the problem pertains to ‘what’ frequencies of sound they happily and competently produce, and how the laws of physics influence this.
What is true subbass?
Rather than descending into a scintillatingly complex magnetic discussion full of references to Tesla, Weber, Halbach spheres and so on; let's instead keep our head above water and simply state that the densest flux of a magnet is located within a specific point. Therefore in order to keep the voice coil well controlled we need to keep it moving in close proximity to this point throughout its entire range of motion. In short; the further a cone moves the less controlled its output becomes. Not only because its moving away from the magnetic influence but also because the suspension, comprising of the spider below and the surround atop; also become less effective in combating these idiosyncrasies the further they stretch. In short this means the entire motor structure often succumbs to quite serious levels of axial and radial float during peak excursion periods.
The shallow conundrum.
I’m doomed to be forever without subbass then?
But they’ll be gutless right?
In conclusion yes; if you have the depth available then a single full size 10” or 12” subwoofer is a wonderful starting point for true subbass. However if you own a car where the available mounting depth is minimal then rather than compromise your subbass with a shallow subwoofer, why not look into multiple smaller subwoofer arrangement instead?
One small disclaimer; it's important to recognise that the spiel above is in reference to actual shallow subwoofer designs. We say this because companies will sometimes label certain subwoofers within their stable shallow simply because they are when compared to other full size ones. I.e. they're not shallow designs in the true sense of the term. For if you're alleged shallow subwoofer has a deeper motor than most full size ones then not only will it avoid the problems aforesaid; perhaps it ought to go by a different moniker too.
Note; images above have been borrowed from the Comsol website, permission pending.