this free e-book has been floating around the net for some time now. i thought it might help some of the noobs.
10 Big Bass Secrets
I have been asked probably just about every bass question in the book. I'm guessing you have questions too. Here I try to answer them. The crazy thing about bass, is that sometimes you hit, and sometimes you miss. I have seen many car stereo's that were put together with barely any knowledge, hit real hard. I've also seen a lot of money spent with poor results. This book will help you hit, every time. I write this book today because I want you to enjoy your stereo system without headaches. I want yours to be as good or better than the guy winning that competition. I want you to be able to help your friends with their systems and I want you to go into the car stereo store armed with knowledge. It has been almost 25 years since I was bit by the stereo bug and I have learned a lot since I was a kid. Here is some very important stuff that could take some time to discover. I've done it all, set cars on fire, blown amps, woofers, you name it. I've torn my moms car apart and put it back together rigged with speakers. I've won competitions, judged competitions, SQ and SPL alike. Having the biggest bass is more complex than buying the heaviest or largest subwoofer, more complex than buying the longest amp, or the one that says 5000 watts across it. It's more complicated than any one or two of these things. Now that you possess these 10 secrets, your chances of a loud, efficient, reliable and clean subwoofer system are greatly improved. Each of the ten chapters is designed to give you the competitive edge. These industry secrets are the tricks used by the pro's and utilized by manufactures to produce the loudest, most accurate, efficient and reliable systems of today. In no particular order of importance, here they are. #10. ORIENTATION AND PHASE A subwoofer system will create sound pressure. This actual air pressure needs to make it to your ears or microphone in an efficient manner. It will not make it there efficiently if you allow this pressure to escape, diffuse, or become out of phase. So, first lets look at your enclosure. Where are your woofers mounted? Secret: Place all the woofers and ports on the same plane for maximum output. Aim this plane rearward. This is the best way to get loud unless your subwoofers are on a wall, completely sealing them on all four walls of your car. Ok next, play with distance from rear of vehicle. You can change the output of your enclosure at different frequencies by playing with this. If you like flat response, your gonna want your enclosure most rearward with room for excursion. This setup is ideal because, it allows the pressure to find its way to your ears at about the same time. If your subwoofer enclosure had woofers on two different planes, the sound pressure would reach your ears at different times. Sound travels at a predetermined speed. If one of your woofers is further away from you its pressure will arrive at a different time creating a loss in pressure. Imagine a simultaneous punch in the chest from two pro boxers. That's woofers on the same plane. Imagine a left jab from a pro boxer as I pull you back, this is two or more woofers on different planes. The first woofer may actually reduce the impact of the second woofer and be weaker than one woofer alone. #9. POWER VS. CONE AREA Here I am giving away the secrets about amplifier power vs. size/number of woofers. This Chapter will be short and sweet. Here I will give you the secrets to help you decide to get more woofers or more amplifier power. Secret: Subwoofers are more efficient than amplifiers. This is quite funny as I am comparing apples to oranges, but you will understand in a moment. Woofers are more efficient than amps and this is why. When you double your amplifier power on a woofer, you will gain a maximum of 3 decibels. When you double your woofer count, you will gain 6 decibels. Why would I say a maximum of 3 decibels from a doubling of amp power? Because just because you feed a subwoofer more power, doesn't mean it can effectively turn it into sound. A subwoofer can only turn power into sound pressure in a linear fashion up to a point, where power compression sets in. This is caused by suspension resistance and loss of magnetic strength at extreme excursions. Contrarily, you will always gain 6 decibels by doubling your subwoofer count. Keep in mind, you will need to give every subwoofer its proper enclosure. You cannot simply add more woofers to existing enclosure volume. Here are examples of the formula... I have two twelves + 100 watts = 120 decibels I have four twelves + 100 watts = 126 decibels I have two twelves + 200 watts = 123 decibels I have four twelves + 200 watts = 129 decibels I have four twelves + 400 watts = 132 decibels So, what we have discovered is, if you have the space, add subwoofers instead of more amplifier power. #8. SUSTAINED VOLTAGE Amplifiers need Voltage. Good Voltage. Hopefully better than 12.6 volts DC. 12.6 volts is a typical automotive battery at rest. An automotive battery has 6 cells, each 2.1 volts, wired in a series. A charger with higher voltage is needed to charge this battery. The charger, in the form of an alternator, supplies the charging power, at 14.4 volts, and also power to your cars accessories when it is running. A typical alternator will provide at 65+ amps of current at 14.4 volts. This power is distributed to all of the power drawing components of your car. Your dome light, your computer, injectors, dash lights, headlights, power seats, heater fan and more. Some of these are constant and some are intermittent. Constant needs will reduce the available power available to your aftermarket stereo system. If your Alternator supplies 65 amps, and your cars constant needs are 45 amps, you have 20 amps available to feed your system. If you use this 20+ amps, there will be no power to keep your battery charged. If you use more than this available 20 amps, you will be stealing power from your battery and reducing your 14.4 volt running voltage to 12.6 volts and even lower depending on demand. If this goes on too long, your battery will deplete and may not start your car next time. Secret: To keep your whole electrical system happy with a high demand aftermarket stereo, you must upgrade your electrical charging and storage system. Look for a higher output alternator and battery with more storage capacity. Speaking of capacity, have you heard of a capacitor? It is a common misconception, that a capacitor is a magical device that creates and sustains voltage for your amplifier. The truth is, this capacitor feeds off of your supplied power and will affect your entire cars electrical system. Every single electrical component in your car will be affected by it. But what are the effects? A capacitor is merely a battery with the ability to charge and discharge at a rapid rate. This means, when your cars accessories demand a great amount of current in a hurry, your capacitor is there most willing to give it up. In this scenario, this is an advantage because, a capacitor will give up this power without causing a big system voltage drop. The capacitor will actually smooth the voltage of the system by charging when voltage is high and discharging when voltage is low. In the case of a high demand car stereo with capacitor or capacitors, instead of a great variance in system voltage caused by musical transients, the overall system voltage will be reduced determined by the capacity of the capacitors and the demands of the stereo. Wiring: The voltage and current provided by your cars electrical system need an efficient means of transport to your amplifiers. Thick wiring is the way. Follow your owners manual for recommendations. remember, the longer your wires, the thicker they should be. I've seen it a million times. A car stereo shop will install a huge car stereo system. They will upgrade batteries, capacitors, power wires and all. In the end, the headlight dim to the beat. Why??? They ask themselves. They implemented everything they could to keep this from happening. The customer hates it. He feels this is the sign of a ghetto system. Another big secret. Your vehicles electricity flows in a circle through your car. All that power makes its way to your amps with HUGE power wire but what about its return? It returns to your batteries ground by way of the sheet metal. This sheet metal is grounded to your negative terminal by this tiny little wire connected to your fender. Oh no. Our ground potential is limited by this little wire. Lets fix it! There are two ways to fix this. Leave it alone. Let your stock accessories use it for ground. Run ground wires, similar to your power wires, from your amps Negative terminal to your batteries Negative terminal. Or, keep using your cars sheet metal and upgrade that wire on your fender. I've seen it done both ways. In the end, your headlights and all of your cars stock accessories will be love you, and your big system will now be getting the ground potential it deserves. #7. ACTUAL AMPLIFIER OUTPUT Your woofers need to be getting all the power they deserve! I like to over power my subwoofers. Not to hurt them, but to use them to their potential. If you have a lot of power on hand, you can feed your subwoofers nice clean power, and they love it. A subwoofer is designed to reproduce a sine wave. A sine wave is a beautiful power signal created by an amplifier within its electrical capabilities. If you run an amplifier too hard, outside of its capabilities, That beautiful sine wave becomes clipped at its extremes, resembling a square wave, even more as it is overdriven. A square wave is easy to display on an oscilloscope, but impossible to accurately reproduce by a subwoofer. A subwoofer fed a square wave can only attempt to track this challenging signal and where it fails, heat is created. A square wave asks a subwoofer to stop and start on a dime, and to reproduce frequencies it wasn't designed for, all at the same time. This can be good for a quick burst in an SPL competition but bad for a listening session. Peak power vs. RMS. Here is a section I am excited to share. Secret. THERE IS NO SUCH THING AS PEAK POWER!!! Are you surprised? Like when you found out a woman is not born with all the eggs she will ever have? Like when you discovered there was no Santa Claus? So, as it turns out, "PEAK POWER" is code for "Exaggerated" and "Distorted". If you want your subwoofer to see 200 watts RMS, and 400 watts peak, you will need an amplifier that will put out 400 watts RMS. This is because if you buy a 200 watt amp, you will be feeding your subwoofer dirty, clipped power beyond 200 watts. Every amplifier is clean up to a point, at which distortion arrives. Clipped waves cause this distortion. Current limits cause the clipping. A quick (but non scientific) way of determining total amplifier output is to add up the fuse values and add a zero. This would tell me that if my amp has two 40 amp fuses, I can expect maybe 800 watts from a class D amp and maybe 30 percent less from a class AB amp. Class D amps are more efficient. Use this only when you can't test properly with a fully regulated power supply, multimeter, oscilloscope and tone generator. The power supply will ensure proper voltage. The Oscilloscope will ensure your wave is not clipped. The multimeter will measure output voltage across the load. The tone generator will provide the signal. It can be a device or a test tone CD. Play your tones into a speaker or load with your Multimeter across the output terminals. You can read the output with the VAC setting. Convert the voltage into watts by using the Ohm's formula, P=E^2/R. This means, Voltage X Voltage / resistance = watts. here is an example... 25 volts X 25 volts = 625 625(volts) / 2(ohms) = 312.5(watts) Our Subwoofer system has a resistance of 2 ohms, so 625 divided by two equals 312.5 watts. This is the perfect way to level match if you have one amp per woofer or one amp per set of woofers. Testing with dummy loads rather than subwoofers, is a more accurate way of finding maximum amplifier output. Subwoofers have a nominal (Varying) impedance or resistance, so your results could vary. #6. BRAND SELECTION Here's another Short and sweet chapter, but by no means unimportant. There are different types of car stereo manufacturers. Some are groups of investors, less interested in product engineering, and more interested in profit margins. Some are Audiophiles, truly concerned with the quality of their products, and there are companies everywhere in between. How can you differentiate? Secret: It probably takes a lot of experience to spot an investment outfit. Look for tech support with no clue. Look for a lot of chrome. Look for product that looks eerily similar to big name products. Look for almost naked women in their ads. When you buy from the big names, your going to get better engineering and expertise. This translates to better sounding products that last. When you buy from a group of investors, you get a flashy product that might not perform well, but for a great price! There is a small number of companies still making their stuff by hand. Your gonna pay a premium for this stuff but it should be worth it. Great tech support. Great products and your helping the little guys. I try to find USA made stuff but its just about impossible today. Buy from an authorized dealer! You won't understand the value of a warranty until you need it. Let me tell you, I just bought a $2000 dollar piano from the wrong seller. No warranty but a good price. This piano arrived broken. Selller won't help. I can't fix it. It will cost me more to have it repaired than a new one would have. I've learned that when you invest more than you can stand to give away, get a warranty or some kinda protection. Spend that 25% more, and in return, you will get good tech support and protection against defects. #5. WOOFER EFFICIENCY The output of your system is not just determined by that big 1000 watts logo on your subwoofers, or that super big amp. Some subwoofers are actually built to give you more bass in certain frequency ranges, and some just waste a lot of it. Using this information can help you build the best subwoofer system for your tastes. Secret: Some subwoofers are merely heaters!!! An awful trend has developed and the blood is on a lot of hands. Stereo consumers love to see huge numbers on amps and speakers. So the industry has obliged with massive subwoofers designed to create and dissipate heat, and amps with huge output or hugely exaggerated output. There is no regulation of car stereo specifications, only voluntary compliance, so a manufacturer can claim anything. The reality is, a subwoofer that might accept that huge 1000+ watts from your amp, but instead of producing a fair amount of sound pressure, it turns it into heat. It takes less engineering prowess to build a subwoofer with more copper in the voice coil and more venting, than it does to build it with extended excursion and low distortion. Early car subwoofers were derived from pro-sound woofers. These have low moving mass and high magnetic strength. This is the key to efficiency. Unfortunately, if you find a set of club speakers and put them in your car, expect the enclosure to be pretty big. This is not the key to super low bass. The key here is high magnetic strength, higher moving mass and extended excursion. A woofer diaphragm with more weight will have a lower resonant frequency and will produce low frequencies better. Now efficiency can be defined by what frequencies you desire. A 6 inch mid-bass will not be efficient at producing 40 hertz and a subwoofer will not be efficient at 5 thousand hertz. So when you think about efficiency, think about how much output you will get in the range you desire. High moving mass = efficient at low frequencies. Low moving mass = efficiency at high frequencies. #4. ENCLOSURE EFFICIENCY How do those competition cars hit such high numbers with only one woofer? Most of the answer lies in the box design. You CAN add over 10 decibels of output with these methods. Subwoofer box efficiency comes from a few things. Secret: Tuning frequency Finding the best tuning frequency for your competition enclosure takes a lot of work. First you have to plot your cabin gain. How much gain does the interior of your add to low frequencies? How much gain does your subwoofer enclosure give you? Sum the gain from the car and the box looking for the frequency with the biggest numbers and you have it. Port size Subwoofers love to load with their environment and their ports, which in turn load with the environment. The best way for a woofer too see its port is by making it big. Sounds like common sense right. When you increase the surface area of your port, you increase the efficiency of your enclosure. Having a small port is like asking a small woofer to cycle at many inches of excursion. This makes for unhappy woofers as well as unhappy ports. This is why there are big woofers. They are more efficient and need to throw a fraction of the distance. When you make a port as big as you can, you are increasing its capacity to move air. more air means more pressure. Keep in mind, larger ports can get really long. Similar to porting and polishing an intake for a car, make sure your port walls are smooth. And here's two more efficiency secrets. Port bends decrease enclosure efficiency. If you must bend, make them smooth. Also, port width to height ratio should be close. this means a 6 inches wide and six inches tall (square) opening is ideal compared to a 3 x 12. Same surface area but much more port wall surface area decreases efficiency. The most efficient port will be round, as big as you can make it, Enclosure size Why do club speakers kick so hard? Why does my woofers manual say to put it in a small 1 cubic foot enclosure? Secret: Big enclosure, Big output. As previously mentioned, early car subwoofers were pro-sound drivers. Enclosures were huge, and so was efficiency. Your car woofer might only need 1 cubic foot to perform says the manufacturer, because they figure space is at a premium. A car is significantly smaller than a club where enclosure size is rarely a consideration. At a certain box volume, a subwoofer enclosure will begin to exhibit a high q. This means that its output will begin to raise in a narrow band of frequencies at its box resonance, as box volume raises. Let's say your subwoofer system response is flat in 3 feet ported. If you jump to 4 feet and keep the same subwoofer and tuning, you will begin adding gain, like I said, in a narrow band at the box resonance. This is called �€ï¿½boomy�€ï¿½ by some, and is undesirable for sq, but perfect for spl. Up to a point, increasing enclosure volume will increase but narrow this band of frequencies until it matches box tuning frequency. You can dial in as little or as much gain as you want up to a point. I have seen designs with over 15 decibels of gain!!! Playing with enclosure modeling software, you can find the perfect enclosure volume / gain ratio. . #3. ENCLOSURE CONSTRUCTION What should I build it out of? Does shape matter? The construction of your enclosure is as important as subwoofer selection, amplifier selection and everything else. Secret: Port placement (previously discussed and elaborated) Can I place my ports anywhere? Lets explore this one plane idea further. I suggested that your woofers and ports all be there. Why? Because of phase. Because a port is an addition to the radiating surface of your woofers. Porting an enclosure is like adding another small woofer. You want all your bass notes to reach your ears at the same time right? It doesn't matter if it comes from ports or actual woofers, this sound pressure needs to be in timing/phase or it will not provide proper impact. As it turns out, you can only achieve proper port function if it is on the same plane as the woofer because they work together. Placing the port and woofer on different planes reduces their coupling, always reducing output and or accuracy. Never run ports through your rear deck or rear seats unless you have a single-reflex bandpass. Ports should be at least its diameter from the rear wall and sides of box, no bends, very smooth and with flared ends. This section is as good as gold. USE THIS INFO!!! Enclosure seal A subwoofer system can create plenty of pressure, and if it is lost through a leaky enclosure, your output will suffer. Your woofers output needs to radiate from two places, the woofers cone, and the tuned port. A tuned port will increase output within a given range of frequencies, but a hole in the enclosure acts like a high pass filter, at a very high frequency, eliminating your bass! Enclosure rigidity A subwoofer can be a powerful device. In an enclosure, it pressurizes and rarifies air. This can be compromised by a flimsy enclosure. A subwoofer system needs to be rigid so that the sound pressure it creates is not undermined by changing enclosure volumes. Build your enclosure out of the thickest wood you can. 3/4 inch particleboard is usually a good starting point. MDF will be a little stronger and damped but will be prone to water damage. 1 inch wood is expensive but could be your best choice for a real competition system. In either case, here are some construction secrets. Never make any length more than double any other length. Woofers don't like this Never make your enclosure perfectly square. Subwoofers don't like this either. It can cause undesirable variations in your frequency response. Brace your walls. Add a 2x4or a slice of your sheet across the two largest panels. We don't want these large panels to flex. Pre-drill holes and countersink. If you pre-drill your screw holes, there will be a minimal chance of splitting the wood. Particleboard is susceptible to this but MDF even moreso. Countersink your screw heads to make a nice clean finish that will accept upholstering much nicer. Screws should be spaced about 10 inches apart for good strength. Adhesives. I like to use a good construction adhesive for my enclosures. The great thing about these ugly brown tubes is that they add strength, even stronger than the wood itself, plus they seal the box as they glue. Spread a bead across all joints after you have drilled holes and countersinks. Don't miss a spot or your box will leak air. Alternatively, You can use wood glue and this is common but you will need to run a bead of pure silicone inside the box on all seams. This method requires a little more work and will not be as strong. The difference between construction adhesive and wood glue is how hard it dries. Wood glue dries so hard it will snap under pressure. Construction adhesive will not. Sealant. I'm not talking about silicone this time. I'm talking about making your Enclosure waterproof. This will extend the life of your enclosure exponentially. Particleboard and especially MDF don't like water. MDF is actually a paper product. Both of these will swell and disintegrate if exposed. I always paint mine. Ask your local home store paint department what they have that's waterproof. Buy whats in your budget. You will probably be covering your enclosure with carpet or vinyl anyway, so color is of no importance. You can use a clear water seal, or even a paint or primer. A premium method of sealing your enclosure that will be cosmetic at the same time is bed-liner. You can pick some up at the auto parts store or you can have it professionally done. The results from the pro's will be much nicer looking but both do a great job of sealing and protecting your enclosure. Screws I use 1.5 inch black coarse thread drywall screws for my enclosures when I use 3/4 inch wood. This assures the perfect grab on both pieces. The finish on the black screws assures they won't come loose. They are strong, economical, and easy to find. Your subwoofer might require something more serious. I will usually make the face of my enclosure double thick and use extra long and thick screws. Don't forget to pre-drill holes for your screws that are just smaller than the diameter of your screws minus the threads. This will hold a heavy subwoofer. If you can, find some bolts and spiked T-nuts. This is a serious approach for the most demanding applications. #2. USING DAMPING MATERIAL (POLYESTER / WOOL / FIBERGLASS) What is this polyester (or other) filling and what is it supposed to do? Why have I seen it in Professionally built enclosures? Can it really make my subwoofer enclosure effectively bigger? Polyester fill comes from the arts and crafts and pillow manufacturing world. It is used to make stuffed dolls and fake snow. It is claimed to effectively make a speaker enclosure seem up to about 30% larger. It will supposedly take a system with a high q (above .7) and reduce it. This is exactly what would happen if you made the enclosure bigger. So, add polyester fill and reduce Q, and similarly, add enclosure volume and reduce Q. Additionally, this fill can reduce in box reflections and make your sub sytem sound cleaner. Guess what people? As it turns out, what we once thought was a great way to effectively increase box size, is really A GREAT WAY TO EFFECTIVELY DECREASE WOOFER SIZE!!! What this fill is actually doing is taking our boomy box response and flattening it. Our low bass output is already reduced because the box is too small. We add some fill, and boom, now we've also reduced our upper bass to make it flat. We have now reduced our woofers total output potential by several db's!!! The exact same effect as using a smaller woofer!!! Secret: Don't add fill to your enclosure because its too small. Save the expense of a bigger amplifier, fill, and the price of that large woofer. Buy a woofer one size down and give it the space it deserves. This will make for a happy woofer, a less complicated build and be less expensive. Additionally, if you are concerned about reflections, do what I do. Grab yourself a new or used piece of convoluted egg-crate style foam mattress pad. Apply it on three inside walls with spray glue, so that no two facing walls are uncovered. Throw a few staples in the edges. This is the perfect way to add a little extra accuracy to your subwoofer system.
#1. SYSTEM MAINTAINENCE / LISTENING Your subwoofer system, if properly maintained, can last many years. This chapter Shows you ways to keep your system in tip-top shape. Audio equipment always has a desired operating temperature range. You can usually find specifics in your products owners manual. Typically, a car amp will work in temperatures below freezing, and up to 125 degrees plus. A car amplifier will have protection against overheating by way of a thermally activated internal switch attached to its aluminum case. An overdriven or underfed amplifier will overheat easily. Keep your amps cool and unobstructed. Your woofers doubtfully have any such protection. This means you might overheat your woofers and cause them to fail without warning. What causes woofers to fail? Well, not just heat, but cold too. A subwoofer with a synthetic rubber surround can fail in extreme cold. Below 32 degrees, the soft rubber surround on your woofer will turn hard like plastic, and when driven with enough power, will crack into pieces. This is also true with foam surrounds. Treated cloth surrounds, although rare in car audio are less affected by temperatures. Secret: Turn the volume up gradually, over several minutes in cold weather. All of your equipment will thank you and your woofer surrounds will have time to heat and soften by way of internal friction. Check connections. As you drive, any number of connections can vibrate loose. It is a good idea to go over your system checking for this every once in a while. A bad connection can cause low voltage, amp failure, burnt and melted fuseholders and more. Check your battery. A bad battery can cause fouled battery terminals. This corrosion, if left to spread can get in between your battery terminals and your battery posts causing a bad connection. Keep these connections clean with a solution of water mixed with baking soda and cover connections with a corrosion preventing spray available at your neighborhood auto parts store. If corrosion is a persistent issue, replace your battery, maybe even with a sealed, maintenance free model. Check for corrosion on your amp terminals and wires. If you find white/green dust on any of your connections, you have corrosion. This corrosion can creep its way through an entire length of power cable reducing its effective ability to supply current. This is usually caused by wet carpet, cheap cables or a bad connection. Treat your system right. This is important advice. Heat kills subwoofers. Heat rises with time. This means, you can play your system quite loud for a short burst without harming it electrically, but if you play your system for extended periods of time, heat rises, and glue starts to burn and melt. These adhesives hold your woofers parts together, specifically the voice coil wire. If this long, thin, spun coil of metal falls apart, your subwoofer has failed. It is now blown. This means, take a break every few minutes of loud playing. Give your system a chance to cool down. Keep in mind, your subwoofer is not only an electrical device but also a mechanical one. This means overpowering can not only cause it to blow, but also to rip apart at any number of places. Most typically, the voice coil will smack the back plate and destroy it. Also, the woofer cone may come detached from the voice coil former and often times, the spider will rip apart from the coil, cone apex. Be aware of noises coming from your subwoofer system other than bass!!! This brings me to the best maintenance tip. Effective listening. This means listening to music and distortion. We all know what music is, although your parents probably would argue your views. But lets explore distortion, what it is and how to hear it. This sounds a bit ludicrous but the truth is, there are several types of distortion. You may not even know your system is distorting because of your limited understanding of the definition of distortion. Distortion in music is defined as sound reproduced with flaws. This could be a tonality difference. This could be a change in dynamics. This could also be a change in harmonics. Distortion as you probably know it is the harmonic type. This is a great sign of a subwoofer system under stress but before this becomes apparent, there is another clue. As mentioned before, a change in dynamics is distortion. Listen at low volumes and notice the volume difference between loud and soft notes. When you push your system to its limits, this ratio will change and soft bass will become similarly loud as the loud notes. This is a sign of compression. The same effect they use on studio vocals so you can hear every detail. You too, are trying to hear every bass detail but you are stressing your system pushing it to failure. No amp likes to clip, and no woofer likes compression. This compression causes a lot of heat. Heat kills Speakers. Tonality Distortion. Your favorite CD was created with a specific tonality in mind. This sound is the vision of the artists and recording engineers. Your goal is to play back this recording as they intended it to sound. This is part of their artistry, just like the notes they strum on their guitars. Of course you are free to adjust the tonality as you wish with your EQ, but in reality this is distortion. Although nearly impossible, especially in a car, recreating the recording as it was intended to be heard is a beautiful thing. Harmonic distortion. This is the best and the worst distortion at the same time. Have you ever heard of Vacuum Tubes? These are classic amplification devices that when over-driven, add desirable harmonics to your sound. On the contrary, not all harmonics are desirable. The harmonics created by a clipping amplifier or woofer cone break-up. This hard to listen to. The best way to keep undesirable harmonics from your system, is to overbuild your system, with great quality products. You will hear this distortion as an addition to the sound you already hearing. If your speakers start to make ugly additions to your music, you are most likely experiencing harmonic distortion and this is a good sign to turn the volume down. System detailing. To keep your system beautiful and ready for showing, you'll want to follow your manufacturers suggestions for cleaning. Of course never use harsh or abrasive cleaners. Because this is a book of "secrets", I'll give you a personal secret I don't share. I use furniture polish in the yellow spray can to make my plastic cone and rubber surround woofers shine beautifully. Its not as greasy and shiny as dash spray. Looks perfect, is supposed to have anti-dust properties plus it smells lemon fresh, my favorite flavor. Check with your woofer manufacturer to see if this would void your warranty. Never use paper towels on your equipment because they leave paper behind especially on rough woofer cones. Some rough paper woofer cones are especially hard to clean. I've found what works best is a small hand towel dusting. Keep some cotton swabs and microfiber cloths handy to detail your amps. I have never used more than a nice cloth to clean my amps. If you do this often and treat them right you will never have to use a cleaner. }
Good read, don't know if I will agree 100% with all it says but most of it is valuable infos. Very rare useful post on here in a long time.. thanks for sharing!
I glanced at it and the first bit I read was incorrect, in regards to power vs volume. double the power is +3dB, but going from 1 sub to two subs, and splitting the power between the two subs that went to the single sub originally, will also yield a gain of +3dB. You only get +6dB from twice the subs and equal power per sub that you had per sub prior to the increase in number of drivers. In other words, double the subs and double the power both.
After seeing that bit, I didn't really read the rest.
Actually, having read more of it, the author has made a number of mistakes, and made a number of things more complicated than they need to be, such as point sourcing, and time delay, and environmental efficiency, cabin gain, and transfer function.
This appears to have been written by someone without a firm grasp of engineering in both the electrical and acoustic fields.