El Duderino's Ten basics of Car Audio

(a rough version of this was posted long ago to answer a noob question. I have re-written it and since that post has received some nice feedback, I post it for noobs everywhere...: )

After years of explaining audio to noobs in stores, on the Internet, and over the phone, I’ve compiled my Ten Basics – things that every car audio enthusiast needs to know. If you know these core principles, they will help you design better systems, buy better products, and give better advice.

1) How our ears work:
Our eardrums detect changes in air pressure – that’s their job. The "audible range" – the range of air-pressure changes that our eardrums can hear - is from 20 air-pressure changes per second all the way up to 20,000 air pressure changes per second. (But most of us can’t really hear that high a note, especially if we go to a lot of rock concerts.)

Each air pressure change is called a "cycle". The term "cycles per second", like lots of scientific terms, is named after a dead guy, in this case a guy named Hertz who was an early radio pioneer. It’s abbreviated Hz. With a “k” in front of it, it means kilo-Hertz, or 1000 Hertz.

So “20Hz to 20kHz”, in car audio terms, means 20 air-pressure changes per second to 20,000 changes per second.

The audible range is carved up into the following rough sections:

Bass - 20 Hz to 300 Hz (Note: Sub-bass is 50 Hz and down, mid-bass 50 to 300)

Midrange - 300 Hz to 3000 Hz

Treble - 3000 Hz to 20K Hz

By the way, the only musical instruments that can play down to 20 Hz or so are huge pipe organs and electronic synths.


2) We can best tell what direction a sound came from when it’s in front of us. Our ears are tilted and shaped forwards. So, if we want to hear what direction a sound came from, we have to turn towards the sound. This becomes important later…


3) We don't hear the direction low notes come from. At some point, we still hear the sound, but not where it's coming from. While some folks used to think that this starts around 300 Hz, I personally think it's below 100 Hz.

This is why we can stick subs in the trunk - because our ears don't know where true sub-bass is coming from.

4) We don't hear all notes the same way. For instance, it's useful to know what an "octave" is. Without going into the acoustic and musical backstory here, you need to know this: an octave is a doubling of a note or halving a note.

Let's start at 40 Hz. One octave up is 80 Hz. One octave down is 20 Hz.

The difference between 20 and 40 Hz is just as big to our ears as the difference between 40 and 80. But the difference between 1000 Hz and 1020 Hz is far, far less noticeable. Why? Because our ears are sensitive to differences in percentage.

The difference between 16,000 Hz and 20,000 Hz may seem like a lot, but it's not - it's less than half an octave. FM Radio can only play up to 15,000 Hz….but it can still sound really good.


5) "Stereo" is not a different word for "radio". Stereo sound can be defined as a system of recording sound, and then playing it back, that uses two channels (Left and Right), to preserve directional cues that the human ear uses to determine where a sound came from. The illusion that can be created by good stereo recording and playback is called the stereo "image".

Here’s the best way to understand what this “image” is, if you’ve never heard one:

Imagine listening to a recording of a three-piece rock band – a lead guitarist, a drummer, and a bass player. If you can close your eyes while listening, and you can tell where the vocalist was standing, and where the drum kit was set up, and where the bass player was standing when they joined in on the backup vocals, then you’ve got a stereo image.

If you close your eyes and hear all the sounds coming from a point in between the two speakers, or you hear sounds from the left or right sides but nothing in the middle, you don’t have a good stereo image. A bad stereo image could be due to the recording, or the speaker setup, or many other causes.

If you go into a real high-end home stereo store, and tell the salesperson that you're not going to buy anything, but you've never heard a real great home hi-fidelity stereo, and could he play one for you, they usually are happy to do so. Close your eyes and listen to where the different instruments seem to be, and where the vocalist is, etc.


It's worth noting that “mono” sound (single-channel audio - usually L and R channels summed together) doesn't necessarily sound "bad" -it just doesn't have any left-right stereo "image". Some people assume that all Mono must sound tinny and harsh, because that’s how AM Radio usually sounds compared to FM radio. In truth, FM Radio sounds different because it has a wider frequency response – it can play both higher and lower notes – than AM does.


6) Our minds fool us - sometimes. The science of how our minds interpret the sounds we hear is called psychoacoustics. These scientists have determined that if we are listening to a good set of front speakers, and those midranges play convincing, real-sounding mid-bass (50 to 300, remember?), then our minds assume that the low notes must be coming from up front too.

To put it in musical terms, if the snare drums are up front and sound real, and the kick drum sounds real, we'll THINK it's also up front.

On the other hand, if we hear the snares in the front and the back, then our ears and our minds are not fooled. This is why some of us are very much against rear-mounted mids and tweets. They are effective at making a system play louder - the more speakers and the more cone area your speaker system has, the louder it can play - but they can ruin the stereo illusion some of us are trying to create.



7) Watts matter, but maybe not in the way you think.

Watt – another dead guy! (James Watt invented various types of steam engines). In the stereo world, when we talk about “watts” we are talking about amplifier “power”. This is not how scientists use the terms, but let’s just go with it for now.

First, speakers don't have watts, they handle watts. “100-watt” speakers may not be any louder, or sound any better, than “50-watt” speakers. Some speaker manufacturers print a suspiciously large “power rating” on the box – like “200 Watts” on a pair of 6” coaxials!. Then when you read the fine print, this is a “peak” power rating, meaning that when you are driving downhill, and the planets are all aligned, and lightning hits your antenna, these speakers will handle 200 Watts – for about fifty milliseconds. There’s usually a “nominal” or “RMS” power rating too… and it’s around 35- 50 watts for those “200 watt” speakers. Just remember that a speaker’s power handling ability is not related at all to how loud it will get or how good it will sound.

Second, remember that some amp makers overrate their amps, and some underrate them. The new CEA guidelines for amp ratings will help this situation, but you will still find expensive amps that will seem underpowered on a watt-per-dollar basis – and cheap amps that seem to good to be true.


8) Volume and decibels (dB). If you didn't study logarithms in school, dBs, or decibels, won't make much sense to you. It’s a complicated way of mathematically comparing large differences. Again, it’s named after a dead guy – in this case, Alexander Graham Bell, the inventor of the telephone.

Let's just stipulate the following:

Acoustically, three decibels (or dB) is the smallest difference in volume that you can hear as a difference in volume. Smaller differences in volume are still audible, but we hear them as changes in the sound quality - not as the sound getting louder or softer. That's just how our ears work.

Ten dB louder sounds twice as loud. Ten dB quieter sounds half as loud.

Say you have two speakers in your car driven by a 100-watt amp, and you want it to be louder. You go out and buy a 200-watt amp and replace your 100-watt amp. Guess how much louder your system will be?

Not much – only three dB louder.

More power gives you lower distortion and better sound - but buying bigger amps is NOT a good way to get louder.

So what if you got two more of the same speakers, for a total of four, and you still put that same 100 watts into those speakers, guess how much louder your system gets?

Again, not much – again, only three dB.

If you are looking to get louder, it's worth noting that when you add speakers to an amp, you lower the impedance it sees, and most good amps then try to put more power into that load - many put out twice as much. So if you get twice as many speakers, for three dB more output, and then your amp doubles its power for another three dB of output, you get a total of six dB more - and that's noticeable!

This means that usually the best way to get louder is to get more speakers, not just bigger amps.


9) How speakers work:
When music is played, there are air pressure changes in the room - that's what everyone's ears are listening to. When you play recorded music, the speaker's job is to generate the same air pressure changes that were originally recorded.

OK, stick with me here...

Think about a pie plate magically floating in space. Now think about a pie plate with an empty toilet paper tube glued to the bottom, like a handle. Take a skinny long piece of copper wire and wrap it on the tube in a spiral, unitl you just have the two ends hanging off of it for 3 inches or so.

Got this picture in your head? Good.

Now think of a huge magnetic doughnut floating in space too. The donut hole is like 3 inches across, and the doughnut itself is like 6 inches across. You can't see it, but because this is a magnetic doughnut, theres an invisible magnetic field inside the doughnut hole.

Now you lower the toilet paper roll into the doughnut hole. The two ends of wire are sticking out.

Now you take these two pieces of wire and you touch them to the terminals of a nine-volt battery. You can't see it, but the coil of wire generates a magnetic field every time you touch the battery terminals to the two wire ends. You notice that using (+) and (-) makes the speaker cone (I mean the pie plate) pop OUTWARDS, and the other way, (-) and (+), makes it pop INWARDS.

Now if you could sit there and reverse the (+) and (-) from the battery fast enough, you could play music. If you could do it 42 times per second, you could play the lowest note a bass guitar can play, for example.

Now you know how a speaker motor works (and how an amplifier works too - a tiny guy inside with a nine-volt battery!) A real speaker doesn't float in space - it has a frame, and a "suspension" which holds the pie plate and the tube (called a voice coil) centered in the magnetic doughnut hole (called a voice coil gap).


It turns out that there are no speakers that can generate 40 Hz, 400 Hz, and 4000 Hz accurately. The differences in speed and response time are too great. This is why we have woofers, mids, and tweeters. (The Japanese don't call midranges midranges - they call them honkers.) We need small speakers for the fast changes, and bigger speakers for the slow changes.

You’ve seen woofers moving as they play. Ever see a tweeter move while it's playing? No. The movements are too small. Again, it's because our ears are more sensitive to some notes than others.


10) The three reasons speakers blow up:
A) The motor-winding wire assembly inside melts due to too much electricity being sent through it. If the skinny copper wire melts, or the glue holding it on the tube melts, the effect is the same – poof, no more voice coil.

This is the power limit that the power rating on the box is supposed to refer to. Truthfully, it’s also the rarest way to blow up a speaker. Amplifiers big enough to melt a speaker this way cost a lot of money.

B) The speaker is asked to play low notes it shouldn't be playing. In trying, the speaker travels farther than it is designed to, and then it physically rips apart.

The causes of this are incorrect crossover setup or putting a woofer in the wrong box. This one’s a lot more common… it can be caused by poor system design, poor installation, or simply by not reading the woofer’s installation manual.

C) The speaker is sent distorted signals, which it can't play, but which end up melting the motor assembly or causing the speaker to rip apart. This is usually caused by the amp “clipping”, or running out of power.

It's easier to blow up a speaker with a small amp than a big amp. This may seem backwards - but the simplest analogy is, if you ask a 40-watt amp to play 80 watts, you will get 40 watts of music and 40 watts of distortion, and distortion blows speakers faster than anything. It's a bit more complicated than that, but as an analogy, it's workable.


Well, those were my Ten Basics of Car Audio. Read them, learn them, live them, and you can learn anything you need to about good sound in your car.

 

amazng work

 

Great Post!

 

 

You da man Eld!!!

 

Good stuff.

Now I'm hungry, but can't decide on pie or doughnuts...

 

Great stuff. I love reading this sort of thing, even if it's repeated, because there's always a way that someone can explain something so that it's easily understood.

There are parts of car audio that still baffle me (no pun intended), but learning is half the fun.

 

Great post! Thanks for all the info.

This might be a good sticky..

 

Make it a sticky - The Stickiest of the Icky

 

Another great post and congrats on breaking 1000 posts!

 

Great post!

#10 reminds me of my favorite thing to say to audio-noobs that they rarely believe until I explain it (and sometimes still argue). I tell them you can't blow a speaker by overpowering it, but you can blow it by under-powering it.

Of course we know this is not technically true, but in practice it is. When you have too much power, as you increase the volume, you will hear audible distortion before any damage occurs. So unless you listen for an extended time to distorted sound (which would be really silly) you're fine.

But with too little power, as you increase the volume, once the amp starts clipping you could lose a speaker in a fraction of a second if the distorted signal spikes bad enough (the crappier the amp, the more likely this is).

 

Actually i dont agree with 10-C whjat youi wrote is not true by any means and infortunatly because of uneducated sales people the general public has been in the dark for a long time on that subject.

the only reason people say you can blow up a speaker with less watts is because it is common practice for inexperienced people to use the gain control on an amp as a volume knob. they turn it up and cause the amp to clip under higher volume settings. therefore having a smaller amp than you should have on a sub has made people to belive that this is factual.
however the very same people that over gain a small amp will do the excact same thing to a larger amp. and i guarentee you that clipping a large amp will blow a speaker way more easy then a small amp will. simple physics shows this.

 

Well, then, BM, I guess we agree to disagree.

Maybe you can tell us how retail customers blow up "200-watt" door speakers using a 12-watt RMS, 25-wpc peak "high-power" head unit with no gain control at all to jack with.

 

many many factors, firstly the 200 watt rating as you yourself stated is probly bogus advertisment.
second how do you know the speaker didnt quit working due to water, dirt or anything of an outside nature were to get into the motor assembly. a door of a car im sure you already know is not sealed and is subject to these contaminents.

how do you know the consumer was not just unhappy with the speakers and blew them up by connecting a car battery to them to get warranty replacement?

why is it with you that everytime someone disagrees with what you say you get all pissy? cant you just admidt your wrong once in a while?
is it because your the "VP of electricity?" LMAO!!!
ill give credit where it's due. most of what you wrote was very good info , very informative and mostly accurate.
why do you get all defensive and demand an explanation? how about with your infinite knowledge of electronics explain with some real physics what causes a speaker to blow up?

first of all there are 2 main reasons speakers fail. you hit both of them
1 temperature
and 2 physical damage due to over excursion.
to make an assumption that speakers usually fail because of mechanical failure is laughable. as well as to say they always fail from thermal reasons.
every speaker has it's limitations i guarentee you i could make any speaker fail if i put it in the wrong application than the design calls for.
but to make a blanket statement that most speakers will fail by running too small of an amp is a flat out falsehood.
if you take a 25 watt amp and a 200 watt amp neither of wich has gains that are adjusted high enough to clip the signal going to a 75 watt sub i guarentee you that the 200 watt amp will smoke the sub a lot easier than a 25 watt amp will.
what you would have everyone belive is that to over power a sub is actually better for it. unfortunatly you like many fall victom to the falshoods sales people tell consumers to buy a larger amo than needed. why do they do this? it's simple a larger amp produces bigger commissions than a smaller amp will.
if you can convince your customer he needs to part with more of his money and he belives more is always better its an easy sale and makes bigger commissions.
the really really sad thing about the whole thing is just like a lot of things in the caraudio industry. if enough people belive the same crap and the same lies get told to enough people that are supposed to be "professionls" in the business it spreads like a disease. sooner or later everyone begins to belive it must be true because everyone else says so. unless someone sheds a little logic on it everyone else goes around beliving a bunch of rumors.
Just look at the evolution of Preamp cables.
for years people have been buying into the fancy, thick, twisted pair, oxygen free, triple shielded, gold plated, harmonically balanced oh and my favorite directional cables that sound best when signal is passed in a particular direction.
they cost like 80 bucks a cable give me a F****** break!
truth is in car audio buy with their EYES not their EARS they buy Caraudio Jewelery they dont buy what WORKS they buy what SELLS!
as with anything bigger magnets, bigger amps, aluminum cones is what sells. your already a victom yourself.
all the tings you said about the acura TSX speakers to down play them tells me what you dont actually know about speakers.
sure they have cheap light weight cones and flimsy cloth surrounds and Noe magnets.
if people realised that because of the lightweight cone and surround material and since Neodimimum magnets are approximatly 8 times more powerfull than conventional ceramic magnets they would know that a speaker of this type of construction is far more efficient and playes a much greater range of freqencies then after market speakers do. also since neo magnets are so much more powerfull in that they have more flux density they dont have to be anywhere the size of ceramic magnets to do the same job. and they are actually belive it or not less expensive.
why dont you see them used on many aftermarket speakers? because small magnets are like small penises, people don't like the looks of them and they dont sell too good.

how about rather than explain to you why i am right and your wrong how about you explain your theroy rather than just post it up and expect people to belive you. dont make me call you out again and prove you wrong. the first time we got into one of these discussions it took about a week and you never did agree you were wrong. in fact you went to someone who you felt was more knowledgable than you for advise and came in here telling me "i told you so" with nothing technical to back it up.
yes in general your knowledge on caraudio is very helpfull here but what gets me is that your so sure your 100% correct about everything you say when in fact your sometimes wrong. it burns my ass when i see somone giving false information to the unsuspecting audience of this board and watch they get brainwashed into beliveing that you are in fact the "VP of electricity" whatever the hell thats supposed to mean.
i guess you get some big jolly off of having everyone tell you how smart you are. give me a flipping break!
yea your smart on electronics ill give you that. but you dont know it all yet! i guarentee you could learn a lot from myself. the difference is i dont go around trying to convince everyone how smart i actually am on this board . i let them find out for themselves. i also dont have the time to sit and type out everything i see you post thats wrong. nor do i have the time to visit this board every single day.
so before you try to call me out make sure you have logic to back up your theries.

you will find in the future i will school ya everytime you try it.

 

my dad can beat up your dad.

 

that might be true since mine is surviving cancer

 

My comment wasn't directed at anyone in particular, but best of luck to your dad.

 

Yeah, best of luck to your father, BM.

My father passed away in 2000 due to the same form of cancer the Chief Justice probably has. Died on Thanksgiving day.

BM, a couple of things. First of all, your posts are damned hard to read. I know people who are not experts at typing or grammer, and they tend to compose on Word before uploading to a forum or an email, so they get the app's help in being more understandable. The whole point in posting is to communicate.

It seems that you want people to be impressed with the fact that you used to order speakers from a supplier, put them in boxes with an amp, and thereby became a manufacturer. Before that, you were a bench tech and an installer. You start almost every post by telling the readers how experienced you are, but you end some of them by trying to sell them something of yours (Power Mouses, remote start alarms, etc.). I think that that is bad form, honestly.

As far as your disagreements on this issue, I think you're wrong, I think you have some kind of grudge against salesmen and against car audio customers which has nothing to do with this thread, and you seem to have a big chip on your shoulder about how much you know. I've said many times, my experience means nothing on an issue - if I'm wrong, I'm wrong. I'm not a physicist, and neither are you, so challenging people for some "geek duel" is pretty funny.

You've posted your explanation of how 200 W speakers plow up on head units, which is what I asked for. Now people can decide what the agree with. That's enough.

Maybe instead of just trying to pick holes in other people's statements, you can compose your own Audio FAQ post, and then people will know more than they do now, and make better decisions, and be happier. Seems a better way to spend time that deciding who knows more, 'cause when we're both dead, no one will care.

 

ok the majority of this im going to ignore because honestly i dont feel up to it at the moment. however i will say for your bennifit that you know nothing of what my background is if that is all you think.
i didnt buy subwoofers from someone and stick them in boxes and sell them.
i designed a sub enclosure that did what no other manufacturered sub enclosure ever did. and i needed a speciffic type of sub to make it all work. for that i enlisted the services of a sub manufacturer who has the materials and equipment to build the subwoofers for me on a mass scale. if you know anything about manufacturers you would know that 99% of all subwoofers are made this way. do you actually think that Alpine, Kenwood, sony, pioneer, rockford, kicker, orion, PPI, hifonics (you get the idea) actually have people employed and build their speakers in house? HA HA HA!!! thats a good one!!! no they have another manufacturer make them to their specs. why? because unless you have millions of dollars to spend to build just your own speakers its far less expensive to have a speaker house make them to your design specifications.

and as for my power mouse.. again you have opened your mouth about somthing you
1. dont know anything about
2. have never seen or heard
3. done have enough understanding of what it actually is to make ano coment about it.
and also for your Info im not building them anymore. i happend to have 1 left that i sold to a guy on this board because i thought it might be exactly what he was looking for and i thought it might be nice to see one in a TSX

and as for the alarm i offered a suggestion and my personal opinion as you do on many of your posts. i just happen to still have connections with wholesalers all over the west coast i still communicate with. and i also happen to be able to buy pretty much any name brand for wholesale. therefore i happen to have some stock left over in my garage. if i was tryuing to sell any of it be it my own stuff or overstock i would be posting pics and prices of the said goods for sale.
the fact is that i happen to have somthing here i think might help someone if they need it. if i needed to sell it and needed money i would have already sold it on ebay.
your just upset and all butt hurt because you cant be touted as the "vp of electricity" and you dont like it when someone steals your center stage here. i don't need to boost my ego on this board as you seem to. that is obvious by the fact i have been a member for 2 times as long as you have and have 1/2 as many posts. and the fact i dont reply to every single thread in the caraudio section.

 

I figured you just type slow.

Have a nice weekend, all.

 

This is absolutely true. However, the point is that the cheap "Wal-Mart" variety amp will not protect itself from clipping like a quality amp will. Clipping is VERY bad for speakers.

So I would agree with you if you compared a 25watt vs. 200watt of the same "high-end" brand that had decent self-protection. However, a comparison that makes the point from #10 above, is to compare a 200watt (peak) cheap-brand to a 200watt (RMS) good-brand. In this case, you are MUCH more likely to do speaker damage with the cheap brand. I’ve never personally been a victim, but I know someone who has.

I'm also not a physicist, but (as you probably know) when an amp starts clipping, the signal becomes erratic. A 200 watt amp may cut completely out for a bit, then send 1000 watts for a fraction of a second, then cut out again. That 1000 watt spike could damage a speaker instantly.

However, if you buy too much amp, the only way to do damage is to do something "dumb" like play it super-loud for a long time, or power on with the volume all the way up. If you have an extreme mismatch (like a 1000 watt RMS amp and 40 watt RMS speaker) then yes, you are also asking for trouble, but even in that extreme case, I'd bet a reasonable person behind the volume control would not have anything to worry about.

But the moral of the story is, the saying "you can't overpower a speaker" is just that, a saying. The truth is, when a speaker is blown by the amp, it’s ALWAYS overpowered, but most likely overpowered due to distortion, not clean power. Overpowering a speaker with clean power is hard to do unless you like distorted sound, or buy and extreme mismatch. So the saying is still true in practice. It's like saying "Unloaded guns kill people". Not true, but makes a valid point about gun safety.

Disclaimer: I've never been an audio salesman, or been in the audio business (other than running sound reinforcement for live concerts, and studio recording).

P.S. I also agreed with you about all that silly pre-amp wiring stuff. I've seen speaker wires as big around as my arms that were $1000’s of dollars. I just laugh at that stuff. One question I’d love to ask the guys that buy that stuff is: "Do you think the recording studios use that stuff? (the answer is No BTW) And if not, how is it helping you getting closer to the original recording?" LOL!

P.P.S. I hope you guys agree to disagree, and don't get disheartened about posting here, because the community benefits from both of you guys posting your opinions.

 

ok i can see a little more light must be shed on the subject here.

firstly what are watts? watts is a measure of power or in the case of electronics as heat.
you can think of the sub as a 200 watt resistor. in the sence it can dissapate 200 watts worth of heat before a meltdown of the coil.
i dont care if the amp is a 25 watt wallmart special or not the fact is if it cannot output more than 25 watts of power there is no way your going to get 1000 watts or anything above 25 watts from it.
the reason it's only rated at 25 watts is because its internals (output transistors and powersupply transistors) cannot pass more than X number of amps and volts into the said load. lets use a little math here to explain it.

lets say for sake of argument that the voltage from the speaker output is 20 volts and the speaker is 4 ohms that = 80 watts. in order for you to get any more power from that amp you would either need to lower the ohms of the sub or increase the voltage to the sub. since neither will change you will never see any more watts than 80. and if you did lower the ohms of the sub which is easy to do by adding another sub in parallel you will overload the transistors of the amp by causing 2 times the current because now it has to feed 2 4 ohms loads or 2 ohms total.
if this were to happen it would smoke the amp or at the least blow the fuse.
just because an amp is cheap makes it no more or less succeptable to clipping. a clipped signal is nothing different than a signal that has been over driven to the output stage. when this happens it turns a sine wave (clean) into a square wave (you called it dirty) which will effectivly make the speaker move out and stay there and then back in and stay there following the square wave. but the duty cycle is exactly the same and the frequency at with the sub moves is also unchanged.

now if you took a 20 volt battery and connected it to the sub and left it there you would deny the sub any movement and heat up the coil. since the coil isn't moving you would eventually over heat the coil since there is no airflow over it to dissapate the heat.

now a clipped signal will generate slightly more heat to the sub only because of the fact that the speaker being mechanical will not physically be able to reproduce a signal that stops and starts so abruptly but the additional amount of heat is negligable in this case.

some other things to consider here. companies like Kicker and i am sure there are others try to boast much higher wattages for their subs in order to compete with other manufacturers who actually spend the money to make subs that can actually take the specified wattage. in the kickers case (at least a couple years ago, and i dont know if anything has changed since)
many of thier subs use a 2.25" diameter coil where as for example my subs use a larger 3" diameter coil. a 2.25" coil can only dissapate approximatly 250-275 RMS watts no matter how much they wished they would take more than that they just simply cant. the larger the coil the more surface area there is to dissapate heat into the air around it. now you can with music exceed these ratings but if you do it for hours you will eventually melt the coil and your sub will lock up and smoke half way through the stroke. i have seen it hundreds of times with these subs in particular.
why does kicker not care to change the wattage ratings of their subs and why do they just offer a free replacement? simple, because they buy their subs from China just like 95% of all the manufacturers do. belive it or not that $250.00+ retail priced sub costs them only about 22 bucks a peice to make and they have literally thousands of them in a wearhouse. even if 25% of them fail and get replaced they still make a killing on them anyway. there is a certain amount of expected losses built in because they know the other 75% of people buying that product arent going to beat on them the way the other 25% does.

also i should mention what is RMS wattage. RMS stands for Root Mean Squared and for simplicity sake just realise that it means the DC equivelent of watts produced in an AC circuit. ill explain breifly:
because AC is a signal that goes one direction and then reverses to go the other direction. the average "ON" time the signal is present to the load is not constant like it is in a DC circuit. therefore AC watts cannot simply be compared to DC watts because they have different duty cycles.
in fact RMS is exactly equal to peak *.707
Peak watts unlike Eludo's example are in fact the watts produced at the peak of a sine wave if you measure from peak to peak on the sine wave you will find that Peak watts are exactly 2 times that of peak to peak watts.

so if you have 100 peak watts you have exactly 70.7 RMS watts its simple math really. and it has nothing to do with lightning striking your antenna and for any breif period of time or max watts for a split second or any of that false crap.

now some manufacturers use the word PEAK differently. some are actually referring to a peak amount of RMS watts a speaker can handle for a very brief period of time. but to understand exactly what the peak watts are you can simply take the RMS wattage and multiply it by 1.414 to get the peak rating if it's important at all which it usually isn't
and since the manufacturer uses the term PEAK so loosly without actually giving a rating on the duration of the said PEAK rating it really doesnt mean anything other than to put a larger number on the box so people will buy the product. again, another marketing ploy to make a sale.

so to sum this up and hopefully close the issue trust me when i tell you that running a smaller amp has far less ability to blow a sub than an amp rated above the subs capabilities.
if you dont belive me take a test amp of say 75 watts and hook it to a 200 watt sub with a 60 hz signal playing on it clipped or not (you choose ) run that setup for about 4 hours and see if the amp fails first or the sub. i guarentee you that the amp will blow before the sub. the amp will get so hot you wont be able to touch it and it will thermal before you blow the sub.
then do the same with the 300 watt amp also running full power clipped or not and see if the sub will blow before the amp will. ill lay a 100 bucks that says the sub wont last.

now having had a through technical explanation and hopefully a clear understanding of the physics at work here which theroy do you belive?
do you
A. belive a theroy proven with mathmatical facts and physics that remain unchanged since the beginning of time?
or
B. what some salesman tells people to make a sale and eventually someone like Eludo comes in here to reinforce to the unsuspecting consumer Joe Q public?
thats why i challenged Eludo to prove his theroy with FACTS and PHYSICS and he didnt. he didnt because there is simply no logic to the theory, do you ever watch Myth busters on TV? you would be suprised how many ledgonds and myths are created in the public eye. i dont know how rumors get started but they sure are tough to prove wrong when the masses of people begin to belive them.

now ask yourself this question. if you had never heard this rumor before and someone told you it was easier to blow a sub with less than its rated watts verses overpowering it. what does your gut tell you? the answer was right in front of you the whole time. but because of the fact someone you respected and felt had more knowledge on the subject told you otherwise you belived the myth only because you didnt have the necessary information to prove it false and what you were told made sence at the time.
now that your more educated on the facts what do you think now?

 

Bass Mechanic, thanks for the explanation. I just did some research on my own. As it turns out, most of the advice I can find via Google supports what I said. However, none of it explains exactly how it works. The only places I could find actual explanations, supports your post.

I have to say, after reading more about it, I'm starting to agree that underpowering a speaker is not as dangerous as I once thought. Assuming it is a myth, it's a big one... had me and a lot of people I respect in the audio business fooled.

However, from other discussions I found, even the ones that support exactly what you said still warn that sending a clipped (square wave) to a speaker is worse than a clean (sign wave) signal. It was also pointed out that clipped signals do often exceed the rated power on the amp's spec sheet.

So if there is anything to be learned here... you should not under or over power your speakers. Underpowering will make your amp sound bad, and overpowering will make your speakers sound bad, and either to an extreme can blow something.

 

thats a wonderfull assesment and i am glad you took the time to do some research. the truth is easy to see when its clear. however the trick is learning who to belive and who not to if you seek the facts.

 

I read the same statements on Google... and all the ones I read assume that the amp will NOT be driven into clipping. Anyone who thinks the amp won't be driven into clipping by a consumer is incorrect, unfortunately - whether it's door-mounted coaxials on deck power, or a trunk-mounted sub where woofer mechanical noise doesn't escape easily like sub-bass.

Some people assume that because clipping sounds bad to us, it sounds bad to everyone. But I've heard a lot of people driver their systems - deck power, boom boxes, mini systems - into clipping and not have the horrified reaction that I do.

Carvin specifically states on their advice web site that underpowering speakers per se does not blow them up - until the amp is driven into clipping and begins sending DC and the attendant odd order harmonics that accompany an amp trying to send DC. For this reason they state that, although speakers blowing up due to too little power is a myth, speakers blowing up due to being driven by overtaxed small amps is very much reality.

The following from http://www.carvin.com/doctorsound/drsound04.php, last column to the right. Italics mine.

 

if you set up your gains properly you'll never have to worry about clipping.

 

But the problem is that your average user has no idea how to do this.

 

its not really a problem as there is a wealth of information on the net. you can learn just about anything you want to these days if you thirst to learn. for starters here is a great article ever car enthusiasts.

http://www.bcae1.com/

 

Nice to see you, tuan!

I concur that if people knew how to set gains properly they can avoid a clipping issue in many cases (in those cases where gains are available, not situations like OE amps and deck power). As we both know, many people want better sound, but aren't willing to learn prinsciples in order to have it. I wish it were different...

But the principle is most valuable to people in these situations! If you have deck power or the OE amp, why NOT buy a set of inefficient speakers and high insertion-loss xovers? Or a small amp for a sub? Why not take a box with 2 four-ohm subs and connect it to the OE amp 6x9 OPs?

I remember when training sessions told people you could drive the sub amp to clipping if it was in the trunk because we couldn't hear it!

 

Oh, if you want to be entertained, download a JL Audio "slash" amp manual (I used the 300/4) and call JL tech and ask them how to set an amp gain. I mean have them really tell you.

The procedure they describe has some validity, but A) It totally makes tuning your system impossible as far as I can tell, and B) about 1% of the shops in the country would ba able to do it, and about 1% of the DIY shadetree installers, either.

 

Let be honest. Most people just want louder sound...


If you need a visual to go with this procedure, try:
http://jlaudio.com/tutorials/Input_S...nsitivity.html

If you need a test tone cd, download a generator such as NCH.

Burn the test tones to the disk, get a multimeter (you should have one anyway), follow the tutorial, then eq your system. If need be, go back and re-check the gains.

 

multimeter was a great investment. I followed this tutorial from a guy named Totoro (though his site is now gone) and it helped a lot. I just tried to see if it was around anywhere, but no dice yet.

 

I don't think our statements contradict each other.


Hey, electro, I like that there's a tutorial... this is good, cause the guy on the phone was really struggling to explain their recommendations. (I called to say, I think I know how to do this, but your appendix on gain setting doesn't make sense to me, can you help me understand what you mean?) The part about lowering from the max OP for tuning was NOT in his explanation.

BTW, I am not convinced that most people know how to burn a test track disc at 0dB. I mean, how do you know when that's the level? Most CD burning SW I know doesn't tell you your dB level. Does that tone generator download help here?

JL recommends the Autosound 2000 test disc over the phone to address that... a new one was hard to find.

I wish that everybody had a digital voltmeter. Hell, I wish every shop has an o-scope - they are affordable and portable now - but they don't. You'd be amazed at how many installers want to get by with test lights, incandescent or LED-type. The only thing I can think of is that most people are more comfortable with on/off binary logic than precise numbers which require judgements on their part to interpret.

 

NCH allows you to set the dB level of each tone. The burning program, such as nero, does not care about the dB and should not be doing any processing.

If they don't have a voltmeter, then they would probley not be worried about gains and sound quality anyway.

 

All this talk about gain setting is another way of saying if the system isn't installed right, the speakers can blow.

Well, isn't this the same category as saying that if the xover points are set wrong, the speakers can blow? Both of these are system misadjustments, and I mention them in the list as ways that speakers blow up.

I made a seperate point that it's easy to blow up a speaker by driving it too hard with too small an amp. Some seem to be making the point that if the amp is never driven into clipping, the speaker never blows up. My point was that the amp is often driven into clipping in real life (subs in the trunk, we don't hear - door speakers, somce people just don't avoid it for some reason), and a speaker often eventually blows as a consequence.

If the amp was set up so that it never clipped (a theoretical possibility not attainable with HU power or OE amp power), I bet that people would notice the lack of output immediately and realize their amp was too small. With HU power or OE power, I've seen people buy nigher-end speakers and discover that they had too little power to run them, but too much volume to ask for. The bottom line is, small amps clip faster than bigger ones, hence the whole topic in the first place. One of the challenges for autosound installers and sellers is getting somebody something that sounds as close to what they wanted as possible, BUT is sustainable without things blowing up as soon as they drive around the block.

The Sony 2001 CD changer controller used to really mess us up here. It had a hockey stick for a volume output level, and many installers found it impossible to set up where the user could not get into clipping trouble, because the output did not increase linearly - the top of the volume setting increased very quickly. It should have worked, but it didn't.

 

I wish that were true, but I know that it's not, unfortunately. I mean, we can decide that their not owning a voltmeter means that, but the installer probably thinks that they do care - they just don't know how to care. Talk to tech support people about how often they have trouble getting an installer to find a voltmeter with a live battery!

 

This is still wrong, poorly designed amps clip faster than properly designed ones, not smaller vs larger.

 

actually no amp clips easier than another does. thats what the input adjustment was put there for. so you an MATCH the level on the amp. however as it was already stated not everyone knows how to do this.
this whole argument is based on 1 assumption. that smaller amps blow speakers easier than large amps do. this in fact FALSE what we should be discussing is the fact that the general public doesnt know clipping when it experiences it. this is a true statement, but the point here is that there is a rumor in the industry that people are directly being told that you can blow your speakers if you buy this smaller amp but a larger amp is the better way to go. which in itself is a lie if both amps have the correct gain setting
the comment about DC is true however the sub still has movement following the square wave and still hase the ability to cool itself. does the coil generate more heat with a square wave, yes it can but if the sub is already being pushed that close to its max heat capacity the additional heat generated by clipping isnt going to be what made it fail with a small amp it would however be the case with the large amp.

 

OR

a small amp clips faster because you are trying to turn it up louder than it is supposed to go. User error, not amp size errror.

 

So are you saying it's easier for the user to make that mistake?