car amp with default speakers?

**273BeLow** · 03-15-2005, 06:34 PM

Originally Posted by 2FastMR2

You need to turn down the amplifier output power and bass dials to zero before you turn it all on, then when running, select a loud track turn your pc volume up to max and turn the amp controls back up in small increments untill you are happy that you have maximum volume and bass without distortion.
With this setup you won't have to worry about accidentally damaging you speakers.

thanks sounds the most sensible thing to do never going to be worried about a sub in my car as long as the people in the front and back can hear what is going on I dont mind.

A nice HT set up with 5.1 is lovely though

in the end if I do somehow blow them well more of an excuse for new speakers eh?

**RedGTiVR6** · 03-15-2005, 07:26 PM

Originally Posted by froop

You actually have more chance blowing expensive speakers with a low powered amp than you have blowing cheap speakers with a high powered amp.

If you crank up the volume on a low power/quality amp, the signal will start clipping, effectively generating DC current for short periods of time. That's what will kill speakers before anything else.

But as Bobby says, let your ears tell you when to turn down the volume.

actyally, this is correct, to a point....it's definately not complete BS

DISTORTION is what will kill a speaker.

By running too little power on a speaker, you will naturally turn it up because you aren't getting the power out of it that you want. Thus the statement above. When turning up those amplifiers that are under powering those speakers, you are pushing that amplifier to its limits, and you will induce distortion because of this. Since the amp is being asked to produce more power than it is built for.

by running too much power on a speaker you are less likely to feel the need to turn it up. usually when you run too much power you are not using all of that power, thus you are not running into the limits of the amplifier. Thus....less distortion.

is it not ture that distortion can lead to more heat in a coil thus causing thermal overload?

So no Blackrazor...froop is not completely wrong...just not fully explained...lol

you are both saying the same things, just getting about them in different ways...

**Blackrazor** · 03-15-2005, 08:08 PM

Originally Posted by Red GTi VR6

DISTORTION is what will kill a speaker.

No it will not.

Originally Posted by Red GTi VR6

is it not ture that distortion can lead to more heat in a coil thus causing thermal overload?

Not in any electrically significant amount it wont, no.

Trust me on this one, i've been through this argument many times before on the other car audio forums, and with customers, and i've always been able to show them why its incorrect. I'd prefer not to have to get technical as that just confuses the average joe, but distortion does NOT do anything to a speaker other than sound crap, and i can scientifically prove you that.

As i stated before, the only things that will kill a speaker is mechanical over excursion, and thermal overload. To a speaker, power is power, it doesnt care whether its clean power or full of distortion. So long as it can dissipate the heat that that power causes in the coil, then its fine.

100w of pure distortion is no worse for a speaker than 100w of perfect signal. Well, ok, to be technically correct, 100w of pure distortion is no worse for a speaker than about 99.9w of perfect signal, but the difference is audibly and measurably meaningless

Feel free to debate the point, but i'll then feel free to being out Mr Physics and Mr Mathematics and i dont think 273 would be too keen on that

**RedGTiVR6** · 03-15-2005, 08:45 PM

wow dood - you sure do like to talk down to people don't you?

awful snotty for a n00b

**Blackrazor** · 03-15-2005, 08:58 PM

I'm not talking down to anyone, just straight talking, different culture remember, and its a forum so dont read too much into the way i type

I am certainly not a n00b... might be new to this forum, but this subforum is titled 'Car Audio', and when it comes to Car Audio, i most definately know what i'm talking about

I'm sorry if i came across as pompous or arrogant, i wasnt meaning that at all, please accept my apology if i did, i'm just being very firm because its important people know whats what on this issue, theres a lot of misinformation and therefore wasted money because of this topic

**RedGTiVR6** · 03-15-2005, 09:17 PM

what's important is that you don't automatically assume that everyone else out there is incompetent at understanding technical talk such as physics and math....which is exactly how you came across to me....

I believe that it is important to correct myths, and I myself am always looking to learn and adjust my views and beliefs, especially when it's something that's important to me

I understand the different cultures, believe me, but there is also a universal way to treat people, and it's with respect....

and I was referring to n00b in terms of this board...

So...if you have something to say, say it, just don't assume that it will be over everyone's heads. Prove your theory with all the technical talk you want....the people on this board aren't your average 18 year old who just wants to bump their system as hard as possible....there are some VERY intelligent people on this board who actually get off to rather technical talk...

**Blackrazor** · 03-15-2005, 09:26 PM

If you're talking in reference to this :

Originally Posted by Blackrazor

Feel free to debate the point, but i'll then feel free to being out Mr Physics and Mr Mathematics and i dont think 273 would be too keen on that

... then i wasnt implying that 273 or anyone else wouldnt understand the technical side of things, i was meaning he might not want his thread cluttered up with a whole heap of slightly off topic techtalk

I wish forums had ways of

implying

voice

inflection without

using

emoticons after every

word

Anyway, all good... do you want a technical explanation about the above, or are you not too worried?

**RedGTiVR6** · 03-15-2005, 10:20 PM

I would love it, it's not something that pertains to my system, but I'd still like to know your side of it, just to hear what you have to say...

**Blackrazor** · 03-16-2005, 04:50 AM

Originally Posted by Red GTi VR6

I would love it

Righty-o.

First of all, i'll clarify what i mean by distortion : i dont mean distortion caused by mechanical over excursion or thermal compression, as those are both a function of too much power, not distortion coming from an amp. Its distortion in the audio signal coming from an amp which people claim will ruin a speaker, and its that that i'm going to talk about.

OK, so the premise is that feeding distortion, or a clipped signal etc, into a speaker will cause it to overheat and die. Its a common beleif. Its also wrong, and heres why.

First of all, you need to understand a little bit about the physics of what goes on inside a speaker. A normal speaker works using a voice coil suspended in a magnetic field, which when you apply an electrical signal to it, it generates an electromotive force which moves the coil in, or out, depending on the direction of the electrical flow, and drags the cone along with it.

Now, speakers are inherently VERY inefficient things. It takes a LOT of power to make a speaker produce a little bit of noise. The ratio of input power to acoustic output power is called a speakers acoustic efficiency, or N0, 'eta nought'. In the vast majority of speakers, the N0 of the speaker is less than 1%. That means if you feed a speaker 100w, less than 1% of it is converted to an acoustic signal via coil movement. The rest is wasted as heat. So for every 100w you feed the coil, about 99w of it just turns into heat.

The argument about feeding distortion to a speaker causing overheating and failure relies on the premise that the speaker doesnt move cleanly, and therefore overheats. So lets take a worst case scenario : lets say that our theoretical distortion is soooo bad, the cone doesnt effectively move at all. So what goes on in the coil? The speaker is now generating no acoustic energy, and all the input energy is being converted into heat. So what difference does it actually make to the heat dissipation? 1%, which in this case is 1 watt. And thats a worst case scenario.

Now i think you'd have to agree with me that if a speaker can handle the 99w when its working cleanly, without any worries at all, then it shouldnt have much of an issue with handling 100w, which in the end is only 1% more. And thats with NO cone movement. Whatever distorted signal you feed it, the cone will still be moving, and still converting some energy into acoustic energy

In practise, a distorted signal is no worse for a speaker than a clean signal. It'll sound crappy, yes, but physically, its still the same maximum voltage, the same power dissipation required, and so forth. You can feed a speaker 100w of pure sine, 100w saw wave, 100w square wave, whatever, and so long as the speaker can handle 100w, it'll be fine, it wont handle any of the signals any better or any worse than the other.

In conclusion, i'll repeat what i said before. There are only 2 things that can cause a speaker to die : trying to make the speaker move too far (either through too much power or poor installation choices), or trying to put too much power into the coil

The biggest risk to any speaker is the person sitting in the front seat. If you install right, and dont drive the speakers beyond what they are capable of, you will never blow a speaker for any reason other than a manufacturers fault

P.S : Just to show how distortion wont kill speakers, some of the judging CD's we use for SQ comps have DELIBERATELY distorted tracks on them for testing purposes

**Nic** · 03-16-2005, 05:57 AM

Originally Posted by Blackrazor

In practise, a distorted signal is no worse for a speaker than a clean signal. It'll sound crappy, yes, but physically, its still the same maximum voltage, the same power dissipation required, and so forth. You can feed a speaker 100w of pure sine, 100w saw wave, 100w square wave, whatever, and so long as the speaker can handle 100w, it'll be fine, it wont handle any of the signals any better or any worse than the other.

the link on the previous page contradicts what you state here
if you are talking about 100w peak for sine waves and square waves the actual power sent to the speaker will be different
this is one of the reasons the speaker is more prone to overheating and failing by sending it a distorted signal

it seams like common sense to me that at a quiet level (i mean a low wattage of the amp output relative to the wattage of the speaker) distorted output will do **** all, but... at a loud level, a distorted signal will induce more wear and tear on the speaker than a non distorted signal at the same level