car amp with default speakers?

**Caitlin** · 03-17-2005, 10:10 AM

Doesn't a clipped signal equate to passing DC through the voice coil for the period of the "clip"? that'll heat the wire quite nicely...

I had a mosfet blow out on an old amp, and it seemed to dump dc to the coil, the cone jumped out of the guide and the coil its self smelled NASTY.....

that was deffo a good way to toast both an amp and a speaker. that was manufacturer defect though.

**ElKeeed** · 03-17-2005, 10:23 AM

I think I know where the confusion lies. Passing in a square wave as opposed to a sine wave is not in itself worse. The difference is that if they have the same peak voltage then the square wave would have a higher average. If they are the same power then that would have already have been taken account of and the square wave would have a smaller peak.

However your ears dont work like that so if you were listening to something that was clipped you would tend to have it turned up just as loud and so more power would be going through the speakers.

**RedGTiVR6** · 03-17-2005, 10:32 AM

but according to Blackrazor....it doesn't matter if it's a sine wave, square wave, etc...they are all the same

**Caitlin** · 03-17-2005, 10:58 AM

the RMS voltage will be higher... dunno exactly how that affects power.

it's change in voltage that moves the coil, if a dc pulse is sent, the speaker will jump up and then fall back, when the voltage then falls, the cone will jump back, and then return to neutral.................... i think.

but the point i'm making is that dc passed through a coil will heat it, and lead to more damage (hotter = more resistance = hotter still!)

I'm not basing this on anything, i'm just discussing 'cause i'm bored at work.

**JC-S60** · 03-17-2005, 11:32 AM

Caitlin has it right.

When you're checking wattage to be shure, you check RMS.

A 100w RMS amp will give you 200w peak-power for example.

The RMS is an average of a non-distorted signal.
When you start pushing square waves (or worse: dc) then the RMS will come closer to the peak-level. This way you can blow 150w RMS speakers with that 100w RMS amp, as the RMS gets close to 200w.

Also frequency plays here. Put a 1Hz signal of 100w to a 200w sub and it will start to smell funny

You can get that effect if your end-amp doesn't reproduce the input frequencies but starts acting funny (really quick switching between safe and on, for example).

Oh and Caitlin, when you apply DC to a speaker, it will stay up/down (depends on polarity) until you cut the dc or until it burns the coil.

**Caitlin** · 03-17-2005, 01:26 PM

yes, i'm not quite sure what i was thinking there.....

**Blackrazor** · 03-17-2005, 02:24 PM

Originally Posted by Red GTi VR6

but according to Blackrazor....it doesn't matter if it's a sine wave, square wave, etc...they are all the same

I'm not saying they are all the same. I'm saying they make very little difference to the speaker if they are the same power. i.e a 100w sine wave doesnt make a lot of difference to a 100w square wave if fed to a speaker. I think what Ciatlin was saying is that when you clip a 100wRMS amp its possible to get up to 200w RMS out of it, and if the speaker is only designed to handle the 100w RMS, that will definately cause issues. But if you feed it either the heavily clipped signal from a 100w amp (which can be up to 200w), or just feed it a nice clean 200w, both have a pretty even chance of effing things up in the short term

But the point to note is that its not getting 100w in the case of clipping. Its getting up to 200w. Which can damage it just as happily as a normal 200w signal

So in this case, the problem is not caused by the fact that the signal is distorting, but by the fact too much power is being put into the coil for what its designed for

**Quattro** · 03-17-2005, 02:42 PM

Ok I'll let you guys get back to your debating after you answer my simple question. I'm about to purchase wiring for my system and I will be using a amp instead of a HU. What I wanted to know is do I connect the wires comming from the amp directly to the speakers, or is there a way to connect the wires to some sort of a wiring kit, likes the ones for aftermaket HU? Which would be better?

**poseur** · 03-17-2005, 03:28 PM

Connecting directl to your amp would be ideal, however, in lieu of this, if you wish to keep wire-pulling to a minimum, you can indeed use a harness for your car, and connect intot he speaker wires of it, However, I wouldn't use the power and ground for much more than a monitor or something with a fairly low draw.

**poseur** · 03-17-2005, 03:32 PM

And, umm, I'm not realyl directing at anyone, simply stating that the main reason for the argument that underpowered setups can do damage isthat people will have a tendancy to use a gain setting as volume and simply clip the amp. This does nto equate to distortion in the signal going into it, or anything else. A clipped amp is putting out DC power which is one way, as opposed to the natural ac (+ - in-out) kind of motion of a speaker. therefore a clipped signal shoves a speaker to one extreme and then bounces it off of that point which will, indeed do all sorts of harm to a speaker, we're not talkign thermally here, but morelike beating on a piece of copper tubing with a hammer (or in this caser a backplate) kind of harm.