Under pwer vs. Over power

Thanks Steven.  Yes, exactly the point I was trying to make.  The power presented to a voice coil is disapated as heat.  The more power for longer durations = more heat whether the power is clipped or not; less cone movement = more heat since it's the cone movement that cools the loudspeaker.  Clipped power = worst of both since not only will it pass too high a voltage, but since it is in effect a DC signal cone movement stops and even more heat results.

Subjecting a speaker to 50KW in a 100msec burst is a completely different thing than the average user "cranking their gains."  Like I said, if the user knows what they are doing, anything is possible!    Thanks for weighing in on this one.

I wasn't sure if you had read the other thread about this topic we just had.  I had Dan come in and comment about the DC signal and he had some interesting information.  Here's the link: https://www.the12volt.com/installbay/forum_posts.asp?tid=51115&PN=2&tpn=3

Steven Kephart

Adire Audio

Ah yes, of course in the strictest sense there is no DC present in even a square wave (100% clipping) since it is a Fourier transform, and even in it's purest, single frequency form is constantly alternating back and forth between two extremes.  What I said was a clipped signal is "in effect" a DC signal, since when the wave is in the flat portion (clipped) it is unchanging like DC.  As the frequency of the signal decreases, and as the tone is more mono-tone (a singal frequency) the net signal approaches two DC signals, one at X+ and one at X-.

My reasoning behind stating that a clipped signal makes an over-power situation worse (or creates an over-power situation like Mr. Wiggins explained in the other thread) is the loudspeaker behaves for each half-cycle as if the signal was DC.  It stops moving at the extreme of the signal-created excursion stroke and thus the heat generated by the current flow must be disipated solely through the conduction and convection properties of the voice coil winding (and mounting system) itself.  There is no air flow created through system movement at these extremes, which can accelerate failure due to heat.  Of course it will as instantaneously as possible shift to the oposite extreme for every other half cycle.

I don't think we're contradicting one another, just looking at the behavior slightly differently.  Dan's more of a pure theoretical engineer; I'm more of an applications guy.

The purpose of the gain control is to match the input sensitivity of the amplifier to the output voltage of the head unit.  This is what ALLOWS the HU to control the volume and to have the full range of the amplifier available.  I really suggest you do some reading.  Here's a decent place to start.

A voice coil is NOT a "semi-conductor."  A voice coil is a pure electrical conductor.  It is made from wire.