Determining power handling of a speaker ?

I seem to recall some manufacturer in the 1980s demonstrating something like this, touting the durability of their kapton voice coil formers. I am not sure that the demo was using actual voice coil wire.

Leonard

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It does, that`s why power compresion occurs.

and the insulation wouldn't last very long.

probably not, I have seen coil formers baked very brown by the heat from the coil without the coil itself failing, I doubt the actual voice coil could withstand glowing red, specially as they are almost always copper or aluminium. Maybe the term red hot was meant as a colloquialism for 'very very hot', certainly above 100c

I`m quite prepared to be educated tho.

Ron(UK)

It does ! The effect is usually called 'power compression' and it can typically knock up to 3dB off the speaker sensitivity with prolonged high power use. That'll give you some inkling as to the temp rises involved.

Since such speakers are invariably used with 'active crossovers' on the inputs to the amplifiers it doesn't cause any adverse issues with crossover responses.

The company that first made that 'red hot' claim was Precision Devices. You can find a 1000W continuous rated speaker of theirs here.

Kapton voice coil formers are now the norm for decent quality speakers.

I have *never* seen a purely thermal failure in any *modern* voice coil.

Graham

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I`ve seen the pigtails melt before the voice coil does.

Ron(UK)

On Sun, 14 Jan 2007 12:25:01 +0000, Ron(UK) Has Frothed:

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I'm a musician who plays bass. My rig is a 1000 watt rms Crown Microtec power amp biamped to a 4x10 cab and 1x15 cab. I caught the Cerwin Vega 15" speaker on fire at an outdoor gig and didn't even know it until people in the crowd yelled at me. Prior to that, the speaker was reconed and I guess the person who reconed it used flammable materials as I'm pretty sure a speaker cone isn't supposed to catch fire. And since we had a fire extinguisher hand I was able to put it out right away saving the cabinet. I measured the voice coil and it wasn't open or shorted. I sent it back to the local reconer and he redid it for free and promised it wouldn't catch fire again which it never did.