Solid state amps -- "don't underpower the speakers"

[xtian]

I've heard this from two sources recently, and I can't believe what I'm hearing. Regarding solid state amps, they say, don't under-power the speakers. If your speaker cabinet is rated at 600 watts, don't use a 300 watt amp.

Anyone know where this comes from?

[xtian]

Damn. RBYP (read before you post).

http://www.bcae1.com/2ltlpwr.htm

http://www.thegearpage.net/board/showth ... p?t=661621

[NickC]

Amplifier clipping is what kills speakers, not power per se.

Driving a smaller wattage power amp hard to get sufficient SPL to cover a room can lead to speaker failure, because the amp output can be driven beyond the published specs of "x" watts at "y" THD.

I drive one pair of mains rated at 600 watts each, with a 1200 watt per channel Crown power amp. I feed the speakers with ample clean power and don't need to push the amp at all to deliver plenty of SPL.

[Leo_Gnardo]

Rich Koerner sounds off about this at Time Electronics website. Can't find the exact spot or I'd give yez a link.

Square waves kill speakers. Especially the ones created by medium to large solid state power amps in deep clip.

Essentially the voice coil tries to follow the voltage waveform of the amp. If the amp clips, it will hold the voice coil still while forcing lots of current through it. The VC depends on moving thru the air to cool itself. You can see how a square-waving amp can roast a voice coil fast.

Tube amps can't sustain a square wave at full power the way sand amps do, much more forgiving when it comes to wrecking speakers. Although I will thoroughly disrecommend running a 100W Marshall thru a single 12" JBL.

[RCGPNY1]

A big reason why this happens is that many people don't understand the way peaks are reproduced by a given amp. Lets just say we have a 100 watt amp. Lets assume a dynamic range of 10db in our program material, which is kinda low, but will work fo this example. If we want things to be clean and not clipped, then the loudest we should use the 100 watt amp is at a continous level of no more than 10 watts. This would ensure that the output will not clip( 10db needs 10x power). So if you try to use the 100 watt amp at 100 watts,everything above that will be clipped to some degree...if a big transient comes along its goodbye speakers...ever see a kickdrum smoke speakers? Happens pretty often....also keep in mind distortion components being mulitples of the fundamental end up in the range of your midrange and tweeter units which like distortion even less.Dynamic headroom is so much more important than "continuous RMS output..it doesnt give a good indication of how loud you can actuall use the amp.
Of course all of this only applies to amps reproducing music, not creating it like a guitar amp...which we know has a different set of rules.

[rdjones]

The underlying truth is "Don't clip the signal".

Quite obviously the 600 watt amp is going to be more dangerous to the 600 watt speaker than the 300 watt amp if both are driven equally into clipping.

rd