amp clipping

[Bob Lee (QSC)]

I agree, but I think most (not all certainly) speakers get damaged by those who have a 300 watt head and pair it to say, a 500 watt cab and drive the head too hard. You know...the old scenario of not having an adequate power amp in the first place, but still trying to crank it to hear themselves.

In that situation, even having a higher-power head would not necessarily be safe. If a 300-watt head isn't loud enough and pushing it into clipping endangers the 500-watt loudspeaker, then a 600-watt head can also damage the loudspeaker as you chase down the desired volume.

 

[Sundogue]

In that situation, even having a higher-power head would not necessarily be safe. If a 300-watt head isn't loud enough and pushing it into clipping endangers the 500-watt loudspeaker, then a 600-watt head can also damage the loudspeaker as you chase down the desired volume.

Well, to sum it up, it's really about using the power you have wisely.

I have a 250 watt head driving a 400 watt cab, but I never need to push the head very hard to hear, and it always sounds clean. I'm usually at 2, maybe 3 max on my volume and it's more than sufficient. Actually it's a 500 watt head into two 4 ohm cabs and the head goes down to 2 ohms. It's splitting the 500 watts (250 into each cab) though obviously not even coming close to really putting that into each cab at my volume. The head has a clip warning indicator light that never comes on, not even briefly, even at my loudest live setting.

Isn't clipping what distortion pedals do, to obtain the distortion? If clipping itself damaged speakers, distortion pedals would damage speakers too, but obviously they don't.

 

[Bob Lee (QSC)]

No. An amp will put out as much voltage and amperage ( the product of which is watts) as its power supply is capable of delivering and no more. 100 watts of clean sine wave and 100 watts of pure square wave is 100 watts, period.

Although 100 watts of sine wave is the same power as 100 watts of square wave, a power amp is not rated by its supply. A power amp that puts out 100 watts (into 8Ω, let's say) of sine wave just before clipping (that would be 28.3 volts RMS, 40 volts peak) would probably be able to put out an almost 40-volt square wave. The actual voltage will sag due to losses in the power supply, unless the supply rails are regulated.

So let's say with the power amp, whose supply is slightly lossy, when it's cranked up into putting out a real square wave (this very rarely occurs, though), the maximum it puts out is 37 volts. The power it puts out then would be 171 watts.

 

[mullet0909]

im glad we are down to an agreement. right? or is more arguing needed? im only a student here.

 

[billfitzmaurice]

So let's say with the power amp, whose supply is slightly lossy, when it's cranked up into putting out a real square wave (this very rarely occurs, though), the maximum it puts out is 37 volts. The power it puts out then would be 171 watts.

Of course this gets into how an amp is rated, which is at a specific THD figure, and if the output voltage approaches the rail voltage the amp is not going to be within that spec. My point was that you won't get a 40 volt output from a 37 volt supply, no matter what the wave form shape. This is along the same line as your comment about peak versus average power output, as stored current in the supply caps can provide short bursts well above the nominal current rating of the power supply. In both cases we're probably in danger of completely losing that portion of the audience that hasn't already nodded off.