PASS LABS X250 Question

I agree that X250 can easy output 400 watts rms into the load of 4 Ohms.

I disagree with the calculation of the sensitivity. Almarg use relation between rms and peak in ....sinusoidal waveform which is not the case here.

I cannot calculate exactly but I would take as a reference peak output current of 65 volts which should be slightly below rail voltage (65-70 volts) and then devide it over 31.6 times so it would seem to me that its sensitivity is 2 volts (go get its peak power whatever it is). Balanced input , in theory should be double indeed or about 4 volts.

Hello Al,
I stand corrected.
Interesting that since 26 dB is equivalent to x20 then the rms voltage is 2.24 x 20 -45 volts and then as per your definitions, maximum output voltage [ = sqrt(2) x V(rms) ] = 65 volts.
If so this amp (200.5) would clip easily as signal from an amplifier into medium load speakers is about 100 volts and difficult loads much more then that (of course during the loud musical peaks)

Thank you
Mike

Hello Al,

I meant +/-100 volts... I took this number from Spectron web site:

"...in reality an amplifier's voltage headroom is limited by the power supply voltage, which limits the peak voltage. Spectron's amplifiers are the highest voltage we know of in the audiophile world, using a plus and minus supply of 120V. By comparison most amplifiers use power supply voltages on the order of plus and minus 85V or even lower. An engineer evaluating an amplifier to determine the required headroom would look at the output voltage of the amplifier with an oscilloscope while playing the loudest music he would reasonably anticipate would be listened to. At Spectron we have done that. What we see is that it is common in high quality recordings to see voltages near 100V peak, with medium efficiency speakers. This means that when listening to the same music with most other amplifiers, the signal would be 'clipped'... "