Current limit onset definition?

The current rating is the amount of current that flows when the power supply is shorted out for 10 milliseconds. As Al pointed out, it has nothing to do with the power or the current that the output section can make.

The rating is really only there to show how the power supply is built up, and it is without question confusing! For example, you might be surprised normally to find that a tube amp (and for that matter an OTL) has the same rating. But we are not talking about anything to do with the output; simply the power supply itself. more:

http://www.atma-sphere.com/Resources/Common_Amplifier_Myths.php

Clearly the 40A figure has nothing to do with power draw...

Ralph (Atmasphere), thanks for your comments also. As a point of information, all of the peak current specs Spectral provides at their site for the recent models as well as for the DMA-180 are described as "peak **output** current" [emphasis added]. So I would have to assume that **if** their wording is accurate those specs are based on the short we have referred to being applied to the output of the amplifier, rather than to the output of the power supply. The numbers, btw, are 60 amps in each of those cases, except for the DMA-400 monoblock which is 90 amps.

Giving it the benefit of the doubt (using the power formula), 90 amps squared is 8100 watts into one ohm (into 2 ohms it would be 16,200 watts...). Looking at the specs we see that the 2 ohm power is no-where near that. So the current cannot be anything to do with the output section! It is how much current occurs when the power supply is subjected to a dead short for 10 milliseconds. It is a measure of the power supply capacity and really not anything else.

By the same measure our MA-2 amplifier, which is an OTL, makes about 60 amps.

No, I don't think so. 90 amps through a 600 watt output section would toast the output devices in a heartbeat. Or less.

The 90 amp figure simply has nothing to do with the output section. It has to do with the power supply.

Thanks Al.