The other problem is current delivery into very low impedance speakers, like the classic linear high end amps can, that could take some more time, but they can drive the speakers that aren’t such a savage/nasty load like Wilson Alexia etc, so it’s not an overhaul big problem.
George, you might want to know something about testing in the US.
Back in the 1970s many companies were making some pretty outrageous claims of amplifier power. So the Federal Trade Commission (FTC) stepped in and made some rules. The first was that the output power of any amp sold in the US had to conform to something called ’RMS Power’ which has no meaning outside of the FTC rules, but is essentially the output power using RMS volts to calculate the power.
The second was temperature pre-conditioning of the amplifier prior to testing it. This was done because in a traditional solid state amplifier if you run it at full power for a few minutes you’ll overheat it. So the pre-conditioning rule is where the amp is run at 1/3rd full power for one hour after which it is then tested at full power, which might only take a few seconds. This was simply to avoid damaging the amplifier during its testing.
It might interest you to know that our prototypes, which are making 200 watts into 4 ohms, can run at full power on an indefinite basis! This is only because our circuit uses GaNFETs and a minimal heatsink design. You can hold the amp module in your hand while this is done and it does not get hot. I have to assume that is true of any module using GaNFETs although I’ve not checked that out.
But this is **quite different** from traditional solid state amps which will blow up if you treat them like that! Additionally its worthy of note that distortion does not change as the module heats up, since bias of the output section is not affecting the distortion.
Since our output devices have a rating of 35Amps, we can easily double power (400 watts) into 2 ohms no worries. We do reach a limit of doubling power into 1 ohm- the safety margin of 50% is exceeded into that impedance at full power (meaning that the module has a chance of surviving that but generally with any solid state design its good practice to not exceed 50% margins of maximum specs). Of course if the amplifier is not being pushed to full power then doubling its output will go on even if the load is less than 0.125 ohms! If we wanted to make more power into such low impedances that could be done with more output devices. Generally when such high powers are needed, the output circuit employs what is known as an ’H’ bridge. This allows the output devices to make more power without their voltage margins being exceeded.
This however is true of any class D amp; the limits **are the same as seen in any traditional design**:
1) the current capacity of the output section
2) the heatsink capacity and
3) the current available in the power supply.
IOW the statement I quoted from you above is outright false. This is very easy to determine. Again you don’t have to take my word for it; Google is your friend.
Willful ignorance is stupidity; misinformation for its own sake is a heinous act.
