Class D and Power Cables

Hi Al, I'm sure external wiring has effects. But we don't get to change that stuff very often, so we also don't get to see how it affects things. The power cable OTOH is something that is easily experienced, and I have been able to correlate audible effects based on some fairly simple measurements.

The other thing I did not mention is voltage drop across the power cord. This can affect any larger amplifier that has a large current draw. I've seen a 2 volt drop across the cord rob an amplifier of nearly 30% of its output power!

How can that be Ralph?? 2 volts drop = 30% output power reduction??

Thankyou Ralph and Al for a learning exsperience with the post the both of you done, I highly enjoy what the both of you always have to say., cheers

Bifwynne, That was on a 100-watt tube amplifier.

The 2-volt drop is bigger on the secondary side of the power transformer(s).

If you think about it, the heaters cool off a little, the B+ is a little lower, the power tubes are not conducting as hard, the driver circuit can't swing as much voltage. It all adds up.

Interesting point, Ralph, which I recall you having mentioned in another thread some time ago.

Conversely, would it follow that if the AC line voltage happens to be GREATER at the location of a particular listener than the line voltage that the amplifier design is optimized for, that (everything else being equal) a relatively narrow gauge power cord that drops significant voltage might provide better results than a very heavy gauge cord?

On the other hand, though, especially in the case of a Class D amp that has very large fluctuations in its current draw as a function of the dynamics of the music, I would imagine that any such benefit might be outweighed by the effects of voltage FLUCTUATIONS resulting from the combination of fluctuating current draw and significant cord resistance.

Audiolab, thanks for your comment. :-)

Best regards,
-- Al