Class D and Power Cables

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

When I upgraded my 12/3 romex junction boxed house wiring to a dedicated sub-panel with 20 amp breakers for each run of metal clad 10 g BX, there was a very substantial improvement.

With the old 1972 wiring my class D PS Audio HCA-2 was creating RF that could be heard through a Sony clock radio on the other side of the dwelling. After the upgrade to the volts AC the RF stopped and the performance of the amplifier as well as the rest of the system was noticeably better. The work was done to a raised ranch style home by a licensed electrical contractor for less than $1,100. Clearly the best dollar for dollar system upgrade/tweak to date.

Lastly, I made some DYI 10g shielded power cables. I can't say if was the the larger wire I used or shielding the cables or both, power cables can absolutly make a difference with class D amplifiers. In my experience they don't like silver anything and the more copper the better.