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RE: Single PSU or dual mono best in amps??

Posted by Mike C on June 18, 2012 at 11:41:51:
Option 3; and it works well if you can manage with 2 stages rather than 3.

Reasons:
The perceived result (noted and commented on by knowledgeable friends) is that it gives fast, clean 'leading edges'; even my low power SETs do not sound in the least slow or lazy!

Remember that Naim use the same principle of splitting PSUs by stage rather than by channel, again getting good leading edges.

More generally, look at things this way. The output stage PSU current is heavily modulated, and if this modulation gets to the driver stage PSU it will corrupt the signal. If the driver stage PSU is taken from the output stage PSU, a carefully chosen decoupling stage (usually a simple RC) is added to the driver PSU. OK so far, it works ...
But I question how well this can work, for this reason.
My 300B SET (with separate PSUs for the stages) uses a GZ34 rectifier for the driver stage PSU. This is followed by a cLCLC filter, which models well in PSUD and is extremely quiet. So any audible effect due to the rectifier valve isn't going to be heard through that filter is it?
WRONG !
The differences between metal base GZ34, black base GZ34 and 5U4GB are clearly audible.
So ... if cLCLC can't isolate a rectifer valve, what chance is there of a simple RC isolating the driver PSU from the major modulations in the output PSU?

All personal experience and opinions, others opinions will no doubt differ! :-)