Dave Clewlow latest system - World-Designs-Forum

#1 25th January 2011, 09:30 PM

Ali Tait · #2 25th January 2011, 09:36 PM

Are those pse's or pp?

Richard · #3 25th January 2011, 09:49 PM

Very nice, good step up from the Quads Dave

#4 28th January 2011, 12:10 AM

Thanks. Agreed.
My only reservation is 4mV of audible hum in zero feedback mode. DC heater has been applied by previous owner. any ideas for tackling this?
Dave

Richard · #5 28th January 2011, 10:20 AM

They're the PSEs then I take it.

It could still be the 300B heaters but further choices there are limited and involved. Look to other designs for a remedy. First stage is high gain pentode, second is a driver with no gain. OP is low gain.

Chances are it's HT or heaters on the 6au6. HT looks decent enough so improve heaters. I found a good reduction in ripple and hence hum which was coming from just this source with Kit88 and that has a relatively low gain triode connected 6au6.

You don't have enough volts for a reg so I'd do the passive shottky heater mod which gets an extra volt and burns it off in a pi filter,
http://www.world-designs.co.uk/forum...read.php?t=573

Ali Tait · #6 28th January 2011, 11:42 AM

Yes, mine were about the same. As Rich says, you won't better this without modding.