"Stewart Pinkerton" wrote in message
news
On Mon, 5 Jul 2004 21:50:25 +0100, Chris Morriss
wrote:

In message , Keith G
writes

A quick thank you to *everyone* who volunteered suggestions to cure the
hum
problem on triode amp project. None of them were without merit, but the
problem was being caused by no more than the B+ being lifted from the
wrong
side of the choke (itself a component of the circuit's 'pi filter') due
to
some wattock reading the circuit wrong!! (Which is a bit of a mystery in
itself, because I'm the only one who's had a hand in actually building
it
!!!??? :-)

Anyway, once the wires had been re-routed the hum disappeared
completely -
absolutely silent!

See, I *told* you it needed a pi filter! :-)

Excellent! So it's a pair of 845s and a couple of Sowter's finest SE
OPTs next then?

Hmmmm, now *that* is a real project - you'll concentrate much more
closely with a 4-figure B+ rail!


Hmm, the first step on the road to valve escalation madness, see Audio
Bizzarro http://www.spiritone.com/~tube/constructor.htm plenty of 845 &
Sowters there. That Altec 816 cab would be perfect for my Cinerama home
theatre project though ;-)


Stewart Pinkerton | Music is Art - Audio is Engineering