In message , Keith G
writes

"Dave xxxx" wrote in message
...
Keith G wrote:
Well, after a week's heavy fettling (on and off) the triode amp is
making noises:



http://www.apah69.dsl.pipex.com/keit...de_project.htm

snip

The Bad - It's humming like a good 'un and I suspect it's going to be
a bugger to sort....

The Ugly - Well, I think it's cute, but you'd never sell 'em looking
like this......

http://www.apah69.dsl.pipex.com/keit.../ampkit136.jpg

.....would you??

:-)

I like it,


Ok, strangely enough so does Shiny Nigel (and me), so you are not
alone........!! :-)


whats the damage to buy one????????????????????????????????


Say £500 worth of parts (comfortably) and a week of my time, so that would
be about £525 in total, but (as it is atm) it would hum loud enough to
silence a washing machine...... ;-)

Phil http://www.bluebellaudio.com/ says one of these ponced up with a fancy
chassis would/will cost anyone about £3,000. How much he would charge for
one made up in a similar 'lab style' (unpainted grey chassis, exposed
trannies, screw heads, bloodstains everywhere....), I don't know - give him
a call.

I gotta say it, present hum notwithstanding, the sound really is
*stunning* - and that's from a confirmed/committed valvie who's no stranger
to the Wonderful Sound Of Valvey Things (and whose current valve amps are
not ****e)......!!!

(Phil's just about to put a couple of 300B triode amps on eBay apparently!)





Do you think the hum is coming from the directly-heated filaments of the
300Bs, or from the HT line? (Heater hum is likely to be 50Hz, HT hum is
more likely to be 100Hz)

If it's the filament, then you could try using a resistive centre-tap on
the winding and earthing the CT, (or taking it to the bias circuitry or
whatever).

You may have a CT filament winding already of course....


--
Chris Morriss