24-07-2015, 04:21 PM
(24-07-2015, 03:33 PM)ppppenguin Wrote: That's a B9A valveholder without any doubt.
So, perhaps we are in agreement. If not, feel free to voice opinion.
I feel a bit of a jerk for pestering the valve supply company but the truth is I'm not too experienced with valve classifications.
You will know the X78 is an expensive valve to buy. When I thought it might be the X78 I came close to calling it a day but, yes, I think it's an X79 and those are affordable.
I should add another thing that threw me was the potentiometer wiring. It turned out the Ohms resistance on the grid of the DDT was wired from the rear part of the pot on lugs and not the front. At the front is only the primary transformer feed from mains. Resistance at the volume checked out at one Meg which is what is in the manual although I'm told most pots have about 500 K. According to Chas Miller it often happened someone would put a 50 K volume wiper in circuit in place of the required 500 K.
