ASR-444 Stromberg Carlson: Channel A Deficient Treble After Rebuild

Grid

Active Member
I've gone over my work for hours at a time. I've swapped tubes. So disappointing after completely rebuilding it.

Thank you.
 
I would look at the 47pf cap at the 6U8, A good pic of that channel from the volume pot to the 6U8 would help would likely help
 
My post was for @Grid, is the Stromberg his, or is it yours? If it's his, then are you speaking for him, or is this a private conversation?
 
I would look at the 47pf cap at the 6U8, A good pic of that channel from the volume pot to the 6U8 would help would likely help
I'd better double check that one. All the caps including those ceramics are brand new. Maybe, since the print of the new ones is so tiny, maybe I messed up. I'll post a photo next.
 
My post was for @Grid, is the Stromberg his, or is it yours? If it's his, then are you speaking for him, or is this a private conversation?

This is a group effort, If you have an idea of what the problem might be, you are welcome to post, we are all in this hobby together! The amp is his.
 
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I thought I had some major fault in a Sherwood after working on it, similar loss of highs, etc. Turns out I had managed to slightly bend one of the tabs on the treble pot and it was shorted to ground. Fixing that took care of the issue. May be worth looking for similar stuff.

Also, make sure its not in "crossover". That turns it into a sort-of bi-amp rig with a low pass filter on one channel and a high pass on the other. If that is engaged you'll get no highs on one side and no lows on the other. Same if that got miswired or if something is touching in that area to keep the low pass on the one channel active.
 
Yes, thanks, I did the chopstick thing. Nothing shorting but I'll look again. Yes, earlier in this project I discovered a cap on the 6U8 shorting to a neighboring lug. It was the cause of a weak B channel. At that time, the now-darker A channel was bright and clear. It was after I completed the 6U8 and the A channel tone controls that I started to notice this treble drop in A.
 
Thank You! I have been fortunate to start collecting shortly after transistors were the rage.
Almost all of my stuff came from yard sales and a flea-market, over 30 years of collecting.
 
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Thank You! I have been fortunate to start collecting shortly after transistors were the rage.
Almost all of my stuff came from yard sales and a flea-market, over 30 years of collecting.
Yep, you seldom find tube gear at yard sales anymore. Your timing was perfect, when everyone thought tubes were outmoded and obsolete. Fools! :rflmao:
 
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