Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: p2pAmps on June 10, 2022, 07:40:21 am
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Here is the latest project on the bench, a 5F6A (Thanks Doug for the awesome board as usual)
I am messing around with 5881s and 6L6s to see which I like best for this setup. I added a 1/2 power switch (Pentode/Triode), 3 way Negative feedback (27K-bypass-10K), and also a passive effects loop for fun. Speakers right now are 2 Celestion Golds (G10 - 8Ω) and 2 Celestion Creambacks 8Ω and so far at least it's pretty great. I did have to massage that chassis to fit with that top left speaker but I got it done. I may order my cabinet 1/4" deeper next round, if there is a next round that is :)
Power supply is (4) 20uF/500v caps. I bumped the bias filter caps to 50uF/100v to hopefully reduce any unwanted 60hz hum, so far so good... I did change the presence pot to a 25K with a 4.7K hanging off it like the later 5F6As had I believe. The tail resistor is a 6.8K 2W. The bass coupling cap is a .1uF. I did try a .022uF and may go back and fourth and see what my ear likes with these speakers etc.
Transformers are Hammonds: PT- 290DX, OT- 1750K 2Ω, and the standard 194B choke
Anyway, I am in no way some sort of expert but I do have a good time
Cheers!
Mike
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