Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: bullkelp on October 01, 2025, 12:29:55 pm
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Probably a fairly common issue.
Im still wokring on my 1961 6g13.
Ive found, unfortanately that the JBL d130f needs a recone. So thats one of the noises accounted for.
Fortunately I haved a weber cali ceramic as a stand in.
Im getting such sweet over drive with the amp and it sounds absolutley wonderful OTHER THAN a pesky fizzing/distortion in the the tail end of notes when pused. Not apparent for the most part when played clean.
It has all the OG blue moldeds. The phase inverter caps arent blue molded. They look to be old thought and yellow like mustards but I dont think they are. Maybe not original but old. All the electrolytics are replaced.
Iv chop sticked and inspected all solder joints.
I do get some DC voltage on the board (which is wonky with age) but nothing ridiculous and it doesnt suffer the same idle noise that my vibrolux did with DC that I ended up lifting the end of some of the componenents off the board to solve.
Could those yellow caps be culprits? Any where else youd reccommend I look?
Thanks in advance
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That kind of fizzyness could be oscillation from unwanted stray EMF coupling. Grid stopper resistors might help. or not. try it and see
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That kind of fizzyness could be oscillation from unwanted stray EMF coupling. Grid stopper resistors might help. or not. try it and see
Good call
I don’t see grid stoppers installed .
My goodness it’s a fine sounding amp otherwise
Once if got it singing properly I’ll post some clips
Big shout out for the Weber Cali