Tweed Bassman distortion @ low volume

[Chris Scott]

It's a homebuilt 5F6 Bassman. Built it 7 years ago, and it's been a stalwart and dead reliable amp - 'til now.

At about 2 on the volume it OCCASIONALLY goes into a light distortion mode - it's a "good" sounding distortion, not unlike if an OD had just been engaged on a low setting.

Checked everything (idle current, voltages, and subbed all pre's) and all seems in order. The bitch is that it's intermittant, which obviously makes troubleshooting a bit of a pain.

Though it seems unrelated, it recently started "ticking" at approx. a 4 sec. interval from the moment I fire it up for about 2- 3 minutes, when it stops. I never paid too much attention to it as it's only happening upon start-up, though I did determine it's in the preamp somewhere, as pulling V1 and V2 made it go away - possibly related?

Anyone have any ideas?

TIA!

[WaltC]

I'd bet on a bad/cracked solder joint someplace in the pre-amp area (pay particular attention to the solder joints on the cathode follower tube (V2)).

[Chris Scott]

Thanks Walt, and I'm leaning in the same direction.

Last night when I posted this, I was thinking "...can you be a little more vague there Chris" , but it was bugging me sort of in the same vein as that scene w/ Richard Dreyfuss in Close Encounters - "I know this" - so I thought I'd post anyway, thinking someone else's experience would jog my memory.

..or somethin' like that - Thanks again mate.

[Blue Strat]

Might also want to look at the PI socket and components. If one side of the PI goes down the amp will go into early distortion that doesn't sound horrible.

[Chris Scott]

Thanks Mike - will do.