The Amp Garage

Attempted to build one. Anyone know what the actual minimum plate voltage the 6SQ7 operates at? I don't necessarily trust the Gibson datasheets. I've tried 3 different tubes, all seem to test strong but it won't oscillate. I'm using a 6SJ7 in the first preamp position. This is an all octal rebuild u...

Has anyone attempted a 6SQ7 Tremelo, such as those in the late '50s Gibsons, or some Valco amps?

Goin' with the Stang, which I'm goin' to call Tanqueray.

Although I like the idea of octals in the preamp, I'm leaning towards either an EF-86 or 5879.
I've got preamp boards made up for both a GA-40 and a Stangray type of circuit, but I want
to stick with EL-84s and I have a speaker ready to go with more of a British sound in mind.

Thanks for the input. I've done a low power Songwriter that I like, but I'm dealing with a lot of real estate so I wanted to up the power. Octals would be cool, but I have iron that's waiting for 40watts. I also was thinking of something more dumblesque, but I really don't want to go down that road ...

Stangray or Songwriter.

The only thing I found was this.

http://www.schematicsunlimited.com/e/en ... atics-new-

Success! Reverse thread and a super stuck speaker gasket.

Thanks for all the suggestions. I will try the less damaging approaches first
and then work from there. The grill came off very easily with some
kind of velcro I'd never seen before holding it on. I tried budging the screws
but all I managed to do was to begin stripping the screw heads.

Unfortunately, that didn't do it. I was able to get a modified putty knife to slip under the speaker rim, so I don't think there is glue there. It may be that the metal rim is hooked up on the screw threads.

A friend of my has asked me to convert his old Fender Stage Lead Cab to something Dumble like, so I suggested a D-Lite type build. The cab's in really good condition and the chassis was an easy removal, but the speaker is another issue. I removed the nuts on the back side of the speaker but it won't...

I'm not sure what I'm seeing, but do the cathode bias cap and resistor have 2 grounding points? I also question the grounding points for the filter caps. The artificial center tap should probably be re-flowed.

6SQ7 in the GA-40 Trem.

Man, I glossed right over that.

It would be interesting to see if it is LTPI or paraphase. I've never
seen one of his PP amps without LTPI so I'm taking that for granted.
I have started my GA-40 project with a preamp board, but stalled
out with other projects taking priority.