The Amp Garage

It ended up being the input grounds, but in a different way than I had thought. They were all solid, with a star washer. But the grounding of the aluminum front panel to the steel chassis was not good -- it had oxidized and developed some resistance. So I took the front panel off, sanded the mating ...

Hi all, A while back, I got an old Ampeg GV-15 chassis for cheap, not working. The power and output transformers had been replaced, and the amp was in pretty bad shape, with rust and nicotine stains all over. I cleaned it up and replaced the electrolytic caps and a couple of bad resistors, and it's ...

Check out how the Standel 50L15 / S-80 uses one of these: gain stage + cathodyne PI.

And a few of the non-trem version:

Here are a few sets of photos from Reverb listings, Instagram, etc. 20837330_136109086994566_2982582310051774464_n.jpg 20766572_2195543070692575_8472337433952780288_n.jpg 20766352_1906567629591003_830828193249230848_n.jpg 20766138_287991248345768_8964549400563023872_n.jpg 20759940_110687016278551_91...

I was able to get some more info and detailed photos of a 20J12T to fill in the gaps. Attached are the new revisions for both tremolo and non-tremolo versions.

tubeswell wrote: ↑Tue Apr 02, 2019 6:43 am I see the 6AX5 is rated for 450 max Volts h-k. What is the high VAC winding putting out (out of curiosity)?

600 VCT (see http://www.classictone.net/40-18079.pdf), so we squeak in just under the rating.

Just finished up a Fender 5B6 point to point build in the style of Little Walter or Tino Zottola. I followed the layout at https://ampgarage.com/forum/viewtopic.php?f=8&t=26177 with a few changes. OT is from a Filmosound 385 projector, and PT is a ClassicTone Vox AC-15 replacement that I got on Amp ...

My schematic is at https://ampgarage.com/forum/viewtopic.php?f=6&t=31949.

I'm curious what the phase inverter looks like in yours. Let me know if it's the same as in the schematic I posted. Also, are there any markings on your PT/OT? Any gut shots you could post would be much appreciated.

Thanks!

Hi all, Based on some gut shots on amps that have been listed for sale, I've put together the following layout/schematic for a Standel 20J12 (combo) / S-50 (head). This is a 2 x 12AX7, 2 x 6BQ5 amp with a 12" Jensen speaker. There are a few values I'm missing: * All of the pots * A few of the cathod...

Sorry to bump a thread from a long time ago, but this appears to be the same circuit as a Standel 20J12. The power tubes are 6BQ5 in cathode bias. This wasn't converted; the 6DQ6 tubes are what the larger S-80 (~30 watts) uses, and it appears they used the same chassis to build the S-50 as well. I'm...

To clarify, I don't have the amp, and I'm working from photos. I found another photo of this from the last time the amp came up for sale, and I was able to work out how the PI is configured. I've attached the schematic and an LTSpice sim of it working. Has anyone ever seen another amp using this PI ...