Tube Amp Archive

I'd recommend a JTM45, for a couple of reasons. It's a head , so there's lots of space (tweed amps not so much). You can build it as a Bassman if you like. Once it's done and working you can mod it as you please. Plus it's like the all time classic!

Sorry, I mean't to stick this on the other SD 60 thread. Well lets see what happens

ps: That's SD as in Naylor Super Drive

I've been studying the schematic and have a few questions for those SD60 experts. I'm just looking at the first two gain stages: 1) the dual 500k pot. This brings both the first and second gain stages up in unison. I suppose two seperate pots would work as good or better. Is this a SD60 innovation o...

Hmmm, I've never seen a brown Bassman. Is it a 4-10 combo or head?

Bob.

He's so underrated you've never heard him!

Yes, I found that clip inspirational! I think my general approach will be to get the first two gain stages and dual gain pot working. After that I will see if additional SD60 tweeks are in order. Got to love that singing distortion!

I'm bumping this to keep it alive. I looking to mod my 50 wt Marshall clone to take advantage of that extra half of the 12ax7. So basically turn it into a JCM 800'y type of amp. In looking at the SD60 circuit, it looks quite similar with the inclusion of the dual 500k pot and a whole bunch of voicin...

Agreed, that ole expansion and contracting thing.

Try Ace Pepper Custom Amps site. Under Useful Info he post a schematic for his Powermatic 50. Basically what your looking for. I used this channel switching concept in a Tweed Twin successfully. Check it out!

Just my two cents: vibration and heat are the killers in tube amps. Probably less of a issue in heads with the tubes pointed upwards. Military spec wiring stipulates some flex in component wiring to avoid heat stress. I've seen resistors that have broken in old Fenders, presumably due to heat. Top H...

FWIW, he gets that dieselbilly tone by using the middle switch position and picking about a half inch from the bridge on the low strings. I always thought it was the bridge pup, but the middle position is the shitz!

If I didn't already have a 2/el84 build , I'd do this in a second!

I just use a simple DPDT switch. One side has the 10k the other a 1.5k/22uf. Worth a/b'ing. I'm guessing KF wanted a real tight preamp driving the output stage.

Just a recollection: I moved to Santa Cruz in 1978. I think I had read about Dumble in Guitar Player. One day I was cruzing by the beach and I came across his shop. Small little dark place. It was closed. I came back some time later (weeks ,maybe a month) and it was closed and empty. Too bad, day la...

Bad me. I am reffering to the 10K resistor on V2a and switching to the 1.5/25uF "Fender" set up.