Tube Amp Archive

thanks to all who posted on this. I have a 20J12T 1961 trem version and was unable to locate much outside of this. Happy to use mine to help fill in any gaps as I can

I built a 3x12 one using a 60s bassman output transformer. It's a monster for sure. If I were you I'd use the tone stack http://www.duncanamps.com/tsc/download.html calculator from seymor duncan to allow you to dial in the frequencies you want since you are wanting to customize for bass.

I am posting this to check for visibility as try to I improve my drafting.

I'm not yet drawing in the PT, rectifier and bias connections because the main board, pots and sockets connections are still in process.

Quick question: the left terminal of the middle pot, that should go to ground right?

on my way to developing skills to handle the rigors of graph paper, this lined school paper struck me as a convenient intermediary not positive on the pi filter or the value of plate load resistor on V2b, but this should have addressed most of the concerns presented by the previous draft. Thanks aga...

that's cool, I'm willing to sacrifice efficiency for more pronounced even order harmonics. the "bang" I want is less about volume and more about tone.

ok so I'm an eager beaver :) very good fellas, thanks for taking the time. Let me digest a few of these comments and recommendations and come to a second draft. The reason for the triple input is simply because I am operating from a 5F11 tweed vibrolux chassis, this is one of the structural limitati...

ok! hold your horses, make a single file line, there's time enough for everyone to chime in. Not all at one time! The schematic is attached as a pdf (above) but you have to be logged in to get access to the download link to show up. Would it be preferable for me to post it as an image? rather than r...

This is from a buddy of mine who proposes adding a couple more 16uf caps to hold the voltage steady when the switch is flipped from full to half power. His description: drop the screen voltage applied to *both* of the 6V6 power tubes in this amp (keeping the quiescent plate voltage constant, 325 Vdc...

Ok let's see how this works. It's an early draft, but gotta start somewhere!

Hello All

I am drafting schematics for a new build, parallel single ended with 5881s into a 10, voiced heavy bottom for harp.

Is this the right location to post a copy of the schematic for comments and suggestions etc?

I am getting intermittent results with this 4 ohm tap. I'll hook it up and it will work and then I'll turn it off and come back later and it sounds low powered again. Resistance measurements to ground show it to be the same as the green (8 Ohm tap); they both read .5 ohms. I thought I would see .8 o...

just fantastic, very empowering! thank you so much for sharing your knowledge. Your generosity is very heartening, resonating with the spirit of this project - a christmas gift of sorts for a close friend who is moving out of town. Will report back with results, and photos sooner or later!

ok - I did all of this except for uncoupling the switching contact from the shield on the main (8ohm) jack. Wonder if this is why I got low power output from the other (4 Ohm) jack? I am also going under the assumption that the sleeve terminal is a ground connection as the jack assembly is mounted t...

ok - got back to this amp last night and got the bias switch properly wired, now just need to fine tune some values based on the tube selection, so that is under control. Really happy with the results so far, she is quiet with good power I am trying out speakers and voicing with tubes now. My OT has...