Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: copperheadroads on August 11, 2018, 09:49:05 pm
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The wife's uncle brought me this old scraped Leslie 122 & still with all the original tubes to & he was wondering if it was of any use to my ..Yes indeed !!!! as it is 2 separate amps. the main amp (122) having 2 6550's & an OC3 voltage regulator tube & a couple of 12AU7's preamp tubes plan is to rebuild this into some kind of guitar amp circuit .
the small reverb amp(145) has a couple of 7189's which are basically el84's & a 12au7 & an OB2 voltage regulator tube .. I think i will try to rebuild the small amp first into a Hammond chassis ..I was basically going to follow the schematic of the power section & & incorporate the preamp section of one of the great classic tube circuits . something with some breakup
For now I want to want to re-purpose the large 122 amp's trannys into an head build & using an Hammond 16"x 8" Aluminum chassis & I'm thinking id like to build some sort of Supro build & the thunderbolt solid state rectifier / 2 6l6 fits the bill . I have build a few amps & for some the new Supro amps (according to videos ) have a tone that i don't think i have in my collection of original amps & the clones . built a bunch of marshall circuits, & fender circuits ,5E3 , Deluxe reverb,Bassman . & have most of those tones covered .
That new Black magick 1696RT head looks very interesting love to do something like that but cant find much info on how to do it .My tranny's output are similar to Thunderbolt but also enough to add another gain stage tube if possible & a ppimv . & this is my first post . Please feel free to comment .
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I've done a couple of t-bolty builds. I love them for guitar or harp.
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Ok Thanks ...... any one have any experience with a Ken Fisher style PPIMV in the thunderbolt circuit ? & utilizing the unused half of V1 for another gain stage . & I'm open to adding an extra preamp tube to this build to make it a little special with it's own input jack . please comment ?.
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Ken Fisher style PPIMV might be tricky to implement in the Supro.
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If some sort of master volume wont work with this circuit ,I might as well do my original plan the train wreck express .
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What is the B+ voltage of the two power transformers? 6550 and 7189 tubes were usually selected for high voltage applications. the t-bolt is a cathode biased power section. There is a thread on this forum where I tried to make a high B+ transformer work in a Airline 62-9052A (same power amp section of the T-bolt) but ended up getting a transformer with the right voltage.
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I never checked the voltage of trannys but the schematic says about 430v
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For now I want to want to re-purpose the large 122 amp's trannys into an head build & using an Hammond 16"x 8" Aluminum chassis
That Hammond chassis is only 0.05" thick. I doubt it will support the big iron meant for 6550s. If I had a 122 amp I'd pick an amp project that uses 6550s. Then you'll know that the transformers will be a nice match for the project. And use an aluminum chassis that's .08" or .09" thick.
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The iron is not overly heavy like a 50 watt marshall or anything , If it needs a stronger chassis i will add a sheet of aluminum to the top of the chassis for reinforcement . I think i will just stick to the Trainwreck express build for this project .