Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Colas LeGrippa on February 04, 2012, 07:27:43 pm
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Hi, I had the chance last night to play my last build in a 300 persons bar. A sort of Marshall 2204,( not the bar, the amp ! ) heavily modified, no tone stack , volume, master volume, presence ( NFB ) and fat boost. I think the major tone upgrade is the use of dissimilar power tubes. One EL34 on one side and and one 6550 on the other.SS recto, push-pull, fixed bias. ( common bias, the 6550 running colder, for sure ).
I play a Gibson flying V , V2 model, heavily modded too, with scalloped fretboard, hot rails from Seymour Duncan, 250k pots with a .047uF, ''earvana'' ,.the list is long.
This amp was originally a Traynor bass master, YBA1A, and I have kept only the power transformer from the original circuit: 310-0-310, 5V tap ( that I don't use ) and heaters tap. The tranny is so huge, it could supply current for 4 power tubes if not 6 or 8. H U G E. Output tranny: 1650N from Hammond. Choke: 5H .
The tone of this amp is VERY DEFINED , highs, mids, lows, and the choice of the pick ups makes a big difference in tone. We could say the amp is hyper sensitive to any change ! Guitar too close to the cab ( Marshall 2 X 12 Vintage 1934 ), the amp is feeding back very nicely with rich overtones. Backing up the volume pot on the guitar doesn't remove highs, ( for rythm purpose ). Briefly, I can say that this amp is my best ever, and although playing it at home gave me a good impression, playing in a club ( vol. 10, master 3 ) revealed the full mojo tone of this marvelous beast. ( No more for sale, hey hey ). Be patient all, soon on youtube, my camera is out for the moment .
Cheers !
Colas
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:smiley:
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You know, i stopped playing gigs probably 8 years ago but i can relate to your excitement. I used to get real excited when i did a gig where a new amp or other gear or a tweak worked exceptionally well and made me play my best. Thats great ! I also must say that i tried the same thing...el34 and a 6550, a el34 and 6l6 or various el34's of different makes. Actually i can't recall exactly, but i have tried that whole mix and match thing and i also thought it was quite nice. It gives you the ability to fine tune by getting the best from different tubes. But since i no longer play out i really don't have the ability to hear how it comes together in the mix. I do play with music at home to get an idea of how it cuts, but no more live gigs. So i tried it then just went back to a pair of 34's. But i'd certainly have tried this if i were still playing out. Then again, i never even built my own till after i stopped playing out. thats one of my biggest regrets, as i have built amps that are better than anything i gigged with back then.
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12ax7, you are absolutely right ! EXCITEMENT is the word. Thanx for sharing your own experience.
Colas