Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: fdesalvo on May 15, 2012, 11:51:15 am
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Ello ello!
I considered naming this thread, "What to do with these trannies?"... :icon_biggrin:
Here's where I am - a few years ago I built a single channel AB763 (no verb/trem) x 4 6l6 and initially liked it, but found that the tone controls were not really all that effective. It had the basic Fender tone, but I don't really think it was all that "blackface". It was actually very flat and midrange heavy, lacking the sparkle and chime I expected, so I probably missed the boat somewhere.. I've decided to strip it down and start over with a new build, as this is my backup amp. So here are the parts that I have available -
Power
Hammond 290FX (335-0-335@450mA, 60V bias tap, 6.3VCT@5.5A) - I think I was getting around 430-440vP out of this
Heyboer JTM-45-E
Output
Heyboer JTM-45, Multi-tap (40w, 6.6K primary)
Choke
Hammond 194B (4H, 90mA)
17.5" x 6.5" x 2.5" chassis
What are some options? I'm not opposed to building another AB763, but was curious about other circuits for nice chime (and maybe a lil grit). Definitely open to hearing any and all opinions.
Thanks!
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The power transformer could support any 2-4 output tube amp. The OT could support a pair of EL34 or (more likely) KT66/6L6.
Your preamp isn't dictated by your transformers.
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trainwreck express.
:icon_biggrin:
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Fix the preamp and tone controls. Don't gut a perfectly working power stage.
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Thanks, guys.
PRR - you beat me to the punch. While I rebuild the preamp in this amp, I will build another amp in tandem.
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Where's the schematic for your existing build fdesalvo? It may simply be a matter of tweaking a few things here and there, and if you put the schematic up, we could all confuse/confound you with our opinions ;-)
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http://www.el34world.com/Forum/index.php?topic=5513.0 (http://www.el34world.com/Forum/index.php?topic=5513.0)
I built this pup - It was suggested that I remove the voltage divider before the PI, but I built it as you see it here. The voltages are fine in the preamp, though the 6L6 plates are about 30V shy of listed specs (fender twin schem).
Where's the schematic for your existing build fdesalvo? It may simply be a matter of tweaking a few things here and there, and if you put the schematic up, we could all confuse/confound you with our opinions ;-)