Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: bruno on June 12, 2010, 07:26:25 am
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I have a vibrolux reverb full transformer set from mojo laying around (most likely heyboer wound), a friend of mine asked for a smaller 4 tube output plexi build, with 6V6, to emulate the response of a late 60s superbass/superlead at 35 wattish mark with 6v6s... Would a the vibrolux reverb set be a good candidate for it? My only two concerns are, plate voltage being to high for the 6v6s, since it will be solid state rectified, plus I'm not sure if the output transformer is beefy enough to get the low end needed?
I'm also a bit undecided regarding cathode or fixed bias, I'm leaning toward fixed to correctly get the marshall tightness however cathode bias would allow me to easily install dana hall's VVR.
any opinions
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IF you go with the cathode bias, you can always use a HUGE cathode bypass cap (1000 uF, 2000 uF, or possibly more.) That would tend to tighten up the cathode bias to more of a fixed bias tightness. Plus it has the added benefit of you won't have to worry if your friend just wants to drop in new tubes, and forgets to rebias.
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Go with JJ 6v6's. They will withstand the high voltages (450v'ish) with absolutely no complaints.
Go with SS rectification and keep the power amp plate/screen supply filtering caps very stiff to emulate the punch of a larger amp.
The undersized OT can sound cool, as a saturated OT does have a particular vibe.
Start with the iron you have and build it up.
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I heard some clips of Mark Huss's 6v6 plexi and it was smokin. I think that one was 2x6v6 though, same difference I'm sure, just a bit louder maybe more headroom. Here's the link if you haven't seen it on the last page is sound clips: http://mhuss.com/Plexi6V6/index.html
D.
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Hey Topbrent,
Is that a Sox & Martin super stock car in your picture?
I just built a 4-6CA7 Overdrive Rocket that's cathode biased.It's delightful!I have 430v on the plates(416v from cathode to plate)
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Hey Topbrent,
Is that a Sox & Martin super stock car in your picture?
I just built a 4-6CA7 Overdrive Rocket that's cathode biased.It's delightful!I have 430v on the plates(416v from cathode to plate)
Dave Strickler, actually. This was his 2% altered 1964 Dodge 330.
Sox & Martin were sponsored by Plymouth.
(my other expensive life....I am a mopar fanatic)