Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Markeebee on May 20, 2020, 08:35:45 am
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I built a Musicmaster Bass clone with the transformer PI, but with TMB tonestack. Didn't like it much.
Then I tried to convert it into something Princeton-esque but ended up getting my knickers twisted and stripped it.
So I'm left with:
18W power txf (0-275V O/P, no centre tap)
18W OP txf (8k primary)
2 x noval sockets, 2 x octal sockets
Chassis with 5 control holes (Gain, T, M, B, Vol)
SS rectifier
I'm looking for a simple 4 tube 6V6 circuit that stays fairly clean as far as possible. Preferably cathode biased.
I think to some extent I'm looking to change the laws of physics.
Any ideas for a build?
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18W power txf (0-275V O/P, no centre tap) 18W OP txf (8k primary)
simple 4 tube 6V6 circuit
I think to some extent I'm looking to change the laws of physics
I don't think you're going to be able to run four 6V6's with an 18w PT? You can run two 6V6's though.
Here is one idea that is a clean sounding amp as I built it for a friend. You could use a 12AY7 in V1 and a 12AT7 in the LTPI for an even cleaner tone. It's cathode biased. The active FX is nice and using a 12AV7 or 12AY7, it doesn't add any significant overdrive and still stays clean. You can certainly skip the active FX loop. With the mid-boost on this and the PAB (pre amp boost) you can switch in some mild OD if you wanted to.
Another option is a blackface Deluxe without reverb. https://el34world.com/charts/Schematics/files/Fender/Fender_deluxe_aa763_schematic.pdf
You have lots of good options available using two 6V6's.
With respect, Tubenit
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Thanks!
Sorry, by "4 tube" I meant 2 x 12A*7 and 2 x 6V6. Mostly because I'm too lazy to make another hole for a tube and rehash the heater wiring. Maybe I should be less lazy......let's call it the Lockdown Effect.
Also, I like the idea of setting some constraints and forming an amp around it. It's like those cookery game shows where they say "You've got some bananas, a cabbage, and a shoe. Make a three course lunch.....".
The Deluxe is a nice idea. I was thinking maybe of a Spitfire type thing but I was wondering how it would work on the lower voltage.
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I don't think you're going to be able to run four 6V6's with an 18w PT? You can run two 6V6's though.
tubenit: sounds more like adding a preamp tube to the existing lineup. Conjecture has been that it wouldnt support it but the vintage replacement hammond PT's appear to have enough current to support it.
As far as a circuit.. if youre looking at a spitfire the constraints and different tubes will make it sound different than the matchless. that being said heres a build thread https://el34world.com/Forum/index.php?topic=11136.0 (https://el34world.com/Forum/index.php?topic=11136.0)
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TN, pretty sure he means that he has a 4 tubes total amp - not 4 x 6V6.
build a plain-jane deluxe? orange TT with 6V6?
--pete
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I hacked out a tube from my last build to meet your 4 tube.
runs clean out to 7-8 on gains n guitar. kinda a Marshall plexi pre.
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CJ-11 with a SS rectifier works with your existing tube holes, Doesn't stay clean forever, but sounds good in the clean range.
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CJ-11 with a SS rectifier works with your existing tube holes, Doesn't stay clean forever, but sounds good in the clean range.
You beauty!
Thank you.
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this one might be of interest - been on the back burner for a while now. i originally envisioned using 7591 for the output tubes.
although for a cleaner approach, you could convert V1 to a AB763 normal channel pre with TMB or jus TB, or insert a James TB stack.
--pete
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this one might be of interest - been on the back burner for a while now. i originally envisioned using 7591 for the output tubes.
although for a cleaner approach, you could convert V1 to a AB763 normal channel pre with TMB or jus TB, or insert a James TB stack.
--pete
Thank you, I really appreciate your help.
This amp is one of a pair that I'm building......the other is planned to be a TT with EL84 (because I already have the chassis made), and I was planning on a James stack with mid shift for that.
So now I'm wondering if I should make your 6V6 TT and then go for something else with the EL84 chassis. Probably not a lot of difference between the TT variants, I guess?
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it would be easy enough to reconfigure if create your layout that is generous in space. i breadboard stuff before i commit to chassis - you may not have that luxury.
--pete
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This is clean. (B+ = 400V) For 2 x 12AX7, ditch the reverb