New Build - Plexi 6V6/October Hybrid with VVR

TomOlsen1 · 2014-10-05T08:17:00+00:00

Howdy! Been a bit quiet on my side, thought I'd share my latest amp build. Pace was very slow on this one, have been working on it since July grabbing the odd hour or two whenever we got a break from the home renovations. Anyway, My 18 watt Lite IIb has not seen much use since I finished my Trinity Plexi Brown. And there was an unused phase inverter input and space for another triode. What to do! Starting from this: Simple design, single volume and tone control, cathode bias EL84 no negative feedback The biggest learning curve in each of my builds has been how critical layout is. My previous Plexi 6V6 had layout issues that resulted in unsolvable noise problems. So the first month was spent with pencil, paper schematic and blank chassis trying to figure out where to put everything. This also helped me choose the design eventually. The chassis had space for 4 input holes, five pots, an indicator and a switch. Hmm. Not quite enough for a Plexi. Decided presence control would go on the back of the amp. Plus, this helped my layout as this chassis puts the speaker jacks off to the side, which can result in parasitic oscillation with poor NFB wire placement. At this point was thinking of doing a variation of SDM's 2203/1959 mod. But more on that next...

TomOlsen1

Early ZZ albums come with the smell of cooking Marshalls. I heard a wonderful comment saying the tone was so good you could tell what colour each guitar was...

Hmmm, burst, burst, burst. That was easy ? Maybe something in Fiesta Red on the clean on "Heard it on the X"

ezietsman

Thomas Selmer-Olsen wrote Early ZZ albums come with the smell of cooking Marshalls. I heard a wonderful comment saying the tone was so good you could tell what colour each guitar was...

Hmmm, burst, burst, burst. That was easy ? Maybe something in Fiesta Red on the clean on "Heard it on the X"

That pink strat came into play (har har) on a couple of numbers. Blue Jean Blues too and It sure got cold (def not pearly I don't think)

Psean

ez wrote Thomas, you never told anyone about this gem,

Its Thomas playing his dimed 18 watt (like mine and Singemonkey's) showing all the sounds one can get from a dimed amp without the floorpedals ?

Bloody hell ? That's proper...

refuogee

I wanna know, can you do a 6v6 mod to an existing plexi so a superbass 100 or superlead?

Chabenda

"That pink strat came into play (har har) on a couple of numbers. Blue Jean Blues too and It sure got cold (def not pearly I don't think)"

I believe that was a '59 strat, straight into the desk.

Pink? Ugghhhh... :sorry: ???

TomOlsen1

Thanks Psean

@Refuogee - you can, but only if you use the JJ 6V6S. Those can handle the higher voltages. Pop em in, re-bias and you'd be ready to go. Not a huge volume drop though. Rather get a fixed bias VVR kit from Hall Amplification or Skipzcircuits.

refuogee

I'm more after the perceived tonal qualities of the 6v6 tubes than the volume drop etc, I didn't know that I could just put them in (with a bias)

Thank you very much for the info ?

TomOlsen1

Just check the voltage in your amp. Think the JJ's can take 500v on the plates, 450v on the screens. You MAY have to add 1k 5w screen resistors.

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