New build - Trinity Plexi II - GuitarTalk Community

New build - Trinity Plexi II

TomOlsen1

So, in a fit 6V6 fueled ire, I've ripped apart my Mark Huss plexi 6V6 down to bare aluminium. Something in the overdrive character was bugging me, and frankly there was too much going on inside the amp with fixed bias VVR (not quite as effective as the cathode bias version, plus I prefer PI/PA to whole amp scaled), FX loop - not much use when the power tubes are part of the drive sound. Couldn't use it as a volume boost for solos. etc etc etc.

A few weeks back I'd taken the FX loop out of the plexi preamp in to the input of the 18 watter. Suddenly the feel and breakup I was looking for came right. And with the PI/PA VVR it was achievable it bedroom level as well as being able irritate, i mean keep up with, the drummer. I wanted a plexi style pre with cathode bias EL84 power amps section, plus the sag of the EZ81.

But this presented a problem, as my PT was too high for EL84s, and I'd drilled out the power tube holes for 8 pin. THe first problem was easliy solved, just put the orginal 18 watt style PT back in. Then folks over at case connection fabricated a blanking plate for 2x 9 pin for me.

After some back and forth, I settled on a design. The Trinity Plexi II, which takes the 18 watt TMB platform and mixes in a few tweaks from the '68 plexi. High gain but very little bass in the pre, with a big coupling caps in the power amp. Phase inverter section toned down a bit in comparison with the standard 18 watter due the higher gain preceding it.

Build will have PI/PA VVR, EZ81 rectifier and sozo caps where space allows. Not that I'm entirely convinced they're any better than Mallory or Vishay. Here's the progress so far:

Blanking plate

PT and EZ81 base installed

Whole Chassis

Heaters wired up

PT and OT half wired

Board layout

Staking in progress

Turret Board

Testing component fit

That's it for now. More tonight/tomorrow.

Attila

Looking good Thomas

ezietsman

Can't wait to hear this one. I also much prefer PI/PA scaling now that I have an amp with VVR that scales the whole amp. Sounds a bit meh at low power but turned up its great (This is the Tweed Deluxe).

Chocklit_Thunda

I wish I understood any of what you just said ? the pictures are nice though ?

Skylark

Point to point wired tube goodness!!

TomOlsen1

Right!

As of this morning the build is complete, and I must say I'm very happy. No ground hum, very little hiss even at high gain and great Marshall tone from Hendrix cleans to Clapton blues to AC/DC crunch to all out EVH brown awesomeness. The feel is surprisingly bigger than I was expecting from a cathode bias EL84 amp, with that real fast unforgiving plexi response. Hit the strings hard and it cracks like a snare.

Hoping to record some clips in the next day or two.

Wiring up the valves

Valves and pots done

Whole amp, just need to put some loktite on the mosfet and star grounds.

About to fire it up

Man, there are few things quite as satisfying as a build working first time.

Now, back to annoying my neighbors with Randy Rhoads riffage.
8)

TomOlsen1

Forgot to post a close up of the turret board

Gearhead

Wely nice build 8)

shaunf

Thomas Selmer-Olsen wrote: Forgot to post a close up of the turret board

Looks really cool! Still on my to build list. Any tips you can share around the build as well as sourcing the relevant bits and pieces?

TomOlsen1

Thanks guys!

Shaun, hmmm. Having seen your builds on this forum, I 'm not sure what to suggest that you don't know already.

The tricky thing with these 18 watt TMB builds is balancing the gain in the pre/PI and PA. The Trinity Plexi II suggests toning down some values in the PI. Dropping the tail resistor from 47k to 56k to help with fizz, as well as a 220k grid stopper between treble wiper and MV. The 470k resistors in the PA are dropped to 100k for some extra smoothness.

I preemptively installed the Paul Ruby buzz fix, but used 3V3 zener diodes, as these function for the whole range of the VVR. I also installed a zobel filter using 10ohm/2u2 on the 8ohm tap to fight rising speaker impedance, which these particular 18 watt OT's tend towards.

Sourcing parts? Iron and chassis are from Steve Smith from Valvepower. Pots, turret board, knobs and some caps are from Antique Electronics. Resistors, some electrolytics and many other parts from Mantech.

Attila

Very nice build well done Thomas

shaunf

Thomas Selmer-Olsen wrote: Thanks guys!

Shaun, hmmm. Having seen your builds on this forum, I 'm not sure what to suggest that you don't know already.

The tricky thing with these 18 watt TMB builds is balancing the gain in the pre/PI and PA. The Trinity Plexi II suggests toning down some values in the PI. Dropping the tail resistor from 47k to 56k to help with fizz, as well as a 220k grid stopper between treble wiper and MV. The 470k resistors in the PA are dropped to 100k for some extra smoothness.

I preemptively installed the Paul Ruby buzz fix, but used 3V3 zener diodes, as these function for the whole range of the VVR. I also installed a zobel filter using 10ohm/2u2 on the 8ohm tap to fight rising speaker impedance, which these particular 18 watt OT's tend towards.

Sourcing parts? Iron and chassis are from Steve Smith from Valvepower. Pots, turret board, knobs and some caps are from Antique Electronics. Resistors, some electrolytics and many other parts from Mantech.

Thanks for sharing that info and tips Thomas. I think you grossly overestimate my amp/electronics knowledge. I am very late to this amp building party and as such am nothing but a beginner and a hack. All information, tips, tricks or anything else is very gratefully received from those more knowledgable than I, which is almost everyone.

Yours, Ez's, Lapdawg's and others' builds have certainly inspired me to do some more reading up on these 18 watters and ultimately try and build one for myself someday.

TomOlsen1

Here's a rough clip of the brown channel. Signal path is guitar, amp, load box, Logic with Redwirez IR. No other post processing.

warrenpridgeon

Thomas Selmer-Olsen wrote: Here's a rough clip of the brown channel. Signal path is guitar, amp, load box, Logic with Redwirez IR. No other post processing.

Niiiiiiiiiiiiiiiiice!

shaunf

Thomas Selmer-Olsen wrote: Here's a rough clip of the brown channel. Signal path is guitar, amp, load box, Logic with Redwirez IR. No other post processing.

Sounds cool!

Norman86

Very neat! Thanks for the share!