Plexi 6v6 - Any mods?

[martinman]

I just finished the plexi 6v6 build - boy is it loud!  Before I button it up I was wondering if there are any popular / advisable mods that I can tackle? 

Some ideas:
1) Power scaling for master volume?  For me, it's almost unusable at bedroom levels.
2) NFB Switch w/ other resistors?  I did this on my Princeton build and it changed things up, but i wasn't too effective.  OTOH, in my 5e3 it was.  Wondering what sort of effect this mod would have in the plexi 6v6?
3) Ok, so a bit of a departure from the main goal of this amp -- but how does one add add more gain at lower volume?
4) I'm using an Eminence Patriot Swamp Thang which is pretty brittle on the top end ... and LOUD.  Maybe I should start here?  What other options should I consider?

Any thoughts?

[scstill]

one of these
https://www.tedweber.com/gadgets/attenuators/

[bmccowan]

I agree that it is not a bedroom amp.
Some things you could try:
Changing to cathode bias - small change in volume but a bit earlier breakup and less "brittle." probably.
VVR if you change to cathode bias - vvr for fixed bias is more complicated.
6K6 output tubes - but it'll still be damn loud.
Use a boost pedal and turn down the volume on the pedal. Works pretty well with some pedals.
Attenuator as mentioned. I have one of the cheap Bugera (something like that) ones - not bad.
Bigger bedroom.
2x6V6 amps are loud. I have a few and none are bedroom friendly.
Speaker - I play mine into a Greenback 12, sounds good - not brittle.

[AlNewman]

You could try a post phase inverter master volume.  Works great on my super reverb, not sure how it would work on your plexi.

[martinman]

I'm still learning....   I can't quite understand how you can get a 5e3, champ, or even Princeton sounding good at a loud bedroom level.  But the Plexi 6v6 or an 18 watt Marshall goes from 0 to uncomfortably loud at "1".  I tamed the 18watt with SkipZ VVR - it was a game changer. 

I searched through the forum and others and found that some builders had success with a PPIMV.  It looks to be a fairly straight forward mod - the Mod5 approach on the 2203 hoffmann build looks like a perfect match.  I'd like to keep it as stock as possible. 

I also have a greenback on order - found a great deal.

We'll see! 

[bmccowan]

Oh and I forgot to mention. The volume and tone pots on your guitar are the most underused controls. If your P-6V6 seems to jump quickly to uncomfortably loud, I would certainly play with the interplay between your guitar pots and the amp pots. The wattage output of the Plexi-6V6 is no higher than that of a Princeton or 5E3, but all are too loud for the bedroom IMO. That's what my basement and camp in the woods are for.
But I actually have had pretty good success using an overdrive pedal and adjusting the volume and gain pedals to get a good lower volume tone. It's cheating for sure, but WTF.

[purpletele]

I just added a PPIMV to my 18 Watt 6 v 6 Plexi.  I had poor results previously and left alone and used the amp as a back up amp for friends performances.  Recently I found a nice sketch that Slucky had provided for me utilizing two conductor shielded wire, and a 250K Dual Pot. 

It worked wonderfully!! I can crank the amp up and get tones that make you think you're playing a 50 Watt amp with full saturation and sustain, I am really enjoying the new freedom.

I couldn't find the thread where Sluckey provided the detail, but I can make a copy of it and post it if you are interested.

Brian V

Edit:  Here is the link https://el34world.com/Forum/index.php?topic=27348.msg300624#msg300624

[d95err]

For me, only one method works for playing a non-master volume amp cranked at bedroom levels:

Amp into reactive load. Output to digital speaker simulation and then to headphones or studio monitors.

For more gain at lower volumes, you could try some type of “hot-rod” mod, a la Friedman, Jose, Cameron. That’s basically ditching the normal channel and using that gain stage to boost the bright channel, then add a master volume. Optional diodes for even more clipping.

With my Plexi-ish amp, I did this, with a low/hi gain input. The high input has the boost stage. The low input is effectively the Plexi bright channel. With the master at max, I can still get that Plexi crunch (albeit at max volume).

[sluckey]

Hello purpletele. Good to see you still hanging around.

[tubenit]

I would suggest the PPIMV, cathode biased and possibly a 12AU7 in the LTPI.


You could also try a 12AY7 in V1. The 1st Marshall jtm45 was modeled after the Bassman 56F-A which uses a 12AY7. Then use some pedal like a Timmy or Zendrive or Klon clone to add preamp gain.


FENDER.PDF (el34world.com)
Marshall_jtm45_first.pdf (el34world.com)


I have a 6V6 amp that is fantastic at "bedroom" levels and can play it at similar volumes as my 6BM8 amp & still have tone I enjoy alot. I use a Warehouse ET65 and it's not brittle or too bright at all.


With respect, Tubenit

[Beezerboy]

I've built two. both with Pre phase inverter master volumes. they both sound great, but at bedroom volumes you still have to roll back the guitar's V knob. I added Slucky's "one tube reverb" to my second build. works great! (thanks man!) that is truly a "no pedals needed" amp.  a friend liked it so much he made me sell it to him. I resisted for a year or so, but eventually gave in when he said "it has changed the way I play". he's a pro and gigs every week (even in these times). I'm in the process of building another

[sluckey]

I added Slucky's "one tube reverb" to my second build. works great! (thanks man!)

I've never had a one tube reverb. That is probably tubenit's circuit.

[dwinstonwood]

I built my Hoffman Plexi 6V6 with his hot switch mod (although, I removed the switch and hard-wired it always on).
I can get a lot of overdrive at lower volumes. I also have a Weber MiniMass, as suggested above.

[Beezerboy]

I was thinking about it last night... the Hoffman 6V6 Plexi has the master volume already in the circuit.... thats why I did it that way.

and 'doh.... Slucky is right, it was Tubnit's One Tube Reverb circuit I used