How to make the most pedal-friendly Plexi?

[rfgordon]

I will soon have the task of building a Plexi style amp for a client.

It's very important to him (he runs a small recording studio) that the amp be very overdrive/distortion pedal friendly.

For y'all that have built Plexi type amps or variations, are there certain component values in certain places that make the most difference in that regard?

I think controlling the top end fizziness must be part of the equation, yes?

I would appreciate your opinions and experience on this.

[Reeltarded]

It sounds like he's going to be a sub-one-watt guy. Not the amp for him?

Normal channel cathode is a copy of the bright channel but no bright cap.

PPIMV. Pedals suck. PPIMV sucks, but not as bad as a pedal. Full drive from the amp at any volume.

And then constantly tweak away all the things he complains about for years because that is pretty typical when someone wants a plexi as a pedal platform. lol

[M Fowler]

If he wants his distortion from pedals then he is going to need a clean higher headroom amp.

The Rocket preamp with octal power section is a great pedal pusher. The Dumble Princeton layout floating around is a great pedal pusher. The Dumble Small Special is a great pedal pusher.

The Plexi would be overkill.

[Reeltarded]

It starts out nasal and stays there until you have it blazing hot.

[bolomule]

45/100...Jimi had pretty good tone with pedals and that amp. I think there is a Jimi Dickinson schem floating around the web FWIW.

[guitarmike2107]

What overdrive pedals, if its a tube screamer type mid hump pedal you need to cut the high mids in the tone stack, if its a boss sd1 type pedal leave the high mids there.

if the pedal has a wooly low end you need to cut the low mids in the tone stack etc etc

What does a pedal friendly amp even mean?? Think he should be looking for amp-friendly pedals instead

[rfgordon]

The guy has been using a plexi style amp I made out of a Bassman 50 donor. It has nice headroom and sounds exquisite when played clean with verb and delay. That said, it's on the bright side, so I suspect some of the guy's pedals may sound a bit fizzy through it. I'm considering putting in a 6 way rotary switch for the coupling cap from the first gain stage that has the .68 mF cathode cap.

Also, I don't know what speaker he's been using, so that could be a big part of it.

I agree that more of a Rocket front end may be the thing for him.

[geetarpicker]

I think the bass spec Marshalls tend to be more pedal friendly amps. I'd suggest a bass spec JMP Marshall 50 build. The bass spec Marshalls have more changes than just the preamp, including a different tone stack, different coupling cap values and more negative feedback. Overall the bass spec amps have less gain, are just a tad mid scooped, break up less, and seem a little less peaky in the upper mids. Personally my '68 Marshall Superbass 100 is my best pedal friendly rig, though a 50 watter can be easier to deal with.

[RWood]

I built a 1987 stock value plexi PTP with PPIMV. Playing it straight (PPIMV dimed, Volume 8-10) it had near perfect tone.
I tried a JB Fuzzface which was not too bad.
Tube Screamer had almost no effect unless the amp was turned down to 6-7 and what effect it did have was not pleasant to me. Dime it and OD was almost nonexistant.
CE2 Chorus was marginal at best except when turned down also.
So I'd say that it is not a pedal friendly circuit.

My question would be...Why pedal a plexi anyway?

[norburybrook]

I think the bass spec Marshalls tend to be more pedal friendly amps. I'd suggest a bass spec JMP Marshall 50 build. The bass spec Marshalls have more changes than just the preamp, including a different tone stack, different coupling cap values and more negative feedback. Overall the bass spec amps have less gain, are just a tad mid scooped, break up less, and seem a little less peaky in the upper mids. Personally my '68 Marshall Superbass 100 is my best pedal friendly rig, though a 50 watter can be easier to deal with.

I have a JTM45 and that works great with pedals, it also has a great clean sound. It also sounds great just cranked, but it's loud.

as Geetarpicker said these early marshalls are great as a pedal friendly amps. If you think about the jtm45 is just a beefier fender Bassman


Marcus

[Teleguy61]

What Reel said.

My 2/4x6V6 Rocket-style is a good pedal platform.
Not too bright, not too high gain.
My normal channel 6G6B Bassman combo is an excellent pedal platform.

[The Ballzz]

It is my considered opinion as a long time tube amp player who achieves tones to die for, that terms & phrases like "Pedal Friendly" or "Takes Pedals Well" actually translate to "Doesn't Add Any Color Or Tone to my already over processed sound!" Whenever the majority of tone/overdrive/distortion/etc. is derived from foot/stomp/pedal/thingies, the amp it's plugged into is of little consequence, until it starts adding it's own distortion, etc, which then often sounds like Doo-Doo on top of the pedal stuff!

Just My $.02 & Likely Worth Even less,
Gene