PPIMV and tone changes

[fierce_carrot]

I'm new to this forum but not new to building amps having built a GDS 18 watter and a Blues Deluxe. I also have a couple of decades worth of electronics experience so I'm not a complete novice but I'm not at "propeller head" like some in here!


Looking at a Ceriatone Express kit with Moose power. My question is the PPIMV modification from Ceriatone based on Ken Fishers PPIMV and will it dramatically effect the overall tone of the amp?

Based on dozens of MV amps I have had in the past, every last one of them SUCKED the tone away. I've never owned an amp with a PPIMV mod to it so that brings me here.

What I dont' want to do is incur any major changes in tone but I do want some additional control over the EL34's incredible volume. I intend to push 2 separate cabinets loaded with (2) 2X12 Celestion Blues and (2) Celestion Greenbacks.

I've used various attenuators such as the MASS, hotplate, powersoak and marshall and thought off of them sucked with the exception of the MASS and it worked best when run in parallel with an existing cab by creating additional load, but the volume drop wasn't enough.

I've looked at the Liverpool but based I already have an EL84 based amp with my GDS/Marshall and my Deluxe is running 6L6's. I usually run a 2 amp setup on my gigs so the different output tube tone is something that really appeals to me.

[philmanatee]

I can't answer your master volume question, but you can run 6V6's in an express if you use the 6600 primary taps on the output tranny. It doesn't reduce the volume massively, but it may be enough. Phil

[pureoldsound]

I don't have a PPIMV on my wreck but I have it installed on my V-plex 100W. I've used regular MV and yes they suck up your tone like there is no tomorrow...The PPIMV works like a charm on my V-plex. I prefer it to an attenuator. Would it give me the same tone as it the amp was to be cranked, not in a million years. That PI tube distorts like crazy so at low volumes that is were the distortion comes from. Having said that but I think most of the gain from a plexi comes from that PI tube and power tubes just add a bit more saturation....On the case of the Wreck I guess it will be a cool thing to try, however if I am not mistaken the gain from the express comes from the power tubes. The question is how much distortion that PI tube has on the Wreck…..?

[rockstah]

i think it depends on what u think good tone is or not -
some drums in pro tools, recorded a rhythm track, improvised a solo, put some doubler on the rhythm and some delay on the lead.

build #1
http://www.soundclick.com/bands/songInf ... ID=4780591

with ken fishers type 2 PPIMV with a slight tweek - 250k lin pot is used instead of his 100k pot. also 2.2m resistence is added to safe guard if the pot fails as well as add up to 220k when dimed = out of the circuit when dimed. - i think it sounds great personally.

here is layout i did for the PPIMV type 2 used here. - more clips in that link as well.
[img:136:120]http://img1.putfile.com/thumb/11/31302520035.jpg[/img]

Mark

[Fischerman]

I've got all the stuff ordered (but not delivered yet) to build one of Nik's Expresseses but I also ordered a Power Scaling Kit from London Power. It seems that with an amp like an Express (i.e. extremely dynamic/touch sensitive), a power scaling approach might work better than a post-PI MV in order to preserve that. But that's just a guess...I like post-PI MVs in Marshalls...rockstah's clips are a great example of how good they can sound.

I've always wanted to try power scaling anyway. BTW - when you install the LP power scaling kit you also install a post-PI MV as part of the circuit...but it's called the 'Drive Compensation' control.

[fierce_carrot]

These are exactly the kind of answers I was hoping to get. Rockstah's tone is SMOKING...no doubt about it.

I've read that the trainwrecks unique preamp stages are where the real tone is developed and that the power stages add warmth to the sound. Having a GDS 18 watter, I know that the tone of that amp is where the el84's are flat cooking, and I'm very leery of viewing the express any differently.

I don't want to sacrifice touch sensitivity and that TONE. I've done research on both the Richter and Ultimate Attenuators thinking that if the PPIMV is a tone killer, then an attenuator (ughhh) may be the only way out.

[dobbhill]

The only way for me to get Express tone is:
Guitar + wire + Express + 4x12 cabinet
Just my opinion. That's why I only play my express (clone) outside!!!
D

[UR12]

I've always wanted to try power scaling anyway. BTW - when you install the LP power scaling kit you also install a post-PI MV as part of the circuit...but it's called the 'Drive Compensation' control.

You can also scale the whole amp, meaning not just the power amp section but the preamp also. If you try this approach you won't need the DCC.

[David Root]

I am starting a build with a Hiwatt type power end, i.e. 100K instead of 220K resistors, so I go back to the 100K pot, unless I want to have the capability to go up to 220K or so? In any event there should be a 10:1 or better relationship between the bypass resistors and the pot value?

FWIW, the earliest use of a dual pot as a PPIMV I have seen is on the Park 100W "Rockhead" model 1210/1240, designed by Steve Grindrod around '79-'80. However, this does not involve the bias supply.

[David Root]

I just read all 20 pages of the metro amps thread, so I know exactly what to do now! For 100K bias resistor, use 180K safety resistor instead of 2.2M. If you want 150K or so, use 470K instead of 2.2M. But still use the 250K pot because it picks up less crap from the air than higher values.

Rockstah's clips did it for me!

I also registered on the metro amps forum. Another great site I didn't know about! Randall Aiken lurks there too, like he does here, so I know both forums (fora?) are the real stuff. Also Larry from Germany, on the metro forum, is owed a debt too.