# Peavey Rockmaster Mods



## loktide (May 9, 2007)

I bought this thing a long time ago and haven't been using it since almost 6 years now after it went crazy. As its 100% analog, and designed pretty simple, I want to fix this thing myself. I assume it's just a minor loose connection on the PCB since i never seriously mishandeld this thing... Anyway, I read about this webiste (FJA) that mods this things and listened to their modded rockmaster soundclips. I REALLY dig the sound after the mod, so i decided to "resurrect" my rockmaster and mod it. The only problem is: I live in germany, so shipping costs plus getting the mod done for 175$ would be waay to expensive. 

So here comes my question: Does any of you guys got a schematic for this mod, or knows roughly what is getting modded? All I have so far is the original schematics of the rockmaster.


----------



## starsnuffer (May 9, 2007)

Why don't you write Jerry and tell him about your situation and see what he has to say? He might be able to make some suggestions.

-W


----------



## LordOVchaoS (May 10, 2007)

Jerry would probably help you troubleshoot it, I don't think he'll expect you to pay the shipping back and forth for him to fix it. He's a good guy and he knows his Peaveys!


----------



## dpm (May 10, 2007)

If you don't mind waiting a while there is always standard parcel post which is actually quite cheap for a 1u device. I've had a couple of 1u rack units shipped from the USA to Australia. 
Otherwise I'm sure there are some techs in Germany more than capable of doing what you want


----------



## loktide (May 10, 2007)

F*CK! I... eh.... kinda broke my rockmaster yesterday while trying to change a relay that decided to stop working. So i'll definitely will have to send it in to somebody who knows what he's doing and maybe even mod it. The problem is, I don't have money right now so I'll have to put this aside for a while


----------



## starsnuffer (May 10, 2007)

I'd have Jerry buy one, mod it, and sell it to you before I tried to ship it back and forth. They're easily available and cheap used. You can just sell the one you have.

-W


----------



## dpm (May 10, 2007)

I'm interested in buying the now broken one for the right price


----------



## Jeff (May 10, 2007)

Also ask Jerry (and also Trace at Voodoo) if they have any modders in your area that they recommend. I remember Trace in particular had recommendations for overseas modders. It's worth an e-mail.


----------



## zivblumberg (Sep 15, 2007)

say, could you upload here the schematics for the rockmaster?

or send it to me.. [email protected] thanks..


----------



## zlittell (Aug 12, 2009)

damn man i wish i was in germany lol i would be able to at least fix it if you have the schematic... if you have a buddy thats a us soldier stationed there its extremely cheap to ship to bases. it was just as cheap as regular us shipping.

check it out if its a possibility

fuck i just noticed this is old as hell... damn now i feel like a dumbass


----------



## op1e (Aug 13, 2009)

I thought I read somewhere that the Rockmaster is the same preamp as whats in the Ultra head. Is this true?


----------



## zlittell (Aug 13, 2009)

thats what has been said lol


----------



## silentrage (Aug 13, 2009)

So I've been looking around for mods to try on the rockmaster, and I've located a few, from a member on HC named heath mostly, I'm going to try them on mine and post the results here for those who have one and would like to improve it.

This being said, most people seem to think the easiest and fastest way to improve the preamp is to buy nice tubes for it, maybe NOS mullards or whatever other cork-sniffer-grade stuff you fancy. So if you're not into tweaking and possibly fucking up your rockmaster, stop reading now. 

Without further ado, here are the mods, straight from Heath: anything said after "NOTE" is my addition or comments.

1. Change the coupling caps (c4, c5, c14) out for .0022uf caps. This will thicken up the preamp alot and get rid of the cocked wah sound. Also warms up the clean channel too.
The coupling cap(C14 .001uF) feeding v2a rolls off everything below 340hz, replacing this with 0.0022uf (aka 2200 pf) makes it roll off at around 150hz, restoring some bottom. 

Also the cathode bypass cap on V2a (C17 .47uF) is cutting below 450hz. Replace that one with a 1.0 uF to move the cutoff frequency to 205hz. 
NOTE that heath said the C17 mod made the preamp borderline muddy, and he later reversed it back to stock.

2. The stock voltage the preamp tubes are seeing is 260v give or take. This is not the best sounding voltage for a preamp like this. 320 or so is much better. Change R33 and R34 out for 4.7k resistors. This will bring this preamp to life.
NOTE: I think he's referring to the plate voltage feeding the preamps. This will raise the current going through the tubes, and should cause more grid-current-limiting which is what you get when you bias warmer. 

3. Change the plate resistors to 100k(R3 and R13 only) This will give less distortion but a rounder gain. 
NOTE: The stock resistors are 150k. Lowering this value causes higher grid current, similar to the above mod which sounds more "vintage" or "mellow" due to slightly more even-order-harmonics. Using a larger value here results in harder clipping and slightly more odd-order harmonics, which sounds more "aggressive" and "modern". The highest you should go is 200k, anymore and it will oscillate.

4. Replace the ultra gain pot with a 50k This will make it a clone of the crunch channel(I did the opposite and changed the crunch pot to a 1M...I am gain freak I guess). 

5. The Mid control on the clean channel EQ doesn't really work so 
well. As you turn it clockwise it adds more mid-bass, but keeps an 
overall scooped response. This is caused by a capacitor across the Mid 
potentiometer. Peavey used a .015uF cap (C9) there. You could simply 
remove it, but that will result in the mid pot turning into more of a 
gain control considering its 50k ohm value. Instead, I recommend 
replacing C9 with a smaller value, between .003uF to .005uF.

6. The effects send & main outputs' coupling caps are too small, and may 
act as a low cut filter. This is noticeable if the unit is plugged 
into products with an input impedence below 100K ohms. The result is a 
thin sound, which is especially noticeable on the clean channel. To 
prevent this replace C40 & C30 each with a 1uF 400V film cap. You may 
be able to get by with a 250V cap, it all depends on the cathode 
voltages at each location."


These are in no particular order, and have not been personally tested by me, so grain of salt is in order. However I do plan on doing all of these soon, so watch out for a post reviewing the mods, or an angry rant about how I fucked it all up.


----------



## scott from _actual time_ (Aug 13, 2009)

silentrage said:


> So I've been looking around for mods to try on the rockmaster, and I've located a few....


very cool--thanks for posting. do report back after you try these.


----------



## Concerto412 (Aug 13, 2009)

Good Looking list of mods, I'm getting interested in swapping a few caps at least. I've been wondering about modding one of the many FX loops on my RM to function pre-gain, just need to finally dig out that schematic again.
Be sure and let us know how things go.


----------



## I is be sexy (Sep 7, 2011)

Did anyone ever do the mods posted by silentrage? If so, what's the verdict?


----------



## Jedi_Ekim (Jan 5, 2012)

I guess the verdict is "We don't know!" 

I'd be interested in this stuff too. I like the RM okay for now, but I'd like to clean up the distortion channels a bit to make them less distortion-y. Less buzz, more definition.

I really don't feel like dropping any dough on any more pre-s or amps right now.


----------

