YAROGP: Peppermill

Noplasticrobots · August 03, 2006, 02:15:17 PM

Yet Another Run Off Groove Praise: Peppermill!

I breadboarded the circuit a while back and enjoyed it so I soldered the circuit together on perf without the jacks and pots and forgot about it. I opened a drawer a couple nights ago and rediscovered it. Nothing like finding a half done project! Wired it up in about an hour and after debugging two (yes, two!) dead batteries, the thing worked pefect ("...I knew I had it wired correctly!"). I threw it in the mystical mojo enclosures I mentioned earlier this week and commenced to jigglin'.

I don't know what else I can add to the already numerous build reports on the Peppermill, so I guess I'll just have to say this: build this thing! It's simply amazing. Playing through a solid state Park G10R with Gain 1 all the way up and Gain 2 all the way down, this thing gives me a great bluesy tone and I'm positive it could be adequately put to use in any musical situation. If you've been heistant about this build, it's about time to give in to it's ROG goodness.

markm · August 03, 2006, 02:37:35 PM

Yep, that Peppermill is a real nice sounding stomper.
I think I did a couple of mods to mine that gave it just a tad more grit but not too much.
Have fun with yours!!

Noplasticrobots · August 04, 2006, 12:52:49 PM

Why type of mods did you do? The only difference in my build from ROG's was using a 500k pot on the gain instead of a 250k. Because of the higher pot value I used a 220k resistor from the pot to ground. I don't think this adds any significant change to the circuit but it still sounds magical.

I love it when I crank the gain all the way up and play on the bridge pickup. I don't know what the correct "tonal adjective" is in this case but it sounds very "saturated" to me. It really is one of the best sounding circuits I've built. I think instead of putting "Peppermill" on the enclosure, I'll put "Mojomill".

markm · August 04, 2006, 01:55:18 PM

Don't hold me to this because I don't remember exactly what I did to mod the PM but, I think I may have changed the source resistor values and a couple of the caps.
This was a while ago before I started saving info on various mods I have done to various circuits along with the end result.

This may be what I did but like I said I don't remember exactly, It did provide just a tad more "grit" to an already superb sounding circuit.

KerryF · August 04, 2006, 02:53:45 PM

Sound clips? I would like to hear it other than the ROG clips.

markm · August 04, 2006, 03:33:31 PM

I have no soundclip capabilities at the moment. I can listen to them but alas, I cannot make 'em.
Like I said, it sounds just a little bit grittier than the ROG samples.
There's a little bit more umph to the gain control.
I do beleive it was the source resistor I changed, maybe I'll have to open it up and see for ya.

Noplasticrobots · August 04, 2006, 07:29:16 PM

If you could, that'd be great because someone else on the boards just asked about Peppermill mods.

KerryF · August 04, 2006, 08:04:58 PM

What would it be like if I put a 100k trim pot instead of the 50k one, and a 100k linear pot instead of the 250k linear pot? Would it be a huge change? Anyone know what it will sound like? Will it be bad sounding?

markm · August 04, 2006, 08:55:40 PM

Quote from: markm on August 04, 2006, 03:33:31 PM
I have no soundclip capabilities at the moment. I can listen to them but alas, I cannot make 'em.
Like I said, it sounds just a little bit grittier than the ROG samples.
There's a little bit more umph to the gain control.
I do beleive it was the source resistor I changed, maybe I'll have to open it up and see for ya.

Quote from: Noplasticrobots on August 04, 2006, 07:29:16 PM
If you could, that'd be great because someone else on the boards just asked about Peppermill mods.

Yeah, I was right.
I changed the source resistor on the BS170 to a 680R and the cap from the gate to lug 3 of the gain pot to a .01
I also used a different layout than ROG.....

I think the changes sound good but, I told ya it was nothing radical!
Just a tad more grit to it.
What a great sounding little circuit!

billings · August 06, 2006, 08:03:35 PM

I built this on the breadboard yesterday and plugged it in. I decided to bias Q2 according to the guidelines given in the fetzer valve revisited article; for whatever reason I also decided to up V+ to 18V, which put me at an Vs of 0.36 and Vd of 10.9 for the components i was using.

The result didn't really distort that much, but it had a wonderful clean sound. It sounded as described, like a fender amp; probably moreso since the Q2 stage was more of a rip from the fetzer valve circuit. When I put a booster in front it would break up very nicely, but on its own it still sounded kind of helpless. I tried swapping the 100k resistor underneath the gain pot for a 1M resistor; that seemed to help a bit, but it still won't add much if any distortion to the sound. Is increasing the gain from the MOSFET the best solution here, or is there something else I should try to overcome the higher source resistor value? Or should I abandon all this and try the stock JFET setup?

Oh, and due to the 18V supply it is way too loud. I'll probably change it back to run on 9V instead. I'll also probably try messing with the MOSFET gain to see if that helps...

lessthanmatt88 · August 10, 2006, 03:09:10 PM

Just an idea, but has any one ever thought about maybe changing the JFET part of the circuit to how they set up the fetzer valve to emulate a triode? I'm not looking at the schematic right now so I dont even know if its possible, but the thought just came to my mind.

lessthanmatt88 · August 10, 2006, 03:10:32 PM

Hmm, acutally it looks like billings did that, I must be pretty out of it to have missed that...

billings · August 10, 2006, 05:00:58 PM

Yeah - I cut the circuit back to 9V and it is just a dream. Not a real fierce overdrive, but does give those gorgeous clean tones. Using it plus a MOSFET booster into the marshall is a lovely afternoon. I've found happiness replacing the 250k+100k q2 input resistor setup with a 1M pot, but I think it might have changed the way it plays a bit for the worse. I'll put the original stuff back and try lowering the source resistor on q1 and see if that helps.

I haven't built the original, though, so I can't tell you if those changes improve anything. I'm still a little hands off with the stuff I build... hopefully I'll get over that soon.

DuncanM · August 10, 2006, 05:52:05 PM

Quote from: lessthanmatt88 on August 10, 2006, 03:09:10 PM
Just an idea, but has any one ever thought about maybe changing the JFET part of the circuit to how they set up the fetzer valve to emulate a triode? I'm not looking at the schematic right now so I dont even know if its possible, but the thought just came to my mind.

Yup, I was doing just that last weekend - the fetzer sounds very nice so I put the mosfet section from the Peppermill/BlueMagic in front of it to overdrive it.
For me, it sounded a bit flabby on the low notes, so I added a little filtering between the sections (470k/470pF in parallel before a 500k pot for the drive control from the BSIAB II).
Sounded OK, not quite good enough to get me excited - there seemed to be a strange overtone that I didn't like. I tried messing with the mosfet's bias without much improvement.
Others might have better results - I didn't have enough time to play with it... $:-\$

Ge_Whiz · August 10, 2006, 07:46:31 PM

More classic B.U.M.

RaceDriver205 · August 10, 2006, 09:01:27 PM

QuoteI have no soundclip capabilities at the moment. I can listen to them but alas, I cannot make 'em.

Build the Marshall Speaker Sim/ DI box ! Works insanely well and its very very simple to make.
Check it out: http://home.worldonline.dk/jradmer/diy/spsim.htm

In addition to that you obviously need a computer (which you obviously have), and youll need to download free software called 'wavepad'.

markm · August 10, 2006, 10:59:06 PM

I've been meaning to get hooked up for making soundclips, just doing too many other things...
like building effects!

DuncanM · August 11, 2006, 05:46:12 AM

Quote from: Ge_Whiz on August 10, 2006, 07:46:31 PM
More classic B.U.M.

B.U.M.

MartyMart · August 11, 2006, 07:46:25 AM

Quote from: DuncanM on August 11, 2006, 05:46:12 AM
Quote from: Ge_Whiz on August 10, 2006, 07:46:31 PM
More classic B.U.M.

B.U.M.

"B.U.M" = "Blind Urge to Mod" !!
I dont see this thread as that though, just a desire to get a tad more "grit" from a Peppermill
.... fair enough ?

MM.

stm · August 11, 2006, 09:22:32 AM

So you want to get more gain out of the Peppermill?

Place a 4.7u in parallel with the 1k source resistor of the MOSFET. Instant mid boost a la TS!

Want higher gain but retain more fattness?

Increase the value of said capacitor to 10u, 22u or 47u as desired.

Wanted more gain, but not that much as above?

Place a series resistor with said capacitor. Values between 220 ohms and 1k will help to tame the gain boost.

Want to mess up with the gain of the second (JFET) stage also?

...I'll save this for another time, as I prefer hearing back from the above mods first.

Happy boosting and cheers!

P.D. yup, I got fun out of using the smileys!

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YAROGP: Peppermill