Big Muff Plus

Original effects with schematics, layouts and instructions, freely contributed by members or found in publications. Cannot be used for commercial purposes without the consent of the owners of the copyright.
User avatar
grrrunge
Diode Debunker
Information
Posts: 810
Joined: 20 Mar 2010, 10:51
Completed builds: Loads!
Location: Copenhagen, Denmark
Has thanked: 50 times
Been thanked: 206 times
Contact:

Post by grrrunge »

mictester wrote:BTW, a very "well-known" guitarist recently described this as his favourite distortion pedal, and that it was "as good as any three others put together because it's so flexible". Now it's getting serious "word-of-mouth" support in the musical community here, and I'm having to make quite a lot of them. I'm thinking about making some PCBs. If I do, I'll offer them on here for the price of the materials and the postage plus one beer!
I'm seriously up for one of those too, if you decide to make pcb's :)
...heck! I'll chip in for a sixpack. That 'one beer' thing never seems to work out for me anyway :D
A true believer in the magic of Sherwood Forest Pedal Pirates
---
New base of operations: http://www.knucklehead.dk

User avatar
JOHNO
Cap Cooler
Information
Posts: 563
Joined: 21 Jun 2009, 07:13
Has thanked: 47 times
Been thanked: 53 times

Post by JOHNO »

This layout has been built and VERIFIED. Just need to do a BOM for you guys. I'll do it tommorrow or next year sometime. :thumbsup You will need to tweek the 220k resistor (R24) to get the fet biased correctly. Or maybe you could put a 500k trimmer in there instead.
STUPER MUFF.png

User avatar
JOHNO
Cap Cooler
Information
Posts: 563
Joined: 21 Jun 2009, 07:13
Has thanked: 47 times
Been thanked: 53 times

Post by JOHNO »

I can't get the fet to bias for the life of me. I used a BS170.I think i have it in correctly,drain to 9v and source to ground, Is that right? The most voltage i can get on the source is 2.5v and if i turn the bass control down the voltage drops to around 1.5 or something like that. Is that supposed to happen or do I have a problem? The circuit seems to work ok all controls work, but the bass has minimal effect. I must have a problem somewhere that i'm over looking.

User avatar
mictester
Old Solderhand
Information
Posts: 2923
Joined: 11 Sep 2008, 20:29
my favorite amplifier: Mesa Boogie, Roost Sessionmaster, AC30
Completed builds: Hundreds! Mostly originals, a few clones and lots of modifications.
Location: Somewhat closer to Amsterdam than before!
Has thanked: 32 times
Been thanked: 844 times
Contact:

Post by mictester »

JOHNO wrote:I can't get the fet to bias for the life of me. I used a BS170.I think i have it in correctly,drain to 9v and source to ground, Is that right? The most voltage i can get on the source is 2.5v and if i turn the bass control down the voltage drops to around 1.5 or something like that. Is that supposed to happen or do I have a problem? The circuit seems to work ok all controls work, but the bass has minimal effect. I must have a problem somewhere that i'm over looking.
You've probably got a short that's taking out the 100n cap in series with the gate of the second FET. That would account for the variable bias condition as the bass control is varied.

I haven't tried the buffers with BS170s - I use 2N3819. Does the input FET work OK?
"Why is it humming?" "Because it doesn't know the words!"

User avatar
JOHNO
Cap Cooler
Information
Posts: 563
Joined: 21 Jun 2009, 07:13
Has thanked: 47 times
Been thanked: 53 times

Post by JOHNO »

mictester wrote:Does the input FET work OK?
The one i built doesn't have a fet input. I just used the original muff input. At the moment this is how the fet is set up.
22k on the source to ground
180k on the gate to ground
5R on the gate to +9V (supposed to be 220k in the schematic.)
Drain connect directly to +9V
Here are the voltages i have with 8.98V supply.
Drain-8.98V
Gate -4.43V
Source-2.68V

I'm going to lash the fet circuit up in the bread board and see how it works on there.
Just woke up so i'll check the circuit again soon and see if i can find the problem. This is the schematic i used but with standard muff input and with out the electronic switching.
BMPlus.PNG

User avatar
JOHNO
Cap Cooler
Information
Posts: 563
Joined: 21 Jun 2009, 07:13
Has thanked: 47 times
Been thanked: 53 times

Post by JOHNO »

This is it. All working correctly. I ended up with a 56k bias resistor on the fet in place of the 220k and 100k trimmer but i used a bs170. There was a small mistake in my layout but all fixed now. I'll stick up a BOM soon. Can't figure out how to do it in DIYLC.
Stuper muff.png

While this is a good sounding circuit, I guess I just don't dig the muff sound as much as i used to.
PS. Perhaps the Moderators could remove some of my other posts that are cluttering up this thread, thanks.

User avatar
JOHNO
Cap Cooler
Information
Posts: 563
Joined: 21 Jun 2009, 07:13
Has thanked: 47 times
Been thanked: 53 times

Post by JOHNO »

Here is the BOM

R1-39k
R2-82k
R3-390k
R4-100R
R5-22k
R6-Fucked up, just forget this one.
R7-1k
R8-10k
R9-82k
R10-390k
R11-12k
R12-100R
R13-10k
R14-82k
R15-390k
R16-100R
R17-22k
R18-100k
R19-10k
R20-180k
R21-1M
R22-1M
R23-180k
R24-220k/ adjust for fet bias or used a multi turn 500k trimmer.
R25-22k
R26-82k
R27-390k
R28-8k2
R29-22k
R30-1k
R31-100k

C1-100n
C2-560p
C3-100n
C4-100n
C5-560p
C6-47n
C7-100n
C8-560p
C9-47n
C10-100n
C11-1n
C12-10n
C13-2n2
C14-100n
C15-22n
C16-100n
C17-100n
C18-100n
C19-1n
C20-470n
C21-100uf Forgot to put this one on the layout, just stick it in any where you like from Ground to +9volt.

User avatar
Cannibal
Breadboard Brother
Information
Posts: 76
Joined: 24 Jul 2010, 12:53
Location: Milan, Italy
Has thanked: 27 times
Been thanked: 15 times

Post by Cannibal »

JOHNO the bs170 is a mosfet, not a jfet. That's why it wouldn't bias correctly :D
Seiche wrote:there's a difference between being drugged (I don't think it was only booze) and retarded.

User avatar
JOHNO
Cap Cooler
Information
Posts: 563
Joined: 21 Jun 2009, 07:13
Has thanked: 47 times
Been thanked: 53 times

Post by JOHNO »

Really? The data sheet says it's an enhanced mode field effect transistor. The only other thing i have is a mfp102 but it has different pin out. But i'm not sure if thats a fet either. Have to check the data sheet for it. i did get the bs107 to bias correctly though. Thank's Cannibal i will look in to this some more.

Just checked the data sheet for the mpf102 (not mfp102 no wonder i couldn't find the data sheet for it) mabye it would be a better option. I'll try it out later.

User avatar
JOHNO
Cap Cooler
Information
Posts: 563
Joined: 21 Jun 2009, 07:13
Has thanked: 47 times
Been thanked: 53 times

Post by JOHNO »

I pulled out the BS170 which i used inplace of the 2N3819 and stuck a MPF102 in it's place. It biased up with 820k for R24 and has quite a bit more output from the circuit now also.
Voltages on the fet with 9v supply are now,
Drain;9V
Gate;1.46v
Source;4.52v

Also i think i may have the wrong values for the caps in the tone stack. What is the total of two 1n caps in series?

User avatar
JOHNO
Cap Cooler
Information
Posts: 563
Joined: 21 Jun 2009, 07:13
Has thanked: 47 times
Been thanked: 53 times

Post by JOHNO »

I messed up the caps, C13 should be 470p and C15 4.7n. Sorry.

User avatar
mictester
Old Solderhand
Information
Posts: 2923
Joined: 11 Sep 2008, 20:29
my favorite amplifier: Mesa Boogie, Roost Sessionmaster, AC30
Completed builds: Hundreds! Mostly originals, a few clones and lots of modifications.
Location: Somewhat closer to Amsterdam than before!
Has thanked: 32 times
Been thanked: 844 times
Contact:

Post by mictester »

JOHNO wrote: What is the total of two 1n caps in series?
500pF - capacitors in series behave like resistors in parallel (for the purpose of calculation) and capacitors in parallel behave like resistors in series....

The only reason I used capacitors in series was to get values that I didn't routinely stock!
"Why is it humming?" "Because it doesn't know the words!"

User avatar
bigmufffuzzwizz
Breadboard Brother
Information
Posts: 131
Joined: 04 Mar 2011, 21:42
my favorite amplifier: 1973 Sunn Model T
Has thanked: 3 times
Been thanked: 2 times

Post by bigmufffuzzwizz »

Thanks for sharing the schem's mictester! I'm always for building a crazyy fuzz and a modded big muff is right up my alley! I'd like to see your vero/pcb layouts if you ever finished them.. :D
Magic Pedals Home of The Shrine Fuzz!

User avatar
Ben N
Cap Cooler
Information
Posts: 506
Joined: 12 Dec 2008, 03:34
my favorite amplifier: Ampeg J12D Jet
Location: Israel
Has thanked: 192 times
Been thanked: 53 times

Post by Ben N »

There were FET buffers (probably necessitated by the switching) in Ibanez's FZ5 "60s Fuzz" from the Soundtank Series, which was a modded BMP. The sound was a lot brighter than a standard BMP, but that also probably had as much to do with the too-small coupling caps and the screwy values in the tone stack.

User avatar
mictester
Old Solderhand
Information
Posts: 2923
Joined: 11 Sep 2008, 20:29
my favorite amplifier: Mesa Boogie, Roost Sessionmaster, AC30
Completed builds: Hundreds! Mostly originals, a few clones and lots of modifications.
Location: Somewhat closer to Amsterdam than before!
Has thanked: 32 times
Been thanked: 844 times
Contact:

Post by mictester »

Ben N wrote:There were FET buffers (probably necessitated by the switching) in Ibanez's FZ5 "60s Fuzz" from the Soundtank Series, which was a modded BMP. The sound was a lot brighter than a standard BMP, but that also probably had as much to do with the too-small coupling caps and the screwy values in the tone stack.
I just realised that I haven't put the PCB layout up here. I'll dig the whole mess out, complete with additional notes, BOM and panel layout. I built three of them last week, and they were all gigged in London at the weekend! The latest version has a 4066 on the board for the optional switching (and to keep it silent). I had a few issues with the layout at first because I wanted to keep it as compact as possible, but they're sorted out now.

I've also been working on a 3046 Tonebender that should be available as a kit from a well-known kit supplier soon. It includes the filter capacitors that give it that "germanium" sound, and it didn't need any temperature compensation!
"Why is it humming?" "Because it doesn't know the words!"

User avatar
JOHNO
Cap Cooler
Information
Posts: 563
Joined: 21 Jun 2009, 07:13
Has thanked: 47 times
Been thanked: 53 times

Post by JOHNO »

mictester wrote:I've also been working on a 3046 Tonebender that should be available as a kit from a well-known kit supplier soon. It includes the filter capacitors that give it that "germanium" sound, and it didn't need any temperature compensation!
This doesn't sound right to me. I think that once you give the 3046 that germanium sound the chip will start to react like germanium and it will become unstable. I think your lack of experience tuning silicon to "sound" like Ge is starting to show. :slap:

User avatar
minnow
Breadboard Brother
Information
Posts: 145
Joined: 30 May 2010, 03:51
Has thanked: 27 times
Been thanked: 16 times

Post by minnow »

destro wrote:From the other forum:

Hi,
I built the 'Bigger Muff' for Korn and then another one for Sepultura to use on the road.
They were a hybrid of discrete transistors and a single high gain tube distortion stage.
I have no schematic - they were built as a 'breadboard' experimental circuit that worked
so well that everyone wanted to use it for years to follow. I closed and sold the studio a few
years ago.

The original plywood pedal that was used on all the Indigo studio albums went to David Lyons at Sonic Circus.

Best wishes,
Richard
Can I drive a(ny) stock BMP output to a Valvecaster as a quick, dirty and silly attempt on getting the Bigger Muff?

User avatar
RnFR
Old Solderhand
Information
Posts: 4879
Joined: 09 Jan 2008, 06:02
my favorite amplifier: Traynor YBA-III, Fender Super Six
Completed builds: custom fuzz.
Location: Inner Earth
Has thanked: 139 times
Been thanked: 133 times
Contact:

Post by RnFR »

there's no reason you couldn't. you can drive anything into anything. it's just that you won't know how it sounds until you try.
"You've converted me to Cubic thinking. Where do I sign up for the newsletter? I need to learn more about how I can break free from ONEism Death Math." - Soulsonic

Blog-APOCALYPSE AUDIO

User avatar
mictester
Old Solderhand
Information
Posts: 2923
Joined: 11 Sep 2008, 20:29
my favorite amplifier: Mesa Boogie, Roost Sessionmaster, AC30
Completed builds: Hundreds! Mostly originals, a few clones and lots of modifications.
Location: Somewhat closer to Amsterdam than before!
Has thanked: 32 times
Been thanked: 844 times
Contact:

Post by mictester »

Busy, busy, busy....

I haven't had time to get all the board layouts transferred from the notebook (and the acetate) into electronic form for FSB. I'll get it all done this week. There's a really nifty Vero layout, and an even better PCB. I've included 4066 "function switching" to further expand the range of sounds available. It's really quite a beast now!
"Why is it humming?" "Because it doesn't know the words!"

User avatar
destro
Breadboard Brother
Information
Posts: 123
Joined: 06 Oct 2007, 14:24
my favorite amplifier: Peavey Classic Series
Location: Kentucky
Has thanked: 8 times
Been thanked: 36 times

Post by destro »

Still hoping to see your vero and pcb layout for this project, mictester!

Post Reply