Resurrecting Richard kaplan's "Bigger Muff"

[illuminatiNPS]

Hello all,

  I am new to this forum and an avid pedal collector. With the recent passing of the great Richard Kaplan, I decided to try and take up a project that he recently revealed before he died. That is his legendary Bigger Muff pedal. This is used extensively on Sepultura's Roots album as well as Korn, Slipknot etc.. The best way to hear the pedal soloed is to listen to Roots Bloody Roots and go to 1:50 into the song. It gives two soloed guitar parts. This is undoubtedly the pedal.  I spoke with Richard a long time ago and stated it was a DIY project, but being he named it the "Bigger Muff" I had ahunch he used some sort of schematic to get started. AfTER SEACRHING FOR A WHILE, I FEEL I HAVE FOUND THIS SCHEMATIC. Now the only mystery is to figure how he incorporated a transformer and tube into the mix. Here is the original:



Notice to the left you see "Vol" written. The top switch(which I thought was true bypass), is labeled "Tone". Look closely its faded. Then on the bottom right you see another black pot labled "sustain". Alll notice the 4 transistors going across the bottom. After seeing this I knew he had to copy a schematic. I came up on this one:



The resistor and transistor layout seem to be a match. The big mystery seems to be the right side of the original pedal. It has a transformer, a tube and some capaictors. I am wondering how those were incorporated. IF ANY OF YOU GUYS CAN HELP OUT IT WOULD BE GREAT. I THINK THIS WOULD BE A HELL OF A PEDAL TO CLONE. THANKS. NICK 9548021969

[induction]

Notice the power plug: this thing is meant to be plugged into the mains. I imagine the transformer is part of the high voltage AC to low voltage DC conversion circuit. I guess that would make sense if you wanted to use higher voltages for the tube and lower voltages for the transistor, but I'm just guessing now.

No clue about the rest.

[Cozybuilder]

The tube could be a rectifier.

[illuminatiNPS]

ahhhh. Makes sense. The 2 silver wires seem to go where a 9v battery would go on this same schematic. Then there is a red wire going scross. on top. Do you think the schematic for the board matches up??

[illuminatiNPS]

The tube seems to be a regular 12ax7 type tube.  However the big question is where does it fit into the schematic.

[Cozybuilder]

Its difficult to read the values or colors, the tropical fish caps on the board are 100nF, some of the resistors match up, can't tell with the others. Can't read the transistors. Better photo? Did you check what the tube designation is- 6x4?

[illuminatiNPS]

Unfortunately its the only picture that exists. This pedal was kinda kept secret for a while.

[MovingInSloMo]

oh wow I saw this in a guitar magazine in article with korn whilst they were working on the Life is Peachy album. It got me interested in tinkering with guitar effects

[Cozybuilder]

Love these kind of mysteries!

A quick google search didn't turn up that particular transformer, but judging from size and what appears to be a rectifier tube (6CA4 / EZ81; 6X4WA ; 35W4), the 3 huge caps, resistor, smaller electros and tropical fish cap (39nF?), I'm guessing its 12V. I'm not a power systems guy, hopefully someone will chime in and correct any mistakes here. According to this reference (http://www.hammondmfg.com/pdf/5c007.pdf), if half wave rectified with cap load it would yield a max of 0.9x12V = 10.8V , after rectifier loss and smoothing probably closer to 9V to the board.

There is a You Tube video of this: https://www.youtube.com/watch?v=VKv8tmLPZEE

[Fender3D]

the 2 "silver" wires look like coax for input and output...
maybe 12ax additional stage(s)... 220k might be anode resistor...

[illuminatiNPS]

Interesting stuff. Also I wonder where the red wire coming across from the tube ties in. I agree with the two silver wires being for In and Out. Makes sense. Do you guys think there is enough info here to try and build one? I'm looking for some who will take this on for the right price.

[Cozybuilder]

This is reply #11 from a May 2010 thread:   "Big Muff version to get Korn tone"   « on: May 21, 2010, 06:59:30 PM »

Well, I thought it might be fun and worth a try to send Mr. Kaplan an email. He was kind enough to respond. Check it out!

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.

[illuminatiNPS]

Yes I have read that email. What is a "discrete" transistor. At least we know the tube is an actual distortion stage. What do you think cozybuilder?? enough info to build or do we need more.

[Cozybuilder]

I would have to study this some more, not enough there right now. Its intriguing.

[slacker]

Interesting stuff. Also I wonder where the red wire coming across from the tube ties in.

My guess is the red wire is power, unless the left hand board gets power from a separate supply.

I'm afraid there isn't enough information in the photo to clone it. You could make an educated guess that the left hand side is some sort of big muff and possibly figure out the component values but there's no chance of working out what the right hand board does.

[MrStab]

i'm kinda bored at the moment and wanna help even though i have zero experience with the Big Muff or this rare variant.

i doubt you could get in touch with Korn (not capitalising the "R" must be a sign of age...) or the likes, but maybe you could try to get in touch with others associated with the pedal, such as that David Lyons guy or maybe some former road techs for Korn or Sepultura? maybe you've already tried that. worth a shot maybe!

[Blitz Krieg]

made in tawain

[Gus]

A few guesses

I would place the  tube stage between the fourth transistor stage and volume control and switch it in and out with a DPDT maybe the slide switch is a DPDT I think I read harmo(harmonics?) to the left of it maybe the tube stage switched in?  grey wires are in and out of the tube stage

As slacker posted the red wire is most likely the transistor section power supply lead

Can't read what is by the red handle toggle switch

I don't see any rectifier diodes on the tube stage board they must be blocked by other parts in the picture

I would guess the heater is DC and is also used for powering the BMP transistor section 6.3VDC or 12.6 VDC or maybe another voltage.  Maybe 12 volts and the bigger brown resistor at an angle above the BMP like circuit is to drop the 12 to 9VDC?

I only see one 100K possible plate resistor so maybe only one tube gain stage.

The tube could be single triode or a dual triode one side used or a dual triode both sides in parallel or a pentode as a triode or ...

For more dirt maybe a lower voltage B+ around 100VDC and a grounded cathode contact bias( I do not see a cathode resistor in the picture)

The black electro and what is connected in the clear sleeving would be a part of the B+ note they both connect to what I would guess is the 100K plate resistor

Can anyone read the writing on the perf board

[Derringer]

eh ... I see there's four transistors on that board, so most likely the gain recovery stage is standard.

I'd say, if you have the equipment, build the first three stages of a muff and then use a 12AX7 triode as the gain recovery stage with 100 or so volts at the anode and see what it sounds like. Don't forget to tune your guitar down to A or whatever they used to do ... you know, till the strings flap.

Hell, make the first stage of the muff the first triode and the last stage the 2nd triode. Bias and bypass to taste.

[illuminatiNPS]

Correct me if i'm wrong but just below the red switch i can make out an "ECC" and above it a word ending in "DE". Maybe it had the ability to switch between tube and silicon diode, like the Mesa amps. Remember Korn used triple recs. Maybe thats what Kaplan was thinking. Definitly an ECC under that red switch. The "E Harmo" on the left side of the board is probably a joke. It is a Big muff afterall.

OK my number is 954-802-1969. Would any of you be interested in building this for me?? If so call me so we can work out details (parts/ labor). Amazing how much experience on this forum. I think we are close.