Big Muff Plus

nek314 · Post by **nek314** » 06 Sep 2010, 23:33

I, for one, am eagerly awaiting this layout. Many thanks to Mictester for the time and effort he has put into it so far; I certainly don't want to rush him. I'm sure it will be a quality layout.

mictester · Post by **mictester** » 09 Sep 2010, 12:05

devastator wrote:thanks for the response mictester.

I always have a kind of hate/love feeling with the "big muff"

Me too! That's why I've been trying to make it better! The latest version of the circuit is below. There are a few minor component changes and additions (AC bypass to ground in the FET bias circuits).

There are also some optional switches added:

The first one switches in an additional capacitor from base to collector of the first transistor stage - this gives lowpass filtering. The 1 nF value for the additional capacitor is nominal (that's what's on my stage rig), but it can be increased (one client likes 2n2 there).

The second switch disables the clippers in the first distortion stage and turns the effect into (almost) a Jumbo Tonebender Plus! It's an interesting, less distorted option, and gives another tone colour to choose.

The third switch AC bypasses the emitter resistor in the first distortion stage. It has little significant effect when being used as a Big Muff, but in Jumbo Tonebender mode, it gives a bit more gain to get just a bit more distortion from the single clipper stage.

Feel free to experiment with the component values - as always, the values I give will work well, but you may be able to tweak the design to better suit your preferred sounds or your guitar rig. It's interesting to experiment with the values of the collector load resistors in the clipper stages (don't go much below or above 22k for the second clipper as you'll affect the operation of the Tone Controls). Try shorting out the emitter resistors (or AC bypassing them) in the clipper stages - the "Creamy Dreamer" is configured like that, and works well.

Remember that this is a very high gain circuit, and requires intelligent wiring and screening to prevent hum. If you find that it works as an AM radio receiver, a 47pF or 100pf from gate to ground of the first FET usually cures this completely. I've built quite a few of these now (people really like them!) and I build them in a diecast box, with the four pots in a line across the top, three (or four) small toggle switches (one beneath each pot), a super-bright bicolour LED (Green for Big Muff mode and Red for Jumbo Tonebender), and a good quality DPDT footswitch. It sips current from a 9V battery, and I'm really happy with it - it sounds great, has a good range of sounds, is pretty low noise (for a high gain effect) and costs little to build!

Vero and PCB layouts to follow soon!

Improved version:

: BMPlus.PNG (11.5 KiB) Viewed 3581 times

nek314 · Post by **nek314** » 09 Sep 2010, 21:37

Mictester, any solid idea of the dimensions of the pcb you're making? Will it be narrow enough to use board-mounted pots? I'm very excited for this build and want to start planning it out. I have a heavily-modified muff that I love dearly, but your take on it seems like it will be refreshingly different while maintaining the overall muff vibe, plus it will probably take up a lot less board space than an EH reissue.

mictester · Post by **mictester** » 10 Sep 2010, 01:22

nek314 wrote:Mictester, any solid idea of the dimensions of the pcb you're making? Will it be narrow enough to use board-mounted pots? I'm very excited for this build and want to start planning it out. I have a heavily-modified muff that I love dearly, but your take on it seems like it will be refreshingly different while maintaining the overall muff vibe, plus it will probably take up a lot less board space than an EH reissue.

I'm re-working the layout at the moment - I wasn't happy with it. The first few of these have been built on Veroboard. I'll post all the detail in the next couple of days. Sorry for the delay - I'm a bit busy at the moment.

nek314 · Post by **nek314** » 10 Sep 2010, 02:23

Far be it from me to complain about any delay in a completely free board layout done by a professional in his spare time amongst all the other projects you've had a hand in on this forum. Whenever you're done with it is fine by me, however long you feel like taking with it.

DrNomis · Post by **DrNomis** » 10 Sep 2010, 11:14

You know,what would be really interesting and cool,would be a schematic of The Bigger Muff,as used by Sepultura on their "Roots,Bloody Roots" album,I've been looking all over the internet,trying to find the schematic for it,apparently it is a big muff with a 12AX7 valve in it.....

nek314 · Post by **nek314** » 23 Nov 2010, 17:52

A 12AX7 as a gain stage or simply for clipping? I've found using tubes for clipping to be almost entirely pointless, but I'm no tone connoisseur, so opinions may vary.

HydrozeenElectronics · Post by **HydrozeenElectronics** » 24 Nov 2010, 01:28

Id like to hear more about this!

DrNomis wrote:You know,what would be really interesting and cool,would be a schematic of The Bigger Muff,as used by Sepultura on their "Roots,Bloody Roots" album,I've been looking all over the internet,trying to find the schematic for it,apparently it is a big muff with a 12AX7 valve in it.....

destro · Post by **destro** » 24 Nov 2010, 04:22

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

nek314 · Post by **nek314** » 24 Nov 2010, 17:03

I'm still interested in Mictester's take on this circuit, I've been looking to replace my heavily modded NYC Muff with something a bit smaller and more flexible, and this seems like the ticket.

nek314 · Post by **nek314** » 24 Nov 2010, 17:41

Forgiveness, please. I just realized that my most recent post essentially duplicates one I made earlier. It's been a few months, the old memory isn't so good.

Silvestre · Post by **Silvestre** » 05 Dec 2010, 07:08

nek314 wrote:I'm still interested in Mictester's take on this circuit

Hello everybody,

Yes, i think it would be very interesting to have a PCB layout to try the design out...

I hope our generous friend won't see it as beating the table with fork and knife, as much as i hope that the "Sepultura off-topic" had not make him retreat...

My sincere thanks for this post

devastator · Post by **devastator** » 13 Apr 2011, 11:58

any news for this project which seems really intersting ?

I'm thinking about removing the original PCB in my big muff (almost died because of my several modifications on it) for a new low-noise version of the circuit with additional controls.

Is it possible to add a "mid" control in the baxendall to have a total control on the frequencies ?

I played a lot with a mid switch in my big muff and I found it really interesting .

mictester · Post by **mictester** » 05 May 2011, 21:55

devastator wrote:any news for this project which seems really intersting ?

.

Thanks for the interest. I'll be putting PCB and Vero layouts up here shortly (I'm converting them from my hand-drawn scribbles).

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!

sinner · Post by **sinner** » 05 May 2011, 22:12

I up for one Chris

devastator · Post by **devastator** » 07 Jun 2011, 20:47

a little bump .

I was wondering , could we put a dual ganged pot to have a better linearity of the "drive" pot , the first part on the original place and the second part after the first gain/clipping stage ? this way we could give less already satured sound on the second clipping stage and get some kind of nice dirty drive with the gain pot rolled down a bit ?

by the way, putting buffers is the only thing to do to reduce the noise (which is really boring I must say) ?

i think I'll give a shot to this desing when I'll have components for my big muff usa , but mayb the original tonestack with a "mid switch" .

JOHNO · Post by **JOHNO** » 17 Jun 2011, 07:01

Here is a preliminary vero layout I've been working on today. I dropped the input buffer on this version but it does have the gain recovery stage on the end after the fet. I gonna work on it some more because the signal cross's the power line too many times for my liking, although looking at it again it only crosses twice. PCB designs have been promised for 12 months for this project so i thought it was about time somebody did something about it. I wouldn't build this one (it will be hard without a BOM

) It's more or less just to get us started in the right direction and besides that its probably wrong. Actually it is wrong, the output for a start.

STUPER MUFF.png

JOHNO · Post by **JOHNO** » 17 Jun 2011, 07:25

There just are not enough holes to get the thing on to a board 30 holes wide. What is the purpose of the 1k and 100k divider thingy on the output of the recovery stage?
This thing really needs a pcb but my routing skill just are not up to it.
Just found more mistakes.

And more mistakes around the tone stack, that fuckin this is doing my head in.

JOHNO · Post by **JOHNO** » 17 Jun 2011, 08:13

Ok this is closer. The divider thingy on the output will just have to float in the air there just isnt enough room on the board.
The BASS pot should be the TREB pot and visa versa. I'll fix it later.

STUPER MUFF.png

JOHNO · Post by **JOHNO** » 17 Jun 2011, 09:09

I'm positive i have the layout correct now. Not the one above, thats wrong. I suppose I had better start building it, although I could not be fucked building another muff.
There are some mistakes around the fet in the layout above but I've fixed those. I'm thinking that i will build it stage by stage and check each stage as i go to make sure its working before i move on to the next. That should guarantee a working circuit at the end. I don't want to spend all fucking night debugging the stupid thing.