EHX - Big Muff Pi 1977 & 1978 version

RnFR · Post by **RnFR** » 13 May 2010, 06:28

topics merged.

ShortScaleMike · Post by **ShortScaleMike** » 16 Aug 2010, 13:06

ShortScaleMike wrote:I just did this for an IC Muff, it's unverified but may help anyone wanting to build one:

As always, build reports and corrections are welcome

This is now verified, just FYI

Ben N · Post by **Ben N** » 16 Aug 2010, 19:56

Mike, doing a demo?

ShortScaleMike · Post by **ShortScaleMike** » 17 Aug 2010, 13:00

I wish I had the time (or a working amplifier for that matter, my SF Champ just died

)

minnow · Post by **minnow** » 17 Aug 2010, 14:03

Mike, did you encounter any oscillation/squeals?
I did one recently, and it squealed like mad.
I did not use your layout though.
I am not sure whether it is the layout issue or my choice of components.
Definitely not the circuitry right? Haha.

Mictester was kind to help me out, finally got it sorted.
Just want to ask if you faced any issues with your build... Tq~

ShortScaleMike · Post by **ShortScaleMike** » 18 Aug 2010, 08:27

Nah it seems well behaved to me, in the little time I've been testing it.

minnow · Post by **minnow** » 18 Aug 2010, 11:15

Thanks Mike!

dune2k · Post by **dune2k** » 18 Aug 2010, 12:01

Didn't have any problems either (used shielded wire for in/output though).
Just have to find some error on my build. It behaves a little weird (I have to pick really hard on my bass guitar, otherwise the signal is pretty much clean... oO).

Ben N · Post by **Ben N** » 18 Aug 2010, 15:01

ShortScaleMike wrote:I wish I had the time (or a working amplifier for that matter, my SF Champ just died )

I feel your pain. My SF Vibrochamp is showing signs of its age, with volume dropouts and suddenly NO headroom. I think its time for new filter caps, but I just don't have the time to do, so I took the easy out and just switched amps. I've got three old dowagers waiting for cap jobs now--it's only a matter of time before I run out of amps, LOL.

timhulio · Post by **timhulio** » 21 Aug 2010, 18:53

Here's my pbc layout:
http://fredric.co.uk/index.php?blog=129

http://www.fredric.co.uk/misc/opamp_muff_verified.gif
http://www.fredric.co.uk/misc/opamp_muff_pcb.gif

SPeter · Post by **SPeter** » 22 Aug 2010, 10:15

Thanks!

Is it verified?

timhulio · Post by **timhulio** » 22 Aug 2010, 19:23

Sorry, should have said. Yes it is verified.

liorm · Post by **liorm** » 26 Aug 2010, 18:49

Thanks man!

Can you please specify capacitor's (+) and (-) - polarity - direction? for capasitor of micro and above?

Thanks again

BR.
Lior

minnow · Post by **minnow** » 27 Aug 2010, 01:45

liorm wrote:Thanks man!

Can you please specify capacitor's (+) and (-) - polarity - direction? for capasitor of micro and above?

Thanks again

BR.
Lior

Hi Lior, the info is in the layout which was provided: http://www.fredric.co.uk/misc/opamp_muff_verified.gif
For caps - the one with the square pad are +ve while the other (which is round) is -ve.
Similar for IC, square pad - pin 1 orientation.

jay42 · Post by **jay42** » 27 Aug 2010, 20:21

When did people get interested in these? I've got one...always thought it was one of the more despised EH creations. fwiw, I played with diodes and op amps. I found an op amp set that lets a the attack through better (imo). MC1456 (not a typo) and an LT1013. Audio taper volume pot, disconnected the battery switch, added TB and a millenium bypass ckt. for an led. I found that assymetrical diodes did nothing...1 or 2 mated with 3.

johnnyg · Post by **johnnyg** » 28 Aug 2010, 06:59

jay42 wrote:When did people get interested in these? I've got one...always thought it was one of the more despised EH creations. fwiw, I played with diodes and op amps. I found an op amp set that lets a the attack through better (imo). MC1456 (not a typo) and an LT1013. Audio taper volume pot, disconnected the battery switch, added TB and a millenium bypass ckt. for an led. I found that assymetrical diodes did nothing...1 or 2 mated with 3.

I think it could have something to do with the belief that this was the pedal used by Billy Corgan and the Smashing Pumpkins - the Siamese Dream album especially?

I have to admit that did raise my curiosity (along with Dirk Hendrik's comments here

). The SP are not a band I think are great, but I like some songs and that sound they had... no idea if there's a Big Muff involved here, but it sounds pretty good (before they murder Sunshine of your Love

)

Also, in my case, the four transistor Big Muff has so far been one of the bigger pedal disappointments I've had (and there have been plenty

)... I was probably expecting too much. Anyway, I need to try this one out.

ShortScaleMike · Post by **ShortScaleMike** » 31 Aug 2010, 11:03

I got into it after playing my friend's 70s one, it sounds pretty great. So I designed a layout and built my own. They're a different flavour of Distortion/Fuzz, and the Siamese Dream guitar sound is pretty great - this pedal nails it with a Fender single coil guitar.

Nyquist5 · Post by **Nyquist5** » 31 Aug 2010, 18:23

I own 3 of them (2 in the Little BMP format) and I agree with the fact that you can get pretty close to the SP tone in Siamese Dream. Definetly more so than with a transistor BMP.

I put a small cap accross the clipping diodes on mine to remove some of the fizz (I often do that), and it is true that the opamp type greatly influences the tone. They also sound great with a treble booster in front of them.

John Lyons · Post by **John Lyons** » 31 Aug 2010, 22:45

There is already a cap across the diodes. (150pf)
I like a bigger cap there for less fizz.

ShortScaleMike · Post by **ShortScaleMike** » 09 Sep 2010, 09:37

My friend made a demo of the pedal I built for him as a present using the layout in this thread.

EHX - Big Muff Pi 1977 & 1978 version [schematic]