It always seems like the builds with the least amount of parts are the biggest headaches. The muff fuzz came in to variations. The first was a dual transistor version that was something of a fixed gain fuzz face. The version this is based on the the 70s opamp version that was gone when EHX did the opamp muff. Like all things EHX back then, nothing was consistent and revisions were constant. It seems that the schematic of this pedal going around the internet was not complete and gives some issues.
First, the schematic in the build docs is incorrect. R1 should be 100k not 1k. My second issue is the use of germanium diodes. Ge with it's lower threshold cuts to much volume and this barely hit unity with the volume maxed out. I used 1n4148s and that was much better. Final issue is missing component on the schematic floating around the web.
As is, the pedal sounds good, but does not sound as good as the transistor version. The transistor one had good volume cleanup and smooth not decay. This one had no volume cleanup and a horrible gating on initial attack and a sizzle misbias sound on the decay. After much internet sleuthing I ran across a couple threads on diysb that led me to the issue.
One soul who was fixing a broken unit with the help of Marc Hammer, traced the original to find a resistor in parallel to the diodes in the feedback loop. The way the circuit is designed pushes the diodes at or above their limit for a second, causing the initial gating. The way Hammer breaks it down is pretty interesting and I learned alot thru the process. The resistor EHX used was 100k. I experimented, it was a balancing act of taming the gating/decay and not lowering the gain too much so it would still sound the same. I landed on 220k.
Now we have a circuit that sounds good, is very similar to the transistor version and has excellent volume cleanup. For the enclosure I went with the Secret Wars black symbiote suit because I'm doing a series of Spiderman based muff builds. This is the first of three. UV print on matte white enclosure with a big ass Davies knob I've had for years. Sound clip coming tonight or tomorrow.(https://uploads.tapatalk-cdn.com/20220211/cec3f9b25d3181ce38f569fc9ca3f4b1.jpg)(https://uploads.tapatalk-cdn.com/20220211/5d897ed0cd0c56ed82502ca51dc7d033.jpg)
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Seems like all the hard work has paid off. Looks like you've got another banger there!
Sometimes dealing with those "headaches" can be pretty rewarding.
Thanks Drew. It is rewarding, especially when you do it yourself. I don't like to ask for help until I've ran out of options. I have a double muff coming up next and that should be cool, it's two of the muff fuzz transistor circuits in series with a switch for one or both.
Wow. There really isn't much in one of these, it seems... good candidate for someone's first 1590A build!
Interesting write-up -- I knew that this existed, and pre-dated the four-transistor Muff that we all know and love, but didn't know anything else. I'm looking forwards to your dual transistor one.
Hmm, I didn't realize there was an opamp version.
I have the reissue Muff Overdrive nano which is supposedly the original 1969 Muff Fuzz. It sounds fantastic so it's too bad it's a positive ground it says "do not daisy chain" so I almost never hook it up.
Heres some guts. The two transistors are both 2n5088. Not sure what the black tubes are? They are labeled FB1, FB2, FB3
Looks great! Love the graphic :)
Quote from: alanp on February 12, 2022, 12:38:17 AM
Wow. There really isn't much in one of these, it seems... good candidate for someone's first 1590A build!
Interesting write-up -- I knew that this existed, and pre-dated the four-transistor Muff that we all know and love, but didn't know anything else. I'm looking forwards to your dual transistor one.
Thanks, I just finished the double muff so build report incoming.
Quote from: Aentons on February 12, 2022, 04:36:32 AM
Hmm, I didn't realize there was an opamp version.
I have the reissue Muff Overdrive nano which is supposedly the original 1969 Muff Fuzz. It sounds fantastic so it's too bad it's a positive ground it says "do not daisy chain" so I almost never hook it up.
Heres some guts. The two transistors are both 2n5088. Not sure what the black tubes are? They are labeled FB1, FB2, FB3
The double muff is the same as your muff overdrive (which is the same as the 69 muff fuzz except it has 1n 914s instead of the original GE diodes. The double muff is just 2 circuits with one cascading into the second one, either one or both is switchable.
Quote from: nzCdog on February 12, 2022, 08:51:18 AM
Looks great! Love the graphic :)
Thanks, upping my illustrator skills and taking advantage of tayda's UV printing service.
Quote from: Thewintersoldier
Quote from: nzCdog on February 12, 2022, 08:51:18 AM
Looks great! Love the graphic :)
Thanks, upping my illustrator skills and taking advantage of tayda's UV printing service.
Wow! I just checked UV printing out at the Tayda website. Didn't know they offered printing! :o
Quote from: Aentons on February 12, 2022, 04:36:32 AM. Not sure what the black tubes are? They are labeled FB1, FB2, FB3
My guess is that they're ferrite beads.
Quote from: Thewintersoldier on February 12, 2022, 08:23:40 PM
The double muff is the same as your muff overdrive (which is the same as the 69 muff fuzz except it has 1n 914s instead of the original GE diodes. The double muff is just 2 circuits with one cascading into the second one, either one or both is switchable.
I looked at the factory schematic and the double muff definitely has some extra stuff in there. I did notice that one of the knobs is disabled when cascaded mode. Not sure what the other stuff is
Quote from: benny_profane on February 12, 2022, 11:17:14 PM
Quote from: Aentons on February 12, 2022, 04:36:32 AM. Not sure what the black tubes are? They are labeled FB1, FB2, FB3
My guess is that they're ferrite beads.
That would make sense. The positive ground stuff is such a pain...
Quote from: Aentons on February 12, 2022, 11:25:39 PM
Quote from: benny_profane on February 12, 2022, 11:17:14 PM
Quote from: Aentons on February 12, 2022, 04:36:32 AM. Not sure what the black tubes are? They are labeled FB1, FB2, FB3
My guess is that they're ferrite beads.
That would make sense. The positive ground stuff is such a pain...
The pedalpcb board I built mine on is traced from the big box version in the late 80s or the 90s big box reissue I believe. In dual mode both volumes work. I'm not sure what's going on in the nano version. I was wondering what those were in your pictures.
Cool, looking forward to it
Very cool. I have been thinking about laying out a double muff. It's very Fascinating.
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Quote from: jimilee on February 13, 2022, 12:25:40 AM
Very cool. I have been thinking about laying out a double muff. It's very Fascinating.
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do it Jimi. It's an easy circuit and good sounding. You might consider making the switch a footswitch
Had a look at the pedalpcb double entendre schematic and it looks like the extra stuff is the on the input. C1,R2, and C3. Probably doesn't make a huge difference but idk. Also the clipping diodes are before the volume rather than after, not sure that makes a difference either... just making a note
Edit: nevermind about the diodes, I must have been looking at it cross-eyed
This is definitely an overlooked circuit. It sounds great and is an easy build. Nice work!