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Interview with Op-Amp Big Muff Designer Howard Davis
Manager of Analog Circuit Design for Electro-Harmonix from 1976-1981


Howard Davis was Manager of Analog Circuit Design for Electro-Harmonix from 1976-1981. He was the circuit designer for the op-amp version of the Big Muff, along with EHX designer Michael Abrams. Howard was also responsible for over a dozen E-H pedal circuit designs. These included most the the ”deluxe“ Electro-Harmonix models that appeared in the late 1970s to early 1980s, such as the superb op-amp Deluxe Big Muff, Deluxe Memory Man, and Deluxe Electric Mistress. At the time of this interview in 2009, Howard was still involved with his E-H creations, doing custom mods and repairs to vintage Big Muffs, as well as his other E-H pedals.

This short email interview was conducted with Howard Davis by Kit Rae in November of 2009.

KR: How did you get involved in the Big Muff circuit redesign?

HD: As chief engineer for Electro-Harmonix, I was aware of all the projects underway in the engineering department, not just my own. The op-amp design Big Muff was assigned to me to fill a desire for a simpler, less costly product that would do all that the transistor version does. Due to the differing distortion characteristics of op-amps it turned out to have a somewhat "grungier" sound than the transistor design, an effect preferred by some musicians.

KR: What direction were you given by (Electro-Harmonix owner and founder) Mike Matthews?

HD: I can't recall after all these years, but basically it was to design a Big Muff using op-amps. He often would just tell me to "think about" something, and I took it from there.

KR: Did you create any other Muff designs that did not get made?

HD: No.

KR: What are your thoughts on the IC version and how it was received, and your thoughts on the transistor version.

HD: The transistor version is somewhat sweeter sounding. Grunge and punk-style players though often want something with more edge or coarseness, more crunch, and the IC Big Muff is just what they want. It can give you the Mountain sound - the guitar rough around the edges, but with the rest of the band playing, melodic overall.

KR: What are your thoughts on the Deluxe Big Muff and it's development (I will be putting the Deluxe in a future section on the Big Muff website including all of the Muff variations)

HD: Distortion is usually accompanied by sustain, and people generally want LONG sustain when they use it. The Deluxe Big Muff gives you the option of a clean sustain, fuzz/distortion with its own sustain, or any combination of the two. As it is an old design there are better clean sustainers available today, but the Deluxe has it all in one box. I now do custom mods on these old pedals to reduce noise and alter tonal characteristics.

KR: Who came up with the tone bypass idea?

HD: I don't recall, but I believe it was already a feature of some transistor Big Muffs.

KR: It is interesting that you say the tone bypass feature may have  already been in use before the op-amp version was made. I have come  across a few V3 transistor Muffs with pot dates around 1977-1978 that  have the old V3 circuit, but also have the tone bypass switch. I had  always thought these were comped from different Muffs, but now I am  thinking that was a real version just prior to your op-amp version. From what I have have been able to determine looking at dozens of  Muffs from the late 70s, the non tone bypass op-amp version came out  first around 1978, then the tone bypass op-amp came out about a year  later. Does that sound about right? 

HD: I have one schematic that I drew upon designing the IC Big Muff. It is dated 4/6/78, and it has the tone bypass switch. As I have no other schematics, and I would if I had designed another version, I can only assume that if a non-tone bypass op-amp version exists, it is not my work.

KR: Do you know why Mike wanted to change back to the transistor version, and was that done while your were still there?

HD: I can only assume that the op-amp version did not sell as well, or the musicians whose opinions he depended on didn't like it as much. I don't think the transistor version ever went out of production.

KR: The non bypass op-amp version definitely exists. They are rare, but I have a couple and know several people who own them. They have the on-off switch and "AC" marked on the lid just like the last V3 Muffs. From the pot dates -1977-1978- we all assumed they came before the bypass version,  but pot dates are not the best way to date anything.

HD: I would not judge manufacturing dates by the pot dates. 

KR: Would any of the other designers at E-H have done that version  without it going through you? It may have come after the tone bypass  version, possibly after you left, but I have never seen a pot date  later than 1978 on one.

HD: Sometimes there were changes done that I was not made aware of in a product I designed, so I cannot say for certain.

KR: Are you responsible for the change to the pot positions so all the knobs were aligned the same on the circuit  board, with all starting zero in the same place? The V3 transistor  Muffs, and all Muffs previous to that, had each pot mounted to the  circuit facing differently, so none started started with zero in the  same position. The op-amp Muff, and all Muffs that followed, had them  all mounted exactly the same so the zeroed in the same spot. A much  needed improvement! 

HD: I did the electronic circuit designs only. Physical layout and packaging were not my responsibilities, though I certainly made my thoughts about them known to those that did the work!

KR: I know this was just a short period of your life over and it was over thirty years ago, but believe me when I say that many of us find anything you say about it of value. A lot of us would love to see the op-amp version, or the Deluxe Big  Muff, go back into production one day.

HD: Thank you!

Copyright Kit Rae.

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