Here is a great story I found from Mike Matthews about the Big Muff and Jimi Hendrix:

How did the Big Muff come about.

Back in 1969, I ( Electro-Harmonix ) was already selling the Muff Fuzz, which was a mild overdrive circuit in an LPB-1 box.. I wanted to come out with a 3 knob distortion unit in a bigger box. I asked my buddy, Bell Labs designer Bob Myer to design a unit, one that would have a lot of sustain.

When I got the prototype from Bob, I loved the long sustain. this was done by cascading the circuit into additional sections, each one clipped by twin diodes. However, when you clip, the tone can be a bit raspy…………so I spent a couple of days changing capacitors to roll off distortion in the highs, and eventually found that the best long sustaining tone that was a “sweet violin like sound” was done by having 3 capacitors in different parts of the circuit rolling off the rasp.

we plunged into production and I brought the very first units up to Henry, the boss at Manny’s Music Store on 48th Street, NYC. About a week later, I stopped by at Manny’s to buy some cables, and henry yelled out to me “Hey Mike. I sold one of those new Big Muff’s to Jimi Hendrix..”

Now let me tell you a little history of me and Jimi. Back in the mid 60’s I was a concert promoter. I had the Isley Brother, Coaster, Drifters, Cadillacs, Lovin’ Spoonful, Young Rascals, Byrds, Turtles, Shirelles….and many more acts. I booked Chuck Berry for 2 nights, and was looking forward to this gig… especially because Chuck traveled alone and the promoter had to get the back up band. I decided to play keyboards, and got some buddies of mine who mostly did Chuck Berry covers to back up Chuck. A week before the gig, that agent who sold me Chuck called me and said ” hey Mike, I need you to do me a favor and book another band…. I can give you that will play 3 nights for $ 600.” I said “Bob I don’t need another band. the crowd is coming to see Chuck Berry and I’d just be spending another $ 600. for nothing.” Bob said” please I need this favor,. You can have them for 3 nights for only $ 500. And, they have a guy that can play guitar with his teeth” I figured ok and booked them and in the future Bob owed me the next favor. the name of this band was Curtis Knight & the Squires.

When Chuck played, and me and my guys backed him up, I was a little burnt out after the first set, and went to check to see how much money came in so far at the gate. Curtis Knight’s band was now playing and I didn’t pay much attention until my guitarist that backed up Chuck, Steve Knapp, came running up to me and said “Hey Mike, you gotta catch this guitar player. he’s a gas.” Well that guitar player was Jimmy James. His style at the time was strictly loose R&B. We became best friends and I snuck out of my day gig several times a week as a computer salesman for IBM, to go to his hotel room where we rapped music talk. Jimmy was quiet dude, and lived in a rundown narrow hotel room with no private toilet. He usually had his hair set with pink hair curlers.

One night I went to see him play with Curtis at a club in the upper west side called the Lighthouse. Now, Curtis Knight was a real gangster. mainly a pimp, running a big operation. At that gig Jimmy hung with me at the breaks and told me ” Mike I gotta get away from this dude. I wanna form my own band and headline it.” I said “Jimmy, if you’re going to be the front man, then you have to sing.” Jimmy said “yeah, that’s the problem. I can’t sing.” I said ” Jimmy if you really wanna sing, all you gotta do is practice and you’ll be cool. Look at Mick Jagger and Bob Dylan. they can’t sing but thy can phrase their asses off and project dynamite soul.” Jimmy said “Yeah, you got a good point. I’ll work on it”

Soon Jimmy formed his own band, the Blue Flames. I went to catch them at the café Au Go Go in Greenwich Village. Sitting with me was my friend Bobby Colomby who later on was a co-founder and drummer with Blood Sweat & Tears. He invited Eric Clapton to sit with us. Jimmy and The Blue Flames were dynamite…still playing a loose blues style. At the break we all went across the street for some grub.. The only thing Clapton kept saying again and agin and again was ” I just can’t believe how good this guy is. I just can’t believe it.”