We set out to take a classic design with lots of history and make it obviously something new. We took the op-amp version of old PI and inverted one of the stages, brought out the midrange, tightened the bass, and most importantly, added a Germanium transistor output! Yes, this is a opamp-transistor hybrid. Don’t be miffed by op-amps in your pie folks, the germanium touch at the end makes everyone smile around the shop here.

We wanted to celebrate our 12th pedal of the year by offering it in two forms. Two choices, 1) Custom Art in a late 1960’s style or 2) Greek Gold Deco. The first is hand drawn by Erin Lofties. Her stunning artwork looks out of the 60’s and was completed this week specifically for this pedal. Then then Gold Brick Greek God model. Stripped down, simple and clean.

How do you make a design different? Put your own spin on it? You can make it distort differently, you can make the tone different, add some features, you might even be able to put a little lipstick on it. At the first audio/video repair shop I worked at in 1989, I remembered seeing clipping or limiting diodes, LEDs in fact, in certain types of gear where there were A/D converters. I noticed as I was working on the equipment that the LEDs were lighting up on the inside of the unit when the program material was high enough. No one could see them except the service tech. How cool would that be if everyone could see them on their distortion pedals?! So I’m pretty sure I was the first to make it a standard feature on a guitar effects pedal by putting the clipping LEDs on the outside of the pedal when I built the DS-1 Seeing Eye mod and later the Ultra mod. It’s done pretty regularly now on my pedals including the latest Red Dirt Pro and Stahlhammer. They might not light up very brightly, but that doesn’t matter, they are still doing their job. And so, I wanted to dive into the old Muff and make it mine. Rearrange things, add some bling, make it Psi Fuzz!

It seemed like I could have fun doing an all germanium one, but that was done already. It seemslike there isn’t gross overpopulation of op-amp versions of the old gal. But what to do to make it mine, at least in some way? Well we can add to the circuit. Again, I was thinking germanium transistors since they always have a fun sound. So let’s add a common emitter amplifier to the end. That would put a germanium spin on the overall sound. But we have phase inversion then. Input and output are in phase on the vintage pedals and I wanted to maintain that. Great! I get to play with the stages! The first thing I wanted to alter was the 2nd “gain-stage” and filter. That’s a Sallen-Key filter and you can only make it using a non-inverting style op-amps. I got to play around with values and changed things up a bit. I wanted to know how it felt to swing that 1KHz 2nd order filter around. So I made it go up and down. In and out came the harmonics…and the noise. Very cool. I can set that filter to where I want it. I want it to have a bit of fire and life and not feel too cramped in the high end. I’ll use a lower noise, mildly more expensive IC to combat noise instead of kill the guitar tone. Okay, still have to invert the phase somewhere! Yup, the first stage is where it gets it. I changed a few things around to make it a non-inverting op amp and it works well. I’m still playing with those values but I dig it. Right now the low pass filter for the first stage is about 10Hz if I remember correctly and that’s okay with the girls I date. Phase is correct (with the soon to be added germanium gain stage) and I’ve changed the design so far, even if trivially.

The Big Wazoo

So I changed the 6 silicon diodes in the feedback of the third stage to 2 LEDs and yes, one of them will poke through the hole in the top. The “Keeley Mod” has been done to it, including blue as Neptune Psi Fuzz Blue LED. (Yes, another first from Keeley Electronics.) And finally, the pre-climax to this story, our phase is in crisis, the hero takes action, the germanium amplifier stage! Ahhh, fitting like a glove between the Voice control and the Voltage control is a common emitter amplifier using a AC187. I am pretty happy with the biasing of it. The collector sits around 4.5V and we get a gain of 10dB out of it. Oh wait! We don’t want this thing not putting out when it gets hot! That would be as wrong as a double negative! You know, when it’s a 113 degrees in the shade and some Rock God is on stage in Texas, just working it for all it’s worth, he don’t want things to blow ya know. Craighton and I get the heat gun out and sure enough, Mr. Semi-Conductor from the 60’s sags and wimps out in the heat. Just like your poor old fuzz face. When the mercury hit 115 the lights went out. Okay, off to the parts room. Out comes a real germanium diode. Not the Shenzhen China Schottky ones, but some good strong American ones. Ones that behave the same as the transistor when it gets hot. We used the germanium diode in a reverse polarity fashion across the base-emitter junction of the transistor to offset the temperature coefficient problem. Turned on the heat gun, just let it blow…it got hot..really hot…well over 140 degrees…and it never stopped pumping out the lov

  • Fuzz Head
  • Keeley Compressor
  • Neutrino
  • Nova Wah
  • Overdrive
  • Phaser
  • Seafoam Chorus
  • Time Machine Boost
  • Make a Muffin Better”, Frank Zappa
  • The Big Wazoo
  • A quad op-amp, and a single transistor
  • That’s a Sallen-Key filter
  • UPC : 00854295005253

Audio MIDI Plus is committed to deliver the best experience for our customers. If for some reason you are not satisfied with your purchase, you may return it for a refund of the purchase price, an exchange or a store credit within 30 days from the ship date. 

In the unlikely event that you received a defective product, a wrong product, or damaged product, Audio MIDI Plus will replace it at no charge of any additional shipping cost. We will send you a prepaid label to return the item, and ship you a replacement. You will not incur any shipping charges. Please notify us of any of damaged, defective or misshipped products within 14 days.

After 30 days, you may request manufacturer warranty if your item malfunctions. Unless otherwise specified, Audio MIDI Plus is an authorized dealer for all the brands we represent.

How to request a return:
Please email us or call us to obtain a RMA number. All returns must be in a re-sellable condition and include all packing materials, accessories and paperwork. We may apply a restocking fee if the returned products fall into these following categories:

  • Missing original packaging, manuals, accessories, or any contents that was included
  • RMA number was not associated with the return
  • Items not in original like new condition

Please send all returns to:
Audio MIDI Plus Returns
3725 Saddle Drive,
Carlsbad, CA 92010

The following items are not returnable, unless received DOA, in which we will send a replacement:

  • Software
  • Electronic Delivery of Software
  • Special orders
  • DVD’s

Items that fall into the in mouth and in ear use category, such as mouthpieces, earphones, ear plugs, harmonicas, cannot be returned due to health regulations

Thank You for shopping with us!

If your item is eligible for shipment outside of the United States, Tax, Duty, and/or VAT and brokerage fees are the buyer's sole responsibility. Please check with your local authorities to assess these extra fees.

Import duties, taxes, and charges are not included in the item price or shipping cost. These charges are the buyer's responsibility. Please check with your country's customs office to determine what these additional costs will be prior to bidding or buying.

International Friends: If you refuse a delivery due to Tax and/or Duty, we reserve the right to refund you only when the package is successfully returned back to us, and MINUS all shipping charges

Most software items are now Electronic Delivery Only. Once payment is received, we will Email you the necessary codes and/or download links. Please be sure to check your junk mail and spam folders for this Email.

While most items are in stock either in our retail store or fulfillment warehouse in Carlsbad, CA, in some cases items may need to be ordered and/or drop shipped from the manufacturer. Please allow 3-10 days for order processing, fulfillment, and setup, as well as transit and delivery time. Tracking will be available within 48 hours in most cases.

Please call us at (844) 577-4502 10AM-6PM PT M-S for an IN-HAND description of the item that you are interested in. We are always happy to help, and look forward to speaking with you if needed. Live Skype may also be available for you.

Related Products

< >