Development Hell: multiple fuzz pedal

Today, I am going to introduce the concept of Development Hell: it is a special place where projects stay when they need a lot of fine tuning before properly work. Unfortunately, I have a few projects that are still burning there, like the one I am going to present today.

It is a multi-fuzz machine! I always felt that a lot of Fuzz are quite a "one trick pony", they have a very characteristic sound that can be modulated by mods, but still sounds "like a fuzz face", "like a big muff"...etc. Moreover, fuzz are usually quite simple circuits, and I find that allowing one spot per fuzz on a pedalboard can quickly be space-inefficient.

So I decided to create a multi fuzz pedal, with no more than 3 different fuzz inside : a germanium Fuzz Face, a Muff Fuzz and a Companion Fuzz, which should provide the 3 main "flavors" of fuzz in this world: a classic warm, soft fuzz face, a "chainsaw", very raspy Companion Fuzz, and a compressed and heavy Muff Fuzz.

On top of that, I added an upper octave generator that allows to combine it with any fuzz, with a potentiometer to adjust the amount of octave. It is based on the Green Ringer circuit, which is a small, but efficient analog octaver circuit.

And of course, I made it fit in a 125B enclosure...

Here it is in its current form:





The top three knobs allow to set the gain for each fuzz : Fuzz face (1969), Muff Fuzz (1970) and the Companion Fuzz (1971). There is an output volume knob, a tone knob and the octave knob which allow to set the amount of octave.

The central switch allows to activate or not the octave, so you can have the fuzz with or without octave. You can also have the octave on a clean sound !

The last "pot" is a 4 positions switch that allow you to choose between clean and the 3 fuzz. I also added my relay bypass system for soft switching and silent switching.

As you guessed it is a fairly complex build. Moreover, I had some troubles with it and had to modify it quite a bit. I added a klon buffer before the tone circuitry, and also tried several capacitors and resistor values on several parts of the circuit. Here is the inside of the pedal, beware it is quite messy!

Outside the box it looks like this (messy as well!):

 

I used a small 4P2T rotary switch to select between the fuzz. Note that there is a jack that does not fit the PCB because of this switch (facepalm).

Conceiving the PCB was really difficult, I think it is the most complicated PCB I ever made! Indeed, there are 3 fuzz circuits on the top, the Green Ringer build, a LPB1 for the final volume, and my relay bypass system! (who said that fuzz were simple circuits?)

Here is the schematic:

I separated every circuit (and added some notes for the prototyping. Here is the annotated circuit schematic:

It is quite a modular system. The signal first goes through the Green Ringer (or not depending on the switch), then it goes to the fuzz that is selected through the 4P2T switch, and then it goes through the tone 

I had to add a Klon buffer to lower the impedance in order to make the tone control section to properly work. The final scheme is like this : 

In the end, it works! However, it is still in the development hell for a few reasons:

• The Fuzz Face and the Muff Fuzz circuit sound quite similar. Indeed, the two circuits are really close. The Muff Fuzz sounds more like a silicon Fuzz Face than a Big Muff. I think I will replace it by a "mini IC muff" with a different schematic. Thus, we would really have three "flavors" of Fuzz.
• The Klon buffer is not on the PCB originally, so I have to add it as well. It is essential to make the tone section properly work
• The volume levels between the fuzz are not similar at all. The Companion Fuzz is especially low in volume because of the tone section on the fuzz. The Muff fuzz is also slightly louder than the Fuzz Face. I added a resistor at the end of the circuit to "flatten" the final volume, but the LPB1 boost is not "strong enough" to increase the volume without distortion.
• The LPB1 boost will be replaced with a IC based volume section for less distortion and more output volume.

So, I still have plenty of work to do with this one, and frankly, I am still really busy with the crowdfunding campaign. Modifying the PCB is not easy as well as it is fairly complex. However, I will do it soon! Hopefully, it will be available in 2017...