Black Arts Toneworks Pharaoh Fuzz clone

I want to make  Big Muff variants using my Coda Effects Big Muff PCB, and show you how to make them yourself. Lets start with the boutique version of the Big Muff that made it popular again on the stoner / doom scene: the Pharaoh Fuzz! Produced by Black Arts Toneworks since 2011, it was an immediate success because of the huge, warm, doomy sounds it can produce.

Here is my version:

As you can see, the Pharaoh has more controls than a classical Big Muff. There are the classic gain / volume / tone controls, like a classical Big Muff, plus a few other options. Here is the original version of the Pharaoh:

There are a "high" potentiometer that allows us to set the amount of trebles, and two switches. The first switch is a 'high / low' switch, that allow us to have 2 types of gain settings for the pedal: low gain and high gain. It modulates also a bit the trebles. Finally, you can choose the type of diodes in the last distorsion stage with the second switch: classic silicon diodes, no diodes or germanium diodes!

Finally, there are some modifications on the circuit. For instance, input and output capacitors are 10uF tantalum capacitors, which will let a looooot of bass go through the circuit!

Here is a gutshot (yes, I had fun drawing this!):

 

You can see the tantalum capacitors that are drop-shaped. I try to avoid as much as possible to use it in my guitar pedals. They are not especially good for audio, expensive, and most of all there are not really "ethical friendly". Tantalum is produced from coltan, a mineral that is the root cause of many conflicts, especially in Congo. Illegal mines were opened without any regulation, degrading environment in an uncontrolled way, with many Human right issues (a bit of reading about that on wikipedia). Traceability is a big problem with electronics. Most of the time we do not know how, where or in what ecological context components are made... For tantalum capacitors, just know that they are easily replaceable by electrolytic capacitors.

Wima capacitors are much better for that: they are made in Germany (and thus, their production must respect European ecological laws and regulations). This is why I try to use them as much as possible:

 

So, how can we make the Pharaoh from a classical Big Muff PCB?

Here is the schematic from the Big Muff page:

As you can see, it is very similar to the Big Muff circuit! We can use the Coda Effects PCB and modify it following the above schematic. Here are the modifications to do:
- no mid knob, 470k for R5.
- no R2 resistor (we will use a switch instead)
- no D1/D2 diodes (switch here too)
- no R8 resistor. (replaced by a "high" potentiometer)
No big changes!

If you want, Rullywow sells a PCB especially conceived to make the Pharaoh Fuzz, named "King Tut". If these mods seems a bit difficult to do, you can buy this PCB to make it easier ! Rullywow creates really nice PCB, and this one is no exception, and is of very nice quality.

First, we will remove the mid knob by placing jumpers on the mid knob pads, like indicated on the build document.

To include the switches, we will have to use a 125B enclosure, it will not fit in a 1590B. We will have to use long lugs potentiometers to place switches so they do not touch the circuit board and create false contacts.

For R2 and D1/D2, we will use switches:
- SPDT on-on for choosing R2
- SPDT on-off-on to choose D1/D2 diodes.

Choosing R2: switching between the Hi/Lo setting of the Pharaoh

We use a "on-on" SPST. Signal arrives to the center of the switch, and goes through a resistor, 39k ("high" setting), or 390k ("low" setting):

Try to make the connections on the other side of the PCB, it will be simpler. With this switch, you can choose the R2 value! In "high" position, there will be a lot of gain and trebles, whereas in "low" position, the sound will have more bass, less trebles.

It can apply to any resistor in the circuit, so feel free to experiment! Of course, some resistors are more interesting than others... I let you try!

Diodes choosing: 3 positions switch

We will use the same system for the diode switch. We are going to use a 3 positions on-off-on SPDT switch in order to have: germanium diodes (3 to have assymetric clipping), no diodes or classic silicium diodes. The second set of diodes to replace is D1/D2:

There it is! We have our two switches. Beware of false contacts with these switches: try to reduce the length of naked cables.Voilà ! On a déjà nos deux switchs !

Treble potentiometer

Last mod to add to have exactly a circuit like the original design: the treble potentiometer. In fact, you just have to replace R8 (tonestack resistor) by a 25k potentiometer. Just connect the lug 1 and 2 to each pad of the R8 resistor:

It can also apply to any resistor! You can investigate to find your favorite resistor to modulate ;)
There it is! Voilà! We have got our Pharaoh Fuzz PCB!

You can solder the other potentiometers now.  Beware: if we use "classic PCB-mount" potentiometer, the switches will not fit in the enclosure (they will touch the PCB and create false contacts). We will have to use "long lug" potentiometers like this ones:

You can also use classic potentiometer and make the lugs longer with soldered wire with solid copper wire or cur resistors / diodes lugs for instance.

You can now drill the 125B enclosure, and rock! :)
Have fun!

To go further:
Official Pharaoh webpage : if you are interested in buying the original pedal
Veroboard version of the pharaoh: a bit annoying and complex to make, but doable!
King Tut PCB: dedicated PCB conceived by Rullywow