If you're in the USA, for $75 you may as well buy the kit. otherwise, this should be a really simple build.
The Earthquaker Devices Spires green channel is a variation of one of my favourite fuzz circuits - the Rosac Nufuzz. It's a progression of a fuzzrite from the original designer, but it has a tone control on the output sweeping between a small and large cap to provide a thin to thick fuzz sound. There's no fuzz control, it's set to full all the time.
I used an old layout from the D*A*M FR-70 to adapt for this, as it's almost the same. I skipped the 10k resistor on the input for this reason. Could always squeeze one in if you wanted it.
Schematic located here on Pedal PCB and if you're wondering about the other channel on Spires (the red one), it's a silicon fuzz face. It probably has some tweaks, but you get the idea.
A classic Japanese guitar effect - the Shin-Ei Companion Fuzz - it has its roots in the Fuzzrite, with a notch filter at the output.
After spending some time on the germanium Fuzzrite, time for a bit of silicon action. It's a bit less interesting, as there seems to be less variance to the circuit - or none?
Some differences in construction methods occurred, but that's about it as far as I can tell. Although I need to do a bit more research on this, as I'd like to see some pot values on an original to confirm what the internet has been saying.
It seems that most people have settled on 350k for Depth, with was a common value used in Mosrite guitars at the time and also used in the germanium version, so this seems likely.
I've seen a few different values for the Volume pot floating around - anywhere from 33k to 500k. The value of the Volume pot has a direct effect on the frequency response of the pedal.
The differences in values show up the most when the Depth pot is set to Q1 (Depth blends between Q1 & Q2). A smaller volume pot reduces bass in this setting.
There's still conflicting information floating around about the inclusion of the 22k resistor that forms the 3.3khz high-pass filter with the 2n2 capacitor on Q2. Some people like to have it on a switch or change the value to 47k
The chart below used identical settings to the one above - except that the 22k resistor was removed. As you can see, it significantly changes the frequency response and output level.
The original used TZ82, which if you find any will probably cost a lot. The general consensus is that almost any low-gain silicon transistor will provide good results (about 200 hfe and under).
Usually, people report good results with Q1 having a higher hfe than Q2.
Modern subs PN2222A, 2N3903
I think you can see where I was going with this Fuzzrite layout - visually satisfying on top, quite the mess underneath, but who's going to see it once it's in a box? It is a good looking board when finished.
There are more than a few versions of the germanium Mosrite Fuzzrite out there - seems like they went through a few different construction technics and capacitor combinations along the way. The details mostly seem to be lost to time (and rust).
Here's a bit of info that I've pulled together from various sources while I was trying to work out what was going on with all the variations.
100n caps were used on early versions, later changing to 50n ceramics. Some good references and photos on the Fuzz Boxes website.
2n caps seem to be the most common, with the one coming off Q2 paired with a 22k resistor to form a high-pass filter.
There does seem to be some evidence of other cap values being used for the depth control - I recently saw a post on Instagram with 7.5n tropical fish caps in this position. They seemed to be original. I've also seen photos of a 1n cap on Q1 and a 2n on Q2. Maybe this is the classic vintage construction technique, of use what we have available today or was cheap at the time it was needed. Close enough right?
I was surprised to see the 7.5n caps were not radically different - noticeably so I'm sure.
The most likely scenarios for pots are either 350k or 500k pots. Despite 350k being an odd value, it is what was used in a lot of Mosrite guitars. I have seen the code BA8-11-3901 on a volume pot, which is a Mosrite part number for a 500k pot.
On Guitar FX Layouts, Travis pulled his vintage GE Fuzzrite apart and listed 470k and C350k as the values for the pots. Probably a safe bet that these are correct values.
A 1.2meg resistor across pins 1 & 3 of a 500k pot with give you a 352k pot, so close enough, especially considering the 20% variance on most pots.
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The Rosac Nu-Fuzz is an Ed Sanner design, of Mosrite Fuzzrite fame - the Nu-Fuzz is an evolution of the Fuzzrite.
Key differences to a Fuzzrite: both sides of the tone (or depth on a fuzzrite) pot are taken from the same transistor, and are subsequently in phase, with the same amount of fuzz on each.
A Fuzzrite mixes signal from each transistor together at the depth pot - so one is cleaner than the other signal, and they're out of phase.
This is a standard germanium Fuzzrite with a 250k depth pot instead of a 350k. I found the old layout while doing a clean-out and a correction and realised that I had not posted the 0.15” version.
The layout is a copy of the D*A*M design - mind you, I’ve never actually seen the value of the blue caps, so there’s an assumption that these are 2n2 caps. Like anything produced by D*A*M - expect a solid guitar effect at the end of the build.
Just putting together some options for some leftover 0.15" vero - and I was going to do a standard Fuzzrite, but I ended up doing this instead - which is of course the Ghost Effects Lunar Incantation.
A very close relative of the Conrad Buzz Box, the UMI Buzz Tone. Same same but with a contour control on the output.
Another simple one - the Conrad Buzz Box and Volume Expander - there is no volume expansion happening; this is just fuzz.
This is an easy one to convert to NPN, and there's quite a bit of discussion on the usual forums re transistors. Good results have been seen with low-gain silicon in Q1, and germanium on Q2.
There are also a few different schematics out there with varying pot values. example: 100k for buzz; one even has 150k for both pots, which will be a little hard to find.
Unlike the D*A*M Fuzzrong FR-69, which is very much a straight germanium Fuzzrite, the D*A*M Fuzzrong FR-70 is a little different.
It's a version of the Rosac Nu-Fuzz, which was designed by Ed Sanner, the designer of the Fuzzrite. There are a some changes with component values, but you are basically looking at the bones of Nu-Fuzz.
It uses very common transistors - so there is no hunting for expensive/rare germanium only to find out they sound 95% like the ones you already have...
This is the layout that D*A*M used for the Fuzzrong FZ-69, which is essentially a germanium Fuzzrite.
I couldn't make out the pot values or the 2n2 cap values on the photos I could find, so will have to take this at face value.
The Earthquaker Devices Terminal Fuzz is based on the Shin-Ei Companion Fuzz, with a few tweaks to improve performance and versatility. The first section is actually a lot like a silicon Fuzzrite. Q1 feeds directly into Q2 - they feed into either side of the treble control with quite small capacitors.
The treble pot is followed by a notch filter, found on many fuzz circuits of the day, but the EQD Terminal Fuzz has included a voice control, to adjust the filter. The notch filter is followed by a gain recovery section, as a notch usually drops a bit of level from the signal chain - a common issue in many old fuzzes with notch filters.
Read the comments below, as there has been a bit of disappointment with this one. A good suggestion was made by Tom, the 4n7 capacitor should be increased to 47n, which is the same as the Shin-ei.
The Ghost Effects Lunar Incantation is part Mosrite Fuzzrite and part Rosac Nu-Fuzz - what a combination... time to break out some NOS low-gain silicon transistors? Maybe not. BC108s will be fine; probably anything with lowish gain that's NPN silicon will do. Ghost Effects recommend 150 to 300hfe, with the second transistor having a higher gain.
I've left enough room for power filtering/diodes / 1M input resistor etc, if you want to add that.
This is an early two knob Guild Foxey Lady, which is very similar to a silicon Mosrite Fuzzrite. However it’s different to other schematics I have seen online -
I traced this from the circuit shown below - it's easy to make out part values, excluding the pots and transistors. I left some room for power filtering too, should be able to fit an extra cap / resistor / diode on there without any trouble.
