Build - Pedal Project: Park Fuzz Sound 2-Knob
The Park Fuzz Sound is a variant of the Tonebender Mk3. Sola Sound sold their own Sola Sound Tonebender Mk3, but that circuit or a variant of it made its way into a variety of pedals that were branded differently. Sola Sound built (or were suspected of building) the Bell Electrolabs Fuzz, Carlsbro Fuzz, CSL Super Fuzz, Park Fuzz Sound, Rotosound Fuzz, and the Vox-branded Tonebender Mk3. These were all variations of the same 3-transistor fuzz circuit. For the most part, all Mk3 variants have three knobs - a Volume control, a Fuzz control, and for the first time in the Tonebender series, an added Tone control. The Park Fuzz Sound is unique in that there was also a 2-knob version that was still based around the same Mk3 circuit. Unlike other 2-knob fuzzes of the era which tended to have a Volume and a Fuzz control, the 2-knob Park Fuzz Sound has a Volume and a Tone control, and is wired as if the Fuzz control is internally set to the max.
This layout is for the 2-knob variant of the Park Fuzz Sound, which is great for a compact build in a 1590B. The Park Fuzz Sound can be picky about which transistors are used. Three are included in the BoM below, but you may need a larger batch of transistors you can try out in the circuit. The build pictured here uses transistors with the measurements seen in the below table. These were taken with a Peak Atlas DCA75 at room temperature.
| Transistor | hfe | Leakage (µA) |
|---|---|---|
| Q1 | 53 | 0 |
| Q2 | 67 | 11 |
| Q3 | 117 | 253 |
There are many transistor arrangements that will work, but that above transistor set sounds great and may give you something to aim for. Note that the DCA75 reads 0 leakage for anything below 10uA, but those should be considered ballpark values given how sensitive germanium transistors can be to temperature.
This is a PNP build and uses battery power only. With no LED indicator, this pedal will last a very long time on battery power. If you would like to build this pedal with a DC jack, please see our PNP "Positive Ground" Pedal Considerations tech article.
Figure 1: Turret board layout of the Park Fuzz Sound 2 Knob.
See Figure 4 in our Guitar Pedal Footswitch and Jack Wiring article for the recommended footswitch and I/O wiring.
Figure 2: Park Fuzz Sound 2 Knob Schematic
Parts List
| Value | Qty | SKU | Type | Notes | |
|---|---|---|---|---|---|
Capacitors | |||||
| 10 µF | 1 | C-SA10-25 | Electrolytic | ||
| 25 µF | 2 | C-SA25-25 | Electrolytic | ||
| 2.2 nF | 1 | C-MD0022-630 | Film Cap | ||
| 100 nF | 2 | C-MKT-D1-400 | Film Cap | ||
| 200 pF | 1 | C-SM220 | Silver Mica Cap | ||
Potentiometers | |||||
| 100k Linear | 2 | R-VAM100KL-SS | Volume control, Tone control | ||
Resistors | |||||
| 3.3 kΩ | 1 | R-I3D3K | Carbon Comp Resistor | ||
| 10 kΩ | 5 | R-I10K | Carbon Comp Resistor | ||
| 18 kΩ | 1 | R-I20K | Carbon Comp Resistor | Alternatively, use 1× R-I22K and 1× R-I100K in parallel for 18 kΩ | |
| 100 kΩ | 1 | R-I100K | Carbon Comp Resistor | ||
| 470 kΩ | 1 | R-I470K | Carbon Comp Resistor | ||
| 680 kΩ | 1 | R-I680K | Carbon Comp Resistor | ||
Semiconductors | |||||
| 1N60 | 1 | P-Q1N60-KBK | Germanium Diode | ||
| 2N527 | 1 | P-Q2N527 | PNP Germanium Transistor | Q3 | |
| OC46 | 2 | P-QOC46 | PNP Germanium Transistor | Q1, Q2 | |
Other Items | |||||
| 2x6 eyelet board | 1 | P-HTB-2X6 | Board | ||
| Black 3PDT | 1 | P-H501-L-BLK | Footswitch | ||
| Black Marshall-style knob | 2 | P-K393B | Knobs | ||
| Cable Tie Mount | 1 | P-HTIEMOUNT-BLK | Battery Strain Relief | ||
| Carbon-zinc battery | 1 | S-9V-GCELL | Battery | ||
| Low profile 1/4" jack | 2 | S-H534 | In/Out jacks | ||
| Vinyl battery snap | 1 | P-BATC-SN-1S | Battery snap | ||
| White 1590B | 1 | P-H1590BW | Enclosure | ||