1590BB2 · 3 knobs
Hurts Harmonic Percolators
Based on the Latent Lemon Audio Hurts· 2 other boards clone it
Want a PCB? Naegele Audio laid out a PCB for this circuit and sells boards, as well as relay bypass and I/O boards: message PedalBuilder on the PedalPCB forum.
From the vendor
After tracing the Latent Lemon Hurts , an interesting contemporary take on the venerable Interfax Harmonic Percolator, I laid out a couple of PCBs for a similar Harmonic Percolator build. I couldn't make up my mind as to whether I wanted to build a 1590BB2 pedal like the Hurts or whether I wanted a more compact 125B version. After hemming and hawing back and forth, I ended up getting both fabricated. I've really enjoyed the look of some Robert's recent PCBs with their curvy traces, so I leaned into that aesthetic for these builds. I deviated somewhat from the Latent Lemon circuit in both builds. The actual circuit draws about 55µA, excluding the LED, so I was able to increase R101 from 47Ω to 4.7kΩ while only dropping the voltage by 0.28v. Theoretically it should reduce any noise coming in via the power rail. I added a 1kΩ limiting resistor to the Harmonics control so that it didn't mute the pedal when turned all the way down. I also replaced the 5M trim pot that the Hurts uses for the Q2 collector-base resistor with a 2.7M resistor and a 2M trim pot because the 2M is the largest 3296 that Tayda carries. The two builds were largely identical, with a couple differences: Transistors: Both builds used Texas Instruments 182505 germanium PNP transistors for Q1. The 1590BB2 build used one with a slightly lower gain (hFE 44, leakage 7µA) than the 125B build (hFE 57, leakage 13µA). That small difference was enough to make a very noticeable difference in sound and dynamic behavior. Despite having otherwise identical biasing (and identical silicon transistors for Q2), the 1590BB2 build is fuzzier and harmonic-laden, and never fully cleans up with the guitar's volume knob. The 125B build is more polite, for lack of a better term, and while it certainly fuzzes, it always sounds a little more polished and cleans up nicely as you roll back the volume knob. Both have a nice and very prominent suboctave undertone. Diodes: The 1590BB2 used 1N914 for the silicon clipping diodes; the 125B used 1N456. The 1N456 looks cooler, but both sound identical to my ears. Both are fun builds and sound different enough to justify keeping both of them around. Here's the schematic that I used for my builds; gut shots are below. <a href="https://forum.pedalpcb.com/attachments/hurts-png.103308/" target="_blank"> <img src="data:image/svg+xml;charset=utf-8,%3Csvg xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg' width='2000' height='1638' viewBox%3D'0 0 2000 1638'%2F%3E" data-src="https://pedalpcb-forum.nyc3.digitaloceanspaces.com/data/attachments/103/103327-3abbcaee08d5837cbb920d84da283409.jpg?hash=YeUn2T8AqY" class="bbImage lazyload" style="" alt="Hurts.png" title="Hurts.png" width="184" height="150" /> <img src="https://pedalpcb-forum.nyc3.digitaloceanspaces.com/data/attachments/103/103327-3abbcaee08d5837cbb920d84da283409.jpg?hash=YeUn2T8AqY" class="bbImage " style="" alt="Hurts.png" title="Hurts.png" width="184" height="150" /> 1590BB2 <a href="https://forum.pedalpcb.com/attachments
Schematic
The schematic is in the post. Open it at Naegele Audio. No KiCad fragment has been drawn for this circuit yet.
Parts list 30 rows
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Check before you build · 2 values the reader of this schematic was not sure of
- R102: LED resistor drawn as 'CLR' with no value
- Deep and Ge/Si: switch types are not printed; read from the poles drawn
| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 8 | ||||
| R1 | 1k | 1k | under the Harmonics pot so it never mutes; read from the schematic by eye | |
| R2 | 220k | 220k | read from the schematic by eye | |
| R3 | 1k | 1k | read from the schematic by eye | |
| R4 | 2M7 | 2.7M | Q2 feedback, in series with the Octave trim; read from the schematic by eye | |
| R5 | 91k | 91k | read from the schematic by eye | |
| R6 | 4k7 | 4.7k | in series with D1 (asymmetric germanium clipping); read from the schematic by eye | |
| R101 | 4k7 | 4.7k | supply filter (the post says raised from the Hurts' 47Ω); read from the schematic by eye | |
| R102 | ? | ? | LED current limiting resistor, drawn as CLR; read from the schematic by eye | |
| Capacitors 8 | ||||
| C1 | 150p | 150p | read from the schematic by eye | |
| C2 | 47n | 47n | read from the schematic by eye | |
| C3 | 100n | 100n | switched in parallel with C2 by Deep; read from the schematic by eye | |
| C4 | 47µ | 47u | read from the schematic by eye | |
| C5 | 100n | 100n | read from the schematic by eye | |
| C6 | 1n | 1n | read from the schematic by eye | |
| C7 | 100n | 100n | read from the schematic by eye | |
| C101 | 47µ | 47u | supply filter; read from the schematic by eye | |
| Diodes 4 | ||||
| D1 | D18 | D18 | germanium; read from the schematic by eye | |
| D2 | D18 | D18 | germanium; read from the schematic by eye | |
| D3 | 1N914 | 1N914 | silicon; the post says the 1590BB2 build used 1N914 and the 125B build 1N456; read from the schematic by eye | |
| D4 | 1N914 | 1N914 | silicon; the post says the 1590BB2 build used 1N914 and the 125B build 1N456; read from the schematic by eye | |
| Transistors 2 | ||||
| Q1 | 2N404 | 2N404 | germanium PNP; the post says both builds used a TI 182505 (1590BB2: hFE 44, leakage 7µA; 125B: hFE 57, leakage 13µA); read from the schematic by eye | |
| Q2 | 2N3904 | 2N3904 | read from the schematic by eye | |
| Potentiometers 3 | ||||
| Harmonics | A100k | A100k | Potentiometer | read from the schematic by eye |
| Sputter | A100k | A100k | Potentiometer | read from the schematic by eye |
| Balance | A100k | A100k | Potentiometer | read from the schematic by eye |
| Trimmers 2 | ||||
| Octave | 2M | 2M | Q2 collector-base feedback, in series with R4; read from the schematic by eye | |
| OSC | 1M | 1M | switched across R2 by Deep to stop low-frequency oscillation; read from the schematic by eye | |
| Switches 2 | ||||
| Deep | DPDT | DPDT | adds C3 and the OSC trim; read from the schematic by eye | |
| Ge/Si | SPDT | SPDT | germanium or silicon clipping diodes; read from the schematic by eye | |
| LEDs 1 | ||||
| D101 | LED | LED | status LED; read from the schematic by eye | |
Other boards based on the Latent Lemon Audio Hurts
- Latent Lemon Audio Hurts Dirtbox Layouts
- Latent Lemon Hurts (trace) Naegele Audio