125B · 2 knobs
ConvexParallel Compressor
Based on the Dinosaural OTC-201
- Category
- Compressor
- Controls
- Sustain · Balance
- Difficulty
- Intermediate
- Price
- $12.50in stock
From the vendor
An exceptionally rare and unique optical compressor designed by Dan Coggins of Lovetone fame.
The Convex Parallel Compressor is a clone of the Dinosaural OTC-201 Opticompressor, an all-original optical compressor designed by Dan Coggins, the chief engineer & circuit designer for Lovetone. It was originally traced by Aion FX in 2019.
The OTC-201 was made in very small numbers between 2013 and 2016 and remain exceedingly rare today. Despite this, they are universally acclaimed by the few who have had a chance to try one, and an OTC-201 can even be found on the pedalboard for Ed O’Brien of Radiohead.
Today, an updated version of the Opticompressor called the Fat General is available from ThorpyFX, also designed in collaboration with Dan Coggins. This version adds a treble control to allow a more jangly tone to be dialed in, but is otherwise basically the same circuit as the original.
The Convex is a direct clone of the original OTC-201, with two modifications. First, the internal Mode switch has been moved to the outside, so the blend/direct modes can be more conveniently switched between. Second, while the original OTC-201 was buffered bypass, the Convex adds an internal slide switch that allows you to select between true bypass or buffered bypass.
Schematic
The schematic is in the vendor's build document, page 7. Open the build document. No KiCad fragment has been drawn for this circuit yet.
Parts list 73 rows
Report a wrong parse| Ref | Value | Normalized | Type | Notes |
|---|---|---|---|---|
| Resistors 30 | ||||
| R1 | 10k | 10k | Metal film resistor, 1/4W | |
| R2 | 1M | 1M | Metal film resistor, 1/4W | |
| R3 | 10k | 10k | Metal film resistor, 1/4W | |
| R4 | 10k | 10k | Metal film resistor, 1/4W | |
| R5 | 10k | 10k | Metal film resistor, 1/4W | |
| R6 | 13k | 13k | Metal film resistor, 1/4W | |
| R7 | 10k | 10k | Metal film resistor, 1/4W | |
| R8 | 10k | 10k | Metal film resistor, 1/4W | |
| R9 | 39k | 39k | Metal film resistor, 1/4W | |
| R10 | 330k | 330k | Metal film resistor, 1/4W | |
| R11 | 10k | 10k | Metal film resistor, 1/4W | |
| R12 | 8k2 | 8.2k | Metal film resistor, 1/4W | |
| R13 | 4k7 | 4.7k | Metal film resistor, 1/4W | |
| R14 | 100k | 100k | Metal film resistor, 1/4W | |
| R15 | 2k2 | 2.2k | Metal film resistor, 1/4W | |
| R16 | 180R | 180 | Metal film resistor, 1/4W | |
| R17 | 4k7 | 4.7k | Metal film resistor, 1/4W | |
| R18 | 100k | 100k | Metal film resistor, 1/4W | |
| R19 | 180R | 180 | Metal film resistor, 1/4W | |
| R20 | 2k2 | 2.2k | Metal film resistor, 1/4W | |
| R21 | 180R | 180 | Metal film resistor, 1/4W | |
| R22 | 39k | 39k | Metal film resistor, 1/4W | |
| R23 | 180R | 180 | Metal film resistor, 1/4W | |
| R24 | 39k | 39k | Metal film resistor, 1/4W | |
| R25 | 100R | 100 | Metal film resistor, 1/4W | |
| R26 | 10k | 10k | Metal film resistor, 1/4W | |
| R27 | 1k8 | 1.8k | Metal film resistor, 1/4W | |
| R28 | 8k2 | 8.2k | Metal film resistor, 1/4W | |
| RPD | 2M2 | 2.2M | Metal film resistor, 1/4W | Input pulldown resistor. Can be as low as 1M. |
| LEDR | 10k | 10k | Metal film resistor, 1/4W | LED current-limiting resistor. Adjust value to change LED brightness. |
| Capacitors 18 | ||||
| C1 | 33n | 33n | Film capacitor, 7.2 x 2.5mm | |
| C2 | 470n | 470n | Film capacitor, 7.2 x 3mm | |
| C3 | 330pF | 330p | MLCC capacitor, NP0/C0G | |
| C4 | 220n | 220n | Film capacitor, 7.2 x 2.5mm | |
| C5 | 10n | 10n | Film capacitor, 7.2 x 2.5mm | |
| C6 | 330pF | 330p | MLCC capacitor, NP0/C0G | |
| C7 | 33n | 33n | Film capacitor, 7.2 x 2.5mm | |
| C8 | 10uF | 10u | Electrolytic capacitor, 5mm | |
| C9 | 33n | 33n | Film capacitor, 7.2 x 2.5mm | |
| C10 | 10uF | 10u | Electrolytic capacitor, 5mm | |
| C11 | 1uF | 1u | Film capacitor, 7.2 x 3.5mm | |
| C12 | 1uF | 1u | Film capacitor, 7.2 x 3.5mm | |
| C13 | 100uF | 100u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C14 | 100uF | 100u | Electrolytic capacitor, 6.3mm | Power supply filter capacitor. |
| C15 | 10n | 10n | MLCC capacitor, X7R | Power supply filter capacitor. |
| C16 | 10uF | 10u | Electrolytic capacitor, 5mm | Reference voltage filter capacitor. |
| C17 | 10uF | 10u | Electrolytic capacitor, 5mm | Reference voltage filter capacitor. |
| C18 | 100n | 100n | MLCC capacitor, X7R | Power supply filter capacitor. |
| Diodes 7 | ||||
| D1 | 1N5817 | 1N5817 | Schottky diode, DO-41 | |
| D2 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D3 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D4 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D5 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D6 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| D7 | 1N914 | 1N914 | Fast-switching diode, DO-35 | |
| Transistors 5 | ||||
| Q1 | J113 | J113 | JFET, N-channel, TO-92 | |
| Q2 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | Substitute. Original uses BC549C. |
| Q3 | 2N3906 | 2N3906 | BJT transistor, PNP, TO-92 | Substitute. Original uses BC307B. |
| Q4 | 2N3906 | 2N3906 | BJT transistor, PNP, TO-92 | Substitute. Original uses BC307B. |
| Q5 | 2N5088 | 2N5088 | BJT transistor, NPN, TO-92 | Substitute. Original uses BC549C. |
| ICs 1 | ||||
| IC1 | TL072 | TL072 | Operational amplifier, DIP8 | |
| Potentiometers 2 | ||||
| SUST. | 100kB | B100k | 16mm right-angle PCB mount pot | |
| BAL. | 10kA | A10k | 16mm right-angle PCB mount pot | |
| Switches 3 | ||||
| MODE | SPDT | SPDT | Toggle switch, SPDT on-on | |
| LEVEL | SPDT cntr off | SPDT CNTR OFF | Toggle switch, SPDT on-off-on | |
| FSW | 3PDT | 3PDT | Stomp switch, 3PDT | Available from Aion FX. |
| LEDs 1 | ||||
| LED | 5mm | 5MM | LED, 5mm, red diffused | |
| Jacks & sockets 4 | ||||
| IC1-S | DIP-8 socket | DIP-8 SOCKET | IC socket, DIP-8 | |
| IN | 1/4" mono | 1/4" MONO | 1/4" phone jack, closed frame | Switchcraft 111X or equivalent. |
| OUT | 1/4" mono | 1/4" MONO | 1/4" phone jack, closed frame | Switchcraft 111X or equivalent. |
| DC | 2.1mm | 2.1MM | DC jack, 2.1mm panel mount | Lumberg NEB/J 21 C or equivalent. |
| Hardware 2 | ||||
| BATT | Battery snap | BATTERY SNAP | 9V battery snap | Optional. Use the soft plastic type—the hard-shell type will not fit. |
| ENC | 125B | 125B | Enclosure, die-cast aluminum | Can also use a Hammond 1590N1. |