Akashic Guitar effects PCB lookup
SUSTAINBALANCE

125B · 2 knobs

Aion FX

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

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RefValueNormalizedTypeNotes
Resistors 30
R110k10kMetal film resistor, 1/4W
R21M1MMetal film resistor, 1/4W
R310k10kMetal film resistor, 1/4W
R410k10kMetal film resistor, 1/4W
R510k10kMetal film resistor, 1/4W
R613k13kMetal film resistor, 1/4W
R710k10kMetal film resistor, 1/4W
R810k10kMetal film resistor, 1/4W
R939k39kMetal film resistor, 1/4W
R10330k330kMetal film resistor, 1/4W
R1110k10kMetal film resistor, 1/4W
R128k28.2kMetal film resistor, 1/4W
R134k74.7kMetal film resistor, 1/4W
R14100k100kMetal film resistor, 1/4W
R152k22.2kMetal film resistor, 1/4W
R16180R180Metal film resistor, 1/4W
R174k74.7kMetal film resistor, 1/4W
R18100k100kMetal film resistor, 1/4W
R19180R180Metal film resistor, 1/4W
R202k22.2kMetal film resistor, 1/4W
R21180R180Metal film resistor, 1/4W
R2239k39kMetal film resistor, 1/4W
R23180R180Metal film resistor, 1/4W
R2439k39kMetal film resistor, 1/4W
R25100R100Metal film resistor, 1/4W
R2610k10kMetal film resistor, 1/4W
R271k81.8kMetal film resistor, 1/4W
R288k28.2kMetal film resistor, 1/4W
RPD2M22.2MMetal film resistor, 1/4WInput pulldown resistor. Can be as low as 1M.
LEDR10k10kMetal film resistor, 1/4WLED current-limiting resistor. Adjust value to change LED brightness.
Capacitors 18
C133n33nFilm capacitor, 7.2 x 2.5mm
C2470n470nFilm capacitor, 7.2 x 3mm
C3330pF330pMLCC capacitor, NP0/C0G
C4220n220nFilm capacitor, 7.2 x 2.5mm
C510n10nFilm capacitor, 7.2 x 2.5mm
C6330pF330pMLCC capacitor, NP0/C0G
C733n33nFilm capacitor, 7.2 x 2.5mm
C810uF10uElectrolytic capacitor, 5mm
C933n33nFilm capacitor, 7.2 x 2.5mm
C1010uF10uElectrolytic capacitor, 5mm
C111uF1uFilm capacitor, 7.2 x 3.5mm
C121uF1uFilm capacitor, 7.2 x 3.5mm
C13100uF100uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
C14100uF100uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
C1510n10nMLCC capacitor, X7RPower supply filter capacitor.
C1610uF10uElectrolytic capacitor, 5mmReference voltage filter capacitor.
C1710uF10uElectrolytic capacitor, 5mmReference voltage filter capacitor.
C18100n100nMLCC capacitor, X7RPower supply filter capacitor.
Diodes 7
D11N58171N5817Schottky diode, DO-41
D21N9141N914Fast-switching diode, DO-35
D31N9141N914Fast-switching diode, DO-35
D41N9141N914Fast-switching diode, DO-35
D51N9141N914Fast-switching diode, DO-35
D61N9141N914Fast-switching diode, DO-35
D71N9141N914Fast-switching diode, DO-35
Transistors 5
Q1J113J113JFET, N-channel, TO-92
Q22N50882N5088BJT transistor, NPN, TO-92Substitute. Original uses BC549C.
Q32N39062N3906BJT transistor, PNP, TO-92Substitute. Original uses BC307B.
Q42N39062N3906BJT transistor, PNP, TO-92Substitute. Original uses BC307B.
Q52N50882N5088BJT transistor, NPN, TO-92Substitute. Original uses BC549C.
ICs 1
IC1TL072TL072Operational amplifier, DIP8
Potentiometers 2
SUST.100kBB100k16mm right-angle PCB mount pot
BAL.10kAA10k16mm right-angle PCB mount pot
Switches 3
MODESPDTSPDTToggle switch, SPDT on-on
LEVELSPDT cntr offSPDT CNTR OFFToggle switch, SPDT on-off-on
FSW3PDT3PDTStomp switch, 3PDTAvailable from Aion FX.
LEDs 1
LED5mm5MMLED, 5mm, red diffused
Jacks & sockets 4
IC1-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IN1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
OUT1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
DC2.1mm2.1MMDC jack, 2.1mm panel mountLumberg NEB/J 21 C or equivalent.
Hardware 2
BATTBattery snapBATTERY SNAP9V battery snapOptional. Use the soft plastic type—the hard-shell type will not fit.
ENC125B125BEnclosure, die-cast aluminumCan also use a Hammond 1590N1.