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SUSTAINSENSITIVITYCOMP VOLUMECLEAN VOLUMERANGE

125B · 5 knobs

Aion FX

ProximaOptical Compressor

Based on the Flatline Compressor· 1 other board clones it

Category
Compressor
Controls
Sustain · Sensitivity · Comp Volume · Clean Volume · Range
Difficulty
Easy
Price
$12.50in stock

From the vendor

A simple, cheap and surprisingly effective optical compressor that works great on bass or guitar.

The Proxima Optical Compressor is an expanded adaptation of the Flatline Compressor, a DIY classic originally invented by John Hollis in 2001.

There have been several community modifications and revisions during the past two decades, so while the original version only had Sustain and Volume controls, the Proxima has a more deluxe control set.

This version includes several additions: a JFET input buffer to split the signal, a sensitivity or threshold knob, a clean blend by way of separate Effect Volume and Clean Volume controls, and an output buffer to correct the phase from the mixing stage. If you like the Flatline but wish it had more flexibility, the Proxima is what you’re after.

In addition to John Hollis, we are indebted to the work of Madbean and Stompville for many of the ideas utilized in this version, and we’re hopeful that ours will in turn inspire others to take it even further.

Note: This project uses a type of capacitor that has been temporarily discontinued by WIMA. Please see our news article about the issue and the substitution spreadsheet for project-specific recommendations. We are stocking a limited supply in the mean time. The build document has not yet been updated to reflect this.

Schematic

The schematic is in the vendor's build document, page 6. Open the build document. No KiCad fragment has been drawn for this circuit yet.

Parts list 56 rows

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RefValueNormalizedTypeNotes
Resistors 20
R110k10kMetal film resistor, 1/4W
R21M1MMetal film resistor, 1/4WLeave empty if using a BJT for Q1. See build notes.
R310k10kMetal film resistor, 1/4W
R41M1MMetal film resistor, 1/4W
R5100k100kMetal film resistor, 1/4W
R610k10kMetal film resistor, 1/4W
R722k22kMetal film resistor, 1/4W
R810k10kMetal film resistor, 1/4W
R922k22kMetal film resistor, 1/4W
R10330R330Metal film resistor, 1/4W
R1110k10kMetal film resistor, 1/4W
R1222k22kMetal film resistor, 1/4W
R1310k10kMetal film resistor, 1/4W
R1410k10kMetal film resistor, 1/4W
R15100R100Metal film resistor, 1/4W
R16100k100kMetal film resistor, 1/4W
R1710k10kMetal film resistor, 1/4W
R1810k10kMetal film resistor, 1/4W
RPD2M22.2MMetal film resistor, 1/4WInput pull-down resistor. Can be as low as 1M.
LEDR10k10kMetal film resistor, 1/4WLED current-limiting resistor. Adjust value to change LED brightness.
Capacitors 13
C147pF47pMLCC capacitor, NP0/C0G
C233n33nFilm capacitor, 7.2 x 2.5mm
C3220n220nFilm capacitor, 7.2 x 2.5mm
C41uF1uFilm capacitor, 7.2 x 3.5mm
C5220n220nFilm capacitor, 7.2 x 2.5mm
C6100uF100uElectrolytic capacitor, 6.3mm
C81uF1uFilm capacitor, 7.2 x 3.5mm
C9470n470nFilm capacitor, 7.2 x 3mm
C1047pF47pMLCC capacitor, NP0/C0G
C111uF1uFilm capacitor, 7.2 x 3.5mm
C12100uF100uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
C1347uF47uElectrolytic capacitor, 5mmReference voltage filter capacitor.
C14100n100nMLCC capacitor, X7RPower supply filter capacitor.
Diodes 5
D11N58171N5817Schottky diode, DO-41
D2BAT46BAT46Schottky diode, DO-35
D3BAT46BAT46Schottky diode, DO-35
D4BAT46BAT46Schottky diode, DO-35
D5BAT46BAT46Schottky diode, DO-35
Transistors 1
Q12N54572N5457JFET, N-channel, general purposeCan also use 2N5088. See build notes.
ICs 2
IC1TL072TL072Operational amplifier, DIP8
IC2TL072TL072Operational amplifier, DIP8
Opto 1
VACTVTL5C3VTL5C3OptocouplerCan also use VTL5C2, NS-32 or others. See build notes.
Potentiometers 4
SUSTAIN100kAA100k16mm right-angle PCB mount pot
SENSITIVITY50kBB50k16mm right-angle PCB mount pot
CLEAN VOL.100kBB100k16mm right-angle PCB mount pot
COMP VOL.100kBB100k16mm right-angle PCB mount pot
Trimmers 1
RANGE500k500kTrimmer, 10%, 1/4”
Switches 1
FSW3PDT3PDTStomp switch, 3PDT
LEDs 1
LED5mm5MMLED, 5mm, red diffused
Jacks & sockets 5
IC1-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IC2-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IN1/4" stereo1/4" STEREO1/4" phone jack, closed frameSwitchcraft 112BX or equivalent.
OUT1/4" mono1/4" MONO1/4" phone jack, closed frameSwitchcraft 111X or equivalent.
DC2.1mm2.1MMDC jack, 2.1mm panel mountMouser 163-4302-E or equivalent.
Hardware 2
BATT.9V9V9V battery snapSoft vinyl type. The hard-shell type will not fit.
ENC125B125BEnclosure, die-cast aluminumCan also use a Hammond 1590N1.

Other boards based on the Flatline Compressor