Akashic Guitar effects PCB lookup
SUSTAINLOW CUTHI CUTVOLUME

125B · 4 knobs

Aion FX

SomaVintage Overdrive

Based on the Cornish SS-3 Soft Sustain

Category
Overdrive
Controls
Sustain · Low Cut · Hi Cut · Volume
Difficulty
Intermediate
Price
$12.50in stock

From the vendor

An evolution of the MXR Distortion+ that adds two passive tone-cut controls as well as the classic Cornish input buffer.

The Soma Vintage Overdrive is adapted from the Pete Cornish SS-3, traced by Aion FX in 2019.

Cornish pedals are best known for being extremely expensive. There are two reasons for this. First, the build quality and reliability is unmatched. Second, the mysterious nature of them, partially due to the fact that the circuit is obscured and partially because of the A-list of clients such as Brian May and Pete Townshend.

The SS-3 in particular is owned by Jeff Beck, David Gilmour, Keith Urban and Carlos Santana among many others. It’s an update to the earlier SS-2 that adds a low-cut control, since the original was fairly bass-heavy. With the low cut control set fully clockwise, the circuit is identical to the SS-2.

Under the hood, the SS-3 appears to have originated from the MXR Distortion+ circuit and then had passive low & hi-cut tone controls added, along with the classic Cornish buffer at the input.

The Soma is a faithful reproduction of the SS-3 circuit, but with one major addition: an internal slide switch allowing the pedal to be used in true-bypass mode instead of buffered bypass. As with the Klon KTR, the buffered mode is “almost always better”, but with this feature, you can determine for yourself.

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 67 rows

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RefValueNormalizedTypeNotes
Resistors 31
R110M10MMetal film resistor, 1/4W
R21k1kMetal film resistor, 1/4W
R3120k120kMetal film resistor, 1/4W
R4120k120kMetal film resistor, 1/4W
R5200k200kMetal film resistor, 1/4W
R67k57.5kMetal film resistor, 1/4W
R710k10kMetal film resistor, 1/4W
R851R51Metal film resistor, 1/4W
R91M1MMetal film resistor, 1/4W
R1010k10kMetal film resistor, 1/4W
R111M1MMetal film resistor, 1/4W
R12100k100kMetal film resistor, 1/4W
R13510R510Metal film resistor, 1/4W
R1415k15kMetal film resistor, 1/4W
R151k61.6kMetal film resistor, 1/4W
R161k61.6kMetal film resistor, 1/4W
R171M1MMetal film resistor, 1/4W
R181M1MMetal film resistor, 1/4W
R191M1MMetal film resistor, 1/4W
R202k42.4kMetal film resistor, 1/4W
R2110k10kMetal film resistor, 1/4W
R226k86.8kMetal film resistor, 1/4W
R2310k10kMetal film resistor, 1/4W
R2491R91Metal film resistor, 1/4W
R25100R100Metal film resistor, 1/4W
R26150k150kMetal film resistor, 1/4W
R27180k180kMetal film resistor, 1/4W
R28100R100Metal film resistor, 1/4W
R2991R91Metal film resistor, 1/4W
R3051k51kMetal film resistor, 1/4W
LEDR4k74.7kMetal film resistor, 1/4WLED current-limiting resistor. Adjust value to change LED brightness.
Capacitors 20
C1100n100nFilm capacitor, 7.2 x 2.5mm
C24.7uF4.7uElectrolytic capacitor, 4mm
C31n1nFilm capacitor, 7.2 x 2.5mm
C422uF22uElectrolytic capacitor, 5mm
C510n10nFilm capacitor, 7.2 x 2.5mm
C6220pF220pMLCC capacitor, NP0/C0G
C7470n470nFilm capacitor, 7.2 x 3mm
C83n33.3nFilm capacitor, 7.2 x 2.5mm
C910uF10uElectrolytic capacitor, 5mm
C1010n10nFilm capacitor, 7.2 x 2.5mm
C11220n220nFilm capacitor, 7.2 x 2.5mm
C1210n10nFilm capacitor, 7.2 x 2.5mm
C13220n220nFilm capacitor, 7.2 x 2.5mm
C14220pF220pMLCC capacitor, NP0/C0G
C1510uF10uElectrolytic capacitor, 5mm
C1622uF22uElectrolytic capacitor, 5mm
C17100n100nMLCC capacitor, X7RPower supply filter capacitor.
C18220uF220uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
C1910uF10uElectrolytic capacitor, 5mmReference voltage filter capacitor.
C20220uF220uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
Diodes 3
D11N58171N5817Schottky diode, DO-41
D21N34A1N34AGermanium diode, NOSExact part number is unimportant, any NOS germanium diode should work about the same here. Can also substitute BAT46 Schottky diode.
D31N34A1N34AGermanium diode, NOS
Transistors 1
Q12N50882N5088BJT transistor, NPN, TO-92Substitute. Original uses BC549C.
ICs 2
IC1TL071TL071Operational amplifier, DIP8
IC2TL071TL071Operational amplifier, DIP8
Potentiometers 3
SUST.50kCC50k16mm right-angle PCB mount pot
HI CUT25kBB25k16mm right-angle PCB mount pot
VOL.10kAA10k16mm right-angle PCB mount pot
Switches 1
FSW3PDT3PDTStomp switch, 3PDT
Jacks & sockets 5
IC1-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IC2-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 mountMouser 163-4302-E or equivalent.
Hardware 1
ENC125B125BEnclosure, die-cast aluminumCan also use a Hammond 1590N1.