1590B · 3 knobs

ROG Supreaux-Deux V1.3

Based on the Run Off Groove Supreaux Deux· 6 other boards clone it

Category: Overdrive
Controls: Gain · Tone · Volume
Price: €7.14in stock

Buy the PCB at TH Custom Effects Build document1.3

From the vendor

A faithful PCB of runoffgroove's Supreaux Deux — a JFET-based emulation of small Fender / Supro valve amplifiers. Three JFETs in cascade running from a clean 18 V rail (onboard charge pump doubler), simple TONE control, optional bass-boost switch. Designed for Fender-flavoured edge-of-breakup and mid-gain crunch. The Supreaux Deux is runoffgroove's JFET-based emulation of small Fender / Supro valve amplifiers — three JFET stages in cascade approximating the sound of a Champ-class or Supro 1×8 valve amp pushed into break-up. It runs three transistors with no source bypass caps (so the gain per stage is modest and the headroom is higher), and the JFETs run from an 18 V rail generated by an onb

Schematic

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

Parts list 34 rows

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Ref	Value	Normalized	Notes
Resistors 14
R1	100k	100k	Q1 gate series input resistor.
R2	1M	1M	Q1 gate pulldown / input impedance setter.
R3	390R	390	Q1 source resistor — unbypassed, sets gain and headroom.
R4	56k	56k	Q1 drain output series resistor.
R5	1k	1k	Q2 (J201) source resistor — unbypassed.
R6	100k	100k	Q2 drain output series resistor.
R7	1M	1M	Q3 gate pulldown / bias return.
R8	390R	390	Q3 source resistor — unbypassed.
R9	22k	22k	Q3 drain output series resistor.
R13	100R	100	VA rail series resistor — final filtering after the charge pump.
R14	1M	1M	Bass-boost HP path resistor — works with C10 to set the bass-boost corner.
R10	10k	10k	6 mm trimmer — sets Q1 (2N5457) drain bias. Probe at TP1 with multimeter. Target: ~12 V at TP1.
R11	50k	50k	6 mm trimmer — sets Q2 (J201) drain bias. Probe at TP2 . Target: ~12 V at TP2. Note the higher value (50k) — J201 needs more bias-resistor range.
R12	10k	10k	6 mm trimmer — sets Q3 (2N5457) drain bias. Probe at TP3 . Target: ~12 V at TP3.
Capacitors 9
C1	270p	270p	Ceramic — Q1 gate input shunt to GND for RFI rejection (above audio).
C2	470p	470p	Ceramic — Q1 drain HF shunt (C2), GAIN pot to Q2 gate coupling (C4).
C4	470p	470p	Ceramic — Q1 drain HF shunt (C2), GAIN pot to Q2 gate coupling (C4).
C3	2n2	2.2n	Box film — Q1 to GAIN pot coupling.
C5	1n5	1.5n	Box film — TONE pot shunt (C5), Q3 output HF rolloff (C7).
C7	1n5	1.5n	Box film — TONE pot shunt (C5), Q3 output HF rolloff (C7).
C6	4n7	4.7n	Box film — TONE output to Q3 gate coupling.
C8	68n	68n	Box film — Q3 output to VOLUME pot coupling.
C10	3n3	3.3n	Box film — bass boost HP path cap tuning . Works with R14 to set the bass-boost corner frequency.
Diodes 3
D1	1N4001	1N4001	Reverse polarity protection — observe polarity, band toward circuit.
D2	1N5817	1N5817	Schottky — charge pump voltage doubler rectifiers. Schottky required (low forward voltage drop) — every 0.3 V drop here costs headroom on the 18 V rail. Observe polarity.
D3	1N5817	1N5817	Schottky — charge pump voltage doubler rectifiers. Schottky required (low forward voltage drop) — every 0.3 V drop here costs headroom on the 18 V rail. Observe polarity.
Transistors 3
Q1	2N5457	2N5457	N-channel JFET, TO-92 — input (Q1) and output (Q3) stages. Pinout (flat side facing you, leads down): D – S – G. J201 MPF102 work but pinout may differ — verify. Sockets recommended.
Q3	2N5457	2N5457	N-channel JFET, TO-92 — input (Q1) and output (Q3) stages. Pinout (flat side facing you, leads down): D – S – G. J201 MPF102 work but pinout may differ — verify. Sockets recommended.
Q2	J201	J201	N-channel JFET, TO-92 — middle stage. Different device from Q1/Q3 — J201 has different pinch-off characteristics, hence the larger 50 k bias trimmer (R11). Pinout (flat side, leads down): D – S – G. Socket recommended.
ICs 1
IC2	ICL7660 SCPA	ICL7660 SCPA	Voltage inverter / charge pump, DIP-8. The "S" suffix is mandatory — non-S parts (plain ICL7660) oscillate in the audio band and whistle through the signal. MAX1044 works as an alternative. Use a socket.
Potentiometers 3
GAIN	A500k	A500k	A taper (audio log) — drive amount.
TONE	A500k	A500k	A taper (audio log) — single-knob treble cut.
VOLUME	A100k	A100k	A taper (audio log) — output level.
Switches 1
SW1	SPST	SPST	Bass boost switch (optional). When closed, grounds the B_B pad and engages the C10 / R14 bass-boost path. Any SPST mini-toggle works.

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