Akashic Guitar effects circuit lookup
BASSTREBLEGAINVOLUME

1590B · 4 knobs

TH Custom Effects

ROG Ginger

Based on the Run Off Groove Ginger· 4 other boards clone it

Category
Preamp / Amp-in-a-box
Controls
Bass · Treble · Gain · Volume
Price
€8.16in stock
Buy the PCB at TH Custom Effects Build document1.0

From the vendor

A faithful PCB layout of runoffgroove's Ginger — a JFET-based emulation of the Ampeg SB-12 "Portaflex" valve bass amp. Four 2N5457 JFET preamp stages with LED clipping, a full Baxandall BASS / TREBLE tone stack, and a 2N5088 BJT output buffer. Originally designed for bass, but equally good for drop-tuned guitar and clean-to-edge-of-breakup tones. The Ginger is a JFET-based emulation of the Ampeg SB-12 Portaflex bass amp, designed by the team at runoffgroove.com . It runs four 2N5457 JFETs to mimic the SB-12's tube preamp stages, uses a passive Baxandall tone stack between stages 1 and 2 for proper shelving bass / treble control, and finishes with a 2N5088 BJT output buffer. The result: ideal

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 39 rows

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RefValueNormalizedTypeNotes
Resistors 21
R168R68Power supply rail series resistor (with C1, C2 forms supply RC filter).
R210k10kVR (virtual reference) bias divider top — sets ≈ 4.5 V reference.
R310k10kVR bias divider bottom.
R433k33kQ1 gate input series resistor.
R51M1MQ1 gate pulldown / input impedance setter.
R6390R390Q1 source resistor — sets bias current with R7 trimmer.
R822k22kBaxandall tone stack — BASS shelving network.
R93k93.9kBaxandall tone stack — BASS pot return.
R1033k33kBaxandall tone stack — TREBLE shelving network.
R11100k100kTone stack output to Q2 gate — high impedance load.
R12390R390Q2 source resistor — sets bias current with R13 trimmer.
R141M1MQ3 gate bias resistor — sets DC operating point from VR.
R15390R390Q3 source resistor.
R1610k10kGAIN pot supply / Q3 drain.
R17390R390Q4 source resistor.
R18100k100kQ5 base series / coupling network — Q3-Q4-Q5 inter-stage.
R19100k100kQ5 base series — together with R18 sets HF response of output buffer.
R2010k10kOutput pulldown to ground at VOLUME pot.
R216k86.8kBelow GAIN pot — sets minimum gain limit.
R710k10k6 mm ACP or Piher (5×5 footprint) — sets Q1 drain bias. See §05 biasing procedure.
R1310k10k6 mm ACP or Piher (5×5 footprint) — sets Q2 drain bias. See §05 biasing procedure.
Capacitors 12
C2100n100nBox film — main supply rail RFI bypass.
C3220p220pBox film — Q1 input shunt to GND (RFI rolloff above audio).
C5220n220nBox film — Q1 drain to Baxandall tone stack coupling.
C622n22nBox film — BASS shelf high-frequency corner cap.
C7100n100nBox film — BASS shelf low-frequency corner cap.
C83n33.3nBox film — TREBLE shelf high-frequency corner cap.
C910n10nBox film — TREBLE shelf low-frequency corner cap.
C11220n220nBox film — Q2 drain to GAIN pot coupling.
C14220p220pBox film — Q5 output stability / HF rolloff.
C15220n220nBox film — output coupling to VOLUME pot.
C10100p100pCeramic — Q2 gate RFI rolloff.
C13470p470pCeramic — inter-stage HF rolloff in Q3-Q4-Q5 network.
Diodes 1
D11N40011N4001Reverse polarity protection — observe polarity, band toward circuit.
Transistors 1
Q52N50882N5088NPN BJT, TO-92. Output buffer / recovery stage. Pinout: E – B – C (flat side facing you, leads down). 2N3904 works as a substitute (same pinout).
Potentiometers 4
BASSA100kA100kA taper (audio log) — Baxandall bass shelving (~72–329 Hz).
TREBLEA100kA100kA taper (audio log) — Baxandall treble shelving (~480 Hz–1.5 kHz).
GAINA100kA100kA taper (audio log) — pre-amp drive amount.
VOLUMEA100kA100kA taper (audio log) — output level.

Other boards based on the Run Off Groove Ginger