Enclosure not stated · 3 knobs

BJF Sea Blue EQ

Based on the BJFE Sea Blue EQ· 2 other boards clone it

Category: EQ / Filter
Controls: Treble · Bass · Volume
Price: see vendor
Also as: Vero layout · from Revolution Deux
Tags: freestompboxes.org trace

Read the post at Revolution Deux Schematic image freestompboxes.org thread Vero layout

From the vendor

Bjorn Juhl's EQ booster with light distortion, meant to fine-tune the in-between bands that amp tone controls miss. It is a James-style passive bass/treble network between two JFET gain stages. The post warns that op-amps could replace the JFET stages only if the output impedance driving the EQ stays the same, since it shapes the tone section's response.

The JFETs are unknown; 2N5458 or 2N5452 bias to the correct voltages (the vero layout uses 2N5458). The vero layout suggests a higher value for R1 if the LED is too bright.

Schematic

The schematic is in the post. Open it at Revolution Deux. No KiCad fragment has been drawn for this circuit yet.

Parts list 35 rows

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Ref	Value	Normalized	Type	Notes
Resistors 15
R1	1K	1k		LED resistor; read from the schematic by eye
R2	1K	1k		read from the schematic by eye
R3	14.7K	14.7k		read from the schematic by eye
R4	14.7K	14.7k		read from the schematic by eye
R5	14.7K	14.7k		read from the schematic by eye
R6	1M	1M		read from the schematic by eye
R7	14.7K	14.7k		read from the schematic by eye
R8	1K	1k		read from the schematic by eye
R9	1M	1M		read from the schematic by eye
R10	14.7K	14.7k		read from the schematic by eye
R11	1M	1M		read from the schematic by eye
R12	47K	47k		read from the schematic by eye
R13	5.6K	5.6k		read from the schematic by eye
R14	5.6K	5.6k		read from the schematic by eye
R15	1K	1k		read from the schematic by eye
Capacitors 12
C1	100u	100u		electrolytic; read from the schematic by eye
C2	1n	1n		read from the schematic by eye
C3	1n	1n		read from the schematic by eye
C4	1u	1u		electrolytic; read from the schematic by eye
C5	1u	1u		electrolytic; read from the schematic by eye
C6	22u	22u		electrolytic; read from the schematic by eye
C7	22n	22n		read from the schematic by eye
C8	470n	470n		electrolytic; read from the schematic by eye
C9	4.7n	4.7n		read from the schematic by eye
C10	22n	22n		read from the schematic by eye
C11	220n	220n		read from the schematic by eye
C12	22n	22n		read from the schematic by eye
Diodes 2
D1	1N4007	1N4007		read from the schematic by eye
D2	5.1V	5V1		zener; read from the schematic by eye
Transistors 2
Q1	2N5458	2N5458		JFET, original unknown; read from the schematic by eye
Q2	2N5458	2N5458		JFET, original unknown; read from the schematic by eye
Potentiometers 3
Treble	B50K	B50k	Potentiometer	read from the schematic by eye
Bass	A50K	A50k	Potentiometer	read from the schematic by eye
Volume	B50K	B50k	Potentiometer	read from the schematic by eye
LEDs 1
D3	LED	LED		5mm; read from the schematic by eye

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