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BOOST

Enclosure not stated · 1 knob

Revolution Deux

Xotic EP Booster

Based on the Xotic EP Booster· 12 other boards clone it

Category
Boost
Controls
Boost
Price
see vendor
Tags
freestompboxes.org trace
Read the post at Revolution Deux Schematic imagefreestompboxes.org threadTagboard Effects vero layoutHandmades.br PCB layout (Masca)

From the vendor

Xotic's boost said to be based on the Echoplex EP-3 preamp, though the traced circuit does not much resemble it: a JFET gain stage whose source bypass is set by the Boost pot, a switchable passive low-pass filter, and a BJT emitter-follower output. Internal DIP switches choose the boost voicing and EQ.

The author would run it at 18V, replace the drain resistor with a 25k trimmer to find a sweet spot, swap the low-pass filter for Mark Hammer's Stupidly Wonderful Tone Control, and use a JFET or MOSFET follower in place of the BJT output buffer. To reduce the low end, lower the input cap to 33nF and change the bypass cap on the Boost control to 220nF-1uF to taste. Replace the first JFET's drain resistor with a 10k trimmer and set 5.5V on the drain.

Schematic

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

Parts list 30 rows

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Check before you build · 1 value the reader of this schematic was not sure of
  • The drawing shows Q1 as a J201 and Q2 as a 2N5088; the post says the originals are supposedly a 2N5457 and a 2SC1815.
RefValueNormalizedTypeNotes
Resistors 14
R14.7K4.7ksource; read from the schematic by eye
R28.2K8.2kdrain; read from the schematic by eye
R31M1Mread from the schematic by eye
R433K33kinput; read from the schematic by eye
R51M1Minput pull-down; read from the schematic by eye
R61K1kread from the schematic by eye
R715K15kread from the schematic by eye
R810K10kread from the schematic by eye
R910K10kread from the schematic by eye
R101M1Mread from the schematic by eye
R1110K10kemitter; read from the schematic by eye
R1247K47kread from the schematic by eye
R13100100output; read from the schematic by eye
R1433K33kLED resistor; read from the schematic by eye
Capacitors 9
C147n47ninput (0.047); read from the schematic by eye
C210u10uelectrolytic, source bypass; read from the schematic by eye
C3100u100uelectrolytic, switched by SW1; read from the schematic by eye
C410u10uelectrolytic; read from the schematic by eye
C510u10uelectrolytic; read from the schematic by eye
C64.7u4.7uelectrolytic; read from the schematic by eye
C747u47uelectrolytic, supply filter; read from the schematic by eye
C810u10uelectrolytic, output; read from the schematic by eye
C93.3n3.3n3300pF; read from the schematic by eye
Diodes 1
D21N41481N4148polarity protection; read from the schematic by eye
Transistors 2
Q1J201J201said to be 2N5457 in the original; read from the schematic by eye
Q22N50882N5088said to be 2SC1815 in the original; read from the schematic by eye
Potentiometers 1
BoostC10KC10kPotentiometerread from the schematic by eye
Switches 2
SW1DIPDIPinternal, bass boost; read from the schematic by eye
SW2DIPDIPinternal, EQ; read from the schematic by eye
LEDs 1
D1LEDLED3mm; read from the schematic by eye

Other boards based on the Xotic EP Booster