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FUZZTONEVOLUME

125B · 3 knobs

Aion FX

PhobosGermanium Fuzz

Based on the Tone Bender Mk III· 1 other board clones it

Category
Fuzz· Germanium Fuzz
Controls
Fuzz · Tone · Volume
Difficulty
Easy
Price
$12.50in stock

From the vendor

A reproduction of the third version of the Tone Bender germanium fuzz sold by Macaris in London in the late 1960s.

The Phobos Germanium Fuzz is a clone of the Colorsound / Sola Sound Tone Bender Mk III. While the first version was essentially the same topology as a Fuzz Face, and the second version added a gain stage in front, this third version from 1967-1968 was a completely different circuit, using a Darlington-pair transistor configuration to drive a third transistor, followed by a tone control which the earlier versions were missing.

While the Mk. III Tone Bender was itself a variation of the Baldwin-Burns Buzzaround, it had a few variants of its own, both official and unofficial. The Vox Tone Bender was a licensed variant with a few parts substitutions. The Park Fuzz Sound by Park Amplification (Jim Marshall’s side-brand) was a contemporary clone. The Elka Dizzytone and the Prescription Electronics Yard Box were two others. Aside from the Buzzaround, all of the rest of these variations can be build on this PCB.

A note about the name: the original Colorsound / Sola Sound unit was not called the “Mark III”, but the Vox-licensed version was. As a result, this circuit is commonly called both the “Mark III” and the “three-knob” Tone Bender. This project will refer to it as the Mk III to differentiate it from the Mk II, which is available as another project called the Deimos.

The Phobos project has a voltage inverter which allows you to power the effect with a standard center-negative adapter while maintaining the positive-ground operation of the original. The PCB also includes biasing trim pots so you can dial in a perfect bias without having to swap out resistors.

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 46 rows

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RefValueNormalizedTypeNotes
Resistors 12
R147k47kMetal film resistor, 1/4W
R2220k220kMetal film resistor, 1/4W
R31k1kMetal film resistor, 1/4W
R410k10kMetal film resistor, 1/4W
R53k33.3kMetal film resistor, 1/4W
R618k18kMetal film resistor, 1/4W
R71k1kMetal film resistor, 1/4W
R810k10kMetal film resistor, 1/4W
R910k10kMetal film resistor, 1/4W
R10220k220kMetal film resistor, 1/4W
RPD1M1MMetal film resistor, 1/4WInput pulldown resistor. Can be as low as 1M.
LEDR10k10kMetal film resistor, 1/4WLED current-limiting resistor. Adjust value to change LED brightness.
Capacitors 11
C1100n100nFilm capacitor, 7.2 x 2.5mm
C2220pF220pMLCC capacitor, NP0/C0G
C3220n220nFilm capacitor, 7.2 x 2.5mm
C410uF10uElectrolytic capacitor, 5mm
C5100n100nFilm capacitor, 7.2 x 2.5mm
C62n22.2nFilm capacitor, 7.2 x 2.5mm
C7100uF100uElectrolytic capacitor, 6.3mm
C810uF10uElectrolytic capacitor, 5mm
C947uF47uElectrolytic capacitor, 5mm
C10470n470nMLCC capacitor, X7R
C11100n100nMLCC capacitor, X7R
Diodes 3
Z11N4742A1N4742AZener diode, 12V, DO-41
D11N58171N5817Schottky diode, DO-41
D2GermaniumGERMANIUMGermanium diode, DO-07Original uses 1N270, but part number isn’t important. Just use any NOS germanium diode.
Transistors 4
Q1GermaniumGERMANIUMGermanium transistor, PNPRecommended to buy a selected Tone Bender Mk III set. See build notes.
Q2GermaniumGERMANIUMGermanium transistor, PNPRecommended to buy a selected Tone Bender Mk III set. See build notes.
Q3GermaniumGERMANIUMGermanium transistor, PNPRecommended to buy a selected Tone Bender Mk III set. See build notes.
Q3B50k trimmer50K TRIMMERTrimmer, 10%, 1/4"Bias trimmer for Q3. See build notes.
ICs 1
IC1TC1044SCPA VoltTC1044SCPA VOLTage inverter, DIP8
Potentiometers 3
FUZZ100kBB100k16mm right-angle PCB mount pot
TONE100kBB100k16mm right-angle PCB mount pot
LEVEL100kAA100k16mm right-angle PCB mount pot
Trimmers 1
Q1-2B50k50kTrimmer, 10%, 1/4"Bias trimmer for Q1 and Q2. See build notes.
Switches 1
FSW3PDT3PDTStomp switch, 3PDT
LEDs 1
LED5mm5MMLED, 5mm, red diffused
Jacks & sockets 7
Q1-STO-5 socketTO-5 SOCKETTransistor socket, TO-5
Q2-STO-5 socketTO-5 SOCKETTransistor socket, TO-5
Q3-STO-5 socketTO-5 SOCKETTransistor socket, TO-5
IC1-SDIP-8 socketDIP-8 SOCKETIC socket, DIP-8
IN1/4" stereo1/4" STEREO1/4" phone jack, closed frameSwitchcraft 112BX 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 2
BATTBattery snapBATTERY SNAP9V battery snapOptional. Use the soft plastic type—the hard-shell type will not fit.
ENC125B125BEnclosure, die-cast aluminumCan also use a Hammond 1590N1.

Other boards based on the Tone Bender Mk III