Akashic Guitar effects PCB lookup
SUSTAINVOLUME

125B · 2 knobs

Aion FX

OctagonOctave Fuzz

Based on the Tycobrahe Octavia· 3 other boards clone it

Category
Fuzz· Octave fuzz
Controls
Sustain · Volume
Difficulty
Easy
Price
$12.50in stock

From the vendor

The very first octave-up fuzz effect, originally invented by Roger Mayer for Jimi Hendrix and later copied by Tycobrahe for a commercial release.

The Octagon Octave Fuzz is based on the Tycobrahe Octavia, a transformer-based octave fuzz pedal originally released in 1973.

The circuit itself was designed by Roger Mayer for Jimi Hendrix and dates back to 1967. He designed somewhere between 15 and 20 iterations for Jimi between ’67 and 1969, some of which only lasted a week before being tweaked again. The Octavia was never sold commercially, so there was no final or standard version of the circuit, but units were made for several other guitarists such as Syd Barrett and Peter Frampton.

One of these units was sent to the Tycobrahe Sound Company in California for repair. (Accounts vary as to whose unit it was, but it wasn’t Jimi’s.) They traced out the circuit and later released a commercial pedal in 1973, also called the Octavia since Roger had only used the name informally and never commercially. It was accompanied by a wide advertising campaign, but it ceased production sometime around 1976. According to Roger, the specific unit Tycobrahe copied was intended for 24V operation, but they dropped the power supply 9V without scaling any of the values, so the transistors are biased improperly.

Roger Mayer was never satisfied with any of the transformer versions and by 1970 he had redesigned the circuit to use all silicon transistors with no transformer. Jimi did play one of these new versions before his passing, but it has not been linked with any actual recordings and may have just been for evaluation and feedback. Roger has produced versions of the transistor Octavia ever since, but has never reissued the transformer version because he felt it was inferior.

Because of this, the transformer Octavia is more closely associated with Tycobrahe, and the transistor Octavia is called the “Roger Mayer version” even though he invented both. But since the transformer version was almost the only version Jimi ever played, it still lives on as its own circuit in the pantheon of early guitar effects.

All in all, it’s a complicated history that has caused a lot of confusion in the past fifty years. The two Octavias don’t have much in common and don’t sound alike, but both are worth building if you like octave fuzz. The transistor Octavia is available as our Octahedron project.

The Octagon is a direct adaptation of the Tycobrahe circuit, with the only addition being a toggle switch that disables the octave for a more traditional fuzz effect.

Schematic

The schematic is in the vendor's build document, page 6. Open the build document. No KiCad fragment has been drawn for this circuit yet.

Parts list 38 rows

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RefValueNormalizedTypeNotes
Resistors 13
R1820k820kMetal film resistor, 1/4W
R2180k180kMetal film resistor, 1/4W
R3680k680kMetal film resistor, 1/4W
R4220k220kMetal film resistor, 1/4W
R5220R220Metal film resistor, 1/4W
R622k22kMetal film resistor, 1/4W
R7470R470Metal film resistor, 1/4W
R81k1kMetal film resistor, 1/4W
R947k47kMetal film resistor, 1/4W
R101k21.2kMetal film resistor, 1/4W
R11100R100Metal film resistor, 1/4WPower supply filter resistor.
RPD2M22.2MMetal film resistor, 1/4WInput pulldown resistor.
LEDR10k10kMetal film resistor, 1/4WLED current-limiting resistor.
Capacitors 9
C1100n100nFilm capacitor, 7.2 x 2.5mm
C2150pF150pMLCC capacitor, NP0/C0G
C333uF33uElectrolytic capacitor, 5mm
C41n1nFilm capacitor, 7.2 x 2.5mm
C5220uF220uElectrolytic capacitor, 6.3mm
C6100uF100uElectrolytic capacitor, 6.3mm
C733uF33uElectrolytic capacitor, 5mm
C8100uF100uElectrolytic capacitor, 6.3mmPower supply filter capacitor.
C9100n100nMLCC capacitor, X7RPower supply filter capacitor.
Diodes 3
D11N58171N5817Schottky diode, DO-41
D2BAT46BAT46Schottky diode, DO-35The original Octavia used Ge diodes, but BAT46 will perform better.
D3BAT46BAT46Schottky diode, DO-35The original Octavia used Ge diodes, but BAT46 will perform better.
Transistors 3
Q12N39062N3906BJT transistor, PNP, TO-92
Q22N39042N3904BJT transistor, NPN, TO-92
Q32N39042N3904BJT transistor, NPN, TO-92
Potentiometers 2
DRIVE1kCC1k16mm right-angle PCB mount potReverse audio (reverse log or antilog) taper.
VOLUME500kAA500k16mm right-angle PCB mount potAudio (log) taper.
Switches 2
OCT SW.SPDT center offSPDT CENTER OFFToggle switch, SPDT on-off-on
FSW3PDT3PDTStomp switch, 3PDT
Jacks & sockets 3
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 1
XFM142TM02242TM022Transformer, 1.5KCT/600RCT

Other boards based on the Tycobrahe Octavia