Electro-Harmonix EHX B9 Manual

EHX B9 Organ Machine Modification
by giorgpasq1
(ehx B9) - When I was a little boy I was fascinated by an incredible musical instrument: the Godwin Organ-Guitar of
Peter Van Wood (build in Italy by Sisme) ! I believe Peter represented the army of guitarists born in the analog jurassic
that looked at organists (yes organists, not keyboardists!) as the luckiest one that could play, sustain and modify
notes and chords forever!
A lot of attempts has been done to "imitate" the Organ (pipes or electronic) through the guitar (Roland, Casio...) but
the Ele ct ro Ha rm o nix B9 Ele ct ro Ha rm o nix B9 is, by far, the best one: simple, solid and addicting!
But there are few things that are missed...
In this project I modi ed a standard B9 (I believe that all the "9s" series of EHX are similar) to cover what I believe are
extremely useful features:
1. OLED DISPLAY: reading the position of the rotating switch is close to impossible in live situations, so a
nice bright Oled display is very welcomed to be visible and add some more info.
2. ROTARY ENCODER: a smoother encoder can be used for changing the preset and more.
3. PRESET FUNCTION: introduce a simple way to move between 2 di erent presets is essential to
introduce some fun in your playing!
4. MUTE/DRY FUNCTION: if you use a separate amp for the Organ OUT it's possible to avoid to have the
guitar signal there as well (Mute). This function is standard on the B9 but requires to open the unit
and move a microswitch: the rotary encoder can do it any time you want without open it.
5. LESLIE SPEED-UP FUNCTION: actually this is the original reason why I started to think to modify the
B9. There is no Organ Sound without Leslie! But the most fundamental use is to move from low-
speed to high-speed and back.
Supplies:
1. Arduino Nano Every
2. OLED Display IZOKEE 0.96" I2L 128X64 Pixel 2 colours
3. Rotary Encoder with push button (Cylewet)
4. Digital Potenziometer IC MCP42010
5. Multiplexer IC 74HC4067
6. 3 x Reed Relays SIP-1A05
7. Momentary stomp foot-switch push button
8. Double sided PCB ( Printed Circuit Board) for DIY
9. .1uF ceramic capacitor (for MCP42010 lter)
instructables
EHX B9 Organ Machine Modification: Page 1