Electro-Harmonix EHX B9 User manual

instructables
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 Elect ro Harmonix B9Ele ct ro Ha rmo 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)
EHX B9 Organ Machine Modification: Page 1

Step 1: What You Can Expect From Your Electro-Harmonix Modified...
The new features that the B9 will have:
OLED DISPLAY that shows the status of the unit:
1. OFFOFF the text is in reverse - O NON the text is normal
2. D ryD ry ( default ): organ and guitar are both present on "Organ OUT"
3. M ut eMut e : only organ is present on "Organ OUT", the guitar is Mute!
4. the eect selected by numbe rnum ber and de script io n: des cript ion: on the top in yellow a reference to the kind of
use of the eect like Deep Purple, Procol Harum, Jimmy Smith...- on the bottom the same (more or
less) description as the rotary switch
5. the kind of modulat io nkind o f modulat io n - Leslie/Vibrato/Tremolo
6. the spe edspe ed of MODULATION
7. the m odula t ion spe ed- upmodula t io n spe ed- up in progress scrolling from left to right the name of the selected eect
.
ROTARY ENCODER:
1. at power up the de fa ult se le ct iondef a ult se le ct ion is B9, meaning that the control of the eect is managed by the
B9 original rotary switch
2. rotating c lo ckw is eclo ckw is e to select eect 1, 2, 3...9, 1, 2, 3...
3. to return the control to B9 rotate it co unt e rclo ckw is eco unt erclo ckw is e ...3, 2, 1, B9 or...
4. ... press the ro t ary e nco der pus h but t o nro t a ry e ncode r pus h but t on to toggle between the selected eect and the B9
rotary switch selection: this is a simple way to move between 2 dierent pre se t s . 2 die rent pre se t s . (choosing a
taller rotary encoder facilitate to press it with your foot while you're playing! See the side picture)
EHX B9 Organ Machine Modification: Page 2

.
MUTE/DRY FUNCTION:
1. from OFF status move the rotary encoder counterclockwise to select eect 9
2. press the rotary encoder push button
3. the display will change from D ryD ry (default) to Mut eMut e
4. to go back to Dry remove the power and power up again!
.
LESLIE SPEED-UP FUNCTION:
1. to move from OFF to ON and viceversa press briey the foot-switch (we have to remove the existing
foot-switch and install a momentary push button)
2. select the LOW speed with the existing MOD potentiometer (you'll see the speed value on the
display)
3. press and keep pressed the foot-switch and the speed of the MOD will automatically progressively
increase to the MAX speed (100 on the display or less if you release it before 100 is reached) and
remain to the max until the foot-switch is pressed
4. release the foot-switch and the speed of the MOD will smoothly decrease up to the LOW speed
selected by the pot. MOD.
.
Ready to play A Whiter Shade of Pale?
EHX B9 Organ Machine Modification: Page 3

Step 2: Hardware...
EHX B9 Organ Machine Modification: Page 4

First of all, a disclaimer: I am an old-fashioned Electric
Engineer, maybe well capable to design a high
voltage distribution network and maybe sort of
capable to design and program a PLC controlled
equipment!
At University I used to program in Fortran on the
perforated cards, then in Basic and Assembler on the
Sinclair ZX80 (1Kb of memory...): practically I'm a
dinosaur!
Of course I like to play guitar and i like the sound of
organ: when I saw the B9 I was blown away!
To implement the speed-up function I thought to
simply add an external foot-switch that shortcuts the
MOD potentiometer to the max value or something
like the JHS modication that requires an external
expression pedal.
But I would like to reproduce the same feeling of the
organ player that is pressing a foot-switch and the
motor of the Leslie does the rest!
So I realised that some programming were needed:
time to learn this Arduino devilry!
Please be generous when you'll make comment on
the way I have developed the program ( I believe now
you call it "code"... ) and the hardware solution ( I use the
"electromechanical" approach ): I use all the resources
available on i n s t r uc t a b l e si n s t r uc t a b l e s and A r d u i n oA r d u i n o site and
I'll try to thanks the people that wrote the code I have
used to inspire me!
OK, let's talk about ha rdw areha rdw are .
Arduino Na no Ev eryArduino Na no Ev ery is controlling all the
functions:
INPUT
D2D2 Rotating Encoder -> pinA
D3D3 Rotating Encoder -> pinB
D4D4 Rotating Encoder -> push-button
D5D5 foot-switch: the standard foot-switch installed on
the B9 activates 3 contacts: opening the back of the
B9 you'll see the foot-switch connected to the PCB
(Printed Circuit Board) via a ribbon cable, the PCB
connection is marked CN2 and you can numbered the
EHX B9 Organ Machine Modification: Page 5

connections 1 (close to CN2 mark) to 6.
In OFF position the contact 3-4 is closed, in ON
position 5-6 is closed, in Dry selection 2-6 is closed.
You have to remove the existing foot-switch and
install a new simple momentary push button and
manage the 3 contacts though 3 relays.
I have used reed relays: small, stable contact and
cheap! In the Fritz schematics I couldn't nd the reed
relay SIP-1A05 so I used the most similar one. In the
pictures attached you'll see that the reed relay has
only 4 pins (instead of the 8 pins in the schematic): the
external ones are the contact, the inner ones the coil.
I've tried the digital switches CD4066 and the TM1134
but the On-resistance and probably the impedance
generate some distortion and "sound leakage" on
Mute position. So I went back on my
electromechanical approach that works noiseless!
A7A7 the pins of the potentiometer MOD (marked VR1
on the PCB) have to be cut (so disconnected from the
PCB) and connected to Nano: the pin on the min. to
the 5V - the pin on the MAX. to GND - the central pin
wiper to analog input A7
OUTPUT
D6D6 contact 3-4 (close is B9 is OFF)
D7D7 contact 2-6 (close is B9 is in Dry mode)
D8D8 contact 3-4 (close is B9 is ON)
D10D10 on the digital potentiometer MCP 42010 to CS
(pin1)*
D11D11 on the digital potentiometer MCP 42010 to S1
(pin3)*
D13D13 on the digital potentiometer MCP 42010 to SCK
(pin2)*
* on the breadboard schematic the digital potentiometer
chip is visualised by a generic 14pins IC with a trimmer
overlapping the pins 8-9-10. This is only a graphic
representation: you don't need anything else than
MCP42010.
A0A0 on the multiplexer 74HC4067 to S3
A1A1 on the multiplexer 74HC4067 to S2
A2A2 on the multiplexer 74HC4067 to S1
A3A3 on the multiplexer 74HC4067 to S0
A4A4 on the OLED display on SDA
A5A5 on the OLED display on SCL
POWER SUPPLY
VINVIN connect the Nano Vin to the +9V on the B9
socket: you can see from the pictures the pin that I
choose but be careful and check with the multimeter
the correct pin!
MULTIPLEXER
In order to double the function of the rotating switch
to select one of the 9 dierent organ eects, I have
used the rotating encoder that can (sort of ) easily
inform Arduino about directions. Then you need to
physically duplicate the existing rotary switch to
inform the B9 of which eect to select. My rst
prototype worked with 10 relays (I have attached a
picture to prove it!). Then I realised that it was a little
too much and, even if I was scared of this mystied
device, I bravely faced the multiplexer world and... I
succeed!
The multiplexer 74HC4067 is capable of 16 positions. I
have used position C0C0 to connect to the common pin
of the rotating switch (you have to cut and isolate the
pin marked "C" from the PCB and connect it to the C0
on the multiplexer): in this way you can "give back' the
control to the rotating switch when needed (...as a
preset!).
The other positions C1.. .C9C1. .. C9 have to be connected to
the 9 pins of the rotating switch: the easiest way is to
use the opposite side of the PCB (I have attached a
picture but, again, pay attention to nd the right
ones!)
I hope that with the help of the breadboard Fritz
schematic and some hints from the pictures, you can
EHX B9 Organ Machine Modification: Page 6

realise a cleaner PCB for the few components needed.
1. connect to CO of multiplexer
1
EHX B9 Organ Machine Modification: Page 7

EHX B9 Organ Machine Modification: Page 8

Step 3: ...& Software
https://www.instructables.com/ORIG/FBN/IUWI/KFFEDHKG/FBNIUWIKFFEDHKG.pdf
Download
EHX B9 Organ Machine Modification: Page 9

Step 4: Fit the Arduino Nano Every in the B9 Box
The code is a result of many inspirations from
instructables and Arduino sites. As I said, I learned
C++ just to be capable to do this project and my
approach is quite plain: I'm sure someone can write a
much more well-constructed code...
You'll notice that some piece of code are placed not in
the most logical position, this is because of my
successive-approximations way to x some problem!
First part is to variables and constants declaration (I
hope the comments are self explanatory): I added as
well the original description of the eect from the B9
manual.
The part related to the dig it a l po t e nt io me t er digit a l po t e nt io me t er has
been inspired by Henry Z haoHenry Z hao
https://wiki.dfrobot.com/Dual_Digital_Pot__100K__...
The part related to the mult iple xe rmult iple xe r has been
inspired by pmdwa y hkpmdwa y hk
https://www.instructables.com/id/Tutorial-74HC406...
that I re-adjusted for Arduino Nano Every.
The part related to the ro t a t ing e nco der ro t a t ing enco der has been
inspired by
Simo nM8Simo nM8 https://www.instructables.com/id/Improve
d-Arduino... : it has been hard to adapt to Arduino
Nano Every but... I did it after Simon's encouragement!
For the double f unct ions pus h but t ondouble f unct ions pus h but t on I've been
inspired by S cuba St ev e S cuba St e v e and M icha el Jam es M ichae l Ja me s
https://www.programmingelectronics.com/make-one-
b...
...and the rest (it seems a little but it's a lot for me) I
did it!
I believe that there are enough comments to explain
how the software works: I'll be happy to help if
someone nd some diculty to interpreter it.
https://www.instructables.com/ORIG/FV7/2AHL/KFFEDHDV/FV72AHLKFFEDHDV.fzz
Download
https://www.instructables.com/ORIG/F07/K9BU/KFFEDHHP/F07K9BUKFFEDHHP.ino
Download
EHX B9 Organ Machine Modification: Page 10

First of all you have to rem ov e t he PCB from t here mo ve t he PCB f ro m t he
boxbox: it is quite straightforward (remove back screws,
knobs, bolts from jacks and potentiometers) just be
gentle to avoid to damage the SMD on the PCB.
The most lucky part of this project has been to nd a
na rro w s lo tnarro w slot on the PCB close to the Output jacks: I
positioned the OLED display with the pins passing
through this slot and it's magical exactly where I
wanted it! Maybe Electro-Harmonix was planning to
introduce an OLED display at the time of the original
design: anyway I'm going to propose it to them!
With the OLED display in position use a piece of paper
to trace a t em pla t et em plat e (use a soft pencil) as shown in
the picture and then report the window of the display
on the box.
You'll need some patience and manual work to have a
reasonable rectangular window using drill and le...
I glued a piece of transparent plastic from inside to
protect the display and seal the box to avoid dust.
To connect the display to Arduino Nano Every use
screened cable (I have used a piece from a broken
iPhone USB cable...) and place a screen under the
display itself : the OLED device is quite noisy!
The ro t at ing enco derro t a t ing enco der is placed in the LED position
(removed) so you just need to enlarge the existing
hole.
You can see from the pictures that I used 2 small
pieces of PCBs for DIY: one for the Nano and the
digital potentiometer and one for the reed relays. The
only reason is because my rst attempt was to use
electronic switches IC and then I moved back to the
relays... For sure you can do all on one single PCB.
To keep noise away, use s cre ene d ca blesc re ene d ca ble for
connecting the MOD potentiometer and the relative
connections to Nano analog input.
For all the other connection I have used a v e ryve ry
e xible wiree xible wire (Plusivo 22AWG Hook Up Wire).
Once all the connection have done re-assemble the
B9 PCB and gently accomodate the Nano PCB in the
space around the foot-switch: I have used some
exible plastic to be sure no accidental contact will
happened.
Done.
EHX B9 Organ Machine Modification: Page 11

EHX B9 Organ Machine Modification: Page 12

EHX B9 Organ Machine Modification: Page 13

Step 5: Final Result.
The B9 is now ready for live performance!
- You'll see the display in the dark (it seems little but
it's quite visible and clear in normal playing position...)
and you know what sound is going to be heard...
- You can switch between the eect showed on the
display and the one selected on the rotary switch...
- You can decide if the Dry signal is there on the organ
output...
- ...and, nally, you can speed-up your Leslie like Billy
Preston, Jimmy Smith, Keith Emerson, Joey
Defrancesco, Jon Lord and... Peter Van Wood: my
guitar-organ hero!
Please be compassionate with the videos attached:
they have been recorded with my iPhone and with the
only intention to show the usage and not my "artistic"
poor capability!
Enjoy.
EHX B9 Organ Machine Modification: Page 14

EHX B9 Organ Machine Modification: Page 15

https://www.instructables.com/ORIG/FID/VIE3/KFFEDHHK/FIDVIE3KFFEDHHK.mov
Download
https://www.instructables.com/ORIG/FQO/FDS8/KFFEDHHL/FQOFDS8KFFEDHHL.mov
Download
https://www.instructables.com/ORIG/FLA/6YMP/KFFEDHHO/FLA6YMPKFFEDHHO.mov
Download
EHX B9 Organ Machine Modification: Page 16