MIDI Drawbar Controller for Native Instruments B4 Digital Organ (Hammond Clone)
obxwindsurf
Posts: 3
I'd like to take this opportunity to post my completed project which is a MIDI control surface for the Native Instruments B4 Digital Hammond Organ Clone.
This unit uses a Basic Stamp 2sx and a handful of support components to interface real Hammond drawbars, toggle switches and rotary switches to provide real-time control of 28 different parameters of a digitally modeled clone of a Hammond B3 organ.
You can view an assembled view of the unit at: http://www.vintagemusicprojects.com/B4RTC_images/Assembled.jpg
Several of the pins on the BS2SX are used for memory map decoding of the output devices.· Drawbars and Rotary switches are encoded from 8 bits to 3 by a priority encoder to a 4 bit input bus.· The toggle switches and "Leslie" switch are arbitrated along with the 4 bit bus.· There is also several 4 line to 16 line decoders used in combination with a pin that selects one mux or the other and these are used to address individual drawbars, rotary switches, and groups of 4 toggle switches as "select" lines.
The program which runs this fits into a single code page.· Since MIDI is a "modal" messaging protocol, previously scanned and read values are persisted into scratch pad RAM (in case code had to span multiple pages - it had to survive code page switches).· If a scanned value has changed from a previously persisted value a MIDI message for that controller is generated and sent via a MIDI out using the SEROUT protocol.
The BS2SX and support components are wirewrapped onto a 4.5x6 "vector" board and a 44 pin edge connector is used to interface the controls, serial console port and MIDI port with the board.
I will be posting construction schematics, pics, and source code on my web site as soon as I can get the docs finished.
This unit uses a Basic Stamp 2sx and a handful of support components to interface real Hammond drawbars, toggle switches and rotary switches to provide real-time control of 28 different parameters of a digitally modeled clone of a Hammond B3 organ.
You can view an assembled view of the unit at: http://www.vintagemusicprojects.com/B4RTC_images/Assembled.jpg
Several of the pins on the BS2SX are used for memory map decoding of the output devices.· Drawbars and Rotary switches are encoded from 8 bits to 3 by a priority encoder to a 4 bit input bus.· The toggle switches and "Leslie" switch are arbitrated along with the 4 bit bus.· There is also several 4 line to 16 line decoders used in combination with a pin that selects one mux or the other and these are used to address individual drawbars, rotary switches, and groups of 4 toggle switches as "select" lines.
The program which runs this fits into a single code page.· Since MIDI is a "modal" messaging protocol, previously scanned and read values are persisted into scratch pad RAM (in case code had to span multiple pages - it had to survive code page switches).· If a scanned value has changed from a previously persisted value a MIDI message for that controller is generated and sent via a MIDI out using the SEROUT protocol.
The BS2SX and support components are wirewrapped onto a 4.5x6 "vector" board and a 44 pin edge connector is used to interface the controls, serial console port and MIDI port with the board.
I will be posting construction schematics, pics, and source code on my web site as soon as I can get the docs finished.
Comments
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Chris Savage
Parallax Tech Support
csavage@parallax.com
pretty cool looking setup too.
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**************
daniel woolston
Teksystems Inc.
www.danwoolston.com
**************
BTW, Native Instruments offers a drawbar controller in the meantime www.nativeinstruments.com/b4dc.info. But I like your approach much better because it has separate drawbar sets for the upper and lower manuals, and it looks more "vintage".
I'm using the B4 software since a couple of years and I really like it. Nevertheless, I now also have the "real thing" here at home - a B3 and a 147 Leslie.
As a matter of fact, a couple of years ago, I have developed SX28-based control panels for a German organ company, including drawbars, pushbuttons, LEDs, and an incremental data wheel. The panels communicate with a master controller via an I²C bus, and the master itself communicates with the organ electronics (actually a PC main board) via MIDI.
Now that you have finished the control interface for the B4, are you planning to "mimic" a complete B3 next
Hats off - I like your project!
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Greetings from Germany,
Günther
Danke f
yes, the original Hammond drawbars are not the best choice for such an application. On the boards I had designed, I'm using potentiometers instead, scanned by an SX controller with a dedicated ADC virtual peripheral program.
Hey, I also like your Leslie project - had a look at your http://www.vintagemusicprojects.com/HomebrewLeslieConstr.html site. I do have an original 122 Leslie here and I'm still dreaming of replacing the "classical" two-speed units by a "modern" brushless drive motor with variable RPMs.
Yes, I agree with you, the B4 is the best "replacement" for a "real" B3. Nevertheless, I also have the "real thing" here but it's way too heavy to be moved. In my next live, I'm going to play a piccolo flute instead
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Greetings from Germany,
G
I actually prefer the original two speed motor stack. If I had to do the control part over again, I would use solid-state relays for their zero-cross turn off feature, but for now I'll just be resigned to replacing de-spiking caps every so often on the motor control relays.· In my schematic they were originally 1 uf, but they weren't fast enough so I replaced them with 0.1 as in the original Leslie chassis.
Viele Grüße
Kevin
I have re-built a Leslie Power Relay which used a solid state relay instead of the mechanical one. I've also been asked for a replacement of the mechanical relay in the Leslie. Solid state would be fine, especially in studios where the mechanical relays can actually generate nasty spikes, and even the mechanical click can cause irritations.
Concerning the brushless motors - yes, I know - this is not "vintage" at all
Even worse (i.e. a complete change in style), a brushless motor could also replace the main motor of the tone generator. No need for a start motor anymore, the possibility to fine-tune the organ, and no problem with 50/60 Hertz mains. I my B3 (imported from the US), I'm using a step-down transformer and a frequency converter to get the right tune right now.
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Greetings from Germany,
G
--tom
Probably a dead end. Thread went dead 7 years ago. Tom has not been on since 2005, and Gunther has not posted in quite a while, (although he logged in last year).
Jim