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Rodgers 321B - adding MIDI whilst keeping original specs

Connecting Hauptwerk to MIDI organs, sequencers, ...
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adelaideviewer

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Rodgers 321B - adding MIDI whilst keeping original specs

PostSun Jan 23, 2022 6:05 am

Hi all,

I do have a bit of knowledge of electronics and adding MIDI to devices, but I am wondering what the easiest way would be to add MIDI to a RODGERS 321B organ. It was of the era prior to MIDI. My father would like to keep the original specification intact but to add MIDI capability for Hauptwerk. I know that the manuals and pedals would need to get MIDI connections. Are there already systems that let you add this to the key contacts etc?

Many thanks
Stuart
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larason2

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Re: Rodgers 321B - adding MIDI whilst keeping original specs

PostSun Jan 23, 2022 1:45 pm

I’m afraid there is no easy way, and there is no pre-existing system to do this for Rodgers.

I’m not sure if the organ is analog or digital, but the approach differs based on the technology.

Analog is probably the easier one to go, piggybacking off the switches. However you need some kind of system to protect modern Midi circuits from the higher voltage of analog keying, usually transistors. Another approach is to add a second set of contacts, perhaps reed switches.

For digital, the reed switch approach would also work, but piggybacking off the switches is harder, because you get interference from the organ’s keying. In that case, the best way forward is to reverse engineer the keyboard encoder board, and use the keying signals developed there to drive the Midi board. This has been done for MOS1 Allens, but not Rodgers.

So no matter how you go about it, a lot of work ahead!

There are a number of commercial boards out there, I’m most familiar with the ones from Midi Boutique. There are also quite a few of us who have developed Arduino based solutions.
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Frank-Evans

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Re: Rodgers 321B - adding MIDI whilst keeping original specs

PostMon Jan 24, 2022 12:11 pm

HI,
I did this to my Rodgers 340 (before gutting it and completely converting it). Look at the products from Artison Organs. They have a system called MicroMidi. Not cheap but works very well. Since the Rodgers uses 12 volt keying it is a natural.
Frank Evans
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rayjcar

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Re: Rodgers 321B - adding MIDI whilst keeping original specs

PostThu Jan 27, 2022 6:59 pm

The first time I modified my Rodgers 333 for Hauptwerk I kept the existing analog tone generation intact. The harnesses from the keyboards go to a keyer board on one of the wooden frames. You can solder wires on the PC board and run them to an encoder card. As stated by FrankEvans, the keying voltage is +12 volts, which can be used readily by many cards. I would suggest considering the DTS Midisystems encoders (you would have to order the HV version for positive keying). They are very simple to program using DIP switches.
The stop switch outputs also go to PC boards on the frame, but they are more widely dispersed than the keyboard outputs.
If you send me a personal message with your email, I can send you photos and a writeup of the procedure.

The other wrinkle is that you need to replace the potentiomenters on the swell shoes with dual ganged potentiometers - a 500 ohm for the LDR controlled audio, and a 5k or 10 linear pot for the midi encoder. I can give you the exact specification.

One wrinkle you will have is that the Rodgers analog circuits have no latency, and Hauptwerk has a varying degree of latency depending on buffer settings, the sound card driver, etc. You would have to fiddle the adjustments to minimize the latency, but even then there is likely to be a noticeable differential. If you just want to play only the analog stops or only the digital stops, it doesn't matter what the latency is.

Now having gone through all the tedium of keeping my organ intact, one day there was a power surge which blew the diodes in the power supply, and caused irreparable damage to the transposer time division multiplexing. This effectively killed the keying outputs to the midi encoders. So I totally gutted the analog electronics, rewired directly from the keyboard harness (which makes for a very neat job), and never looked back.

My initial reluctance to avoid gutting the original (and horribly expensive) electronics was overcome by the incredible difference between sampled sounds and the old analog tone generators. The Rodgers tone generation was excellent for its era (see the video of George Wright on Youtube playing the Robert Powers custom Rodgers).

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