Anyone built a Theremax to use MIDI fader for CV-MIDI output?

Posted: 6/24/2007 3:38:29 PM
kidelectric

From: Napa, CA

Joined: 6/9/2007

After PAiA replaced the missing parts (well, they sent a wrong resistor AGAIN, but I had a 120 ohm lying around which I will use in place of the 100 ohm and I don't think it should affect anything), the Theremax is coming along nicely (built into an Atari 2600 case.) I have soldered all components onto the board and same with the MIDI fader kit. Now is where things get tricky.

I need to figure out how many toggle switches I am going to use as well as how/where to lay them in the case. I also may need to purchase and install an extra 1/4" phone jack. In order to figure out my next steps, I need to understand how the MIDI fader works. Reading the schematic of the MIDI drum kit makes sense (in which consistent voltage inputs from drum triggers are fed to specific inputs of the drum EPROM, which then send a MIDI note based on which drum was triggered)

However, the Fader works a bit differently, and reading the PAiA documentation notes hasn't helped me figure it out. If anybody (I know teslatheremin is one, is there anybody else?) has tried using the MIDI fader to convert Theremax CV to MIDI (or even if you have just used the PAiA MIDI fader for any purpose whatsoever), I would appreciate some help on any of the following:

1) It seems only ONE voltage input can be used with the Fader. Is this the case? I was originally going to hardwire the CV's from the Tmax into the MIDIFader inputs, but if only one CV is allowed at a time, I can't do this unless I use some sort of switch to select between the different CV-outs as I see fit.

2) If only 1 CV-in is allowed for fader mode and I don't hardwire, I presume I could use a 1/4" phone jack for CV in, and then use a patch plug from my selected CV-out to the CV-in.

3) I am definitely uncertain of where to feed the CV input(s) at J5 since it is normally used with a multi-input trigger device to trigger the different drum pads/notes. Since the fader works differently, I can't determined how the J5 input routes are being used.

4) I plan on having a toggle switch to choose between Single channel (open) and Multi-channel (grounded) modes. I will also have a switch to switch into Volume Gate mode as shown on the PAiA site. Finally, I would like the included 8-switch component to be readily available (so I can change MIDI CC's I want to send to) so I was going to mount it right into my front panel. (the other switches I will have are one to jump in/out of PAiA's RCA-tone mod and one for Kkissinger's tone mod) Any foreseeable issues with these plans?

I will also contact Scott with these questions, as he seemed willing to help me figure it out.
Posted: 6/26/2007 5:31:11 PM
kidelectric

From: Napa, CA

Joined: 6/9/2007

wow wow wow. Scott Lee is a very thorough man! I sent an email with these questions regarding the midi fader and within a couple days not only did he respond, but he drew a diagram and scanned it in as an email attachment to help explain how I could wire or configure the inputs!

Now I can see why PAiA's customer service has received such high marks in the reviews I had read....
Posted: 6/27/2007 6:50:23 AM
teslatheremin

From: Toledo, Ohio United States of America

Joined: 2/22/2006

kidelectric,
Scott didn't even do that for me! He's becoming even better at his job!
Your above plan seems fairly thought out, although your assumption about the fader only being able to receive one CV at a time doesn't coincide with the performance of my Midi-fader. I can control volume and pitch at the same time.

I am working on some pictures and sound samples from my 'Mod-ded' T-max-Midi-fader unit and will post some soon.

teslatheremin
Posted: 6/27/2007 9:19:08 PM
kidelectric

From: Napa, CA

Joined: 6/9/2007

Thanks, tesla.

Yes, as Scott clarified, each input (as in MIDI drum would be a separate trigger/pad) can receive its own CV input... so multiple CVs can be used simultaneously. This helps clarify that question, but what that leaves me scratching my head about is... how does the fader set different MIDI cc channels for the different CV inputs? Looking at the docs, it seems only one cc can be set, or a sequence of cc's in incremental order, specified to different MIDI out channels. (perhaps I am misreading it? Are the channels referring to MIDI outs, or to the CV ins?)

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