Moog Prodigy: past methods used, DPDT tips, and reference file

Additional Moog Prodigy Information
Past methods used, DPDT tips, and reference file:

Though this effort will not be supported, this is how it would be done if the synth were here:

Do it exactly like the article says and hope for the best. It worked perfectly on that synth.

If it is like others, where the note pitch goes up and down in a strange way:

Remove all your I/O lines and tape them up. Utilize the Original MIDIJACK direct outputs (not bypassed) at the SP1 and SP2 solder pads, using your own wires, and wire the new CV/gate connections to the MIDIJACK SP1 and SP2 using a hardware DPDT switch to do a hardware bypass. This worked on two that failed the above.

If that still needs further tweaking, consider the information in this internet post from the 1990s. It is unverified, but seems to have come from experience with a lot more than the one synth we used here in 2000.

Here is a copy of previous Q & A with a customer who had to use the hardware DPDT switch:

> I’m still trying with that one. I remember you suggested something about “Using the SP1 and SP2 pads and a hardware DPDT switch was the solution that mostly corrected the problem.” I don’t understand where a DPDT switch is used,

It is used in place of the internal analog bypass of the Original MIDIJACK, and therefore the MIDIJACK blue, white, yellow, green, and brown wires are not used. This input/output structure is explained in the Original MIDIJACK Quick Installation Manual.

The DPDT will replace that.

The common poles go to the CV in and gate in points on the Moog Prodigy.

Two of the switched poles (the MIDI off position) will go to the CV out and gate out points on the Prodigy.

Two of the switched poles (the MIDI on position) will go to the SP1 and SP2 solder pads on the MIDIJACK.

It isn't known why, but the Prodigy has some analog weirdness that doesn't react well with the active bypass circuit, and the passive path of the hardware switch tends to lessen the problem. This DPDT is the standard way a MIDI kit would go in a synth, but it is a mess of wires and another hole chopped in the synthesizer, so the better-designed MIDIJACK did away with that with an internal circuit under software control. The MIDIJACK uses the industry-standard analog switch used in almost every polyphonic analog synth that ever existed, and the on resistance is only about 100 Ohms, but the Prodigy reacts badly to it. This may be because the internal CV/gate points of the Prodigy are unbuffered and could use an active op amp buffering circuit, but that is for you to decide as you work with it.

Every Prodigy done here reacted differently, one ended up perfect, and two did not, and all had a different solution to make them work as well as possible.

Once you solve that problem, you may be able to get a closer look at other Prodigy problems, and move those insert points around or add extra components as necessary.

> or what sp1 and sp2 pads are.

You'll know after you have read the Original MIDIJACK Quick Installation Manual.

> Are you suggesting a switch between the internal CV and Midijack?

Yes, as above.

> Possibly so the Midijack isn’t in series?

Right, so it is removed from the path when off, and the synth has no resistance or capacitance in the path when the MIDIJACK is bypassed.

Good luck with your project.

Analog User Support

(Note: None of this information is actually new, during the years when the website was rarely updated it was mailed to countless MIDIJACK customers/Moog Prodigy owners before their orders were processed, and the orders were not processed unless they read, understood, and approved of all of this. Some of them did not, most of them did, but it created hundreds of e-mails and many days of waiting for approval, and further questions, and lots of confusion and complaints about "lost" orders because some people think they are so incredibly clever in fighting spam by giving Synhouse a fake e-mail address when placing an order, thus cutting themselves off from important updates from the only relevant MIDIJACK application knowledge base in the world, and also because many free e-mail providers block e-mails from Synhouse. Now that this warning and information has been posted in bold red text atop the Moog Prodigy Analog User Modifications article, all customers will be considered duly warned in advance and such orders will be processed immediately.)

For Moog Prodigy customers who have read the above, tried the above, read it again, and are still unsatisfied with the results, you can read the additional testing and verification information in this support mail.

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