Model 15: Behavior of Controller Outputs

[goldhamster]

Hi, I'm new to the forum here. I'm from Germany, have an vintage Minimoog and fulfilled my teenage dream one year ago: I bought a new Moog Model 15 (the re-issue). Not the usual teenage dream, I know, but buying a Model 15 is also not the usual mid-life crisis compensation. But it does the trick for me

I bought the Model 15 without a keyboard and have fun controlling it from the CV outputs of an Elektron A4. The sad thing is that the right half of 15's control panel (with the Controller Outputs) is unused, but that's how it is. Nevertheless, I patched one of the controller CV outputs into one of the frequency modulation inputs of the 921, which was oscillating in the audio range. To my surprise I the 921 frequency exhibited a jitter. I thought these jacks are merely trunk lines for CVs and S-Trigs from keyboards.

For those on the board with a Model 15 (vintage or re-issue) – would you be so kind and check on you instrument how it behaves in this case?
And if your instrument's oscillator also start to jitter, does this jitter go away if the Moog keyboard is connected?

Thanks much in advance!

[M00G]

Hmm. Just checked on my Model 15 RI (no kb) and do not get that effect at all.
I understand that the controller outputs are totally passive until a kb is connected (so much so that I use them as extra mults a lot!) I also could not see any voltage at all on the CV outs and the scope certainly shows nothing but a flat line.

Questions:
Does the frequency of the glitching change?
Can you change the glitch with any other module change or setting?
Do you get the same effect with the 921a/b?

....

[goldhamster]

Thanks for the test, highly appreciated. I will try to perform the tests you suggested tomorrow evening and report back!

Any more Model 15 users who can chime in?

[goldhamster]

Sorry for the long silence, here's an update.

If no other signals are present in a controller output row (i.e. no signal present via the multipin plugs on the Moog's back, or no other signal patched into the row on the front), the output row carries an odd jittery signal. Checked with Moog: In this case the open circuit is basically acting as an antenna, and the jittery ghost signal should go away as soon as I
(a) either use the front panel controller row jacks as a multiple (with nothing connected to the rear multipin)
(b) or have a signal connected to the controller row via the rear multipin connector.

And indeed, the ghost signal vanishes in both cases (a) and (b),hooray!

So currently I am building custom cables that allow me to connect the CV/Gate outputs of my Elektron A4 to the Moog's rear multipin jacks, so that the front
• Control Voltage controller row 1 carries CV A from the A4,
• Control Voltage controller row 2 carries CV B from the A4,
• Control Voltage controller row 3 carries CV C from the A4,
• Trigger controller row 3 carries CV D (set to S-Trig) from the A4.
Trigger controller rows 1 & 2 remain unconnected.

Controlling my Model 15 from the A4's sequencer is more fun than I thought it would be…!

[strum]

Hi Goldhamster,

I want to do the same with the barrel connector.

On synthfool I found the following from the schematics.

Controllers 1&2
--------------------
A: +12 V
B: GND
C: -6 V
D: CV 1
E: CV 2
F: S-Trig 2
G: S-Trig 1
H: Trig GND

Controller 3
--------------
A: +12 V
B: GND
C: -6 V
D: CV 3
E:
F:
G: S-Trig 3
H: Trig GND

--------------
A few questions
Is B the GND for the CVs ?
Can I ignore A and C pins ? I assume this is only to power an attached controller?
Did you find the barrel connectors ?

thanks!!