That’s a little thing that is missing big time on the Voyager OS. It’s pretty cumbersome to move a 3 oscillators patch up or down one octave when performing.
Pursuing my exploration of the Voyager cv’s, and plugging an expression pedal into the pitch jack, I had a pretty good idea of what would happen. Just as I thought. From there it was easy. Five resistors connected in series, a 6 position switch, each pole connected to the next resistor in serie. The most simple voltage potential divider there is.
On the TRS plug :
Sleeve is ground. One end of the resistor serie is connected here
Ring is connected to the other end of the resistor serie
Tip is connected to the switch output.
From that, voltage at each point of the resistor serie differs exaclty one volt from one to the next. Resistor value can be just about anything. To be on par with that of the expression pedal, I used 2.2k resistors for a total of 11k. Anything from 500 Ohms to 5Kohms will work. Power of the resistors does not matter, there is very minimal current going through these, 1/8 watts resistors will work well (that’s what i had on hand), use the standard 1/4 watts if you have them. Precision does not matter all that much. With 5 resistors from the same batch, their resistance value should be pretty even. Voltage measured at the ring was 5 volts right on, so calibration is not even required.
Et voilà. A five octave switch for my Voyager OS that moves all oscillators frequencies at the same time.
Total cost : Zippo, all built from spare parts.
A fun project for those of you owning a welding iron
Well yes, it’s an OS. I love my OS, yet it lacks a few tiny things here and there. The Octave switch is more than a tiny little thing, I was missing it a lot. I just can’t figure why they did not build one right on. I am glad to learn there is one on the regular ones. Anyway, this is not the end of this. I have a few things in mind and there is going to be a little bit more circuitry added to this very soon.
How many [of my] kids does it take to shift the octave up a notch (answer=2), I have my 9 year old take the OSC1 Octave and my 12 year old take the OSC2 while I get the 3rd. You’ve just put two enterprising youths out of work!
What else do you have in mind? (I would like to see a pitch wheel mod that would allow the up/down to be different sort of like on the Little Phatty with 1.4+ code) Likely soldering required for this one because I think the jumper only allows for the up/down to be set the same # of steps.
Nope. This is my first mod directly tapping into the voltage provided by the red jack for an expression pedal (or else). From the specs of the CP-251, I kind of expected the voltage to be 5.6 volts (with .6 volts spent somewhere in the circuit). But no. The voltage on the ring connection of the red jacks is 5 volts even. And because the voltage divider is so simple, it is accurate with reasonably matched resistors (same batch) even if these are low quality parts with a large tolerance. The mod is simple, foolproof and calibration is not required, while accuracy is guaranteed.
The black mod and pitch wheels of the OS are not the nicest. I have been thinking of replacing them with the rubberized gray wheels of the LP for a better feeling. They are the same size so replacement is probably trivial. Tapping in the power of the OS to add a high luminance level blue led should not be very difficult either.
I would also like to add some range to the pitch wheel, but for that, I am currently building my own CP-251 style voltage control processor. The unit will be housing my Doepfer A-190-2 midi-to-CV converter, replacing the 1/8 jacks with 1/4 standard jacks, a couple of 4-in-1, and 4 to 6 “expression levers”. Some of them will be 0-5 volts, some others -5 to 5 volts. I have yet to decide on the exact parts, but I bought 3 dozens quarter inch stereo jacks (.30 a piece) at an electronics warehouse last week so I can move ahead on the building.
In order to augment the playability of the Voyager, I made a second version of the above mod. The situation is this : during/after a melodic line, i often miss a few notes on either side of the keyboard, generally on the lower pitch side though, for bass lines.
So I mounted 4 small normally open push type switches on a small board. While playing, when I need just a temporary octave switch to finish a riff, the free hand can now reach one of the switches and the pitch will go -2, -1, +1, +2 octaves only while one of the switch is depressed, resuming normal pitch when the switch is released. The small board is conveniently located on the wood strip below the main panel, easier to reach and operate during performance than a rotary switch located farther away.
That’s the principle, the mod works right now, but not exactly as described above, since it’s only positive voltage. In a second step, i will make the electronics use negative voltage so that the switches can feed in -2, -1, +1 and +2 volts respectively into the pitch jack, hopefully adding only passive components.
I will postpone the negative voltage mods on the little board for a little while. I have plans to do some more serious circuit design later on. For now, I have re-worked the wiring so that the two leftmost switches are routed to the CP-251 mixer for inversion, then back into the Voyager’s pitch input jack.
The mod now performs as per plan, with a couple of twists if I feel like turning knobs at the same time
