MIDI 1U Feature Request: Precision Scaler

A shot in the dark here…

It would be awesome to scale 1v per octave up +5v to accommodate unipolar oscillators on a separate CV out from the MIDI 1U in the config app. Is this possible?

EDIT: Transpose up 5v, not down

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Have you tried using the coarse tuning option for the synth to which the output is assigned?

I have. The problem is on uni osc inputs, nothing registers below MIDI note 60 (C3), whereas my other oscs do. Would be nice to have that additional range for sequencing from the DAW, or other MIDI devices (and to have them match up).

The workaround is of course to buy a precision adder that can transpose voltage down 5v, or to create separate note sequences to within the unipolar range (which is king of a pain).

I’m not sure what the problem is? The output is capable of the full bipolar range, it’s just centered around the note determined by the coarse tuning. Perhaps I’m misunderstanding your request?

Well, @Danjel did say he was considering making one

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I have the same problem…
With the old µMIDI the pitch output was 0-10V. This worked great for Piston Honda and Hertz Donut MkIII because you could get a full 8 octaves on them… but it sucked for my complex oscillators, because the workflow on them is much more productive when you tune them to C3 or C4, so you can shift the ratio of modulator:carrier. So if you tune them to C4 - it means you can’t go lower than C4 in pitch.
Now with MIDI 1U - my Complex Oscillators are very happy! Tune them to a mid point on their scale for your convenience, and you can theoretically play a full 10 octaves - unless your modulator drops to 0Hz at -3V. But it is very usable.
The problem with MIDI 1U and various other bipolar sources when used with unipolar oscillators (like my Donut and Piston, and I think NE modules have the same “crippling issue” :wink: ) is the oscillators don’t recognize anything below 0Hz, so the best you can get is 5 octaves without a precision adder. I don’t really feel the need for it, as I am usually using those two oscillators in a 4 octave range at the most… but it is a pain… and an annoying limitation as @illiac describes.

There is an idea for a tiny 1U module. pitch CV goes in the top jack, comes out the bottom jack with 5V added to it.


Thank you, @studioutopia: I was struggling to describe the issue. Indeed, wondering if it would be possible to implement a 0-10v volt per octave range on the MIDI 1U, ala uMIDI, for a separate pitch out, alongside the standard +/-5 out?

Also, there seems to be a bug in the config app, where the coarse tuning at +24 semitones will not update to the device; it simply snaps down to -24 semitones.

If it’s not possible to implement, this looks like the next best solution (but it would be nice to save $70 and not have to rearrange the case):

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Quadratt, Duatt and Triatt, can all offset the voltage (and of course other MFRs make similar utilities.) to level it up by 5V.

To me it’s very odd that a module wouldn’t accept a negative voltage on it’s frequency CV input. That totally kill any useful Audio-rate or LFO FM possibilities from any oscillator module of even the same manufacturer, the negative half of the waveform would be ignored! Had a similar discussion recently on Modwiggler.


It’s fairly common with digital oscs (Harvestman, Noise Engineering, etc.) for volt per octave, but they usually include bipolar FM ins (that don’t track). I also tried adding +5 from Quadratt, but it didn’t seem to offset. Maybe I did something wrong (might need half rectification).

Anyways, it would still be a useful feature on the MIDI 1u.

You need to use 2 Channels from the Quadratt, Patching your Source into 1 and the output of the next one, then use the channel without the input to add the 5V Offset. The outputs of the 2 channels are summed.


The Hardware is fixed to +/-5V on the MIDI 1U, this is not something that could be changed with a firmware update.

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Brain dead move on my part lol. Of course. I’ll give it a shot to see if it still tracks precisely. And thank you for letting me know about the feature request.

It should track fine as long as the channel with the Input is set to Unipolar and fully clockwise… Your offset will matter less because it won’t affect the scale of the signal, and you can tune your oscillator.

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Indeed - I’ve had a number of skirmishes with the “anti-bipolar CV/Pitch” folks… they don’t seem to see the benefit of balanced FM modulation, or the wonderful mathematical expressions that can be done with subtractive voltage - ie. adding two wandering control voltages:
-3 + 4 = 1; -2 + 3 = 2; -1 + 5 = 4; 3 + -1 = 2; Final series: 1-2-4-2
note that the above additive expressions are a lot more interesting than adding the same inputs scaled unipolar:
2 + 9 = 11!; 3 + 8 = 11!; 4 + 10 = 9; 8 + 4 = 12!; Final Series (clipped): 10-10-9-10
Notice that the output voltages are nearly all above the 10V ceiling and get clipped, and have very little variation. Even attenuating those unipolar sources 50% leads to a less than interesting output curve.
1 + 4.5 = 5.5; 1.5 + 4 = 5.5; 2 + 5 = 7; 4 + 2 = 6; Final series: 5.5-5.5-7-6
I am no mathematician, but I am sure that trying to accomplish interesting things (ie. variation, modulation) while being crippled to only using positive integers as inputs is a lot more difficult, and in practice requires a lot more utilities to create inversions and attenuation.
Rubicon2’s WARP function is an amazing example of the exciting things you can do with adding two bipolar waveforms.
If I were to define a standard (heaven forbid) for modular synthesis, all control voltages would be +/-5V bipolar, with trigs and gates being a subset and only using the positive end of that spectrum.
fortunately the manufacturers I have and love the most - Intellijel, Frap Tools, Instruō and Xaoc all fundamentally work within these specs.
Not to get too far down that rabbithole… but I’ve read Buchla is unipolar-only for pitch and CV, which is unfortunate - but does something interesting with gates and trigs being signalled on the same wire - a “Pulse”, with gates occupying the 0-5V range, and trigs being momentary spikes to 10V. This would do wonders for creating retriggerable and sustaining ASR and ADSR envelopes using one input cable.
(see Buchla pulse/gate specs? - MOD WIGGLER)


The closest that exists is the original Doepfer A-100 spec. See the section “Signals in the A-100”. There are a few oddities like audio being ±5 V but bipolar CV being typically ±2.5 V… which is kind of contradictory as most audio oscillators also operate in the LFO range. Even Doepfer’s own modules don’t follow all the guidelines here, but to be fair they are all recommendations and there’s liberal use of the word “typically”.

I don’t really care about a voltage standardization (although it would be nice), what I want is for everybody to list whether the jacks are protected from having too much voltage, and what amount breaks the module if there isn’t protection. My first day in modular I broke my wasp filter by accidentally putting it in a positive feedback loop.