Octave switch?

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Mr D
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Octave switch?

Post by Mr D » Fri Jun 01, 2018 5:56 pm

Hey folks,

You know how on many OSC modules you've got an octave switch, normally giving you a choice of 3 or 4 octaves?

Well, i love the sound of switching octaves during a sequence.

So, that got me to a-thinking: would it be possible to automate (modulate) this effect via CV?

Obviously (presumably) there's no (analog) OSC module that'll let you switch octaves via CV.

So how else could you do this? I suspect it has something to do with a module that can halve / double CV voltages that control pitch, but i haven't got any further then that.

Any tips warmly received!

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Nino
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Post by Nino » Fri Jun 01, 2018 6:03 pm

Maybe the WMD Octavus will be something for you?

[video][/video]

(starting at 3:23)

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bradpickapiper
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Post by bradpickapiper » Fri Jun 01, 2018 6:06 pm

that looks pretty interesting!

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outfigurable
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Post by outfigurable » Fri Jun 01, 2018 6:09 pm

You could use a precision adder. A nice module that does this is ALM Beast's Chalkboard [1], another example would be the classic Doepfer A-185-2 [2] which lets you add a cv value to a sequence, thus changing octaves. Yet another (different from just octave switching) module would be the Intelljel Shifty, which takes an incoming sequence and distributes it among different outputs, allowing you to vary a sequence with several oscillators [3].

But basically, you want a precision adder.

[1] http://busycircuits.com/alm002/
[2] http://www.doepfer.de/a1852.htm
[3] https://intellijel.com/eurorack-modules/shifty/

widgetoz
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Re: Octave switch?

Post by widgetoz » Fri Jun 01, 2018 6:27 pm

Mr D wrote:Hey folks,

You know how on many OSC modules you've got an octave switch, normally giving you a choice of 3 or 4 octaves?

Well, i love the sound of switching octaves during a sequence.

So, that got me to a-thinking: would it be possible to automate (modulate) this effect via CV?

Obviously (presumably) there's no (analog) OSC module that'll let you switch octaves via CV.

So how else could you do this? I suspect it has something to do with a module that can halve / double CV voltages that control pitch, but i haven't got any further then that.

Any tips warmly received!
There are a few modules that generate voltages and can be switched (or more correctly stepped). A sequencer is a prime example but our Programmer modules are a simply form. With both of these you can set an output voltage for each step (typically 0V to 5V so thats 5 octaves). You can connect that to a LOG FM input of your VCOs and then step through the stages to get different offsets. Pass the output through a processor modules' too get a negative offset for down transposition. Of course a sequencer is a bit messy in terms of having clock back and forth and is harder to jump steps. that is where the Programmer comes in as it lets you select a step either manually or by a crontrol. Look at our ES23, ES24 and ES28

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wavejumperr
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Post by wavejumperr » Fri Jun 01, 2018 6:32 pm

you can't automate it with CV, but i think it's worth mentioning the intellijel dixie ii+, rubicon ii, and the atlantis are all analog oscillators that have octave switching built in.
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helix
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Post by helix » Wed Sep 11, 2019 1:38 am

Are any of these voltage controlled? Or are they all manual switches? Looking at the chalkboard and the doepfer suggests you have to manually switch them, which is no good for accuracy in a sequence

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MarcelP
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Post by MarcelP » Wed Sep 11, 2019 2:20 am

helix wrote:Are any of these voltage controlled? Or are they all manual switches? Looking at the chalkboard and the doepfer suggests you have to manually switch them, which is no good for accuracy in a sequence
I tend to use a VC switch to flip between the Chalkboard out and the original sequence if I don’t want to do it manually.

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Summa
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Post by Summa » Wed Sep 11, 2019 2:21 am

so your sequencer can't switch octaves? then the t43 might be worth looking at, it was mentioned in another topic today and it has an CV (C) input that adds to the sum.

https://vpme.de/t43/

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Re: Octave switch?

Post by Arneb » Wed Sep 11, 2019 2:45 am

Mr D wrote:So how else could you do this? I suspect it has something to do with a module that can halve / double CV voltages that control pitch, but i haven't got any further then that.
First things first: No. Not halving/doubling. Under the 1V/oct standard what you need to do is add an offset, not attenuate, because what "1V/oct" means is that your VCO will convert an offset of +1V to your pitch CV into frequency doubling.

As for how to do this... the only one-module solution I found while browsing Modulargrid is the Disting's A-1 algorithm (the integer precision adder), as that one quantizes the Z input to multiples of 1V which is exactly what you want.

Anything else is trickier because unfortunately most octave switches (ALM002, NE Quant Gemi etc.) don't have CV and most precision adders (A-185-2, VPME t43 etc.) don't quantize. Best non-Disting solution I can come up with is generate a constant 1V voltage somewhere, patch it into a CV-controllable switch, and patch that switch into a precision adder.
(Edit: Or MarcelP's solution, which is the same idea but with the CV switch after the adder instead of before it.)

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maltemark
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Post by maltemark » Wed Sep 11, 2019 3:30 am

WMD Volt is expensive but allows trigger-enabled octave switching. Would love to find a cheaper solution but just as compact...

[EDIT: sorry, doesn't to semitones I now realize, which was asked for]
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acidbob
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Post by acidbob » Wed Sep 11, 2019 3:38 am

Cant the ladik easy quantizer do what you want?

andybizarre
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Post by andybizarre » Wed Sep 11, 2019 4:32 am

You could just attenuate your gate to the desired octave and patch it to a precision adder or your VCO`s FM input - voilà, octave switching via gate.

However, a quantizer is needed in between to match the exact voltages.

R.U.Nuts
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Post by R.U.Nuts » Wed Sep 11, 2019 4:41 am

Just plug a gate signal into the exponential FM input of your VCO and adjust it's attenuator in a way that each time the gate goes high the VCO's pitch is transposed an octave up.

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ggillon
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Post by ggillon » Wed Sep 11, 2019 5:12 am

The easiest way is through your sequencer.

For example rené2 does it through the FUN.CV.ADD parameter.

Though this is a 2018 question so maybe you have solved it already :mrgreen:

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evs
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Post by evs » Wed Sep 11, 2019 5:23 am

just let your sequencer run through a quantizer.. not that hard:-)

adaris
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Post by adaris » Wed Sep 11, 2019 6:06 am

The Precision Adder on the Disting Mk4 can be used for voltage controlled octave-switching, in fact it's designed for that.

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Post by barnbrook » Wed Sep 11, 2019 6:06 am

agree a precision adder is a good way to go for this.

alternatively i have the trans europa module by frequency central which does octave switching by CV and more:

http://www.frequencycentral.co.uk/?page_id=1311

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Foghorn
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Post by Foghorn » Wed Sep 11, 2019 7:49 am

T43 by vpme.de is a most useful module and I think it works better than most precision adders, although I have not tried the disting adder.
Plus, only 4HP

I realize it is probably a calibration issue but my Doepfer precision adder was not quite adding correctly.

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gruebleengourd
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Post by gruebleengourd » Wed Sep 11, 2019 10:19 am

check out the frequency central trans europa

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Groundloop
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Post by Groundloop » Wed Sep 11, 2019 10:55 am

Foghorn wrote:I realize it is probably a calibration issue but my Doepfer precision adder was not quite adding correctly.

Foghorn

T43 on modulargrid
It might also be the age of the A-185-2. My understanding is that at some point in the last couple years Doepfer changed the opamps from LM324 to LT1014, which are apparently more accurate.

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maltemark
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Post by maltemark » Wed Sep 11, 2019 11:16 am

http://ladik.ladik.eu/?page_id=2795

Just saw this:
T-240 Transposer allows making transposition of input CV controlled by triggers or gates. Transposition amount for appropriate input is set by knob. Knob range (each channel) can be 1 octave up/down or 2 octaves up/down. Transposition is semitone quantized, knob LED alternately shows semitone selection (+-12 semitones or +-24 semitones).

There are two trig/gate modes: in “gate mode” is CV transposed while input gate(s) is active, in trig mode transposition lasts while another trig comes. Manual button for ch4 allows setting of desired transposition and recall it manually (if zero transposition is selected in the mid knob position then discards transposition).

Input trigs/gates can be evaluated in three modes:

lowest = if two or mode trigs/gates are present together lowest channels is selected for transposition, others are ignored
sum = traspositions from all active channels are summed
last = last trig/gate is taken into account, others are ignored (if two or more trigs/gates begins in exactly same time evaluation of last one is almost random)
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skreetis
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Post by skreetis » Wed Sep 11, 2019 12:20 pm

Ornament and Crime provides vc octave switching, along with four lanes of quantization.

helix
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Post by helix » Wed Sep 11, 2019 2:45 pm

R.U.Nuts wrote:Just plug a gate signal into the exponential FM input of your VCO and adjust it's attenuator in a way that each time the gate goes high the VCO's pitch is transposed an octave up.
Great idea! Seems so obvious :yay:

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mskala
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Post by mskala » Wed Sep 11, 2019 7:51 pm

I sell a Dual VC Octave Switch with precision adder/subtrator features too: https://northcoastsynthesis.com/product ... witch.html

The exponential-modulation trick is nice too, but using a quantizing module like this one allows for both manual and CV control; less dependence on getting a consistent voltage from your gate source and precise adjustment of the knob; and more than two states.

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