Sample Select and V/Oct

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Paroxysm01
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Sample Select and V/Oct

Post by Paroxysm01 » Fri Mar 13, 2020 9:33 am

After looking at many different sample modules in Eurorack and trying out the STS I've been pretty confused about one thing. Many samplers have a "Sample Select" Jack where you can switch between samples with CV, but this input is almost never V/Oct, making it difficult to assign each sample to a key on a musical keyboard. How do people get around this and why is this the case? Do the designers of the module expect for you to use LFOs and Non pitch voltage sequencers to control what sample is selected?

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Re: Sample Select and V/Oct

Post by KSS » Fri Mar 13, 2020 11:48 am

Paroxysm01 wrote:
Fri Mar 13, 2020 9:33 am
After looking at many different sample modules in Eurorack and trying out the STS I've been pretty confused about one thing. Many samplers have a "Sample Select" Jack where you can switch between samples with CV, but this input is almost never V/Oct, making it difficult to assign each sample to a key on a musical keyboard. How do people get around this and why is this the case? Do the designers of the module expect for you to use LFOs and Non pitch voltage sequencers to control what sample is selected?
Simply scale and -possibly- offset the input to the sample select jack to achieve the results you need.

Choosing to use V/Oct means everyone has to agree on what that means in a "sample' context.

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Re: Sample Select and V/Oct

Post by Pelsea » Fri Mar 13, 2020 12:19 pm

Remember, volt/octave is the the way pitch changes in an oscillator-- a better label would be 1 octave per volt. Your keyboard, either a direct CV or MIDI through a convertor puts out 1 volt per 12 keys. (With some rare exceptions.)
A keyboard ought to work fine for selecting samples in a sample player works that way (most of them seem to use a pulse input to step through the files.) You may need to scale the voltage with an attenuator.

Not all sample players change pitch at one octave per volt. Many just manipulate the sample rate, which behaves like a varispeed on a tape deck. Some modules manage v/8va, but it's tricky. If you have something originally recorded at 32kHz, going down two octaves leaves the SR at 8kHz, which sounds pretty gnarly. Proper pitch change requires resampling.
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Re: Sample Select and V/Oct

Post by tito_tunes » Fri Mar 13, 2020 12:27 pm

This is why I don't think CV is a good way of interacting with samples. It's done much better with midi. I do have a couple of Radio Music modules and I sequence them with an SQ-1 or Vector Sequencer, but I put at most 5 samples per bank (basically 1 per octave of a 5v CV) otherwise you'll never find the one you're looking for.
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Re: Sample Select and V/Oct

Post by Kattefjaes » Fri Mar 13, 2020 1:40 pm

Works fine for me via my sequencer, and is the most obviously sensible way to handle it. There might be problems with specific modules not tracking sensibly, but that's always a danger with cv, and the nature of the beast.

If you don't like it, maybe a MIDI sample player would make sense, if your sequencer of choice can also speak MIDI sensibly.

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Re: Sample Select and V/Oct

Post by KSS » Fri Mar 13, 2020 2:09 pm

Pelsea wrote:
Fri Mar 13, 2020 12:19 pm
Remember, volt/octave is the the way pitch changes in an oscillator-- a better label would be 1 octave per volt.
Better how? V/Oct literally means Volt divided by an octave.

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Re: Sample Select and V/Oct

Post by Monofunk » Fri Mar 13, 2020 2:13 pm

Depending on what your goal is using an LFO or random source might be desirable otherwise using a sequencer with step addressable voltage will enable more precise selection. Using a MIDI to CV converter would work.

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Re: Sample Select and V/Oct

Post by Pelsea » Fri Mar 13, 2020 2:57 pm

KSS wrote:
Fri Mar 13, 2020 2:09 pm
Pelsea wrote:
Fri Mar 13, 2020 12:19 pm
Remember, volt/octave is the the way pitch changes in an oscillator-- a better label would be 1 octave per volt.
Better how? V/Oct literally means Volt divided by an octave.
How many gallons per mile does your car get? How much does it cost? :despair:
Books and tutorials on modular synthesis at http://peterelsea.com
Patch responsibly-
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Re: Sample Select and V/Oct

Post by KSS » Sat Mar 14, 2020 5:53 am

Pelsea wrote:
Fri Mar 13, 2020 2:57 pm
How many gallons per mile does your car get? How much does it cost? :despair:
edit: If my car got 1MPG then there might be some equivalence between your analogy and what we're discussing. But it doesn't and there isn't. /edit

Again i'll ask, what is better about one volt per octave compared to one octave per volt?

Commutative property, much? :despair:

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Re: Sample Select and V/Oct

Post by Pelsea » Sat Mar 14, 2020 12:57 pm

KSS wrote:
Sat Mar 14, 2020 5:53 am
Pelsea wrote:
Fri Mar 13, 2020 2:57 pm
How many gallons per mile does your car get? How much does it cost? :despair:
edit: If my car got 1MPG then there might be some equivalence between your analogy and what we're discussing. But it doesn't and there isn't. /edit

Again i'll ask, what is better about one volt per octave compared to one octave per volt?

Commutative property, much? :despair:
I feel like the math professor who has to spend an hour at the blackboard showing how something is obvious.
If I put two gallons of gas in my van, I can drive 50 miles. But I can't put two octaves into a Buchla VCO and get 2.4 volts. It's not math, it's just a quirk in our labeling. Most ratios are expressed as output per unit input.
Books and tutorials on modular synthesis at http://peterelsea.com
Patch responsibly-
pqe

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Re: Sample Select and V/Oct

Post by KSS » Sat Mar 14, 2020 2:40 pm

Pelsea wrote:
Sat Mar 14, 2020 12:57 pm
KSS wrote:
Sat Mar 14, 2020 5:53 am
Pelsea wrote:
Fri Mar 13, 2020 2:57 pm
How many gallons per mile does your car get? How much does it cost? :despair:
edit: If my car got 1MPG then there might be some equivalence between your analogy and what we're discussing. But it doesn't and there isn't. /edit

Again i'll ask, what is better about one volt per octave compared to one octave per volt?

Commutative property, much? :despair:
I feel like the math professor who has to spend an hour at the blackboard showing how something is obvious.
If I put two gallons of gas in my van, I can drive 50 miles. But I can't put two octaves into a Buchla VCO and get 2.4 volts. It's not math, it's just a quirk in our labeling. Most ratios are expressed as output per unit input.
And i feel like the English student whose professor is using semantics to attempt to support an unsupportable point. Wasting an hour at the blackboard rather than concede that a ratio can be looked at from either direction. And engineers -and musicians- often do exactly that.

If I need to drive 50 miles, it will take two gallons of gas. (because my van gets 25MPG)
Honey, how much gas do we need? Well, we've got fifty miles to go, better get -at least- two gallons.

If I need two octaves change from my Buchla VCO, it will require 2v4 input.

And as any mathematics professor knows and teaches, with word problems one must first put the problem in a solvable order, and resolve-account for unit differences. Your two contrived sentence structures fail to make your point.

There is nothing inherently "better" to looking at a ratio from either direction. That's not a quirk of labeling.

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