Help with v/Oct and pitch from multiple sources

Anything modular synth related that is not format specific.

Moderators: lisa, Kent, Joe.

Room07
Learning to Wiggle
Posts: 8
Joined: Mon Jan 06, 2020 6:51 am

Help with v/Oct and pitch from multiple sources

Post by Room07 » Sun Jan 19, 2020 4:25 pm

My first post here, but I've been lurking for a while. I hope I'm in the right place. I'm not new to music, but I'm just getting started with modular and could really use some help getting some of my gear to play nicely together. Any assistance or advice appreciated!

I'll try to explain this the best I can as I suspect I'm dealing with several issues, all VCOs were given hours to warm up:

I have a Minibrute 2s and some Euro modules. The MB2s has 2 VCOs. If I have the sequencer play a solid C4 note, both VCOs from internal routing play a C4 as expected (yay!).

If I route externally, plugging the MB2s KBD output into the Pitch input of VCO1, a C4 is played as expected.
If I route externally, plugging the MB2s KBD output into the Pitch input of VCO2, it returns a flat C6 (around 1016Hz).

Using a multimeter, the MB2s KBD output for a C4 is 3.00v. But applying that 3v to VCO1 and VCO2 give me very different pitches, with VCO2 not even scaling correctly. Transposing an octave up or down is more or less than an octave.

I also have Plaits and Bloom. If Plaits is playing a clean C4 and I plug the KBD output from the MB2s into the v/OCT I get a C7 (around 2087Hz). I guess this makes sense because a C4 plus 3 volts from the MB2s at 1 v/Oct would raise the pitch by 3 octaves (math!). But...what is the best way to use the MB2 with Plaits if the base voltage is so far off? I can change the base note pitch for the MB2s in the software, but that breaks the internal sequencer. I can set up Plaits to be 3 octaves lower, but that feels clumsy, if not irresponsible.

Bloom with a 1v output (measured with a multimeter) raises Plaits by 1 octave (makes sense to me, yay!).
Bloom with a 1v output plugged into VCO1 of my MB2s put out a sharp C1, about 33Hz (low register analog explains the sharpness, I assume). A C1 is too low to be useful though! Do I have to change all my Bloom root notes to play well with the MB2s?
Bloom with a 1v output plugged into VCO2 on the MB2s puts out an agonizing 126Hz, a very flat C3.

I think the Pitch input for VCO2 is broken. Is Arturia this freaky with their voltage outputs? It seems that for a synth they've designed as semi-modular, with a companion Eurorack case, their default voltage outputs don't play well. Am I missing something?

User avatar
luketeaford
Super Deluxe Wiggler
Posts: 1484
Joined: Wed Jan 08, 2014 9:54 pm
Location: Columbus, Ohio
Contact:

Re: Help with v/Oct and pitch from multiple sources

Post by luketeaford » Sun Jan 19, 2020 5:01 pm

Welcome!

This is perhaps due to MIDI. Imagine that oscillator was playing 3 octaves higher when MIDI froze or was disconnected or something. That explains why you're getting a similar 3 octave jump-- if my hypothesis is correct, something internal to the MB is tuning one of the oscillators down 3 octaves or... 36 semitones.

Can you clear the MIDI or reboot? Even if you totally shut everything off, you should expect to be within a semitone pretty quickly in my experience-- will definitely not be out by 3 octaves!

Arneb
Wiggling with Experience
Posts: 349
Joined: Thu Jul 04, 2019 4:50 pm

Re: Help with v/Oct and pitch from multiple sources

Post by Arneb » Sun Jan 19, 2020 5:07 pm

Room07 wrote:
Sun Jan 19, 2020 4:25 pm
I also have Plaits and Bloom. If Plaits is playing a clean C4 and I plug the KBD output from the MB2s into the v/OCT I get a C7 (around 2087Hz). I guess this makes sense because a C4 plus 3 volts from the MB2s at 1 v/Oct would raise the pitch by 3 octaves (math!). But...what is the best way to use the MB2 with Plaits if the base voltage is so far off? I can change the base note pitch for the MB2s in the software, but that breaks the internal sequencer. I can set up Plaits to be 3 octaves lower, but that feels clumsy, if not irresponsible.
Just to get the Eurorack part of your question out of the way before discussing Minibrute stuff, no, that's the normal way to do things. There's a reason why Mutable and other VCO makers have that big fat Frequency knob instead of hiding the base pitch somewhere in the firmware behind three layers of menu diving.

Addendum: Noise Engineering's blog is often useful for beginner questions. NE on 1V/oct and on VCO tuning.

My own way of explaining this is that Eurorack tuning is more like guitar tuning than piano tuning. Think of Plaits as a string of your guitar, pitch CV (Bloom or the Minibrute's KBD Out) as your weaker hand moving on the neck, and of VCAs and CV modulation as your stronger hand hitting strings.

Room07
Learning to Wiggle
Posts: 8
Joined: Mon Jan 06, 2020 6:51 am

Re: Help with v/Oct and pitch from multiple sources

Post by Room07 » Mon Jan 20, 2020 1:46 pm

luketeaford wrote:
Sun Jan 19, 2020 5:01 pm
This is perhaps due to MIDI. Imagine that oscillator was playing 3 octaves higher when MIDI froze or was disconnected or something. That explains why you're getting a similar 3 octave jump-- if my hypothesis is correct, something internal to the MB is tuning one of the oscillators down 3 octaves or... 36 semitones.

Can you clear the MIDI or reboot? Even if you totally shut everything off, you should expect to be within a semitone pretty quickly in my experience-- will definitely not be out by 3 octaves!
Thanks! I was actually thinking midi might be part of the problem. I did have midi connected, and tried the same with midi disconnected with no improvement. I've just been informed how to do a hard-reset (4-buttons at once lol) and I'm going to give that a shot.

Room07
Learning to Wiggle
Posts: 8
Joined: Mon Jan 06, 2020 6:51 am

Re: Help with v/Oct and pitch from multiple sources

Post by Room07 » Mon Jan 20, 2020 1:56 pm

Arneb wrote:
Sun Jan 19, 2020 5:07 pm
My own way of explaining this is that Eurorack tuning is more like guitar tuning than piano tuning. Think of Plaits as a string of your guitar, pitch CV (Bloom or the Minibrute's KBD Out) as your weaker hand moving on the neck, and of VCAs and CV modulation as your stronger hand hitting strings.
Thanks for the advice, I do appreciate it. As a guitarist (of 20+ years), an artist, and a programmer, I'm struggling with this analogy but I get where you're coming from. I just don't like the fact that an output of a C4 note is different volts for different devices. And... different devices take those different volts and do different things with them.

Hardware VCO issues aside, is a precision adder module a valid solution or am I just not accepting the issue? :)

jorg
Wiggling with Experience
Posts: 422
Joined: Fri Apr 03, 2015 9:38 am
Location: East Coast USA

Re: Help with v/Oct and pitch from multiple sources

Post by jorg » Mon Jan 20, 2020 2:14 pm

Most VCOs have an adjustable base pitch; you tune it to play conveniently in whatever patch you are building at the moment. For example the Doepfer A110-1 VCO has an octave switch that covers a wide range (5 octaves believe), plus a fine tune knob that covers about an octave total. In many multi-VCO patches, you might set the oscillators to different octaves, or even set them apart by a fith, or detune them by a few cents. It's a deliberately flexible way to work.

Arneb
Wiggling with Experience
Posts: 349
Joined: Thu Jul 04, 2019 4:50 pm

Re: Help with v/Oct and pitch from multiple sources

Post by Arneb » Mon Jan 20, 2020 3:17 pm

Room07 wrote:
Mon Jan 20, 2020 1:56 pm
Arneb wrote:
Sun Jan 19, 2020 5:07 pm
My own way of explaining this is that Eurorack tuning is more like guitar tuning than piano tuning. Think of Plaits as a string of your guitar, pitch CV (Bloom or the Minibrute's KBD Out) as your weaker hand moving on the neck, and of VCAs and CV modulation as your stronger hand hitting strings.
Thanks for the advice, I do appreciate it. As a guitarist (of 20+ years), an artist, and a programmer, I'm struggling with this analogy but I get where you're coming from. I just don't like the fact that an output of a C4 note is different volts for different devices. And... different devices take those different volts and do different things with them.

Hardware VCO issues aside, is a precision adder module a valid solution or am I just not accepting the issue? :)
First of all, a valid solution is every solution which gives you a sound and workflow you enjoy. If I wanted to artificially limit myself to certain paradigms in order to conform to some "trueness" standards I wouldn't work in modular to begin with.

You can use a precision adder to subtract 3V from your CV, yes. I personally wouldn't do it since you'd need to get those -3V from somewhere - the precision adder itself if you're using something like t43 or Quant Gemi, or some external voltage source - and keeping track of that "somewhere" is an additional mental effort. Now if that's important to you your idea does have the advantage of not having an octave difference between Plaits without MB2 and Plaits+MB2.

Room07
Learning to Wiggle
Posts: 8
Joined: Mon Jan 06, 2020 6:51 am

Re: Help with v/Oct and pitch from multiple sources

Post by Room07 » Tue Jan 21, 2020 7:33 pm

I agree with the first part of what you're saying. What attracts me to modular is that there are standards, and those standards can be tweaked and combined to create interesting sounds. The concept of pitch IS a standard. If I have 10 modules that output a default pitch of C4 and one that outputs C6, the C6 module is a problem. Either I accept it as a new paradigm and develop systems to deal with it, or I reject it as a system that doesn't work for me. I'm making up my mind.

Arturia has responded to my technical inquiry and confirmed that their output has "an offset", as they put it. To my "trueness standard" it's 2-volts too high. I've also concluded that the Pitch input on VCO2 is actually broken. I suspect it's the jack itself but I'm sending the whole unit back for replacement. Not a great start with my first Arturia product! But it does sound good to me and the price is right. :)

Thanks for the feedback.

nigel
Veteran Wiggler
Posts: 616
Joined: Wed Jan 16, 2013 6:49 am
Location: Melbourne, Australia

Re: Help with v/Oct and pitch from multiple sources

Post by nigel » Tue Jan 21, 2020 7:43 pm

Room07 wrote:
Tue Jan 21, 2020 7:33 pm
I agree with the first part of what you're saying. What attracts me to modular is that there are standards, and those standards can be tweaked and combined to create interesting sounds. The concept of pitch IS a standard. If I have 10 modules that output a default pitch of C4 and one that outputs C6, the C6 module is a problem.
The modular standard is one volt per octave - it's a relative value, not an absolute one. One volt change produces a one octave change. The absolute frequency for a particular fixed voltage is not determined.

Room07
Learning to Wiggle
Posts: 8
Joined: Mon Jan 06, 2020 6:51 am

Re: Help with v/Oct and pitch from multiple sources

Post by Room07 » Tue Jan 21, 2020 8:36 pm

Thanks. Yes, I get that1 volt per octave is a relative standard. It's easily understandable and I appreciate that. :)

Since you've shown up to the conversation, how do you manage pitch outputs that are 2 or 3 volts off in the positive direction? Do you do as suggested and adjust each voice/oscillator down several octaves to compensate? What if the "dial" doesn't go that low?

nigel
Veteran Wiggler
Posts: 616
Joined: Wed Jan 16, 2013 6:49 am
Location: Melbourne, Australia

Re: Help with v/Oct and pitch from multiple sources

Post by nigel » Tue Jan 21, 2020 9:28 pm

Room07 wrote:
Tue Jan 21, 2020 8:36 pm
Since you've shown up to the conversation, how do you manage pitch outputs that are 2 or 3 volts off in the positive direction? Do you do as suggested and adjust each voice/oscillator down several octaves to compensate? What if the "dial" doesn't go that low?
My dials all go that low - my system is all analog, no midi.

Room07
Learning to Wiggle
Posts: 8
Joined: Mon Jan 06, 2020 6:51 am

Re: Help with v/Oct and pitch from multiple sources

Post by Room07 » Wed Jan 22, 2020 7:13 am

Ha. Well, I'm not that pure.

User avatar
Chrutil
Veteran Wiggler
Posts: 502
Joined: Thu Mar 21, 2013 11:39 am
Location: San Rafael, California

Re: Help with v/Oct and pitch from multiple sources

Post by Chrutil » Sun Jan 26, 2020 10:28 am

Room07 wrote:
Tue Jan 21, 2020 8:36 pm
how do you manage pitch outputs that are 2 or 3 volts off in the positive direction? Do you do as suggested and adjust each voice/oscillator down several octaves to compensate? What if the "dial" doesn't go that low?
There are modules that do specifically that. Look at ‘precision adder / transposed’ modules.
Often they just add two signals, but some of them have voltage sources built-in for +/- a few octaves.

Room07
Learning to Wiggle
Posts: 8
Joined: Mon Jan 06, 2020 6:51 am

Re: Help with v/Oct and pitch from multiple sources

Post by Room07 » Sun Jan 26, 2020 10:43 am

Thank you!

User avatar
nostalghia
Ultra Wiggler
Posts: 883
Joined: Sun Apr 07, 2013 2:46 pm
Location: central usofa

Re: Help with v/Oct and pitch from multiple sources

Post by nostalghia » Sun Jan 26, 2020 2:08 pm

Have a look at the Klavis Caltrans module. Provides octave and semitone transpose, and an automatic calibration feature that can solve the issue of some VCOs not tracking pitch accurately over a wide range of voltages (especially the ones lacking a user accessible internal calibration method). Four inputs, four outputs. Portamento/glissando, transpose and quantize per output, your frequently used settings can be stored in 4 presets. Very flexible and useful. Check out the videos and manual.

https://www.muffwiggler.com/forum/viewtopic.php?f=16&t=217384

http://www.klavis.com/index.php/all-products/caltrans
“If you look for a meaning, you'll miss everything that happens.” - Andrei Tarkovsky

KSS
Ultra Wiggler
Posts: 858
Joined: Mon Jan 25, 2016 7:28 am

Re: Help with v/Oct and pitch from multiple sources

Post by KSS » Sun Jan 26, 2020 3:41 pm

Room07 wrote:
Tue Jan 21, 2020 7:33 pm
The concept of pitch IS a standard. If I have 10 modules that output a default pitch of C4 and one that outputs C6, the C6 module is a problem. Either I accept it as a new paradigm and develop systems to deal with it, or I reject it as a system that doesn't work for me. I'm making up my mind.
And when musicians -acoustic and electronic- come together they tune their individul instruments to some arbitrary agreed pitch. If "instruments" is replaced with "VCO", it's the same thing.

And your point about what if the knob doesn't go that far? Could be compared to a classic harpsichord which cannot be retuned to modern day concert pitch. The others adjust to it, or as you say, they abandon either the harpsichord or the gig. Of course with a VCO, it's easy enough to provide a means to apply and adjust an offset. So you re-tune the VCO to match the lower Harpsichord pitch.

Flexibility in approach is a primary factor of modular synths and electronic music. Even something as defined as MIDI does not mean the same note number will obtain the same note pitch. It will often be different on various instruments or connections between instruments. C4 or C6 on a synth could be any of the available keys. It's a given reality. As you say, for you to accept or not.

Thankfully since it is so common, nearly every instrument and module have means to adjust their pitch response.

edit: FWIW, classic CV/Gate synths have two different ways to assign keys to note, and this does in fact result in the difference you hypothesize. Where in a room of ten classic synths, 9 can work one way and the last works differently by two octaves. I sincerely doubt anyone in that situation -and there have been many of us over the years- considers the one "a problem" (perhaps with fewer than ten, but that analogy still holds) /edit

edit2: This is also one reason most all MIDI KBDs have an ability to apply an arbitrary offset. To allow the MIDI to 'align' with other -both MIDI and non MIDI synths. /edit2

jorg
Wiggling with Experience
Posts: 422
Joined: Fri Apr 03, 2015 9:38 am
Location: East Coast USA

Re: Help with v/Oct and pitch from multiple sources

Post by jorg » Mon Jan 27, 2020 9:49 am

I've never read anything that claims there should be a specific voltage-to-pitch mapping, except that (in most synths) it's 1V/octave. I've been doing this since the mid-1970s. Even MIDI is not quite so standardized. Our synths and oscillators provide a variety of options, and the flexibility to adjust pitch to suit the sound/song/instruments. I am very glad of that.

Room07
Learning to Wiggle
Posts: 8
Joined: Mon Jan 06, 2020 6:51 am

Re: Help with v/Oct and pitch from multiple sources

Post by Room07 » Mon Jan 27, 2020 5:55 pm

KSS wrote:
Sun Jan 26, 2020 3:41 pm
And when musicians -acoustic and electronic- come together they tune their individul instruments to some arbitrary agreed pitch. If "instruments" is replaced with "VCO", it's the same thing.
I'm figuring this out for synths and I've heard this analogy, thanks for the in-depth explanation.

As a guitar player of 30 years, what I'm experiencing with synths is like plugging my guitar into one amp and hearing one pitch, and plugging into another and hearing an entirely different pitch -- which... would never happen. So I guess the instrument analogy has its flaws.

I feel more like I'm playing the pickups and plugging into the strings. Haha.

As far as pitch standards go, yeah, there's some wacky stuff out there but everything I have is literally labelled v/Oct so I'm running with that.

dros3raq
Learning to Wiggle
Posts: 13
Joined: Sat Sep 22, 2018 10:10 am
Location: US

Re: Help with v/Oct and pitch from multiple sources

Post by dros3raq » Mon Jan 27, 2020 6:23 pm

AJH's V-Scale Variable Precision Buffer works great for this.

nigel
Veteran Wiggler
Posts: 616
Joined: Wed Jan 16, 2013 6:49 am
Location: Melbourne, Australia

Re: Help with v/Oct and pitch from multiple sources

Post by nigel » Mon Jan 27, 2020 7:14 pm

Room07 wrote:
Mon Jan 27, 2020 5:55 pm
As a guitar player of 30 years, what I'm experiencing with synths is like plugging my guitar into one amp and hearing one pitch, and plugging into another and hearing an entirely different pitch -- which... would never happen. So I guess the instrument analogy has its flaws.
But if you play the fifth fret on one string, it gives a different note to the fifth fret on another string. Not all VCOs are the same string, that's all.

KSS
Ultra Wiggler
Posts: 858
Joined: Mon Jan 25, 2016 7:28 am

Re: Help with v/Oct and pitch from multiple sources

Post by KSS » Tue Jan 28, 2020 2:44 pm

Room07 wrote:
Mon Jan 27, 2020 5:55 pm
As a guitar player of 30 years, what I'm experiencing with synths is like plugging my guitar into one amp and hearing one pitch, and plugging into another and hearing an entirely different pitch -- which... would never happen. So I guess the instrument analogy has its flaws.
Nope. The analogy holds. Mistake is mixing terms. You've inserted "amp" for "instrument". The analogy says to exchange "instrument" for "VCO". VCO, like a guitar is a sound generator. Both a guitar and a VCO plug into an 'amp'. Amp has no pitch adjustment. Instruments -and VCOs- do. (without trying to muddy the waters, it's good to note that filters also have pitch adjustments.)

So the analogy holds when you plug different guitars -or instruments- into the same amp, and get different results. For best example, plug a bass guitar into the anp and then plug a standard guitar -or a mandolin- into the amp. Different pitch results. Even two guitars with slightly different tuning fit the analogy. Or the same guitar over time. You tune it to the arbitrary agreed upon pitch to work with the rest of what you're using.

jorg
Wiggling with Experience
Posts: 422
Joined: Fri Apr 03, 2015 9:38 am
Location: East Coast USA

Re: Help with v/Oct and pitch from multiple sources

Post by jorg » Tue Jan 28, 2020 4:28 pm

The clarinet family is a musical instrument family including the well-known B♭ clarinet, the bass clarinet, the slightly less familiar E♭ and A clarinets and other clarinets.

If they are playing together in the same composition, each player must make adjustments and play a little bit differently, so they can all hit the correct notes. Same with MIDI, with analog VCOs, and pretty much any musical instrument.

User avatar
Chrutil
Veteran Wiggler
Posts: 502
Joined: Thu Mar 21, 2013 11:39 am
Location: San Rafael, California

Re: Help with v/Oct and pitch from multiple sources

Post by Chrutil » Wed Jan 29, 2020 2:29 pm

No explanation of a concept is complete without a car analogy.
Any takers?

jorg
Wiggling with Experience
Posts: 422
Joined: Fri Apr 03, 2015 9:38 am
Location: East Coast USA

Re: Help with v/Oct and pitch from multiple sources

Post by jorg » Wed Jan 29, 2020 4:03 pm

Chrutil wrote:
Wed Jan 29, 2020 2:29 pm
No explanation of a concept is complete without a car analogy.
Any takers?
I think we also need a sports analogy, though I know nothing about sports and can't provide one.

nigel
Veteran Wiggler
Posts: 616
Joined: Wed Jan 16, 2013 6:49 am
Location: Melbourne, Australia

Re: Help with v/Oct and pitch from multiple sources

Post by nigel » Wed Jan 29, 2020 6:06 pm

Exactly how many olympic swimming pools are there in an octave?

Post Reply

Return to “Modular Synth General Discussion”