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Eurorack DCO?
MUFF WIGGLER Forum Index -> Eurorack Modules  
Author Eurorack DCO?
Blairio
Is there such a module as a digitally controlled analog VCO in Eurorack? The benefits would be rock solid pitch stability, and constantly accurate octave scaling, and maybe even scale quantising. I guess the downside might be unnecessary complexity and cost.

I trawled Modular Grid, and didn't see anything obvious.
rjungemann
I had better luck searching for oscillators inspired by specific synths. I vaguely remembered seeing an article about the Soundforce DCO which looks interesting!
Pictus
https://www.modulargrid.net/e/soundforce-dco


Not a DCO, but with a Voltage Controlled Quantizer...
https://www.modulargrid.net/e/dreadbox-hysteria


BTW, Does the E300 Ultra VCO can track 15 octaves like its big brother the MOTM-300?
https://www.modulargrid.net/e/synthesis-technology-e300-ultra-vco-blac k-panel
CaneMan
Here's a DivKid review I recently watched of the Soundforce DCO.
a100user
MFB OSC-01 which is now discontinued or the MFB VCO/DCO Which is current


http://mfberlin.de/en/modules/vcodcoe/
EATyourGUITAR
All DCO in eurorack are analog control. The tuning stability is dependent on the analog front end. You can have drift and non-linearity. What you lose with digital is that smooth FM without aliasing. Maybe you are suggesting a DCO that has a built in automatic calibration. Those work a bit better than no calibration. Having 15 octaves in tune is a better fit for midi. Those things do exist.

There are probably about 50 different DCO in eurorack. We just call them digital oscillators.

Double deka VCO is kinda a blurred line between early wavetable VCO like the wiard and maybe a fully analog sequencer running at audio rates.
flashheart
EATyourGUITAR wrote:

There are probably about 50 different DCO in eurorack. We just call them digital oscillators.

There's been enough debate on synth forums over the years to agree that DCOs are NOT digital oscillators.

The OP asked about digitally controlled analogue oscillators, clearly digital oscillators (including the Double Deka) aren't.
coolshirtdotjpg
The name escapes me at the moment, but there are polyphonic DCO oscillators in euro now. I sent emails to some of the bigger companies asking them to do this, but, now it's happened and it's the best way to get analog polyphony in a simple way.
nicholasyu
So when traditional synthesizers are DCO everything from the midi input/keyboard up to the timing of the analog VCO is done digitally right?

Seems a little strange to say it's a DCO when there's a 1V/oct right there on the front panel. That's an analog input and so is whatever you plug into it. It's a nitpick for sure...

But in my mind "digitally controlled" should mean you send it digital control sources, for example midi
Blairio
Thanks everyone for your researches. I guess I was thinking about my DSI Mopho / Tetra voices when I posed the question about a DCO - analog VCOs under digital control.

The MFB VCO/DCO and the Soundforce DCO both sound pretty interesting. I am enough of a fan of the Roland Juno 60/106 that I think I will check out the Soundforce module. It may be twice the price of the MFB one, but the feature set would make that worthwhile.

I like the idea of the hybrid oscillator. I already have several analog VCOs, plus one 'pure' all digital oscillator, a ModCan FMVDO. This is basically a 2 operator FM voice. It also has wavetables, though the implementation of those is a bit 'clunky'.

My Mutable Instruments Braids and Plaits don't fit the DCO pattern of an analog core under digital control. It doesn't stop them sounding amazing though.
Mungo
If you have both analog and digital oscillators then all the pieces are in place. A sawtooth VCO with hard sync (most of them) can be slaved to a digital oscillator, have them both track the same V/oct signal and tune the VCO an octave or two lower than the DCO.

Its a modular.... once you have a critical mass of modules you can build those interesting ideas.
Blairio
Mungo wrote:
If you have both analog and digital oscillators then all the pieces are in place. A sawtooth VCO with hard sync (most of them) can be slaved to a digital oscillator, have them both track the same V/oct signal and tune the VCO an octave or two lower than the DCO.

Its a modular.... once you have a critical mass of modules you can build those interesting ideas.


That's a good point. I'll give that a try, thanks.
Blairio
nicholasyu wrote:
So when traditional synthesizers are DCO everything from the midi input/keyboard up to the timing of the analog VCO is done digitally right?

Seems a little strange to say it's a DCO when there's a 1V/oct right there on the front panel. That's an analog input and so is whatever you plug into it. It's a nitpick for sure...

But in my mind "digitally controlled" should mean you send it digital control sources, for example midi


Digital modules (whatever their function) with cv inputs use DACs to render the analog signal into the digital domain, and then ADCs to render the digital information back into an (analog) voltage on the output. Scale quantisers are a good example of this. The scale quantising is performed in the digital domain, even though inputs and outputs are analog.

But, DCOs are not digital modules. They are digitally timed/clocked analog core VCOs. The USP is that digital clocks are inherently more stable than analog ones.
nicholasyu
Blairio wrote:
nicholasyu wrote:
So when traditional synthesizers are DCO everything from the midi input/keyboard up to the timing of the analog VCO is done digitally right?

Seems a little strange to say it's a DCO when there's a 1V/oct right there on the front panel. That's an analog input and so is whatever you plug into it. It's a nitpick for sure...

But in my mind "digitally controlled" should mean you send it digital control sources, for example midi


Digital modules (whatever their function) with cv inputs use DACs to render the analog signal into the digital domain, and then ADCs to render the digital information back into an (analog) voltage on the output. Scale quantisers are a good example of this. The scale quantising is performed in the digital domain, even though inputs and outputs are analog.

But, DCOs are not digital modules. They are digitally timed/clocked analog core VCOs. The USP is that digital clocks are inherently more stable than analog ones.


Yeah yeah I understand that man. Just saying that whenever I've see "DCO" up until now it means you tell it to play note #48 -- C3!, or press the right key. In 1's and 0's. Always get the same thing. Here you feed it 1.5340934V or whatever it is. Whatever you're using to generate that voltage and even the ADC itself will be subject to the mess of the "real world" ie temperature, EMI, component tolerances, &c. As I said it's a huge nitpick, mostly because I'm bored.
EATyourGUITAR
Blairio wrote:
plus one 'pure' all digital oscillator, a ModCan FMVDO. This is basically a 2 operator FM voice. It also has wavetables, though the implementation of those is a bit 'clunky'.

My Mutable Instruments Braids and Plaits don't fit the DCO pattern of an analog core under digital control. It doesn't stop them sounding amazing though.


according to the "experts" here on muffwiggler, your FMVDO is not a FMVCDCO. it is just a digital oscillator aka 2OPFMVCDO.
(hides)
coolshirtdotjpg
nicholasyu wrote:
Blairio wrote:
nicholasyu wrote:
So when traditional synthesizers are DCO everything from the midi input/keyboard up to the timing of the analog VCO is done digitally right?

Seems a little strange to say it's a DCO when there's a 1V/oct right there on the front panel. That's an analog input and so is whatever you plug into it. It's a nitpick for sure...

But in my mind "digitally controlled" should mean you send it digital control sources, for example midi


Digital modules (whatever their function) with cv inputs use DACs to render the analog signal into the digital domain, and then ADCs to render the digital information back into an (analog) voltage on the output. Scale quantisers are a good example of this. The scale quantising is performed in the digital domain, even though inputs and outputs are analog.

But, DCOs are not digital modules. They are digitally timed/clocked analog core VCOs. The USP is that digital clocks are inherently more stable than analog ones.


Yeah yeah I understand that man. Just saying that whenever I've see "DCO" up until now it means you tell it to play note #48 -- C3!, or press the right key. In 1's and 0's. Always get the same thing. Here you feed it 1.5340934V or whatever it is. Whatever you're using to generate that voltage and even the ADC itself will be subject to the mess of the "real world" ie temperature, EMI, component tolerances, &c. As I said it's a huge nitpick, mostly because I'm bored.


This always ends up confusing people because DCOs are very strange. So let's walk through this (of course it is going to depend on implementation):

1. You start with a digital clock, this is digital in the sense that it is either in an on or off state.

2. it is possible in some instances to change the speed of this clock using a voltage.

3. In cases such as the Juno when polyphony is needed, all of the oscillators are sub-divisions of the this high frequency clock. The clock is of high enough frequency that this digitally controlled counter can create subdivisions of that clock all across the audio range. There is no analog control here, the divisions are fixed, the cannot detune from each other. Unless..

4. On something like the prophet 08, you have a high enough speed clock that you can add a certain amount of detune by using finer-grained subdivisions (correct me if I am wrong, this is taken from interviews with Dave Smith, not form looking at schematics, as in the case of the Juno).

5. Unless you are using multiple high frequency master clocks, or it's the situation described in point #4, if you do something like frequency modulate the high frequency oscillator, all oscillators will be effect since they are subdividing the master clock.

6. Each of these divisions can be shaped individually since only their timing is defined digitally.

7. There are going to be other variations on this, but this is most commonly what is referred to as a DCO.

8. I am not sure why you could use a non-polyphonic DCO in euro except for tuning stability, except that perhaps the tuning is more stable. Considering how stable most VCOs are in 2019, I don't see much of a point. With that said, I've always liked the sound of the Juno oscillators, so perhaps there's something to it. I suspect you could just as easily recreate that sound with a VCO, but who knows.
EATyourGUITAR
Sometimes what makes an instrument sound unique is the sum of all the parts. This includes the noise from the power supply. The non-linearity in some octaves. Trying to clone what you see on an oscilloscope or sampler is usually not enough to trick the ears. If you start building something that will replace or clone something you like, be careful and consider if it is even worth the effort.
Funch
So is this a DCO or is it a different process?


"Erica Synths Fusion VCO is a special kind of VCO – it fuses the great tuning of a digital VCO with the warm and unique sound of vacuum tubes that work in suboscillator circuit."

https://www.ericasynths.lv/shop/eurorack-modules/by-series/fusion-seri es/fusion-vco/

The sub oscillators will track either the internal oscillator or an audio input, so it seems its doing some sort of digital pitch tracking via the audio input.

The main osc triggers via the euro standard 1 v/oct.
Blairio
EATyourGUITAR wrote:
Blairio wrote:
plus one 'pure' all digital oscillator, a ModCan FMVDO. This is basically a 2 operator FM voice. It also has wavetables, though the implementation of those is a bit 'clunky'.

My Mutable Instruments Braids and Plaits don't fit the DCO pattern of an analog core under digital control. It doesn't stop them sounding amazing though.


according to the "experts" here on muffwiggler, your FMVDO is not a FMVCDCO. it is just a digital oscillator aka 2OPFMVCDO.
(hides)


My brain hurts. I take my lead from ModCan's own nomenclature - FMVDO. However..... the FMVDO does offer 'standard' VCO waveforms and even PWM, so it does certainly go beyond the basic remit of 2 operator FM.

Whatever, its is a well made, great sounding module that even has scale quantising and an inbuilt VCA. Add a modulation source or two and you have a complete synth voice.
Blairio
coolshirtdotjpg wrote:


This always ends up confusing people because DCOs are very strange. So let's walk through this (of course it is going to depend on implementation):

......

8. I am not sure why you could use a non-polyphonic DCO in euro except for tuning stability, except that perhaps the tuning is more stable. Considering how stable most VCOs are in 2019, I don't see much of a point. With that said, I've always liked the sound of the Juno oscillators, so perhaps there's something to it. I suspect you could just as easily recreate that sound with a VCO, but who knows.


My analog VCOs comprise: MakeNoise STO, Bubblesound VCOb, A-110 (two), SSF Spectrum, 2HP VCO. I used to have more, but ditched the the ones with poor pitch stability. I won't name and shame them, since a lot of folk on this forum seem to regard pitch instability as part and parcel of the modular experience, and I am not about to 'flame' their modules.

My original question about DCOs in eurorack was driven in part by curiosity as to whether any brand had invoked the DCO purely for pitch control, but also because I like the sound of DCOs - such as those in my Matrix 6R, Juno 106 and DSI Mopho & Tetra.

Maybe the digital clock aspect of all these three instruments has no bearing on their sound / timbre. From the explanations given here, it probably doesn't. I still like the sound of DCO instruments though, and a single oscillator eurorack Juno 60 would be a fine thing - including the chorus!

<Blair - edited for spelling>
coolshirtdotjpg
Blairio wrote:
coolshirtdotjpg wrote:


This always ends up confusing people because DCOs are very strange. So let's walk through this (of course it is going to depend on implementation):

......

8. I am not sure why you could use a non-polyphonic DCO in euro except for tuning stability, except that perhaps the tuning is more stable. Considering how stable most VCOs are in 2019, I don't see much of a point. With that said, I've always liked the sound of the Juno oscillators, so perhaps there's something to it. I suspect you could just as easily recreate that sound with a VCO, but who knows.


my analog VCOs comprise: MakeNoise STO, Bubblesound VCOb, A-110 (two), SSF Spectrum, 2HP VCO. I used to have more, but ditched the the ones with poor pitch stability. I won't name and shame them, since a lot of folk on this forum seem to regard pitch instability as part and parcel of the modular experience, and I am not about to 'flame' their modules.

My original question about DCOs in eurorack was driven in part by curiosity as to whether any brand had invoked the DCO purely for pitch control, but also because I like the sound of DCOs - such as my Matrix 6R, Juno 106 and DSI Mopho & Tetra.

Maybe the digital clock aspect of all these three instruments has no bearing on their sound / timbre. From the explanations given here, it probably doesn't. I still like the sound of DCO instruments though, and a single oscillator eurorack Juno 60 would be a fine thing - including the chorus!


Hilariously, I literally own all of those instruments, except a Prophet 08 instead of the Tetra. I like the sound of them, the pitch stability is nice, but I wouldn't say that the parts of their sound that everyone seems to like come from the DCOs, but honestly who knows. As far as tuning stability, I think you are right as far as all of those oscillators are concerned, but it's not because it's a particularly hard thing to do, it's just the particular design. My point was just that it wouldn't be hard to have juno waveshaping with a stable analog VCO, which would be cheaper and easier to implement than a DCO if you just wanted one voice. Anyway, you do you, it's all part of the fun.
hzzzu
coolshirtdotjpg wrote:
The name escapes me at the moment, but there are polyphonic DCO oscillators in euro now. I sent emails to some of the bigger companies asking them to do this, but, now it's happened and it's the best way to get analog polyphony in a simple way.


That might be us. Supercritical Synthesizers and our Demon Core Oscillator.

There's a thread about it.

Regarding DCO's, I do enjoy the ideology behind it. My Prophet08 and Alpha Juno have a certain likable different oscillator sound. In particular the Alpha Juno DCO has many weird waveforms as features. The main thing I like about them is to know that they're in tune. It's very handy for playing with ordinary band instruments which is a routine for me. Our DCO is based on that ideology. To know the precise tuning and phase of each wave, and then having the full control over them. For instance, the Prophet08 has a slop functionality to introduce VCO-like drifting. We did our take on that with our machine.

Of course the vintage VCO's have their own thing (in poly, mono and modular osc's) as well. They do it pretty well. *insert drool sounds here while playing an old Oberheim poly*
coolshirtdotjpg
hzzzu wrote:
coolshirtdotjpg wrote:
The name escapes me at the moment, but there are polyphonic DCO oscillators in euro now. I sent emails to some of the bigger companies asking them to do this, but, now it's happened and it's the best way to get analog polyphony in a simple way.


That might be us. Supercritical Synthesizers and our Demon Core Oscillator.

There's a thread about it.

Regarding DCO's, I do enjoy the ideology behind it. My Prophet08 and Alpha Juno have a certain likable different oscillator sound. In particular the Alpha Juno DCO has many weird waveforms as features. The main thing I like about them is to know that they're in tune. It's very handy for playing with ordinary band instruments which is a routine for me. Our DCO is based on that ideology. To know the precise tuning and phase of each wave, and then having the full control over them. For instance, the Prophet08 has a slop functionality to introduce VCO-like drifting. We did our take on that with our machine.

Of course the vintage VCO's have their own thing (in poly, mono and modular osc's) as well. They do it pretty well. *insert drool sounds here while playing an old Oberheim poly*


Yes, you were the ones I was thinking of. I'd been bugging eurorack companies for a while to do it, and I'm glad someone actually did! I think your module is the best solution for analog polyphony in eurorack. Pair it with some of those doepfer quad modules and the rest of the euro set up most people have and it's the most powerful poly you could possibly own. Hell, now I'm wondering how two of the dual SEM20 vcfs would sound with it.
soundforce
Hi guys,

Nicolas from SoundForce here, the DCO module maker.
Happy to see some DCO (from all brands) talk on MG smile

I started working on a DCO because that was nothing like that in Eurorack at the time (pre Demon-Core), especially with sliders and a mixer. I liked the juno sound a lot, but what I liked even more is the technical side of the DCO. I am neither an analog guru nor a digital expert. I am quit hybrid and I love hybrid designs as well. It keeps me interested for a much longer time. For me the advantages were both the pitch control and also the sound. But it all really starts out of curiosity and me just wanting to understand and research something. I like also the idea of "old" analog circuits meeting modern futuristic controllers.

So on my DCO, the analog data (V/oct and FM inputs) are converted to a number (a digital pitch) with a 16bits ADC built-in the micro-controller. The trick was to adapt the DCO concept used in MIDI poly synths to eurorack, with the normally expect inputs and outputs (there is even a SYNC input that works quite well). That digital pitch is then sent to the timer that drives the analog SAW wave. The master clock is the crystal oscillator running the STM32 micro-controller. The timer is used to divide the master clock and output little pulses to resets the SAW wave.

I think a USP of my module is the built-in mixer. You can create complex signlals from 1 module and make the mixer part of your performance. And with an external VCA you can even CV control the mix and animate the blend with LFOs. The fact that those waveforms are all originating from a common super stable digital master clock will give a certain sound, especially when you mix the waves.

If you have any questions, just hit me up!
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