Question about VCO polys mod matrix


I am curious to know why VCO polys like in DSI’s lineup has a significantly smaller mod matrix than their DCO synths? Is it more difficult to implement modulation features on VCO synths? I hit the wall quickly on my Minilogue, which is why I use my tetra more, for specific modulation pathways. I am still searching for my synth “soulmate”, heh but I don’t think the perfect synth exists yet.

The modulation is typically generated digitally. That means, every modulation destination that sits in the analog domain needs a digital to analog converter that converts the output of the modulation matrix into a voltage. Furthermore the analog circuit itself becomes more complex the more modulation options are added.
For a DCO synth, a part of the oscillator is digital by nature, meaning it is done inside the software. You can easily add modulation destinations there without the need to make the actual circuit more complicated.

For poly synths these kinds of things really add up. If an additional modulation destination would increase the price by 3€ and the synth has 8 voices, well that’ll increase the total price by at least 24€. (Not to mention it’s another complexity added that you have to check and calibrate in the factory testing procedure)

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People wouldn’t be very interested in a VCO synth if it came with digital LFOs and envelopes. And modulation matrices (especially with patch/preset recall) are harder to do in the analog domain than in the digital domain. A 10-slot (analog) modulation matrix with patch recall = 10 multiplexers, 10 digitally-controlled amplifiers (DAC + VCA, or digital pot), and another layer of multiplexers. Per voice!

If you allow yourself digital modulation sources, then it’s not much work at all (like, half a day… 100 lines of code) to implement a fully-featured modulation matrix.

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Oh wow I see, thanks for clearing that up! I knew there was a reason for that because no one was making super flexible VCO polys. It appears in the synth world, more money = more power, lol

The control voltages for the LFO and the two ADSR envelopes on the DSI Prophet-6 are digitally generated. As far as I know, the Prophet-6 uses the same “audio path is analogue, control path is digital” architecture as any other modern analogue poly.

The only exception to this seems to be the ability to route the output of oscillator 2 to oscillator 1 frequency, shape, or pulse width, or to the low-pass or high-pass filter cutoff.

IMHO, the reason why there’s nothing like a mod matrix on the Prophet-6 is that they wanted a control surface and user experience that was as closely to the Prophet-5 as possible. This meant no display, no menus, and thus no way to add a mod matrix.

An interesting aside is that the Pioneer AS-1 contains a single voice of the Prophet-6 using the exact same circuitry and parameters in a menu-drive synth with a display. The AS-1 also contains a touch-sensitive “slider” that lets you control up to seven parameters at the same time with adjustable depth. This feature is not available on the Prophet-6:

Another interesting thing about the DSI Prophet-6 specifically is that the tuning of its VCOs is very stable. This makes them sound indistinguishable from DCOs, unless you turn the Slop knob up.

The tuning drift added when you increase the Slop parameter is digitally generated, so they’re essentially using a digital model of vintage VCO behaviour to make their modern discrete VCOs sound like… VCOs! :wink:

The Rev 2 now also includes a Slop knob, so if you want an analogue poly that sounds vintage and that has a mod matrix, this might be the sensible choice.

EDIT: I really like the filters in the Prophet-6 / AS-1. I wish DSI would do a DCO-based synth like the Rev 2 using these filters.

Does having a digital control path affect the overall sound and tone in any way? Does it affect the natural drift and is there a way to get the modulation without tainting it’s tone? I had no idea the envelopes on the Prophet 6 were digitally generated, that could be the reason im hearing a nail-like transient. I felt the same way about the Prophet 6 oscillators, they’re extremely stiff compared to what I would describe a VCO, really not too much of a step up from the REV2, which is why when i heard the Toraiz AS1 for the first time, i was like… what?? This synth is 500 for that unnatural sound??? Even though I keep bringing this description up for modern synths, I’ll say it again… the Prophet 6 is harsh in the high mids, and a bit plasticky.

I think the Prophet 6 sounds great. All thorough reviews I’ve seen seem to agree that there’s very little if any difference between the Prophet 6 and the Prophet 5 and that the AS-1 is essentially a modern-day Pro One.

From what you wrote, I can only conclude that you’re unable to enjoy any synth you know has even the remotest trace of “digital” in it.

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“In any way”? Yes, through psychology.


One of these days I’m going to submit a research proposal for an experiment to see if auditory perception of the same material can be controlled through priming it as “analogue” or “digital”

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I’d actually love to participate if it would be done, I have done some blind tests before and I got the analog one about 85-90% of the time, maybe people who are trying to distinguish them are searching for different sonic traits than I do, it’s very similar with digital guitar amps, it’s very easy to pull out what is digital for me, almost like looking at a CGI face and knowing it is not real.

Sorry, but I simply do not believe you’ve participated in any properly executed standardized double-blind ABX tests.


I am still searching for my synth “soulmate”, heh but I don’t think the perfect synth exists yet.

Searching for a “perfect” synth soulmate is very similar to searching for a “perfect” human soulmate; the very idea of “perfection” will keep you from the happiness you seek.

There are simply dozens of FANTASTIC synthesizers available today, with which you can make great music and sound.

You might find more satisfaction by moving away from paying attention to labels and just hearing the sounds for what they are - does it REALLY matter how they are made?

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Oh yes absolutely, the construction is part of the art as well as the music itself. I am making music with what I have, as well as chasing more sounds, that’s part of the fun, to keep building up a collection. And the good part with synths, as opposed to humans, is that you can fall in love with hundreds of them, and twist their ti… knobs as much as you like. The perfect synth definitely does not exist, but a collection of a sea of synths you want can be built to perfection. All I do is ask myself what I don’t have, scrape some life savings, and purchase a new box of happiness!..

We can argue all day about this, not everyone is willing to nitpick as much as I do sometimes, close enough is close enough for others too, but not me. And some people may not be able to pick out things that slip past others, we clearly have different ears, and perspectives on gear, but I will stand by mine, because I know the machines I work with and every quirk they may lack that another machine may have. Not all humans can hear over 15000 Hz. Not all humans have perfect pitch. But some do.