The Official DSI/Sequential Forum

DSM03 Filter

chysn

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DSM03 Filter
« on: June 01, 2016, 07:29:16 PM »
Is there any information yet about what kind of low-pass filter the DSM03 will have?
DSI: DSM03; previously: Mopho Keyboard, Desktop Mopho, Evolver, DSM01
Hardware: Eurorack, Arturia MicroBrute
Software: macOS, Ableton, MuseScore2
Modular Grid: https://www.modulargrid.net/e/racks/view/354385
GitHub: https://github.com/chysn

Re: DSM03 Filter
« Reply #1 on: June 08, 2016, 10:11:36 AM »
It's a new design for us, more details closer to shipping time when we finalize all the specs.
Dave Smith Instruments

chysn

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Re: DSM03 Filter
« Reply #2 on: June 08, 2016, 01:48:54 PM »
OK, great! I'm glad it's something new because I just got the DSM01.

Now I've just got this 10HP space to fill....
DSI: DSM03; previously: Mopho Keyboard, Desktop Mopho, Evolver, DSM01
Hardware: Eurorack, Arturia MicroBrute
Software: macOS, Ableton, MuseScore2
Modular Grid: https://www.modulargrid.net/e/racks/view/354385
GitHub: https://github.com/chysn

chysn

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Re: DSM03 Filter
« Reply #3 on: June 23, 2016, 05:34:29 AM »
I'm interested in the thought process behind the low pass filter design choice, given that low pass filters are already pretty ubiquitous in modular systems. How does the low pass filter interact with or enhance the feedback functionality? When designing the DSM03, did you consider integrating a low pass gate instead of a low pass filter? A low pass gate seems like a more natural pairing with a feedback module, and I plan to buy a LPG for that reason.
DSI: DSM03; previously: Mopho Keyboard, Desktop Mopho, Evolver, DSM01
Hardware: Eurorack, Arturia MicroBrute
Software: macOS, Ableton, MuseScore2
Modular Grid: https://www.modulargrid.net/e/racks/view/354385
GitHub: https://github.com/chysn

chysn

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Re: DSM03 Filter
« Reply #4 on: September 22, 2016, 01:53:41 PM »
So, now that the shipping date is announced, can you say anything about the filter? Other than that it's digital?
DSI: DSM03; previously: Mopho Keyboard, Desktop Mopho, Evolver, DSM01
Hardware: Eurorack, Arturia MicroBrute
Software: macOS, Ableton, MuseScore2
Modular Grid: https://www.modulargrid.net/e/racks/view/354385
GitHub: https://github.com/chysn

Re: DSM03 Filter
« Reply #5 on: October 03, 2016, 03:31:44 PM »
The lowpass filter in the DSM03 is a 4-pole fully resonant filter, and is a new digital design of ours. It is based partially on classic analog filters of the past, but with over-sampling, pass band compensation, and a lot of little tweaks in the signal path. There was no attempt to duplicate any specific existing filter, but simply to provide a great sounding filter that works well both in the context of the DSM03 and as a stand alone low pass filter.
Dave Smith Instruments

chysn

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Re: DSM03 Filter
« Reply #6 on: October 03, 2016, 06:49:36 PM »
OK, thanks! I can't wait to hear it.
DSI: DSM03; previously: Mopho Keyboard, Desktop Mopho, Evolver, DSM01
Hardware: Eurorack, Arturia MicroBrute
Software: macOS, Ableton, MuseScore2
Modular Grid: https://www.modulargrid.net/e/racks/view/354385
GitHub: https://github.com/chysn

Steven Morris

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Re: DSM03 Filter
« Reply #7 on: October 04, 2016, 12:46:06 PM »
a great sounding filter that works well both in the context of the DSM03 and as a stand alone low pass filter.

Apologies if this has already been addressed-- but does this mean the filter can be utilized independently from the delay? And can the delay bypass the internal filter (and of course be filtered by an external filter-- the output of which could be part of the feedback loop)?

Re: DSM03 Filter
« Reply #8 on: October 04, 2016, 05:28:49 PM »
Standalone in this case means the filter could be installed in a different hardware application if we decided to, making the its usefulness greater than a single product.

There is only one audio I/O path in the DSM03 so the input must go through the filter on the way to the output. I should be able to post the signal flow diagram shortly.
Dave Smith Instruments

chysn

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Re: DSM03 Filter
« Reply #9 on: October 04, 2016, 08:39:45 PM »
A signal flow diagram would be nice. It would be a considerate practice to post these on your website for all of your modules. Attaching the diagrams to the boxes is cool, but by the time we get that, we've presumably already bought the module.

I'll be looking at the new filter in the context of how it works with the module, probably as a "string" dampener. I've already got several great filters (Doepfer's SEM, the Boomstar ARP filter, the Curtis filter), so the DSM03 isn't likely to be a standalone filter very often. But I would imagine that turning Amount all the way down would basically make it just a filter module....?
DSI: DSM03; previously: Mopho Keyboard, Desktop Mopho, Evolver, DSM01
Hardware: Eurorack, Arturia MicroBrute
Software: macOS, Ableton, MuseScore2
Modular Grid: https://www.modulargrid.net/e/racks/view/354385
GitHub: https://github.com/chysn

Steven Morris

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Re: DSM03 Filter
« Reply #10 on: October 04, 2016, 11:29:48 PM »
Standalone in this case means the filter could be installed in a different hardware application if we decided to, making the its usefulness greater than a single product.

There is only one audio I/O path in the DSM03 so the input must go through the filter on the way to the output. I should be able to post the signal flow diagram shortly.

Thank you for clarifying-- I misunderstood and thought that perhaps some new I/O jacks had been added to the final design!

Still exciting to hear that you've designed a new filter.

Is it safe to assume that leaving the filter wide open will essentially bypass it?

Re: DSM03 Filter
« Reply #11 on: October 05, 2016, 11:04:28 AM »
Yes, open filter essentially means no coloration of the sound.
Dave Smith Instruments

Re: DSM03 Filter
« Reply #12 on: October 05, 2016, 11:39:50 AM »
So is there maybe the possibility of a totally digital DSI synth on the horizon?

Re: DSM03 Filter
« Reply #13 on: October 05, 2016, 11:48:07 AM »
Nothing like that is on the horizon, but with any of our digital effects if we're going to take the time to develop them we might as well design them well enough to use in other applications. Who knows what we'll think of down the road; it's nice to have a large toolbox to draw from.
Dave Smith Instruments

Re: DSM03 Filter
« Reply #14 on: October 05, 2016, 11:57:50 AM »
So is there maybe the possibility of a totally digital DSI synth on the horizon?

Never say never. But if you ask me that would not be a good idea. I mean, the DSI team does work very hard but will DSI ever be able to compete with the many other and much more experienced synthesizer manufacturers with decades of experience in digital synthesis while at the same time being able to produce at much more lower prices than DSI? I would say no.

Integrating a digital filter into an analog voice is an entirely different discussion. That would make very good sense as long as its not high class VCO's being filtered by a digital filter. For instance, expanding on the pre/post parameters of the Tempest digital oscillators in a granular sampler could produce very interesting results including layering filtered digital oscillators over an analog sound. Not to mention its use in synthesis of percussion sounds. Or having both analog and digital voices in a single instrument like the original Boomchik and LinnDrumII design concepts had. There are many interesting and creative voice architecture design possibilities.

But as a digital only voice in a digital only DSI product? Noe!
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Re: DSM03 Filter
« Reply #15 on: October 05, 2016, 12:04:43 PM »
The lowpass filter in the DSM03 is a 4-pole fully resonant filter, and is a new digital design of ours. It is based partially on classic analog filters of the past, but with over-sampling, pass band compensation, and a lot of little tweaks in the signal path.

Is there any official word on how computationally expensive this digital filter design is? I mean, how many instances of it can run simultaneously on the DSP's being used in Prophet-6/OB-6? Could be very useful in a preset manager for Eurorack providing both modulation, sequencing and audio/CV processing of its CV inputs. Or in a future affordable complex voice desktop module.
#!/bin/sh
cp -f $0 $HOME/.signature

Re: DSM03 Filter
« Reply #16 on: October 05, 2016, 12:16:46 PM »
No, we haven't even gotten that far. It's unlikely we'll look at that until if and when we want to use the filter in a different application. Right now we're focused on other things ;)
Dave Smith Instruments

chysn

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Re: DSM03 Filter
« Reply #17 on: October 06, 2016, 07:16:52 AM »
Is there any official word on how computationally expensive this digital filter design is?

Something in there's taking 230mA of power. Compare this to Mutable's Clouds, which is running on an M4 ARM and takes 130mA. Clouds does a lot of impressive DSP stuff; so the DSM03's got to be running on something pretty good, and is probably computationally expensive, in general.
DSI: DSM03; previously: Mopho Keyboard, Desktop Mopho, Evolver, DSM01
Hardware: Eurorack, Arturia MicroBrute
Software: macOS, Ableton, MuseScore2
Modular Grid: https://www.modulargrid.net/e/racks/view/354385
GitHub: https://github.com/chysn

Re: DSM03 Filter
« Reply #18 on: October 06, 2016, 09:01:25 AM »
DSI seem to like Sharcs, so maybe one of the cheap blackfin devices.

Re: DSM03 Filter
« Reply #19 on: October 06, 2016, 12:02:04 PM »
Good guess! It's not a Blackfin, but it is a 266MHz 4th Gen SHARC.
Dave Smith Instruments