1979 DVCM: Dual Voltage Controlled Mixer for Buchla systems

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sempervirent
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1979 DVCM: Dual Voltage Controlled Mixer for Buchla systems

Post by sempervirent » Wed Sep 04, 2019 5:28 pm

1979 DVCM: Dual Voltage Controlled Mixer
1979.ws/dual-voltage-controlled-mixer

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Now taking preorders for the DVCM. This module provides two separate 4-channel VC audio mixers with master gain controls, top-to-bottom audio normalizations, configurable pre/post outputs, and visual feedback of post-mix signal levels. It works well as the final output module in a system, a submixer for blending waveforms within a patch, or a cleaner and brighter alternative to a lowpass gate.

Audio mixing is an area where the 200 series canon has some room for improvement. The initial concept for this module was sketched out a few years ago when I decided that the 206/207 were a bit too limited and the 227 was much more than I needed. The DVCM has gone through a few iterations since then and it's finally ready to make its way out of the lab.

Note that the photos above show a recent prototype, but the illustration accurately represents the final product: separate pre/post outputs, bipolar attenuators on the main mix CV inputs, and monitor LEDs on the right side.

Preorder price is $600 USD which is discounted by about 10% compared to the final price. ETA is mid/late October.
Last edited by sempervirent on Sun Nov 03, 2019 1:13 am, edited 1 time in total.

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Post by dksynth » Wed Sep 04, 2019 7:43 pm

lovely to see!

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Post by sempervirent » Wed Sep 04, 2019 9:15 pm

Thanks, this one's been in the queue for a while, as you know ;)

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Post by Fuzz » Wed Sep 04, 2019 9:58 pm

Look at that price :love:. Fantastic addition to the format!
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Post by meatcliff » Thu Sep 05, 2019 1:58 pm

Wonderful! I've modded my 207r so I can configure it for 2x 3ch, each with one VCA.

This is a much more practical solution and have to assume sounds much better... definitely grabbing it!

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Post by sempervirent » Thu Sep 12, 2019 12:08 pm

Thanks guys. These are in production now, will post status updates as things progress.

I've been storyboarding some demo video ideas too, mostly involving the 245 and 281 in combination with the VC inputs or a pair of DAOs generating chords for example.

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Post by Peake » Thu Sep 12, 2019 12:47 pm

Nice!
This is not the place I'd imagined it to be.

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Post by Lewis# » Fri Sep 20, 2019 1:07 pm

very cool, just ordered! The only thing I probably would have changed is to locate the audio in‘s at the lower end, at least for the lower part ...

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Post by sempervirent » Wed Oct 09, 2019 9:56 pm

Thanks for the preorder. Too late for changes, but I'm curious to know why you'd want the audio inputs on the bottom in the bottom half. Aesthetically, I prefer having identical things be laid out in identical ways. Also I think the question of whether something should go at the top or bottom of a given module is usually subjective because it all depends on where in one's case the module ends up being installed. (The one exception might be touch surfaces, which most people are going to put right in the front/bottom row so it only makes sense to put the outputs on top.)

Got an update from my assembler today, modules should be finished next week, so preorders will start shipping in about two weeks.
Last edited by sempervirent on Thu Oct 10, 2019 11:08 pm, edited 1 time in total.

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Post by lumin » Thu Oct 10, 2019 3:58 am

I had a question. I may be seeing this correctly, but wanted to be sure. Are there any pan controls on this module? It appears as if your mixer is dual mono instead of stereo, but in case it is stereo, are those knobs below the rogans for panning?
Thanks

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Post by sempervirent » Thu Oct 10, 2019 11:05 pm

Correct, it's dual mono. That said, using the module for stereo applications is pretty easy due to all the CV inputs and the way that that the normalizations are set up.

Stereo panning is basically just the result of creating amplitude/gain differences between the left and right channels. With the left gain at 1 and the right gain at 0, the signal is panned fully left. With the right gain at 1 and the left gain at 0, the signal is panned fully right. With a gain of 1 on both left and right, the signal is panned to the center.

So on the DVCM you can implement VC stereo panning by sending different CVs into the modulation inputs of the top and bottom sections to change the gain ratios. Let's say you patch an oscillator into the top left input. It's now also routed to the bottom left input (presuming that nothing else is patched there). The main outputs of the top and bottom sections will now be identical, so you have separate "left" and "right" signals to send out to your external mixer or audio interface.

From there, set both the top and bottom channel 1 sliders to the minimum. Patch a CV from the 281 into the CV input of the first channel on the top half. Now patch the same CV from the 281 into a 257, invert the signal, and add a +10V offset. This creates an inverted version of the original function that's also offset to work within the 0-10V range used by the DVCM. Patch this inverted+offset signal to the CV input of the first channel on the bottom half. The result is that the sound will oscillate back and forth in the stereo field, because whenever the left gain rises, the right gain will fall, and vice versa in a mirror image of the other.

Since there are four channels to play with, you can modulate four different signals separately within the stereo field. Obviously this can be done with other CV sources besides the 281. If you use a FRV from the 266 for example and patch through the 257 as described above, the left will still be the inverse of the right, but instead of rising and falling the panning is random. This mirror image technique isn't required of course, you could also just patch two different FRVs into the two channel CV inputs on the DVCM. The panning would randomly fluctuate between left, center, and right.

And of course you can use this technique to modulate the final mix outputs too, not just the individual channels. Because the Mix sections include inverting attenuators, you don't have to patch through the 257. Just split the source CV in two, patch one cable to the top section's Mix CV input with the attenuator turned fully to the right and the Mix knob to the minimum, then patch the other cable to the bottom section's Mix CV input with the attenuator turned fully to the left and the Mix knob set to the maximum. By doing this, the attenuator handles the inversion and the Mix knob handles the offset, so the inversion+offset technique doesn't require an extra module.
Last edited by sempervirent on Fri Oct 11, 2019 4:52 pm, edited 1 time in total.

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Post by lumin » Fri Oct 11, 2019 2:21 pm

Thank you for the explanation. Opened my eyes up to the possibilities of your mixer. Some very nice ideas!

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Post by MindMachine » Sat Oct 12, 2019 10:24 pm

Gorgeous.
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Post by sempervirent » Thu Oct 24, 2019 10:54 pm

Thanks. These are now en route from my assembler, all preorders should be shipped no later than next Friday (October 31).

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Post by sempervirent » Sun Nov 03, 2019 1:15 am

All preorders have been shipped, thanks everyone.

Still have a few available:
1979.ws/dual-voltage-controlled-mixer

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Re: 1979 DVCM: Dual Voltage Controlled Mixer for Buchla systems

Post by Ossicle » Thu Jan 23, 2020 11:31 am

I'm considering between this and 207r. Has anyone used both? Are there clear differences in sound quality, how is the workflow etc.?

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Re: 1979 DVCM: Dual Voltage Controlled Mixer for Buchla systems

Post by mutierend » Thu Jan 23, 2020 2:31 pm

I have a DVCM. I prefer it over the 206/207 for one simple reason: the VCAs.

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Re: 1979 DVCM: Dual Voltage Controlled Mixer for Buchla systems

Post by Ossicle » Thu Jan 23, 2020 3:16 pm

mutierend wrote:
Thu Jan 23, 2020 2:31 pm
I have a DVCM. I prefer it over the 206/207 for one simple reason: the VCAs.
Thanks! That's a good reason. :nod:

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Re: 1979 DVCM: Dual Voltage Controlled Mixer for Buchla systems

Post by sempervirent » Thu Jan 23, 2020 8:09 pm

Along with being an alternative to the 206/207, the DVCM also overlaps with the 292.

It's not a lowpass gate but each half of the DVCM offers a 4-in/1-out VC mixing setup similar to the 292, while adding a master gain control.

So (vactrols and individual outputs aside) you get two 4:1 VC mixers in the same module space.

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Re: 1979 DVCM: Dual Voltage Controlled Mixer for Buchla systems

Post by lumin » Thu Feb 13, 2020 12:52 pm

Anyone have some audio/video of the DVCM in action?
Im interested in hearing/seeing how CV affects channel output. I know its not a 292, but I am curious as to the sound if a channel is sent, say, an envelope.
I am in need of a mixer, and have my eye on this or possibly 2 NLM hMMs.
Each have their own special sauce, and Ive at least seen a demo on the NLM youtube page.

Big thanks

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