Quad VCA anyone?

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syncretism
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Post by syncretism » Tue Jun 29, 2010 9:19 pm

I'm looking at the next Mattson order. If you can finish these soon, then it would save me getting a second VCA and ADSR, and would be preferable, especially since I have the 4x Gate Delay.

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Post by mmm » Tue Jun 29, 2010 9:37 pm

syncretism wrote:I'm looking at the next Mattson order. If you can finish these soon, then it would save me getting a second VCA and ADSR, and would be preferable, especially since I have the 4x Gate Delay.
Well, I just verified the boards and got them ordered. Ordered the handful of parts that I typically don't stock. So, once I glue some parts on the boards and verify that I didn't screw them up somehow, the DIY portion will be done.

While I'm waiting for those to show up, I'll draw up the graphics for the two modules and see if my supplier can get them done quickly.

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Post by pugix » Wed Jun 30, 2010 8:35 pm

I like the idea of putting a Quad Gate Delay, Quad EG and Quad VCA into one panel with the obvious normaling scheme.
Richard
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"Everything in our world is actually always modulated by everything else." - Peter B

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Post by mmm » Wed Jun 30, 2010 9:59 pm

pugix wrote:I like the idea of putting a Quad Gate Delay, Quad EG and Quad VCA into one panel with the obvious normaling scheme.
I need to come up with one more so we can have a quad, quad conglomeration :) :despair:

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Post by Adam-V » Wed Jun 30, 2010 10:34 pm

Quad gate to trigger converter?

Cheers,
Adam-V

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Post by mmm » Wed Jun 30, 2010 11:03 pm

Adam-V wrote:Quad gate to trigger converter?

Cheers,
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Using the 4X gate delay with the QuAD in AD mode does that. Except the "trigger" would only be 5V

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Post by ach_gott » Thu Jul 01, 2010 12:10 am

I love it! I'll be in for all of the above; probably more than one.

As for the fourth member of the quad quad... quad LFO is probably the obvious choice, but only really interesting if there's a linear FM per LFO (crazy cross-mod possibilities). But that's possible in a number of product lines already.

So my vote: a divider with a 50% duty cycle and a choice of /2 and (if possible) /3 per channel. The reasoning:
1.) You have a sequencer in the works, at least in the Wiki. When Billy gets around to writing slamming techno tunes, he can have 4 going at the same time.
2.) Using them as gate (with gate delay, etc.) could generate some awesome polyrhythms.
3.) Chaining them would give interesting combinations.
4.) Chaining then mixing using the VC Mixer you could have a 'drawbar' organ similar to the one JLR made from the awesome MOTM-730.
5.) Buying more than one makes sense for people into crazy rhythms.
6.) The module itself is a suboscillator if you chain the dividers.

Thoughts from the peanut gallery?

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Post by mmm » Thu Jul 01, 2010 12:39 am

ach_gott wrote:I love it! I'll be in for all of the above; probably more than one.

As for the fourth member of the quad quad... quad LFO is probably the obvious choice, but only really interesting if there's a linear FM per LFO (crazy cross-mod possibilities). But that's possible in a number of product lines already.
I like running the triangle output of one of the VC dual LFO's into the VCinput of the other one, then taking the triangle output of that one and running it into the VC input of the first one.

Good exercise in trying to confuse electrons :hihi:

So my vote: a divider with a 50% duty cycle and a choice of /2 and (if possible) /3 per channel. The reasoning:
1.) You have a sequencer in the works, at least in the Wiki. When Billy gets around to writing slamming techno tunes, he can have 4 going at the same time.
2.) Using them as gate (with gate delay, etc.) could generate some awesome polyrhythms.
3.) Chaining them would give interesting combinations.
4.) Chaining then mixing using the VC Mixer you could have a 'drawbar' organ similar to the one JLR made from the awesome MOTM-730.
5.) Buying more than one makes sense for people into crazy rhythms.
6.) The module itself is a suboscillator if you chain the dividers.

Thoughts from the peanut gallery?
Well, my utility 1 already does a divide by 2 and divide by 4 and will take an external clock in place of the internal one.

....divide by 3...now I have to do math. :bang:

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Post by pugix » Thu Jul 01, 2010 9:35 pm

mmm wrote:
pugix wrote:I like the idea of putting a Quad Gate Delay, Quad EG and Quad VCA into one panel with the obvious normaling scheme.
I need to come up with one more so we can have a quad, quad conglomeration :) :despair:
After I wrote that it occurred to me that your straight mixer would make a nice fourth module for that group, with the inputs normal-connected to the Quad VCA outputs. Would save a bunch of patch cords and still be totally flexible, except for the size of the bugger. Would be 4U wide in MOTM format.
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Post by mmm » Thu Jul 01, 2010 10:49 pm

pugix wrote:
mmm wrote:
pugix wrote:I like the idea of putting a Quad Gate Delay, Quad EG and Quad VCA into one panel with the obvious normaling scheme.
I need to come up with one more so we can have a quad, quad conglomeration :) :despair:
After I wrote that it occurred to me that your straight mixer would make a nice fourth module for that group, with the inputs normal-connected to the Quad VCA outputs. Would save a bunch of patch cords and still be totally flexible, except for the size of the bugger. Would be 4U wide in MOTM format.
Or, better yet, the VCM!. With no CV control, it acts like a mixer but, if you need to suddenly throw a 0-5V on a final mix channel...say, a foot pedal, you're covered. I just did that and ended up lost somewhere in the ether for about an hour and a half. Don't know where the time went. Just got lost in a groove. Nice when that happens. :tu:

Yeah, so many panel components only fit into so much space. But, look at the flexability :)

I'm in a GREAT mood :)

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Post by syncretism » Thu Jul 01, 2010 11:12 pm

I don't have it on front of me, but can the gate delay also act as a CV delay? Say, one envelope turns into four, over time?

I'm drunk and working on a support call. I'm bored and my mind has wandered. Sorry.

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Post by ach_gott » Thu Jul 01, 2010 11:58 pm

syncretism wrote:I don't have it on front of me, but can the gate delay also act as a CV delay? Say, one envelope turns into four, over time?

I'm drunk and working on a support call. I'm bored and my mind has wandered. Sorry.
No, it just waits to go high until the delay time has elapsed.

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Post by klstay » Fri Jul 02, 2010 9:46 am

Since this has gotten completely out of hand anyway... ;-)

In my brain-addled dotage I am seriously halfway to ordering an 8 width blank panel to try and jam all this behind it:

quad gate delay
quad eg
quad vca
dual vc lfo X 2
vc mixer

All kinds of wonderful normal'd wiring and switches. Mixer would possibly have a switch to select between eg, vca, lfo wave1, lfo wave2, jack, nothing for signal in and maybe 3 way for eg, vca, or lfo for cv.

Whole lotta work to build, but it sure could be a joy to use live...

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Post by mmm » Fri Jul 02, 2010 11:23 am

klstay wrote:Since this has gotten completely out of hand anyway... ;-)

In my brain-addled dotage I am seriously halfway to ordering an 8 width blank panel to try and jam all this behind it:

quad gate delay
quad eg
quad vca
dual vc lfo X 2
vc mixer

All kinds of wonderful normal'd wiring and switches. Mixer would possibly have a switch to select between eg, vca, lfo wave1, lfo wave2, jack, nothing for signal in and maybe 3 way for eg, vca, or lfo for cv.

Whole lotta work to build, but it sure could be a joy to use live...
The boards are out for delivery. When they get here, I'll toss a couple together and test them.

I'll announce a Teseract sale this evening. (quad/quad=4th dimensional hypercube=Teseract) :omg:

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Post by mmm » Sat Jul 03, 2010 12:21 pm

The QuAD /ASR board works great!!!

I set up a patch, got totally absorbed and wanted a second one rather quick. This is real handy :tu:

I haven't stuffed the Quad VCA board yet but, I'm confident about that one since it's just a modification of the VCM board. I'll build one soon. No biggie if I screwed up a trace. I can get new boards in 3 days.

I've loaded the pages in my WIKI for describing the functions:
http://mmm.sevcom.com/wiki/index.php/DI ... DIYcisions

I will be able to upload pix next week for the boards. They pretty much look the same as the others, just different parts :party:

For you DIY guys, I use a 4-position DIP switch on the QuAD /ASR board for selecting the AD/ASR mode for each channel. If you want to bring that selection to the front panel, let me know and I'll leave the DIP switch off. With the terminals open, the EG works in AD mode, With them shorted, it works in ASR mode.
Ch 1: pad 1 & 8
Ch 2: pad 2 & 7
Ch 3: pad 3 & 6
Ch 4: pad 4 & 5

My thoughts are just bring each associated pair to a panel switch. Off=AD, on=ASR. I thought it would be nice to get pots for the Attack stages with a pull-on, push-off switch (or vice versa). Just change the mode by pulling or pushing the attack control. I don't have any so, I'm stuck with a DIP switch on the full-blown module.

I'm also thinking of just sticking an 8-pin DIP socket in the spot and offer an 8-pin DIP connector with a ribbon cable on it for bringing it out front. That way, I can either stick a DIP switch on it or send a cable, depending on what the user would like.

I'm posting my Teseract sale as a new thread in a minute. As soon as I can figure out an elegant way to organize and write it. :help:

The core of the sale will be the QuAD EG and Quad VCA with a selection of two of the following complimentary modules:
4 X Gate Delay
4 X Mixer
4 X Buffer
VC Mixer
VC Dual LFO

All modules in the quad group sale will come with the appropriate wire kit for each selected module and power cable of choice.

I'll also discount and list the associated modules individually for the sale in case you would like to grab one outside of the "quad" group.

:mmm:

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Post by mmm » Sat Jul 03, 2010 3:51 pm

OK, I think I posted it clearly.

Let me know if I confused everybody.

G

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Post by patchdub » Mon Nov 15, 2010 2:24 am

hi. does the vc mixer still exist in the quad vca board? meaning, would it be possible to still have the the summed out and inverted out along with the individual outs of the quad vca?

as soon as i collect enough green tickets i am ordering the quad vca and the quad ad/asr!

must get food and firewood first though. trying to keep my priorities straight.

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Post by BananaPlug » Mon Nov 15, 2010 8:00 am

patchdub wrote:hi. does the vc mixer still exist in the quad vca board? meaning, would it be possible to still have the the summed out and inverted out along with the individual outs of the quad vca?
No but you can accomplish that easily with a small add-on as done here very neatly by negativspace.

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Post by mmm » Mon Nov 15, 2010 10:12 am

patchdub wrote:hi. does the vc mixer still exist in the quad vca board? meaning, would it be possible to still have the the summed out and inverted out along with the individual outs of the quad vca?

as soon as i collect enough green tickets i am ordering the quad vca and the quad ad/asr!

must get food and firewood first though. trying to keep my priorities straight.
Food and firewood. :bang: Thanks for the reminder. :tu:

The Quad VCA is essentially the same circuit as the VC Mixer.

It's easy to sum the outputs of the IC's and run a normal and inverted buffer amp for the outputs.

The problem was, to get individual outputs, I had to split the common output between the amp outputs and run them into individual output buffers.

So, I had to add two more op amps to turn the VC mixer to a quad VCA.

Any summation and inversions would have to follow the channel buffers.

Best to do it the way negativspace did as BananaPlug suggested.

G

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Post by patchdub » Mon Nov 15, 2010 12:13 pm

okey dokey! i was just looking at bananaplug's panel last night.

thanks!

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Post by patchdub » Thu Dec 09, 2010 2:43 am

is it possible to get the pcb without the on board gain trim pots so that i can then put them on the panel?

i'm trying to figure out if i can put the vca and the quad vca on a 2u motm style panel.

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Post by mmm » Fri Dec 10, 2010 12:11 pm

patchdub wrote:is it possible to get the pcb without the on board gain trim pots so that i can then put them on the panel?

i'm trying to figure out if i can put the vca and the quad vca on a 2u motm style panel.
Sure. But, I'll have no way to test it. I certainly won't be able to calibrate it. :deadbanana:

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Post by patchdub » Fri Dec 10, 2010 7:37 pm

mmm wrote:Sure. But, I'll have no way to test it. I certainly won't be able to calibrate it.
oh. bad idea then? i thought perhaps there might be a benefit to have the gain on the front panel.

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Post by mmm » Sat Dec 11, 2010 12:18 pm

patchdub wrote:
mmm wrote:Sure. But, I'll have no way to test it. I certainly won't be able to calibrate it.
oh. bad idea then? i thought perhaps there might be a benefit to have the gain on the front panel.
Not a bad idea at all. The trim pots adjust the gain per channel from crap to "slam the rails". There is also a trim pot for adjusting the internal voltage that gets normalled and cascaded to the CV control input jacks that sets the overall max gain for when there is no CV control input patched into the jacks.

You can set them globally to be a set gain with no CV input to be either a unity gain attenuator or a x gain preamp with no CV and set the channels to be a unity gain VCA or, each channel can have it's own unique gain setting.

I just set everything to unity gain across the board because that's what people are instinctively expecting. But, yeah, determining your own gain specs for your needs is OK.

I have mine set up to be 2X gain for individual CV or audio preamps with no CV patched in and, unity gain VCA's responding to 1:1 input to output ratio with a 5V CV patched in. That way, I have a quad VCA or four preamps in case some of my signals need a boost. If I need a couple of preamps AN a couple of VCA's, I used the patched CV on the higher channels numbers for my VCA channels and leave the lower channels numbers attached to the internal voltage in the cascade for the preamps.

Without the trim pots on the board, I can't verify that the board is operational before I send it.

But, nothing says you cant unsolder them and remote them to the front panel if you wish.

I could just "tack" them in enough to make connection and verify operation and not be a SOB to remove....

So, if you replace the 5 trim pots with panel pots remoted to the main user panel, it gives you real-time control of the gain structures.

Since these will amplify big time, you can use two channels, one to slam the rails (thus clipping at the power rails) Thus, distorting the hell out of the original signal and send that to another channel to attenuate the power-rail slammed distorted signal back down to the +/- 5V that should be.

By using the levels properly and being creative with the CV configurations, the module can become a voltage controlled distortion.

OK, My brain has rambled enough.

Keep in mind, I'll be closing the cart just before Xmas and not accepting any new orders until I re-configure my cost structure. Then, I'll re-open the cart in January with the new prices :sadbanana:

But, only one person has used the newcust5 5% discount coupon that is awarded by registering on my cart.

Everybody except one person has the opportunity to grab whatever they've been musing over and grab 5% off before I close the cart for the holidays.

G

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Post by patchdub » Mon Dec 13, 2010 12:53 am

nice! thanks!

well i'm gonna be #2 to use the customer discount then!

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