Quad VCA anyone?

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Quad VCA anyone?

Post by mmm » Thu Jun 24, 2010 11:36 pm

I modified my VC Mixer (I was suppose to be working on the sequencer) and essentially removed the summation portion, separating the individual channel outputs.

It gets rid of the inverted output and pretty much fills out my 16-control format providing a signal input, Control CV input, attenuator and output per channel.

It also added a change from a dual op amp to a quad, 4 caps and 4 resistors. Somehow, I managed to find spaces for them.

Makes for a nice, compact quad basic VCA with cascaded control CV inputs. The bonus is that each channels' maximum gain can be set by the user.

Should I order some boards? Any takers?

:mmm:

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Post by syncretism » Sat Jun 26, 2010 1:04 am

That sounds smart. God knows, the VC mixer is very smart.

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Post by mmm » Sat Jun 26, 2010 10:18 am

syncretism wrote:That sounds smart. God knows, the VC mixer is very smart.
Thanks Niall,

The design is done and my hack job was successful.
I'm going to go play with subtle applications today. Such as, VC of various CV application and routing rather than getting stuck in a groove of just using them for audio applications.

I was sweating the fact that I don't have a lot of EG's until I remembered that CV's don't necessarily have to come from an EG. OK, senior brain fart :bang:

Don't know if I'll actually offer it as a product. Doesn't seem to be a lot of response from anybody. The boards are designed and verified. No biggie...I HAVE one :guinness:

Play time. :cloud:

G

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Post by klstay » Sat Jun 26, 2010 5:26 pm

So what are the differences between this and the CV mixer?

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Post by syncretism » Sat Jun 26, 2010 6:18 pm

klstay wrote:So what are the differences between this and the CV mixer?
The big one's right here:

It gets rid of the inverted output and pretty much fills out my 16-control format providing a signal input, Control CV input, attenuator and output per channel.

Four in, four out. No mixing/summing.

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Post by mmm » Sat Jun 26, 2010 6:27 pm

klstay wrote:So what are the differences between this and the CV mixer?
It's just a variation of the same design.

Instead of all 4 channels being mixed together to one output, they're all available individually. You can route each channel to different applications.

i.e: using one on a feedback loop for a VC resonance, another for voltage control of a modulation source before it's destination module, another for VC control of a support VCO output into a mix...etc. Otherwise, you just have one output on the VCM (2 if you count the inverted out) so, it's great for mixing cv's or audio going to a single destination.

Oddly enough, it took more components to do that since each output had to be buffered independently.

Another fun experiment is to use one channel as an VC audio level of a Modulating VCO going to the FM input of another VCO. Then using another for a voltage controlled CV amplifier controlling the pitch of the modulation VCO. All sorts of VC sideband goodness :bananaguitar:

:mmm:

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Post by BananaPlug » Sat Jun 26, 2010 8:05 pm

Interesting. How involved a mod would it be to add a "Lin/Exp" switch for each input to choose the CV response?

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Post by Low-Gain » Sat Jun 26, 2010 8:12 pm

Sounds like the module i've been designing for the last 2 months.
Due to release in a month or two..

Image

(i dont use fancy graphics programs for showing off panels that are still in prototyping stage, panel design subject to change)

Just need to lay the pcb out. Hope to do that this week.

function details remain my own business till closer to launch.
But i will say it's going to be a very transparent and quiet module :)
4 VCA input, 5 VCA out w/ mix buss and CV master. ;) thats all for now kids.

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Post by mmm » Sat Jun 26, 2010 10:15 pm

BananaPlug wrote:Interesting. How involved a mod would it be to add a "Lin/Exp" switch for each input to choose the CV response?
Actually, pretty involved. I ran out of space on my board for any more parts and/or I/O connectors.

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Post by Adam-V » Sat Jun 26, 2010 10:53 pm

Sounds great George. I've just got far too much on my plate to be considering any new projects at the moment but further down the track I'd be interested for sure.

Cheers,
Adam-V

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Post by mmm » Sun Jun 27, 2010 12:33 am

Adam-V wrote:Sounds great George. I've just got far too much on my plate to be considering any new projects at the moment but further down the track I'd be interested for sure.

Cheers,
Adam-V
LOL. I know that story. I had to make myself do this.

Unfortunately, because I have a quad VCA now, I just HAD to design a quad EG to go with it :help:

It's a simple quad AD, an input, output and an Attack and Decay pot for each channel. Think I'll call it QuAD.

Between the two, it makes for a nice sprinkling of quickie EG/VCA combo's that don't require full blow ADSR's and VCA's.

:despair:

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Post by computer controlled » Sun Jun 27, 2010 3:49 am

I'll have to check these out a the meeting next month!
Stuff: SH-01A . TR-8S . MX-1 . D-20 . Waldorf MicroQ . Ensoniq ESQ-1 . Ensoniq EPS 16+ . Yamaha MODX6 . DX7 . TX802 . MPC Live . RE-303 . Avalon BassLine . Behringer Neutron . Behringer MS-101 . Behringer Pro-1 . Behringer K-2 . Behringer TD-3 . E-mu EmaxSE . E-mu Emax II . E-mu EMAX II rack . PCM 41 . BeatStep Pro . Keystep .

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Post by BananaPlug » Sun Jun 27, 2010 8:14 am

Unfortunately, because I have a quad VCA now, I just HAD to design a quad EG to go with it help
Now you're talking. Will the quAD be strictly AD or is ASR possible? Sorry, I shouldn't be pushing for feature creep so hard on such compact quad modules.

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Post by mmm » Sun Jun 27, 2010 10:32 am

BananaPlug wrote:
Unfortunately, because I have a quad VCA now, I just HAD to design a quad EG to go with it help
Now you're talking. Will the quAD be strictly AD or is ASR possible? Sorry, I shouldn't be pushing for feature creep so hard on such compact quad modules.
Don't know. I designed it but haven't prototyped it. For some reason, my brain isn't sure what it's going to do with a continued gate. ASR is easy, just slew a gate.
I was thinking of that last night. My thought is to put a 4 pos dip switch on the board if I can and let the user decide which they prefer. That would allow for selecting either mode for either channel.

The gate input channels all use my typical interrupting cascade scheme.

I'll keep you all informed. I'm just having fun.

I want to try my 4X gate delay with the QuAD going to the Quad VCA. Not sure what to process but, I like the chain. :headbang:

G

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Post by mmm » Sun Jun 27, 2010 1:59 pm

BananaPlug wrote:
Unfortunately, because I have a quad VCA now, I just HAD to design a quad EG to go with it help
Now you're talking. Will the quAD be strictly AD or is ASR possible? Sorry, I shouldn't be pushing for feature creep so hard on such compact quad modules.
OK, I have it down. It's a self-completing ASR. (sustain being full output level). If I break the latch line it basically turns into an AR that ramps up and down with the settings but short gate repetative pulses will let it ramp up during the gate then, release with no gate and pick up where it left off at the attack rate when the gate is re-applied. So, if you work it right, you could cascade the output in increasing up/down steps until you hit 5V. Basically...a slewed gate. That's a on board user switch selection that's staying.

Now, I'll see about getting it to switch to the release after peaking regardless of if the gate is still present. So, the AD selection.

:mmm:

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Post by BananaPlug » Sun Jun 27, 2010 2:30 pm

Great! Just to encourage you I ordered a VC Mixer PCB which I'll do up in frac like my SVF.

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Post by mmm » Sun Jun 27, 2010 2:58 pm

BananaPlug wrote:Great! Just to encourage you I ordered a VC Mixer PCB which I'll do up in frac like my SVF.
I LIKE that kind of encouragement. :yay:

Thanks Stephen. :party:

I'll reply officially shortly.

G

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Post by mmm » Mon Jun 28, 2010 7:58 pm

BananaPlug wrote:
Unfortunately, because I have a quad VCA now, I just HAD to design a quad EG to go with it help
Now you're talking. Will the quAD be strictly AD or is ASR possible? Sorry, I shouldn't be pushing for feature creep so hard on such compact quad modules.
OK, figured it out simply.

Each channel of the QuAD can be user selected on-board to be either an AD or ASR.

Phew.

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Post by syncretism » Mon Jun 28, 2010 9:19 pm

So that would be AD or attack time/level & release? Whenever someone talks about an ASR, they apparently mean a shift register, but I always think of an envelope, even if I'm not sure I've actually seen one with that spec. ADR, yes. ADS, yes. But not an ASR, I think.
Last edited by syncretism on Mon Jun 28, 2010 10:09 pm, edited 1 time in total.

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Post by pugix » Mon Jun 28, 2010 10:01 pm

I think the Quad VCA is a great idea. :yay: Four DC-coupled VCAs are very useful for CV over CV.

And it doesn't compete with your full-feature VCA, which is AC-coupled and also has the really cool MOD input (fast becoming my favorite feature).
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Post by mmm » Mon Jun 28, 2010 10:16 pm

syncretism wrote:So that would be AD or attack time/level & release? Whenever someone talks about an ASR, they apparently mean a shift register, but I always think of an envelope, even if I'm not sure I've actually seen one with that spec. ADR, yes. ADS, yes. But not an ASR, I think.
In my definitions:
ASR: When gated, initiates the Attack stage. (which is self-completing) Maintains full sustain level with a continued gate and doesn't start the release until the gate drops. In this case, the decay setting.

AD: Initiates the attack phase on gate, self completed both attack and decay phases and ends until the gate drops and is re-initiated.

Clear as mud :bananaguitar:

:mmm:

@Pugix: Yeah, I like the morphing AM--->Ring mod on my full-blown VCA.

These are just down and dirty basic utility-function modules.

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Post by klstay » Mon Jun 28, 2010 11:53 pm

Hmmm.....

This new quad EG, the slightly less new quad "light" VCA, and a pair of the VC LFOs boards all behind a four wide panel and then figure out how to ergonomically fit all the knobs/switches/jacks on the front AND get it all normal'd properly...

I might just have to try and put together a panel layout for that one!

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Post by mmm » Tue Jun 29, 2010 1:27 am

klstay wrote:Hmmm.....

This new quad EG, the slightly less new quad "light" VCA, and a pair of the VC LFOs boards all behind a four wide panel and then figure out how to ergonomically fit all the knobs/switches/jacks on the front AND get it all normal'd properly...

I might just have to try and put together a panel layout for that one!
LOL,

That makes my head hurt just thinking about it and I designed these :)

G

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Post by klstay » Tue Jun 29, 2010 10:15 am

mmm wrote:
klstay wrote:Hmmm.....

This new quad EG, the slightly less new quad "light" VCA, and a pair of the VC LFOs boards all behind a four wide panel and then figure out how to ergonomically fit all the knobs/switches/jacks on the front AND get it all normal'd properly...

I might just have to try and put together a panel layout for that one!
LOL,

That makes my head hurt just thinking about it and I designed these :)

G
My subconscious overnight did me even better...

On the same panel add the quad gate delay in front and then for output a 5 way switch, each with a 2 way mult out, to select nothing or which of the 4 VCA outputs you want. HEEEEEEY! Maybe even a 2 way switch in front of each one to pick the VCA out or the EG out! Now we are cookin' with gas...

And remember, by providing your ready to go boards you sir are ultimately responsible for such insanity.

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Post by mmm » Tue Jun 29, 2010 3:09 pm

klstay wrote:
mmm wrote:
klstay wrote:Hmmm.....

This new quad EG, the slightly less new quad "light" VCA, and a pair of the VC LFOs boards all behind a four wide panel and then figure out how to ergonomically fit all the knobs/switches/jacks on the front AND get it all normal'd properly...

I might just have to try and put together a panel layout for that one!
LOL,

That makes my head hurt just thinking about it and I designed these :)

G
My subconscious overnight did me even better...

On the same panel add the quad gate delay in front and then for output a 5 way switch, each with a 2 way mult out, to select nothing or which of the 4 VCA outputs you want. HEEEEEEY! Maybe even a 2 way switch in front of each one to pick the VCA out or the EG out! Now we are cookin' with gas...

And remember, by providing your ready to go boards you sir are ultimately responsible for such insanity.
I'm insane enough on my own. Nice to see that I can pass it along :goo:

On the up side, I have the QuAD/ASR board layed out and traces run. Now, I get to verify that everything goes to what it's supposed to.

G

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