FREE MODRACK VCA

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doze
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14 Aug 2019

Another cool FREE RE from Murf.

MODRACK VCA

The Modrack VCA Rack Extension is a basic Voltage Controlled Amplifier module.
It features the following:
- Exponential and Linear Audio and CV inputs
- CV Gate in


https://www.propellerheads.com/shop/rac ... drack-vca/

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Catblack
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14 Aug 2019

doze wrote:
14 Aug 2019
Another cool FREE RE from Murf.

MODRACK VCA

The Modrack VCA Rack Extension is a basic Voltage Controlled Amplifier module.
It features the following:
- Exponential and Linear Audio and CV inputs
- CV Gate in


https://www.propellerheads.com/shop/rac ... drack-vca/
Thanks!
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DJMaytag
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20 Aug 2019

Any chance you'd make a VCA capable of controlling CV instead of (or in addition to) just audio?

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challism
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21 Aug 2019

Thank you, Murf!
Players are to MIDI what synthesizers are to waveforms.

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selig
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21 Aug 2019

DJMaytag wrote:
20 Aug 2019
Any chance you'd make a VCA capable of controlling CV instead of (or in addition to) just audio?
you can do that with (cough) Selig Gain (cough)…
;)

And while I'm here, could you make this stereo (I create mostly stereo patches) and make those little knobs on the front a bit bigger (there's plenty of room on the front)?

I love the way the Quad VCA from Intellijel works, with a continuous control to go from linear to exp to log. Not sure you need separate inputs for these, as you would not use them at the same time, right?
Selig Audio, LLC

DJMaytag
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21 Aug 2019

selig wrote:
21 Aug 2019
you can do that with (cough) Selig Gain (cough)…
;)
I swear this is why we need plugin/player/device sorting or some kind of folder system available in the right click menu. I forget what all I already have all the damn time...

Will check that out shortly!

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Loque
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30 Aug 2019

Ok...i kno had a bit time and was throwing all together and was hoping for a quick result. Maybe i miss something but i could not get the ADSR work properly with the VCO - it just did not spit out any envelopes. It cannot be controlled via MIDI and it does not react on a Gate input.

Anybody got this thing to work?
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Murf
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17 Apr 2020

Loque wrote:
30 Aug 2019
Ok...i kno had a bit time and was throwing all together and was hoping for a quick result. Maybe i miss something but i could not get the ADSR work properly with the VCO - it just did not spit out any envelopes. It cannot be controlled via MIDI and it does not react on a Gate input.

Anybody got this thing to work?
Hi Loque,
MODRACK VCA is not meant to be env triggered by VCO, these modules were created to be as simple as possible.
I am sure you have managed to work out how to use MODRACK ADSR to do this by now, but send me a message if not.
Murf.

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Loque
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17 Apr 2020

Murf wrote:
17 Apr 2020
Loque wrote:
30 Aug 2019
Ok...i kno had a bit time and was throwing all together and was hoping for a quick result. Maybe i miss something but i could not get the ADSR work properly with the VCO - it just did not spit out any envelopes. It cannot be controlled via MIDI and it does not react on a Gate input.

Anybody got this thing to work?
Hi Loque,
MODRACK VCA is not meant to be env triggered by VCO, these modules were created to be as simple as possible.
I am sure you have managed to work out how to use MODRACK ADSR to do this by now, but send me a message if not.
Murf.
Hi Murf,
no, not really. It works only on Matrix gate triggers. It does not work on any other gate signals, like RPG-8 or when i route the Matrix Gate through a spider. No idea what is going on there. Can you get it to work with a gate signal from RPG-8?
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Murf
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17 Apr 2020

Loque wrote:
17 Apr 2020
Murf wrote:
17 Apr 2020


Hi Loque,
MODRACK VCA is not meant to be env triggered by VCO, these modules were created to be as simple as possible.
I am sure you have managed to work out how to use MODRACK ADSR to do this by now, but send me a message if not.
Murf.
Hi Murf,
no, not really. It works only on Matrix gate triggers. It does not work on any other gate signals, like RPG-8 or when i route the Matrix Gate through a spider. No idea what is going on there. Can you get it to work with a gate signal from RPG-8?
Hi Loque, I tried a matrix into a spider and it triggers MODRACK VCA fine.
Here is the song file for my test:
Attachments
VCA-spider-trigger.zip
(56.93 KiB) Downloaded 31 times

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Loque
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18 Apr 2020

Murf wrote:
17 Apr 2020
Loque wrote:
17 Apr 2020

Hi Murf,
no, not really. It works only on Matrix gate triggers. It does not work on any other gate signals, like RPG-8 or when i route the Matrix Gate through a spider. No idea what is going on there. Can you get it to work with a gate signal from RPG-8?
Hi Loque, I tried a matrix into a spider and it triggers MODRACK VCA fine.
Here is the song file for my test:
I know, that Matrix works... Could you get it to work with RPG8?
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Murf
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18 Apr 2020

Loque wrote:
18 Apr 2020
Murf wrote:
17 Apr 2020


Hi Loque, I tried a matrix into a spider and it triggers MODRACK VCA fine.
Here is the song file for my test:
I know, that Matrix works... Could you get it to work with RPG8?
"or when i route the Matrix Gate through a spider. "
??

Here is rpg8 trigger working fine Loque
Attachments
VCA-rpg8-spider-trigger.zip
(59.27 KiB) Downloaded 34 times

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Loque
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18 Apr 2020

Murf wrote:
18 Apr 2020
Loque wrote:
18 Apr 2020

I know, that Matrix works... Could you get it to work with RPG8?
"or when i route the Matrix Gate through a spider. "
??

Here is rpg8 trigger working fine Loque
I really must have forgotton something to explain or we have a misunderstanding here...

i cannot trigger the ADSR with a RPG, to control the shape of the sound. The ADSR doesnt not produce anthing not triggered with 100% Matrix output. Can you create a patch, where the ADSR is triggered, outputs a Envelope to shape the sound? And trigger it with an RPG8?

I mean try this (Matrix works, connect it to RPG8 and play it - does it work?):
murfadsr.zip
(1.63 KiB) Downloaded 30 times
murfadsr.jpg
murfadsr.jpg (155.24 KiB) Viewed 2029 times
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madmacman
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18 Apr 2020

Loque wrote:
18 Apr 2020
I mean try this (Matrix works, connect it to RPG8 and play it - does it work?):
murfadsr.zip
murfadsr.jpg
This has aroused my interest. I downloaded your Combinator and played around a little bit. Here are my first observations:

1. The ADSR output is misleading at best: In fact it is the shaped curve and NOT a gate. So connecting ADSR out to Lin In or Exp In of the VCA does the job.

2. However: The RPG8 only really seems to work when S (Sustain) is full CW (= open). But I would expect the continuous gate triggers from the RPG8 would always re-trigger the ADSR as well.

3. The LEV knob on the VCA is also misleading. From my hardware modular experience, I thought it would be some kind of "initial gain", while the small knobs do the CV trimming. But without the LEV cranked up, the VCA refuses to do its job. It's more like a "general attenuator". In the hardware world the LEV knob (called "Gain" or "Bias") would open the VCA without a CV signal (which is not necessary as soon as a ADSR shape or LFO or whatever takes control).

4. I still don't get it either how the Gate In on the VCA is supposed to work. Needs further investigation.

EDIT: No, there's something really odd with the Gates. Even amplified signals from other sources are not accepted in the ADSR - except for the Matrix Gate Out :shock:

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Loque
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18 Apr 2020

madmacman wrote:
18 Apr 2020
Loque wrote:
18 Apr 2020
I mean try this (Matrix works, connect it to RPG8 and play it - does it work?):
murfadsr.zip
murfadsr.jpg
This has aroused my interest. I downloaded your Combinator and played around a little bit. Here are my first observations:

1. The ADSR output is misleading at best: In fact it is the shaped curve and NOT a gate. So connecting ADSR out to Lin In or Exp In of the VCA does the job.

2. However: The RPG8 only really seems to work when S (Sustain) is full CW (= open). But I would expect the continuous gate triggers from the RPG8 would always re-trigger the ADSR as well.

3. The LEV knob on the VCA is also misleading. From my hardware modular experience, I thought it would be some kind of "initial gain", while the small knobs do the CV trimming. But without the LEV cranked up, the VCA refuses to do its job. It's more like a "general attenuator". In the hardware world the LEV knob (called "Gain" or "Bias") would open the VCA without a CV signal (which is not necessary as soon as a ADSR shape or LFO or whatever takes control).

4. I still don't get it either how the Gate In on the VCA is supposed to work. Needs further investigation.
Thanks for having a look at it. Exactly this things are confusing me. I am not sure, how this should work. As i connected it, i would expect it to work, because this way it works on everything modular-stuff i worked on.
* Put a Gate into a ADSR
* The ADSR cpits out a CV curve
* The CV can control an VCA
* Job done

It works, if you connect the Matrix into the ADSR and let the Matrix generate the Gate-Signals instead of the RPG8. And the RPG8 is may go-to way to create a Gate-Signal from MIDI if the device itself does not accapt a MIDI signal. However, i did not tried it via CVPT...
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madmacman
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18 Apr 2020

Gate from RPG8 works as soon as you transform it into a "bipolar" CV, e.g. by using Volt CB-1 or Ponga CVA-7. But this is plain wrong. In "real world" scenarios, the gate in is usually designed as comparator with a certain threshold, and *not* between its extreme values (e.g. 0V and 5V). And certainly not with any negative values.

EDIT: Sorry, maybe my reply sounds too harsh. I appreciate any contribution to a "generic" modular synth approach! The more the better. I would just like to see some closer resemblance to the hardware world. Or at least some detailed explanation of design decisions.

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Murf
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18 Apr 2020

madmacman wrote:
18 Apr 2020
Gate from RPG8 works as soon as you transform it into a "bipolar" CV, e.g. by using Volt CB-1 or Ponga CVA-7. But this is plain wrong. In "real world" scenarios, the gate in is usually designed as comparator with a certain threshold, and *not* between its extreme values (e.g. 0V and 5V). And certainly not with any negative values.

EDIT: Sorry, maybe my reply sounds too harsh. I appreciate any contribution to a "generic" modular synth approach! The more the better. I would just like to see some closer resemblance to the hardware world. Or at least some detailed explanation of design decisions.
Well my explanation is to re-create as close a possible replica of VCV Rack modules, I have no idea why they label a gain knob as level either :cry:

Your point about bipolar CV is well taken though and I will investigate whether or not I implemented this correctly, and patch if not.

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Loque
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18 Apr 2020

madmacman wrote:
18 Apr 2020
Gate from RPG8 works as soon as you transform it into a "bipolar" CV, e.g. by using Volt CB-1 or Ponga CVA-7. But this is plain wrong. In "real world" scenarios, the gate in is usually designed as comparator with a certain threshold, and *not* between its extreme values (e.g. 0V and 5V). And certainly not with any negative values.

EDIT: Sorry, maybe my reply sounds too harsh. I appreciate any contribution to a "generic" modular synth approach! The more the better. I would just like to see some closer resemblance to the hardware world. Or at least some detailed explanation of design decisions.
That could be the problem. Maybe the "gate" was implemented a la switch from positive to negative somehow and not the direction change of the signal.
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Murf
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19 Apr 2020

Hi Loque and madmacman.

I have identified a bug in MODRACK VCA that I think is causing the behavior you are seeing:

MODRACK VCA CV IN wont recognise zero volts when connected
1) Set up a VCO triggered by a VCA
2) Use Aftermath Audio CV8x4 CV Generator and connect one to the VCA CV gate in
3) Dial up and down to see that VCA level behaves accordingly and dial back to zero
4) Disconnect CV in to VCA with CV dialed to zero and audio comes back on as expected BUT plug CV back in and audio stays on, it should go back off


I have patched MODRACK VCA with a fix, and also re-labeled the CV in "gate" as "gain" which is a better description.
Loque I have added you to the beta testers for this one, madmacman if you PM me your reason username I will add you too so can you both please see if this fixes the wrong behavior you were seeing.
Thanks very much for the help,
Murf.

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Loque
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19 Apr 2020

Murf wrote:
19 Apr 2020
Hi Loque and madmacman.

I have identified a bug in MODRACK VCA that I think is causing the behavior you are seeing:

MODRACK VCA CV IN wont recognise zero volts when connected
1) Set up a VCO triggered by a VCA
2) Use Aftermath Audio CV8x4 CV Generator and connect one to the VCA CV gate in
3) Dial up and down to see that VCA level behaves accordingly and dial back to zero
4) Disconnect CV in to VCA with CV dialed to zero and audio comes back on as expected BUT plug CV back in and audio stays on, it should go back off


I have patched MODRACK VCA with a fix, and also re-labeled the CV in "gate" as "gain" which is a better description.
Loque I have added you to the beta testers for this one, madmacman if you PM me your reason username I will add you too so can you both please see if this fixes the wrong behavior you were seeing.
Thanks very much for the help,
Murf.
Hi Murf,
Thanks for investigation and help. I didn't checked VCA, but i will have a look into the beta.
My problem was, that ADSR did not produced any curve on any gate signal except from Matrix. Not sure how this is related to VCA.
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Murf
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19 Apr 2020

Loque wrote:
19 Apr 2020
Murf wrote:
19 Apr 2020
Hi Loque and madmacman.

I have identified a bug in MODRACK VCA that I think is causing the behavior you are seeing:

MODRACK VCA CV IN wont recognise zero volts when connected
1) Set up a VCO triggered by a VCA
2) Use Aftermath Audio CV8x4 CV Generator and connect one to the VCA CV gate in
3) Dial up and down to see that VCA level behaves accordingly and dial back to zero
4) Disconnect CV in to VCA with CV dialed to zero and audio comes back on as expected BUT plug CV back in and audio stays on, it should go back off


I have patched MODRACK VCA with a fix, and also re-labeled the CV in "gate" as "gain" which is a better description.
Loque I have added you to the beta testers for this one, madmacman if you PM me your reason username I will add you too so can you both please see if this fixes the wrong behavior you were seeing.
Thanks very much for the help,
Murf.
Hi Murf,
Thanks for investigation and help. I didn't checked VCA, but i will have a look into the beta.
My problem was, that ADSR did not produced any curve on any gate signal except from Matrix. Not sure how this is related to VCA.
No worries I will take a look at ADSR now

madmacman
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19 Apr 2020

Loque wrote:
19 Apr 2020
Hi Murf,
Thanks for investigation and help. I didn't checked VCA, but i will have a look into the beta.
My problem was, that ADSR did not produced any curve on any gate signal except from Matrix. Not sure how this is related to VCA.
Yeah, sorry. I have mixed things up a bit in my replies. So below is a description for ADSR:

Besides the (temporary) fix with bipolar CV, I also found that the RPG8 must be set from "manual" (default) to the max. value 127.

Attached you'll find a modified combinator with a working solution (as a proof of concept - not a proposed everyday solution).

As soon as the Gate In of the ADSR is fixed, it should work without the CVA-7.

Oh and by the way: I never realized that RPG8 gate output is also velocity control. Compared to the hardware world, this is an unfortunate decision. But the ADSR reacts in a correct way (as far as I can see): It triggers at half the maximum value (64), which corresponds to the usual behavior in the modular world (triggers roughly at 2,5V with given +5V gates)
murfadsr_mmm.cmb.zip
(2.02 KiB) Downloaded 38 times

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Murf
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19 Apr 2020

Thanks Loque and madmacman for helping me to identify a bug in MODRACK ADSR CV in triggering.
Once it is tested I will publish it to the store.
Murf.

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