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Should my filters cv inputs be 5v or 10v ?
MUFF WIGGLER Forum Index -> Fractional Rack Modules  
Author Should my filters cv inputs be 5v or 10v ?
Acid Mitch
I use an Oakley COTA along with my mostly Blacet modules.
The cv inputs on the COTA are set for 5v but my Blacet envelope outputs are 10v.
This means I have to attenuate the envelope going to the COTA filter or I get hardly any range from the cv input knobs on the COTA.
If I want to do something simple like control amp and filter from a single envelope I have to use up an attenuator to reduce the level going to the filter.
In short , in normal operation I'm attenuating the envelope going to the filter 2 or 3 times.( with the envelope output level, with an attenuator and at the filter input).
To make things simpler I was going to convert the cv inputs on the COTA from 5v to 10v but the person doing the mod for me says I might end up with the opposite issue. If modulating the filter with lfo’s that only go from -5v to +5v I might not get enough range and have to boost the signal instead of attenuating it.

So I thought I should ask you guys before changing anything.
Should the CV inputs on my COTA be 5v or 10v when being used along side mostly Blacet modules ?

With things like the Blacet Filthy Filter I notice the cv input is 10v. With that being the case how do you open the cutoff past 50% when modulating it with the micro lfo ?
diophantine
What CV inputs do you have on your COTA? I don't believe I've seen a Frac one, but most others have a 1V/Oct input and then another input with a built-in attenuator.

Acid Mitch wrote:
With things like the Blacet Filthy Filter I notice the cv input is 10v. With that being the case how do you open the cutoff past 50% when modulating it with the micro lfo ?

Using the two unipolar triangle outputs on the left of the LFO; they go from 0-10V.
Acid Mitch
diophantine wrote:
What CV inputs do you have on your COTA? I don't believe I've seen a Frac one, but most others have a 1V/Oct input and then another input with a built-in attenuator.


It’s the same as the 5u COTA only smaller.It has 1v/oct and two other cv inputs with built in attenuators. The cv inputs can be set for either 5v or 10v by changing some components on the pcb.
It’s currently set at 5v. When used with my Blacet envelopes the attenuators on the COTA are close to useless as I get hardly any range from the COTA knobs unless I attenuate the signal first.
If the envelope only controls the filter I can attenuate the signal using the output level on the envelope.
However , if I want to control vca and filter from the same envelope, the envelope needs to be putting out 10v to open the vca but then I need to either atenutate the signal before it hits the COTA or I’m back to hardly any range from the COTAs built in attenuator knobs.
I usually just add another attenuator between envelope and COTA so that the COTA only receives 5v and it’s easier to dial in the amount I want using it's built in attenuators.

On every other synth I’ve played the amp and filter appear to take the same amounts to open/close them. Like if a specific envelope setting is opening the amp by 50% , then it will also open filter cutoff by 50%. Would be nice if my modular worked the same.



Acid Mitch wrote:
With things like the Blacet Filthy Filter I notice the cv input is 10v. With that being the case how do you open the cutoff past 50% when modulating it with the micro lfo ?

Using the two unipolar triangle outputs on the left of the LFO; they go from 0-10V.[/quote]

So if one wants the filter modulated by a square wave one is not expecting it to open past 50% ? That's nuts. Why would anyone want it to work like that ?
fracmonkey
On the Blacet EG1, there is an internal trimmer to set the maximum envelope. Thus, you could set this at 5V. Or use the Level Pot on the EG.

The DAD also has a Level pot along with a full 10V out.
diophantine
Acid Mitch wrote:
So if one wants the filter modulated by a square wave one is not expecting it to open past 50% ? That's nuts. Why would anyone want it to work like that ?

How often does one want to use a square wave to fully open/fully close a filter? Seems to be a pretty strange situation.

But if you did want to do that, you should be able to set the filter's initial frequency pot to 50% and then send in the +/-5V square wave as modulation.
Acid Mitch
fracmonkey wrote:
On the Blacet EG1, there is an internal trimmer to set the maximum envelope. Thus, you could set this at 5V. Or use the Level Pot on the EG.


If I set the eg1 internal trimmer to 5v then I won’t be able to open my quadmix vca and dual linear vca past 50%.

I have two eg1’s. When I have one controlling vca and the other controlling filter I can use the level pot on the one controlling the filter with out an issue.
However , if I want the same eg1 controlling vca and filter at the same time, I’m either giving the filter to much cv or the vca not enough or vica versa.
This is why I thought having the filter set to 10v would solve the issue.
Acid Mitch
diophantine wrote:

How often does one want to use a square wave to fully open/fully close a filter? Seems to be a pretty strange situation.


Fully open - not very often. Fully closed - quite often, open past 50% - quite often and going from fully closed to partially open quite often.

diophantine wrote:


But if you did want to do that, you should be able to set the filter's initial frequency pot to 50% and then send in the +/-5V square wave as modulation.


That doesn't seem a likely situation.
If I change the cota inputs to 10v and I have cut off set at 1/8th open and I use an lfo to give it 5v will I get the filter 3/4 open or will it be short ?
Acid Mitch
oops,dp.
fracmonkey
Do you have the 1V/0ct inputs on the vco and filter both connected to the keyboard/sequencer? This is so the filter sound tracks as you play different notes. Don't use it much myself but it's a good way to get consistency.

Of course, you will need a multi or splitter.

Just a thought...
Acid Mitch
Aye, I quite often have the 1v/oct inputs on vco and filter both connected to the sequencer.
The oscs always get 100% 1v/oct but I vary the amount going to the filter depending on the patch.

I found this thread
https://www.muffwiggler.com/forum/viewtopic.php?t=97553&sid=f87d2944ec 458cad9d07d3a4a92eac5c

It talks about smilar issues and has cleared up a few of the questions I was asking.
I think I might just invest in some more utility modules to deal with the mis matches instead of changing the COTA to 10v.
Thanks for answering guys.
fracmonkey
Acid Mitch wrote:

I think I might just invest in some more utility modules to deal with the mis matches instead of changing the COTA to 10v.
Thanks for answering guys.


I see multis and a SBM in your future....
Acid Mitch
fracmonkey wrote:

I see multis and a SBM in your future....


Is that a psychic cat in your avatar or are you using the crystal ball again ? hihi
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