## Modulation muddles

Scope and XITE Development

Original topic on PlanetZ: https://forums.scopeusers.com/viewtopic.php?t=24953

#### Modulation muddles

Posted: Fri Apr 11, 2008 1:24 pm
by Refrochia
I have a problem that I cant figure out based on my limited knowledge of the various modules and atoms and was wondering if someone could point me in the right direction?
I have a signal were the pitch is modulated by an LFO. I want both the LFO and the inverse of the LFO to be able to modulate the pitch - LFO modulation increases as bipolar pot increases the positive and the inverse LFO increases as the bipolar pot increases the negative. When the pot is 0 there is no modulation (hope that makes sense).
What module / combination of modules can do this? I have the LFO signal, the Inverse LFO signal, a bipolar pot and the mod input of a pitch modulator. What sits in the middle?

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Posted: Fri Apr 11, 2008 11:43 pm
by Warp69
What do you mean by inverse LFO? Are you using the inverse module after the LFO - if thats the case - then you dont need that module at all.
You just need your LFO module and the "Mix 1" module - if you choose the [-2147483647 ; 2147483647] range for the Gain tap on the "Mix 1" you'll get what you want. If you use negative values for the gain parameter on the mix modules you'll get the inverse signal.
Cheers

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Posted: Sun Apr 13, 2008 6:20 am
by Refrochia
Thanks for the reply Warp.
You were correct in your assumptions however, what you suggested wouldnt work for on OSC.
Basically, I want to be able to modulate pitch with a choice of 6 mod source:
Saw down, square, triangle, S&H, Noise and an Env (the bipolar mentioned in my initial post is for +/- mod depth).
In need the mod source to retrigger how can I get it to do this if the mod source is an OSC?

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Posted: Sun Apr 13, 2008 7:57 am
by Warp69

> Refrochia wrote:Thanks for the reply Warp.
> You were correct in your assumptions however, what you suggested wouldnt work for on OSC.

Yes it would!

> Refrochia wrote:Basically, I want to be able to modulate pitch with a choice of 6 mod source:
> Saw down, square, triangle, S&H, Noise and an Env (the bipolar mentioned in my initial post is for +/- mod depth).
> In need the mod source to retrigger how can I get it to do this if the mod source is an OSC?

I have absolutely no idea what you mean!!!!!! Im unable to help, if I dont get additional information, like which modules you're talking about, the meaning of retigger, modulate the pitch of what etc. Pictures might help.
Cheers

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Posted: Sun Apr 13, 2008 11:34 am
by Shroomz~>
Hi,
you should convert bipolar modulation signals to unipolar signals for sending to the mod input of a Pitch Modulator. To build a bipolar to unipolar convertor, connect a sync multiplier in series with a sync adder/subtractor. Connect a range text circuit control to the second input of each module & set the val of both range text modules to 1073741824.
cheers,
Shroomz

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Posted: Sun Apr 13, 2008 11:47 am
by Warp69

> <~Shroomz~> wrote:Hi,
> you should convert bipolar modulation signals to unipolar signals for sending to the mod input of a Pitch Modulator. To build a bipolar to unipolar convertor, connect a sync multiplier in series with a sync adder/subtractor. Connect a range text circuit control to the second input of each module & set the val of both range text modules to 1073741824.
> cheers,
> Shroomz

Its way faster to use the Mix modules as mentioned above. You just need a single Mix2 module, like :
In 1 : Input
C1 : 1073741824
In 2 : 1073741824
C2 : 2147483647
The Mix modules acts like a multiply + adder/subtractor of X inputs in a single module (and with a minimum of DSP cycles)
Cheers

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Posted: Sun Apr 13, 2008 11:55 am
by Shroomz~>
Ah, cool !!

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Posted: Thu Apr 17, 2008 3:56 pm
by Refrochia
Cheers for the replies guys! Much Appreciated.
I actually manged to figure something out shortly after posting that involved a few If modules and a rectifier (going into mix module gains). Havent checked your suggestion Shroomz, about the sync combo but will at some point. I read in some other thread that If modules were a bit hungry? Is that so? Seems a basic function to me. My SDK doesnt show the DSP cycles within the attributes for that module......
Still quite far from this project being finished so no doubt many questions will follow. I think Im just gonna do what it take to get it finished then try to optimize later.
Warp-sorry the retrigger i was on about was for like an lfo starting each time note on

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Posted: Fri Apr 18, 2008 3:19 pm
by Shroomz~>
Hi there
To answer your question, IF modules are a necessary part of the toolkit & wouldn't be there if they weren't.