How to track Filter or Filter Pro to note AND sweep using ADSR?

Post Reply
signality
Posts: 38
Joined: Tue Jul 12, 2016 5:12 pm

How to track Filter or Filter Pro to note AND sweep using ADSR?

Post by signality »

In my post:

https://warmplace.ru/forum/viewtopic.ph ... f41#p20783

I asked - and was given an answer that allowed me to work out a way - how to track the centre or cutoff frequency of a filter to the note frequency.

The basic idea uses the Pitch2ctl module.

In the attached:
tracking_filters_02.sunvox
Demo of different ways to track filters to note frequency and sweep centre/cutoff frequency using envelope at the same time.
(5.83 KiB) Downloaded 98 times
the lower synth uses an Analog Generator internally bandpass filtered whose filter centre frequency is tracked to the note frequency using the Option 75 is also swept by the Frequency Envelope.

I have not however, worked out how to offset the filter frequency from the note frequency using this approach.

This also does not allow me to create an adjustable width bandpass filter with separate upper and lower cutoff frequencies and resonances.

The middle synth uses an Analog Generator internally bandpass filtered whose filter centre frequency is tracked to the note frequency by the Pitch2ctl module and is also swept by the Frequency Envelope.

This is OK but does not allow me to create an adjustable width bandpass filter with separate upper and lower cutoff frequencies and resonances.

The upper synth uses a Generator externally filtered by an adjustable bandpass filter formed from a highpass Filter Pro in series with a lowpass Filter Pro whose filter centre frequencies are set using the Frequency Scale parameters plus being tracked to the note frequency by the Pitch2ctl module.

This allows me to create an adjustable width bandpass filter with separate upper and lower cutoff frequencies and resonances but does not allow me to sweep the cutoff frequencies using an ADSR at the same time.

[*] My question is how, in the upper synth, to also sweep the filter cutoff frequencies using the output of the ADSR module?

I can either track the filter frequencies to the note frequency as demonstrated in the upper example or I can sweep them under control of the ADSR module using the output of the Sound2ctrl module but I cannot see how to add the output of the Pitch2ctl to the output of the Sound2ctl module to do both at the same time.

I have tried using the Amplifier module but that does not seem to allow for the summing of two inputs.

Similarly, although MultiCtl allows outputs to be sent to more than one controller, it only seems to accept one input so cannot be set up to sum two control sources.

Thanks.
User avatar
Logickin λ
Posts: 165
Joined: Sat Sep 08, 2018 8:31 pm
Contact:

Re: How to track Filter or Filter Pro to note AND sweep using ADSR?

Post by Logickin λ »

signality wrote: Sun Jan 16, 2022 1:37 am My question is how, in the upper synth, to also sweep the filter cutoff frequencies using the output of the ADSR module?
I have tried using the Amplifier module but that does not seem to allow for the summing of two inputs.
The trick is:
You can indeed sum 2 signals at once, but before doing that, you need to generate a DC offset for base note and the envelope signal.
To generate a DC offset, simply set a constant 128 DC offset in an amplifier, then feeding to another amplifier for controlling the DC level by changing the fine volume, while the fine volume is controlled by pitch2Ctl.

Here are some examples for key tracking envelope:
SawZer's key tracking envelope: https://warmplace.ru/forum/viewtopic.php?p=21016#p21016
My Key tracking filter: https://warmplace.ru/forum/viewtopic.php?f=11&t=5721
signality
Posts: 38
Joined: Tue Jul 12, 2016 5:12 pm

Re: How to track Filter or Filter Pro to note AND sweep using ADSR?

Post by signality »

Thanks for those examples.

I think I've got the hang of it now. I just needed to substitute the concept of addition with multiplication.

My problem was that I have an analogue synth mindset where VCOs, VCAs and VCFs have exponential converters on their inputs. That means that everything to do with controls happens in the log domain so adding and subtracting produces pitch and amplitude scaling whereas in Sunvox most of it happens in the linear domain, In the linear domain pitch and amplitude scaling happens using multiplication so the concept of adding control signals together in the way I was attempting does not work.

Some of the modules have an exponential control option but I haven't got my head round how to use that in the way I would like without some form of linear summing amplifier. I might be able to do a summing function using two amplifiers in series and adjusting the DC offset of each but that falls apart when pitch information from notes is added because that is already exponentially scaled and, short of using a MultiCtl curve to create one, there's no built-in log converter.

Even with a log converter - because the Generator and the Analog Generator do not offer oscillator frequency either as a controller parameter or with an exponential control option - it'd end up being messy because then I'd need to use another MultiCtl curve to create an exponential converter.
Post Reply