Module that gives absolute CV value?

Ahornberg · February 25, 2023, 4:50pm

Does anyone know a module that gives the absolute |a| value?

marc_boule · February 25, 2023, 5:08pm

Perhaps this can do the trick:

VCVRack/AudibleInstruments/blob/v2/src/Kinks.cpp#L75


      
          		lights[SIGN_NEG_LIGHT].setSmoothBrightness(fmaxf(0.0, -inputs[SIGN_INPUT].getVoltage() / 5.0), args.sampleTime);
          		float logicSum = inputs[LOGIC_A_INPUT].getVoltage() + inputs[LOGIC_B_INPUT].getVoltage();
          		lights[LOGIC_POS_LIGHT].setSmoothBrightness(fmaxf(0.0, logicSum / 5.0), args.sampleTime);
          		lights[LOGIC_NEG_LIGHT].setSmoothBrightness(fmaxf(0.0, -logicSum / 5.0), args.sampleTime);
          		lights[SH_POS_LIGHT].setBrightness(fmaxf(0.0, sample / 5.0));
          		lights[SH_NEG_LIGHT].setBrightness(fmaxf(0.0, -sample / 5.0));
          
          		// outputs
          		outputs[INVERT_OUTPUT].setVoltage(-inputs[SIGN_INPUT].getVoltage());
          		outputs[HALF_RECTIFY_OUTPUT].setVoltage(fmaxf(0.0, inputs[SIGN_INPUT].getVoltage()));
          		outputs[FULL_RECTIFY_OUTPUT].setVoltage(fabsf(inputs[SIGN_INPUT].getVoltage()));
          		outputs[MAX_OUTPUT].setVoltage(fmaxf(inputs[LOGIC_A_INPUT].getVoltage(), inputs[LOGIC_B_INPUT].getVoltage()));
          		outputs[MIN_OUTPUT].setVoltage(fminf(inputs[LOGIC_A_INPUT].getVoltage(), inputs[LOGIC_B_INPUT].getVoltage()));
          		outputs[NOISE_OUTPUT].setVoltage(noise);
          		outputs[SH_OUTPUT].setVoltage(sample);
          	}
          };
          
          
          struct KinksWidget : ModuleWidget {
          	KinksWidget(Kinks* module) {

DaveVenom · February 25, 2023, 6:31pm

Yep - absolute value is the same as full rectification.

Three other candidates besides Audible Instruments Utilities are my Venom WINCOMP (signal input into A, all OFFSETs at 0, invert the OVER output in context menu, and take the OVER output)

Count Modula Rectifier (default settings, signal into IN, take the FULL output)

and Bogaudio AM / RM (signal into MOD, RECTIFY 100%, WET 100%, RECT output)

I imagine there are other possibilities.

Of the four listed, I prefer the WINCOMP for the combination of compactness, CPU efficiency, and polyphony

Module                        | width| mono/poly  | CPU with 4 channels at 192KHz
---------------------------------------------------------------------------------
Audible Instruments Utilities | 4 hp | monophonic |  2.5% mono only
Venom WINCOMP                 | 5 hp | polyphonic |  1.5%
Bogaudio AM / RM              | 6 hp | polyphonic |  1.7%
Count Modula Rectifier        | 8 hp | polyphonic |  2.0%

Ahornberg · February 25, 2023, 7:00pm

@DaveVenom Thanks a lot for your research!

Squinky · February 25, 2023, 7:11pm

I assume you want to use this for CV? I suspect most of these will sound pretty bad if you run audio through them…

DaveVenom · February 25, 2023, 7:34pm

Good point - the WINCOMP certainly does not mitigate aliasing, and the other three give identical spectra on the Bogaudio Analyzer, so I am pretty sure they do not either.

So all four are susceptible to significant audio aliasing, which may or may not be bad, depending on your taste and goals.

If I get moderately ambitious I may add the option for oversampling to some of my modules that typically are used for CV, but could also be used for audio:

WINCOMP
Bernoulli Switch (for when switching at audio rates)
Rhythm Explorer (this one is a bit of a stretch, but it can be used as a VCO)

Squinky · February 25, 2023, 7:38pm

My old “Shaper” module always had oversampling. But it was really meant for Audio. Although if you turn off the oversampling and turn off the DC block it’s supposed to work for CV.

Squinky · February 25, 2023, 7:40pm

fwiw I have a very simple demo of oversampling distortion that you could borrow of course. It uses the filters in VCV, rather than my crazy filter library: Demo/oversample-readme.md at main · squinkylabs/Demo · GitHub

DaveVenom · February 25, 2023, 7:48pm

I may just do that. Thanks