Sq. Wave growls on Matriarch polyphony?

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Ted H
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Sq. Wave growls on Matriarch polyphony?

Post by Ted H » Tue Aug 03, 2021 6:28 pm

Help me understand what I assume is basic physics.
When playing the Matriarch in 2-Voice mode and using all square wave OSCs, I get a bit of a "growl" when playing 2 notes other than an octave. Doesn't matter if Sync Enable is on or not. I've been very careful in getting the Frequencies tuned in Unison. No modulation either.
This doesn't happen on Triangle OSCs. Why does it happen in Square & Pulse wave forms?
(I generally use all the OSCs in unison on the same wave form to better emulate real polyphonic 2 & 4-voice playing. Otherwise, I can't predict the OSC allocations.)

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stiiiiiiive
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Re: Sq. Wave growls on Matriarch polyphony?

Post by stiiiiiiive » Wed Aug 04, 2021 7:52 am

Hey!

I guess it is due to the headroom of the mixer.
I think that it occurs with octave too but it must be less noticeable. Try to play two different notes on a guitar with an overdrive/distorsion pedal and it will be the same: growling with some intervals, apparently smoothing down with others.
And I think it happens more with square waveforms because the carry globally more energy than triangle ones.

Anyone, prove me wrong :)

Markyboard
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Re: Sq. Wave growls on Matriarch polyphony?

Post by Markyboard » Wed Aug 04, 2021 1:17 pm

stiiiiiiive wrote: Wed Aug 04, 2021 7:52 am Hey!

I guess it is due to the headroom of the mixer.
I think that it occurs with octave too but it must be less noticeable. Try to play two different notes on a guitar with an overdrive/distorsion pedal and it will be the same: growling with some intervals, apparently smoothing down with others.
And I think it happens more with square waveforms because the carry globally more energy than triangle ones.

Anyone, prove me wrong :)

I'll do one better ... and prove you right. :lol:

I bypassed the mixer by patching each of 2 osc waveform (squ) outputs, first directly into each VCA and then into each filter (LP/LP). In either case no overdrive/distortion effect. I then routed each of the 4 oscillator outputs to an external euro mixer module (Blinds) and mixed equal signal level from each oscillator to achieve 10V P-P at the mixer output. Routed that back to the Matriarch VCA and then VCF. Again no distortion.

Finally I started cranking up each channel. Blinds will eventually distort in a nasty sort of way, unlike the Matriarch mixer. But before it did the Matriarch VCF and VCA took all I threw at it. With just 2 oscillators I could get 16VP-P signal into the Matriarch VCF and/or VCA with no "Growl".

Q.E.D.
Last edited by Markyboard on Wed Aug 04, 2021 5:15 pm, edited 1 time in total.

Ted H
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Re: Sq. Wave growls on Matriarch polyphony?

Post by Ted H » Wed Aug 04, 2021 2:37 pm

Thanks for the analysis. I semi-verified this also by reducing all 4 OSCs in the mixer to 9:00 positions, then cranking up the VCA-main a bit to compensate. This resulted in less "growl"/distortion with 2-voice harmony.

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stiiiiiiive
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Re: Sq. Wave growls on Matriarch polyphony?

Post by stiiiiiiive » Thu Aug 05, 2021 6:05 am

Markyboard wrote: Wed Aug 04, 2021 1:17 pm I'll do one better ... and prove you right. :lol:
Thanks, it was my first "proved right" time :D
Glad it helped Ted H!

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