Sub 37 unstable Feedback

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DStocker
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Sub 37 unstable Feedback

Post by DStocker » Mon Jan 23, 2017 12:47 pm

Hello there,
Something on my Moog Sub 37 has grabbed my attention lately. When I go into the square and pulse wave range of any of the 2 oscillators and the feedback knob is turned completely up, the tone begins to change octaves randomly. My question is, if that is a normal behavior.

Thanks in advance.

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bichuelo
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Re: Sub 37 unstable Feedback

Post by bichuelo » Mon Jan 23, 2017 10:37 pm

I do think so. I don't have my unit at my side but hopefully I am able to do the same test tomorrow morning and confirm
http://audiotecna.info
T-III, Voyager, VX-351, Slim Phatty, Model D, Sub Phatty, Subsequent 37, Minitaur, all moogerfoogers and minifoogers, EW+, Theremini, Model 15, Filtatron, Animoog, Model D App, iOS 11 Mother-32, DFAM, Werkstatt, Win7, High Sierra

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DStocker
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Re: Sub 37 unstable Feedback

Post by DStocker » Tue Jan 24, 2017 11:05 am

Thank you!

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bichuelo
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Re: Sub 37 unstable Feedback

Post by bichuelo » Tue Jan 24, 2017 11:24 am

Indeed, when you get to the square and pulse the feedback goes nuts.

I couldn't tell if its the pitch that is jumping but the sound does go wild. The same behavior to a lesser extent is shown on the sawtooth and triangle. I found that if you turn the Sub 1 osc up it goes away, almost completely
http://audiotecna.info
T-III, Voyager, VX-351, Slim Phatty, Model D, Sub Phatty, Subsequent 37, Minitaur, all moogerfoogers and minifoogers, EW+, Theremini, Model 15, Filtatron, Animoog, Model D App, iOS 11 Mother-32, DFAM, Werkstatt, Win7, High Sierra

ObtuseMoose
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Re: Sub 37 unstable Feedback

Post by ObtuseMoose » Wed Jan 25, 2017 9:54 am

Yeah, mine does it, too, and I LOVE it! I get some great effects by setting the feedback control just slightly before the wildness starts and then modulating the wave shape with an lfo, velocity, or pressure.

I definitely see it as a feature, not a defect.

--
Moose

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DStocker
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Re: Sub 37 unstable Feedback

Post by DStocker » Thu Jan 26, 2017 12:06 pm

Ok, thank you all! This community is awesome!

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_DemonDan_
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Re: Sub 37 unstable Feedback

Post by _DemonDan_ » Thu Jan 26, 2017 4:04 pm

Hi DStocker,

I think one way of looking at it is that the very point of feeding the output of a system back into itself is precisely to create these types of instability. And that the exact nature of these instabilities can vary per unit.

Why? Because the nature of system feedback strongly accentuates any aspects that have even the slightest amount of gain above unity. As the feedback amount increases, these qualities overpower other sonic aspects that have a gain that's less than unity.

So each unit, while being very similar to other units, may exhibit different feedback behaviors based on slight differences in their component values, as well as their trimpot settings.

Embrace the chaos!
_ :twisted: _DemonDan_ :twisted: _

Stevie Ray
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Re: Sub 37 unstable Feedback

Post by Stevie Ray » Fri Jan 27, 2017 4:26 pm

Yes it is normal behaviour, and even desirable to some (including me).

Feedback by its very nature is inherently unstable and unpredictable and that's what makes it a fun and creative opportunity.

Check out Robert Fripp and Brian Eno's collaborations.

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DStocker
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Re: Sub 37 unstable Feedback

Post by DStocker » Mon Sep 10, 2018 12:25 pm

Thanks again for your responses and explanations!

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