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Osc B triangle wave as modulation source

CPN37

Osc B triangle wave as modulation source
« on: March 23, 2021, 12:56:11 PM »
I noticed when playing around with Poly Mod on my Prophet 5 that the Osc B triangle waveform has almost no affect when modulating Osc A - this surprised me as on my Pro~One you can get some crazy FM sounds with the same settings.

Iím wondering if thereís a small chance I have a defective Osc B triangle waveform, so I wonder if someone here could run the same test for me?

Basically Iím just setting Osc B to triangle waveform, and Osc A to sawtooth. Then, with Osc A set as Destination in the Poly Mod, Iím just turning the Poly Mod Osc B knob- and there is barely any effect, just the slightest wavering in pitch, nothing like what happens with the same settings in the Pro~One. Whereas if you switch from triangle to sawtooth in Osc B you get the expected FM sounds.

Maybe this is just because the Prophet 5 doesnít behave the same way for whatever reason but I thought it was worth checking anyway, just in case!
Sequential Prophet 5 Rev4, Sequential Circuits Pro One, Sequential Prophet Rev2-8, ARP Pro Soloist, Roland Jupiter 4, Roland Juno 60

CPN37

Re: Osc B triangle wave as modulation source
« Reply #1 on: March 23, 2021, 03:39:27 PM »
Hmm I should say the above I was doing with both Osc A & B set to the same octave, however I notice I do start to get some FM if I set the pitch of Osc A higher than Osc B, the higher the pitch, the more the FM sound. So maybe it is all working fine, and just behaves very differently than the Pro~One!
Sequential Prophet 5 Rev4, Sequential Circuits Pro One, Sequential Prophet Rev2-8, ARP Pro Soloist, Roland Jupiter 4, Roland Juno 60

LPF83

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Re: Osc B triangle wave as modulation source
« Reply #2 on: March 23, 2021, 04:03:40 PM »
Do you mean even with LO FREQ turned on for B you don't hear much effect?   Because with it off it could just be that the rate is too fast for the oscillation to have what I'm guessing is the desired effect.  And if that's the case, then yes it would result in a more subtle FM-like timbre variation.
Prophet 10, Prophet 6, OB-6, Prophet 12m, Prophet Rev2-16, Moog SlimPhatty, Hydrasynth desktop, Korg Minilogue XDm, Roland SPD-30, Roland SPD-SX Special Edition, Roland KT-10, Maschine, Focusrite Scarlett 18i20 3rd Gen + Octopre, Strymon Pedals, Cubase Pro 11.

CPN37

Re: Osc B triangle wave as modulation source
« Reply #3 on: March 23, 2021, 04:09:46 PM »
I don't have LO FREQ turned on - although when I do sure enough it just creates a vibrato type effect. I guess I am just expecting the Prophet 5 to behave in the same or similar way to the Pro~One, where the triangle wave creates harsh FM modulating Osc A (even when both oscillators are at the same octave)- for whatever reason however the P5 doesn't seem to, doesn't really matter, I was just checking in case it was faulty :D
Sequential Prophet 5 Rev4, Sequential Circuits Pro One, Sequential Prophet Rev2-8, ARP Pro Soloist, Roland Jupiter 4, Roland Juno 60

Re: Osc B triangle wave as modulation source
« Reply #4 on: March 24, 2021, 09:28:42 AM »
From INIT (REC + PRESET)
*Osc B Tri wave on... any wave should work
*In Poly Mod Section, both knobs fully clockwise to 10
*Freq A on

you should hear it immediately?
--shane

CPN37

Re: Osc B triangle wave as modulation source
« Reply #5 on: March 24, 2021, 10:19:24 AM »
From INIT (REC + PRESET)
*Osc B Tri wave on... any wave should work
*In Poly Mod Section, both knobs fully clockwise to 10
*Freq A on

you should hear it immediately?

Thanks, yes I've just done that and I do hear it.

I guess what I was confused about is that on the Pro~One, you need only turn the OSC B knob in the Modulation section to hear some pretty wild FM (this with a triangle wave modulating OSC A FREQ)- on the Prophet 5 you basically don't hear anything at this point - and you have to (as you have pointed out) turn the FILT ENV Poly Mod knob up full too to hear it - so you only get the FM effect by combining the FILT ENV and OSC B Poly Mod sources, not just OSC B on its own, or as I found out earlier, have the OSC A Freq an octave or more higher than OSC B.

I'm guessing this is just the way the new Prophet 5s have been made/calibrated and it's not an issue. Although if someone could confirm for me that:

From INIT (REC + PRESET)
*Osc B Tri wave on
*In Poly Mod Section, OSC B fully clockwise to 10
*Freq A on & both OSC A & B tuned to same octave/frequency

- that no discernible FM can be heard?

Then I can be sure :D
Sequential Prophet 5 Rev4, Sequential Circuits Pro One, Sequential Prophet Rev2-8, ARP Pro Soloist, Roland Jupiter 4, Roland Juno 60