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P12 FM voice differences - is this normal??

timboréale

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P12 FM voice differences - is this normal??
« on: January 16, 2021, 12:46:30 PM »
So, I've got a strange-to-me issue going on with this P12 I just received - there are inter-voice differences that don't make sense to me. Here is a good example though it's only one of many. I've attached a wav of two sets of 12 sequential notes. The first set is made by the basic program (press left latch + hold simultaneously). The second set have the following changes ONLY:

1. OSC 1 FM to 255, Linear
2. OSC 1 and 2 wave reset ON

The notes are sent by MIDI to ensure consistent velocity (no other modulation is present, I monitored the stream). No footpedals control filter or other parameters that are mapped by the basic preset. I am running the latest OS 1.4.2.3, have reset globals (I remapped the footswitches afterwards to be sure the filter mapping wasn't back), and have run autotune filters.

You can clearly hear strong differences between the voices in the FM example, but theoretically, since wave reset is ON for 1 and 2, the output of each voice should be damn near identical.

Am I missing something obvious here?
Rev2-16, Prophet 12 Keyboard, Nords, etc...

LPF83

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Re: P12 FM voice differences - is this normal??
« Reply #1 on: January 16, 2021, 06:25:09 PM »
So, I've got a strange-to-me issue going on with this P12 I just received - there are inter-voice differences that don't make sense to me. Here is a good example though it's only one of many. I've attached a wav of two sets of 12 sequential notes. The first set is made by the basic program (press left latch + hold simultaneously). The second set have the following changes ONLY:

1. OSC 1 FM to 255, Linear
2. OSC 1 and 2 wave reset ON

The notes are sent by MIDI to ensure consistent velocity (no other modulation is present, I monitored the stream). No footpedals control filter or other parameters that are mapped by the basic preset. I am running the latest OS 1.4.2.3, have reset globals (I remapped the footswitches afterwards to be sure the filter mapping wasn't back), and have run autotune filters.

You can clearly hear strong differences between the voices in the FM example, but theoretically, since wave reset is ON for 1 and 2, the output of each voice should be damn near identical.

Am I missing something obvious here?

I don't get the same results as you..  have you tried removing the footswitch entirely?  One thing to remember, I don't think the voices will sound identical the moment you set FM on one OSC, you'll have some noticeable timbre variation.  You can hold the OSC1 button to edit all OSC at once, and once they are all doing the same thing results get a lot more predictable.

But something sounds amiss in your second run through the 12 voices..  I have the module so I don't have sliders, latch, and other controls of the keyboard, is it possible one of those is wiggling modulation?  Try going through the modulation matrix and eliminating one by one.  One of my MIDI controllers has a moody pitch wheel...  if not used often enough, it starts throwing tantrums and sending random data to whatever its controlling until I wiggle it, get a little rough with it and show it some love, then it starts behaving (sounds familiar eh? ) :)   Could be something on the keyboard unit acting up maybe?
« Last Edit: January 16, 2021, 06:26:41 PM by LPF83 »
Prophet 10, Prophet 6, OB-6, Prophet 12m, Prophet Rev2-16, Toraiz AS-1, 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.

timboréale

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Re: P12 FM voice differences - is this normal??
« Reply #2 on: January 16, 2021, 07:03:04 PM »
I've tried it with all mod slots off, LFOs set to off, no footswitches or pedals  plugged in. It still sounds like that. If you listen carefully it even sounds like some voices have no fm at all - they sound almost identical to the init patch.

Rev2-16, Prophet 12 Keyboard, Nords, etc...

Re: P12 FM voice differences - is this normal??
« Reply #3 on: January 16, 2021, 11:19:46 PM »

Hi,

if 2 saw are modulating them at max things get wild. On paper i would say this should sound identical but i tested and there is wildness going on. Had the modwheel not completely down and it went really wild but thats not whats moving your voices i think. When using sine or other less edgy ones its better to control. For me linear FM is "dentist-synthesis" full of static unpleasant waves until you move things. Lets say you found and edge at 255 take it back to lower and let an envelope do the moving of OSC1FM, did this moments ago, linear can be nice.

I hope you can start to enjoy it, happy Prophet Sunday.

timboréale

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Re: P12 FM voice differences - is this normal??
« Reply #4 on: January 17, 2021, 06:16:17 AM »
Hi Martin, thanks for chiming in. This was just a very basic, very extreme example patch to clearly show off the problem. I'm used to FM synthesis (I program Nord Lead 3 and Digitone, both capable FM machines). On the Prophet 12 it's there if I modulate the fm with an envelope too - I just cannot get consistent FM notes -every other or third voice or whatever almost sounds like its just not FMing at all. This also happens with AM and I've read about a couple people having bad osc boards that resulted in some modulation problems. If this is just how P12 FM is I'm taking the board back asap. This isn't usable FM in any sense of the word.
Rev2-16, Prophet 12 Keyboard, Nords, etc...

timboréale

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Re: P12 FM voice differences - is this normal??
« Reply #5 on: January 20, 2021, 06:41:40 AM »
I've been playing a bit more with it and there are also some crackles that appear randomly. It's not distortion, because they occur at low volumes as well as at high. They occur in patches with as few as a single oscillator set to a lower level < 64, so they're not internal clipping, and they occur more frequently with the delays active than not, but that's not a correlating factor either as they also occur without the delays. I need to do some more diagnosis before pinpointing the source of the issue, but it's definitely concerning me.

I'm also finding that patch design is suuuuuper picky, there are far narrower sweet spots on this instrument (at least so far) than on any of my other synths, but the workflow is fantastic. End of day, though, I'm still on the fence as to whether this is a dud unit or I just don't like the P12, made worse by the fact that I have no idea if this unit is actually acting correctly (due to all the other things that are wrong with it, the voice behaviour is also suspect to me).
Rev2-16, Prophet 12 Keyboard, Nords, etc...

Re: P12 FM voice differences - is this normal??
« Reply #6 on: January 20, 2021, 09:06:32 AM »

hi,

yours sounds a lot freakier then mine in this fm test. Did not say its all good on yours, i got at this saw 255 test some variance with wave reset 1/2 in all settings so not exactly "samples" like i thought might get. In your test file some notes are completely out of line. I tried again what i get and above an amont of 150 variances start to happen in the beginning of the sound. Im now more concerned with understanding what happens during the Release phase :) had to dial it down to zero because it was kind of distracting.

Hope this helps,

Martin

timboréale

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Re: P12 FM voice differences - is this normal??
« Reply #7 on: January 20, 2021, 09:16:14 AM »
Thanks Martin, that helps.

Sounds like something's wrong with my audio board. I'm waiting to hear back on my support ticket with Sequential, it's been in the queue since the weekend and no response on it yet. I'd be fine with some subtle differences (I'd want to know what's causing them, of course - digital oscs should be able to be repeatable, after all!), but this is too much for me. I'm strongly leaning towards returning this synth, it's already been far too many problems and too much hassle for a new unit. Sadly, that will probably end my P12 affair as I won't be encouraged to go for a used one after seeing how badly this one has aged in a music store.

That said, I'm still open to having my mind changed as I can only dream of having a solidly working P12, but the return window is closing rapidly and it would require some serious commitment from support to get it sorted without much more effort on my part. There are other synths in the sea, to ruin the metaphor...
Rev2-16, Prophet 12 Keyboard, Nords, etc...

Re: P12 FM voice differences - is this normal??
« Reply #8 on: January 20, 2021, 09:33:20 AM »

hi,

i recorded what i get here it freaks above 220.

Hope this helps,

Martin

Re: P12 FM voice differences - is this normal??
« Reply #9 on: January 20, 2021, 09:38:13 AM »

hi,

here is from 255 in the beginning going down quick to not exceed filesize.

Hope this helps,

Martin

timboréale

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Re: P12 FM voice differences - is this normal??
« Reply #10 on: January 20, 2021, 10:38:29 AM »
Ok, super helpful yeah. So all your voices sound roughly even, and you just get the usual FM squelch as you go through the amount. For me, it sounds as if the amount itself is varying wildly voice to voice and/or note to note, which (in the init patch) it's got no modulation routed at all.

I have had some other unusual issues on this board too in addition to the noise I also mentioned - sometimes modulations will affect two voices in series - for instance there was a moment when I could turn the modwheel up and then down without playing a note, and the next two voices played would act as if the modwheel was still up. Sometimes I get a voice glitching on a modulation that other voices don't glitch on (but it's rarely the same voice). As a DSP engineer myself, this seems like there's some inter-chip communications that are getting corrupted somehow - perhaps the SPI between the main PIC controller and the SHARCs, or between the SHARCs themselves. It's hard to say.
Rev2-16, Prophet 12 Keyboard, Nords, etc...

timboréale

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Re: P12 FM voice differences - is this normal??
« Reply #11 on: January 20, 2021, 12:18:26 PM »
Here's another example of the glitching, subtle this time, but audible. It sounds like static or clipping, but the levels are much lower than clipping (this was recording 1:1 from the input, everything low, factory patch F1P10 Slider1PipeStops, modwheel down, both sliders max latched).
Rev2-16, Prophet 12 Keyboard, Nords, etc...

timboréale

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Re: P12 FM voice differences - is this normal??
« Reply #12 on: January 20, 2021, 06:03:11 PM »
Ah hah, ok, so it's a bad voice card. *whew* I'm not crazy! Thanks for checking @lpf83 and @martin3, that was a big help. I've since figured out what's making that buzzing noise on some patches too - the delay lines have glitched memory also!

So, back to Sequential it will go, looks like.
Rev2-16, Prophet 12 Keyboard, Nords, etc...

LPF83

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Re: P12 FM voice differences - is this normal??
« Reply #13 on: January 20, 2021, 06:10:37 PM »
Glad you got it worked out!
Prophet 10, Prophet 6, OB-6, Prophet 12m, Prophet Rev2-16, Toraiz AS-1, 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.