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LFO random wave keytrigger bug

LFO random wave keytrigger bug
« on: July 29, 2018, 01:40:52 PM »
The LFO keytrigger restart das not work properly with the random wave selected. As we know, the LFO of the OB6 is keytrigger by default. But there is always some weird delay, just like only the 2nd wave of random has different offset from the initial key press. It works a little better when the LFO is synced to MIDI clock, but not very accurate as well.

Getting this fixed would make the OB6 much more capable of doing percussive FX and „living“ sequences.

Anyone else experienced this issue?
« Last Edit: July 29, 2018, 01:58:44 PM by eisblau »
OB6 desktop x2, DSI Rev2 16, Toraiz AS-1, Prophet 12, Pro 2, Vermona 14, Roland System 8, Matrixbrute, Jomox Sunsyn MKII

Re: LFO random wave keytrigger bug
« Reply #1 on: July 29, 2018, 03:44:44 PM »
PS.: On my Rev2, the random LFO keytrigger behaves correct.
OB6 desktop x2, DSI Rev2 16, Toraiz AS-1, Prophet 12, Pro 2, Vermona 14, Roland System 8, Matrixbrute, Jomox Sunsyn MKII

Re: LFO random wave keytrigger bug
« Reply #2 on: July 30, 2018, 06:25:16 PM »
As we know, the LFO of the OB6 is keytrigger by default.

Uh ? Not really. You have to press the LFO Sync knob for it to sync to keys. And even then it's rather synced to the Clock and Keys (effectively restarting the LFO cycle on separate, non overlapping key strokes), and can be set to any subdivision of that Clock frequency by turning the LFO frequency knob.

What I suspect is happening, is that you press keys faster then the clock, for a given time subdivision, hence you hear sort of a delay because the LFO random waveform falls in between two values each time you press down.

Either that, or your clock is too fast and the waveform changes rapidly right after you've pressed a key, giving you the impression that it didn't start on a step.

You can verify that with the sine waveform, choosing values that will give you the same result each and every time you press a key, and then select the Random waveform whilst playing keys at the same rate.
Minimoog D (vintage), OB6 (Desktop), Oberheim Matrix-6 (MIDI Controller), Prophet REV2-16, DeepMind 12

Re: LFO random wave keytrigger bug
« Reply #3 on: July 30, 2018, 10:02:16 PM »
Hi Alain,

manual says „keytrigger by default“. So I misunderstood it is default before sync gets into count (you can read it both ways). For the described problem it does not matter so much if keytrigger is activated on sync on or not on sync on. What counts, is, that there is a keytrigger mode option. Keytrigger with sync on just makes this little difference you can only change the LFO speed divided or multipled relatively to the master tempo.

Anyway, still there is the exceptional issue with the random LFO wave. All other LFO waveforms (sine, saw, rev saw, square) are starting their cycle flawlessly on keypress, regardless what tempo/note length the sync of the LFO is set to.

But when the wave is set to random, a „keytrigger“ is only in effect if the LFO tempo exactly matches (or divides) the tempo of the master arp or sequencer. Which makes it a bit hard to play well by hand because the keytriggers have to be „on time“ with the clock (you correctly meantioned this in your post, that‘s why I got zu„weird“ delays). This also means you simply can‘t play a keysynced random-LFO free on the keyboard like it‘s working so well with the other LFO waveforms.

I hope I cleared the issue a bit more.
« Last Edit: July 30, 2018, 11:00:49 PM by eisblau »
OB6 desktop x2, DSI Rev2 16, Toraiz AS-1, Prophet 12, Pro 2, Vermona 14, Roland System 8, Matrixbrute, Jomox Sunsyn MKII

Re: LFO random wave keytrigger bug
« Reply #4 on: July 31, 2018, 10:20:33 AM »
Hi Alain,

manual says „keytrigger by default“. So I misunderstood it is default before sync gets into count (you can read it both ways). For the described problem it does not matter so much if keytrigger is activated on sync on or not on sync on. What counts, is, that there is a keytrigger mode option. Keytrigger with sync on just makes this little difference you can only change the LFO speed divided or multipled relatively to the master tempo.

Anyway, still there is the exceptional issue with the random LFO wave. All other LFO waveforms (sine, saw, rev saw, square) are starting their cycle flawlessly on keypress, regardless what tempo/note length the sync of the LFO is set to.

But when the wave is set to random, a „keytrigger“ is only in effect if the LFO tempo exactly matches (or divides) the tempo of the master arp or sequencer. Which makes it a bit hard to play well by hand because the keytriggers have to be „on time“ with the clock (you correctly meantioned this in your post, that‘s why I got zu„weird“ delays). This also means you simply can‘t play a keysynced random-LFO free on the keyboard like it‘s working so well with the other LFO waveforms.

I hope I cleared the issue a bit more.

Hello eisblau.

On page 35 of the manual, it states that the LFO is reset by default when you press a key IN THE LFO Sync SECTION only. If the LFO Sync is NOT set to ON, the LFO is free running, as stated on that same page at the top of the page.
You can easily hear this for yourself in choosing the Sine waveform for the LFO, with a fairly slow speed, and modulate the pitch. Each time you'll press a key, the pitch of the oscillator will be different each time, depending on where the LFO is in its free running waveform.
Whereas if you set LFO Sync to ON, it will always start at the same pitch each time you press a key.

Minimoog D (vintage), OB6 (Desktop), Oberheim Matrix-6 (MIDI Controller), Prophet REV2-16, DeepMind 12

Re: LFO random wave keytrigger bug
« Reply #5 on: July 31, 2018, 02:10:09 PM »

Hello eisblau.

On page 35 of the manual, it states that the LFO is reset by default when you press a key IN THE LFO Sync SECTION only. If the LFO Sync is NOT set to ON, the LFO is free running, as stated on that same page at the top of the page.
You can easily hear this for yourself in choosing the Sine waveform for the LFO, with a fairly slow speed, and modulate the pitch. Each time you'll press a key, the pitch of the oscillator will be different each time, depending on where the LFO is in its free running waveform.
Whereas if you set LFO Sync to ON, it will always start at the same pitch each time you press a key.

Yes, I know the manual very well and keytrigger is only active when the LFO is set to sync. I just wanted to mention above you can read „keytrigger by default“ on page 35 any way you want, the manual on does not state this clear if „default“ means before - or after - keysync (though it is mentioned under sync). This was just a little misinterpretation of mine, but changes nothing on the bug.

So keytrigger is indeed only available with LFO sync on, and we are not having issues with the LFO running free by itself.

The error is, keytrigger is working perfectly on all other LFO waveforms (when set to sync on, as we both know) out of the random LFO. That‘s why I started this thread and reported the issue.

Just try it out - key retrigger with LFO set to sine or saw is working great. Random not.

Greetings Paul
« Last Edit: July 31, 2018, 02:44:55 PM by eisblau »
OB6 desktop x2, DSI Rev2 16, Toraiz AS-1, Prophet 12, Pro 2, Vermona 14, Roland System 8, Matrixbrute, Jomox Sunsyn MKII

Re: LFO random wave keytrigger bug
« Reply #6 on: July 31, 2018, 03:27:13 PM »
It does the same thing as with other waveforms: it restarts the LFO on the same step. Unless the LFO had time to change steps before re-triggering on next key press.
Minimoog D (vintage), OB6 (Desktop), Oberheim Matrix-6 (MIDI Controller), Prophet REV2-16, DeepMind 12

Re: LFO random wave keytrigger bug
« Reply #7 on: August 02, 2018, 10:56:56 AM »
It does the same thing as with other waveforms: it restarts the LFO on the same step. Unless the LFO had time to change steps before re-triggering on next key press.

Nope. It restarts with every keypress (hence the name keysync and not stepsync), only the random LFO does not. Try it out.

PS.: You are right about step sync, there the random LFO is doing it's job as it should. But I am talking of keysync.
« Last Edit: August 02, 2018, 11:29:56 AM by eisblau »
OB6 desktop x2, DSI Rev2 16, Toraiz AS-1, Prophet 12, Pro 2, Vermona 14, Roland System 8, Matrixbrute, Jomox Sunsyn MKII

Re: LFO random wave keytrigger bug
« Reply #8 on: August 02, 2018, 11:15:42 AM »
Just a little explanation:

The random LFO keysync does also not work on my Pro2 and Prophet 12, only with all other waveforms. On the 12 and Pro2, there is keysync (called "wave reset" in the manual) selectable without syncing the LFO to something. If "wave reset" is on with random LFO, the first keypress puts no random value out, it stays on the same level as without LFO. So I think DSI had a little misunderstanding of keysync on a random waveform - they did it that way, that it always starts on "zero" or "full" value (for example like a saw wave up or down), only the 2nd value after a length of the wave (=LFO speed) is different to the start value, but on a random LFO wave you have to apply a value instantly, if you want to hear it. On the Rev2, they changed this problem and made random LFO putting out random values with every keypress. Seems like it was an unpractical design thought in the past until they introduced the "updated" random LFO in the rev2.

« Last Edit: August 02, 2018, 11:24:50 AM by eisblau »
OB6 desktop x2, DSI Rev2 16, Toraiz AS-1, Prophet 12, Pro 2, Vermona 14, Roland System 8, Matrixbrute, Jomox Sunsyn MKII