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Prologue distorted notes

 
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james.b



Joined: 15 Jun 2020
Posts: 4

PostPosted: Mon Jun 15, 2020 8:31 pm    Post subject: Prologue distorted notes Reply with quote

Hi all,

my new Prologue 16 is producing distorted notes, more audible with the triangle wave, but always present with all waveforms: see/listen the video here:

https://youtu.be/leZ-2Gfpwdc

As can you hear and can be seen from the image in the video, some notes have a larger volume, the waveform of these notes is distorted on the peaks of the wave (up/right in the image), and these notes are producing a lot of harmonics at a higher volume than the others.

Now the keyboard is at the service center but they say that "from the electrical and electronic hardware side, thanks to the tests carried out, no malfunctions emerged".
I also tried another Prologue 16 at the shop (serial 600, mine is 11xx don't remember) and is producing the same distorted notes.
I have a Minilogue and is not producing this kind of "things", every note is different from the other but the perception of the timbre is always the same.

Here http://www.korgforums.com/forum/phpBB2/viewtopic.php?t=116490 I think there is another user with the same problem, Synthee.

Please, can you test your Prologue and see if it produces distorted notes like mine? For the test, use a single oscillator, triangle wave.

Thank you.
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Narioso
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Joined: 15 Oct 2015
Posts: 300
Location: Sweden

PostPosted: Tue Jun 16, 2020 3:26 am    Post subject: Reply with quote

I have encountered similar, but only on multiengine. If 3rd oscillator is turned down completely it went away. Just like that every 4 voice or so created a extra klonk in my case.

And only as I have used certain presets with a certain user oscillator in this case, and not consistent. Just happended a couple of times. Power cycle fixes it.

My theory on that one, is some kind of memory overwrite or similar that corrupts memory. That coders of those oscillators exceeded some boundaries or similar.

So probably not the same thing, just mention if rings any bells.

So if you from a sequencer play notes in same consistent velocity - all the time - strange if service center encounter nil. And if you find on another in the shop even more so - what did personal say about that?

How it sounds could be a filter opening more if velocity modulation is there, or high resonance setting or similar - if just hitting notes on random. Being analog it's almost impossible to get that exact amount of resonance on every voice, I gather. It is different hardware for each voice, and extreme values can do that. But it does not sound extreme resonance at all - so no clue.

It does not sound filter is all open though, but been some weeks I used my P8. My P8 is in a box due to a move soon, so cannot check.
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MIDI gear: Sequential REV2.16, Prologue-8, Hammond XK-3C, Kawai MP7SE piano, Nord Lead 2X, Roland D-05
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james.b



Joined: 15 Jun 2020
Posts: 4

PostPosted: Tue Jun 16, 2020 7:41 am    Post subject: Reply with quote

Hi Narioso and thank you for your answer;

all I can say at the moment is:

-the test is done playing the instrument in realtime from its keyboard, and the filter is all open
-I used its init patch for the test, and I think that in the init patch the filter is not modulated by velocity; I also tried the reset to factory state, so Ithink that is not related to a memory overwrite
-the distorted notes are present with the analog oscillators, I did not try the user oscillator
-about the fact that the service center says there is no electonic/electric problem, and the fact that the other Prologue at the shop sounds in the same way...I don't know what to think, but I read somewhere in the forum that some of the Prologues before the serial 2500 are doing strange "things"

Please, when you can, try your Prologue and let me know if it's doing the same thing, and thank you for your insights.

If someone around can try, I'm here.

Thank you.
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RobustAmerican
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Joined: 18 Dec 2018
Posts: 114
Location: USA

PostPosted: Tue Jun 16, 2020 11:40 am    Post subject: Re: Prologue distorted notes Reply with quote

james.b wrote:
Hi all,

my new Prologue 16 is producing distorted notes, more audible with the triangle wave, but always present with all waveforms: see/listen the video here:

https://youtu.be/leZ-2Gfpwdc

As can you hear and can be seen from the image in the video, some notes have a larger volume, the waveform of these notes is distorted on the peaks of the wave (up/right in the image), and these notes are producing a lot of harmonics at a higher volume than the others.

Now the keyboard is at the service center but they say that "from the electrical and electronic hardware side, thanks to the tests carried out, no malfunctions emerged".
I also tried another Prologue 16 at the shop (serial 600, mine is 11xx don't remember) and is producing the same distorted notes.
I have a Minilogue and is not producing this kind of "things", every note is different from the other but the perception of the timbre is always the same.

Here http://www.korgforums.com/forum/phpBB2/viewtopic.php?t=116490 I think there is another user with the same problem, Synthee.

Please, can you test your Prologue and see if it produces distorted notes like mine? For the test, use a single oscillator, triangle wave.

Thank you.



Hello James,

The other post you linked to above was mine before I changed my username. As I said in my original post, the guys at Sweetwater heard it immediately and put it down to slight differences in the voice cards. My Prophet Rev2 does the same thing with square and triangle waves. It's not audibly distorted, just a slightly different tone from note to note. Calibrating the oscillators and filter will mostly fix this on the Rev 2. Since then I've embraced these little oddities of the Prologue. It is analogue after all and those little differences in the tone of the oscillators are part of what make the VCOs sound alive. The VCO square wave on the Prologue is absolutely filthy and I love it.

Good Luck James!

R.A.P.
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Narioso
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Joined: 15 Oct 2015
Posts: 300
Location: Sweden

PostPosted: Tue Jun 16, 2020 2:35 pm    Post subject: ... Reply with quote

...

Last edited by Narioso on Tue Jun 16, 2020 7:39 pm; edited 1 time in total
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james.b



Joined: 15 Jun 2020
Posts: 4

PostPosted: Tue Jun 16, 2020 4:17 pm    Post subject: Reply with quote

Hi RobustAmerican,

in my case the difference in timbre between the notes in the Prologue (as you can hear and see) is really remarkable;
as a comparison here there is the triangle wave of my Minilogue,

https://youtu.be/0LLWgKlocBc

there are small differences between one note and another (desirable in the analog domain), but the perception of the timbre is still the same, there are no big changes.

In the Prologue, I can't imagine that such a large difference between the timbre of the oscillators or filters (if each oscillator has a filter) is intended as desired/by design.

In my case, if I wanted to do a part of bass with the triangle wave of the Prologue, a part would come out with too many jumps of timbre; with the minilogue does not happen.

But does your Prologue have such big differences in the timbre between the notes?
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RobustAmerican
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Joined: 18 Dec 2018
Posts: 114
Location: USA

PostPosted: Tue Jun 16, 2020 6:08 pm    Post subject: Reply with quote

james.b wrote:
Hi RobustAmerican,

in my case the difference in timbre between the notes in the Prologue (as you can hear and see) is really remarkable;
as a comparison here there is the triangle wave of my Minilogue,

https://youtu.be/0LLWgKlocBc

there are small differences between one note and another (desirable in the analog domain), but the perception of the timbre is still the same, there are no big changes.

In the Prologue, I can't imagine that such a large difference between the timbre of the oscillators or filters (if each oscillator has a filter) is intended as desired/by design.

In my case, if I wanted to do a part of bass with the triangle wave of the Prologue, a part would come out with too many jumps of timbre; with the minilogue does not happen.

But does your Prologue have such big differences in the timbre between the notes?



Here's my Prologue doing morse code. The 1st set of 32 blips is straight from an initialized preset flipped to the triangle shape. The 2nd set of blips is exactly the same except for one change. I increased the amp & filter envelopes' release just a little because I had a hunch. Try increasing the release times just a little and see if that improves the situation. It didn't totally remove the changes but it definitely seemed to mitigate them.

Prologue & Morse Together Again

Hope this helps!

R.A.P.
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james.b



Joined: 15 Jun 2020
Posts: 4

PostPosted: Tue Jun 16, 2020 8:33 pm    Post subject: Reply with quote

Exactly the same problem...

The trick of the release time..ok, but if you need a fast release the distorted notes are there.

For me it's something really strange, because in the Minilogue and other polyphonic analog synthesizers this doesn't happen, and if it happens the difference between the tones is not so pronounced.
Honestly, I thought I was buying an instrument very similar to the Minilogue in terms of performance.

Anyway, your test helps a lot. Thank you for your "hunch" and your time and thank you all for your answers.
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RobustAmerican
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Joined: 18 Dec 2018
Posts: 114
Location: USA

PostPosted: Tue Jun 16, 2020 9:46 pm    Post subject: Reply with quote

james.b wrote:
Exactly the same problem...

The trick of the release time..ok, but if you need a fast release the distorted notes are there.

For me it's something really strange, because in the Minilogue and other polyphonic analog synthesizers this doesn't happen, and if it happens the difference between the tones is not so pronounced.
Honestly, I thought I was buying an instrument very similar to the Minilogue in terms of performance.

Anyway, your test helps a lot. Thank you for your "hunch" and your time and thank you all for your answers.


OK, I guess if you are using the Prologue to play one note melodies with no filtering and isolated all by itself, it could be a problem. Smile But for me, in real world use day in and day out, it hasn't been a problem at all. As I said, the Rev2 exhibits this same exact phenom and I suspect many other synths with high voice counts do as well. Synths with lower voice counts, Minilogue, have fewer voice cards so it makes sense that there is less variation.

Good Luck James.


Late Addition:

I've been checking out OBsession by Synapse. It has controls for each voice to increase or decrease these very same differences in the voices.
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