Volca FM Operator Issue

rishabh · Post by **rishabh** » Tue Apr 05, 2016 10:11 pm

So I'm trying to create a basic init patch.

I turned OFF all 6 operators but I still hear sounds. I turned the level down on all 6 operators and I still hear sounds.
I went in and zeroed out all parameters but I'm still hearing sounds. In fact when I change the a algorithm I can hear subtle tonal variations to the sound. So it is not possible to turn off these operators?

volcafmquestion · Post by **volcafmquestion** » Wed Apr 06, 2016 3:49 am

I wasn't able to reproduce this problem - when I turn the operators off, there's no sound. Can you describe in more detail exactly what you're doing? Like, are you turning them off by editing the parameters directly on the Volca FM with the knobs and sliders, or via MIDI sysex messages, etc...?

rishabh · Post by **rishabh** » Wed Apr 06, 2016 1:47 pm

I'm doing it directly on the unit.
Maybe there's something wrong with the one I have.

volcafmquestion · Post by **volcafmquestion** » Wed Apr 06, 2016 11:19 pm

Can you be more specific, like list the buttons you press/knobs you twist/faders you move in order? I can then try doing the exact same thing and tell you what I see, if you like.

rishabh · Post by **rishabh** » Sat Apr 09, 2016 7:44 pm

Turn ON the Volca FM.
Hit the EDIT button.
First parameter is the ON/OFF switch for the operator.
It should be 1 On_01. Using the VALUE Slider set that to 1 On_00 to turn the operator OFF.
Using the OCTAVE up switch go to next operator. You should see the same parameter. 2 On_01. Do the same.
Turn OFF all the operators.

It will seem like all the operators are OFF. But bump up the volume to the max and you will hear something. Change the algorithm with the ALGRTM dial and you will hear more.

This is how I reproduce the problem.

volcafmquestion · Post by **volcafmquestion** » Mon Apr 11, 2016 1:36 am

Thank you! That's very interesting. I was able to reproduce it too. But I found that it doesn't happen for all patches, or even for the same patch consistently if you change the algorithm. (For example, after reproducing it by editing one patch, I was then able to turn the sound off by changing the algorithm to 3.)

I also found that the effect can be eliminated if you change the oscillator mode from RATIO to FIXED on an operator. Interestingly, it sounds like 2 or 3 sine waves of different frequency summed together, so it makes sense that this would be somehow related...

The sound also appears to be affected by the "all" parameters, like pitch attack and so on.

Sorry I don't have any answers but maybe this will be enough to intrigue someone who can investigate more closely!

Temperary · Post by **Temperary** » Wed Jun 29, 2016 9:30 pm

I'm having this same issue. Has anyone found a cause or a fix?

effemm · Post by **effemm** » Thu Jun 30, 2016 6:17 pm

Yes. I can reproduce this, too.

This plus the constant background noise its producing makes me feel that I was a bit too enthusiastic about the machine.

See this topic:
http://www.korgforums.com/forum/phpBB2/ ... p?t=104622

v-pong · Post by **v-pong** » Wed Jul 27, 2016 9:39 pm

Same issue here, i made a recording last week and noticed a extra high pitched tone in the volca fm part. So today I tried to edit my patch, like figuring out where the problem could be. I switched off all operators, then still could play the keys, i can still hear the notes. Then I tried to switch all levels to zero. There's still the notes. When i fully open the carier decay dial it's very very audible, i could make a song with it, except its a not wanted sound. I tried a factory patch that does not have the noise/sound, but when i switch off all operators its there. I hope there will be a fix for this because its annoying, or is this normal for the old dx7 as well? I really love my new volca fm so i hope somebody can help me

OpAmp · Post by **OpAmp** » Fri Jul 29, 2016 11:59 pm

Hi,

Mine does it too.

Seems strange to me, because this is supposed to be a digital synth. So it should be possible to zero out samples coming from an operator that is disabled.
I have to turn up volume of my amplifier quite high to hear it.

I also looked at the spectrum while experimenting with parameters. The best option I found was: for operators that are not in use
* disable them (seems the same as output level to 0)
* put them to fixed mode
* coarse, fine and detune parameters to 0
* optionally select an algorithm where the inactive operators are on a separate 'branch', meaning there is no chance they modulate one of your active operators.

If you try this e.g. on algorithm 32, on all operators, it is quite quiet, according to me. At least the spectrum does not show any tones and remains at -84dB (noise) Very a nice patch btw

That being said, the pure sine wave of an operator is not that clean in the spectrum. It looks like there are still some harmonics at -60dB compared to the pure tone level.

Bye

OpAmp · Post by **OpAmp** » Sat Jul 30, 2016 12:04 am

Coming back on the sine wave and the harmonics. I measured the pure sinewave of my mKXL as well.
Seems the same as for the Volca FM, meaning some higher harmonics at -66dB. So maybe this may be related to my measurement setup.

v-pong · Post by **v-pong** » Tue Aug 02, 2016 8:47 am

Yes, that seems the best way to go about it. coarse, fine and detune parameters to 0 solved my patch problem. Happy patching everybody!

Eamoex · Post by **Eamoex** » Mon Aug 08, 2016 8:28 am

Nice to see people have noticed this too. Still it's not normal IMHO. Turning all operators OFF says it: NO SOUND. So, Korg, please fix this.

Also, but maybe not directly related, I find many patches have a clicky feel to them, and it's quite annoying. It gets really bad if you have some reverb, they will clutter the spectrum badly. You can filter them out, but you lose a large chunk of the top end when you do.

OpAmp · Post by **OpAmp** » Mon Aug 08, 2016 9:25 pm

I agree. What is proposed is a workaround. I would think it is an easy fix as this is supposed to be a digital box, meaning some software update...

Can you elaborate on the clicky feel?

Bye.

Eamoex · Post by **Eamoex** » Mon Aug 08, 2016 10:19 pm

Agreed OpAmp, it should be firmware-fixable.

But then, even though I'm no electronics expert, I know that the layout of a PCB can affect the desired flow of electrons / create interference, and if the fault is hardware related in this sort of way for the Volca FM, we're kind of screwed here. I'm inclined to believe this, also because of the very compact nature of the Volca series, and thus the extreme proximity of all components. Dunno, just thinking out loud here.

The clicky feel thing. I might abuse language I shouldn't be using when saying "spectrum" and "filter" because, again, I'm no expert in audio design. But many of the patches I make produce audible clicks. I would say it feels like they sometimes occur on note trigger, sometimes on release. Because the clicks are better heard when arpeggio melodies are played, I feel they are also related to the 3-voice limit, because with many notes played in short time, voices are often "interrupted" to adapt to new notes pitches. This shift in pitch seems to make a click.

I'm just speaking from my gut here again, but the clicks are here for sure. I'll upload a sample where they are well heard when I get the chance.

And when I talk about reverb I mean that with a reverb that has a "hi-pass" setting, the high frequencies of the clicks are "carried away" by the reverb and "smear" all over the sound.

And when I talk about filtering I mean I have a nice external filter which, when used in "low-pass" mode, kind of muffles the clicks, but it's a relatively coarse adjustment and it eats away other details of the sound a patch produces.

I hope I'm clear and am curious what you and others who read think, or have experienced.

Volca FM Operator Issue

Volca FM Operator Issue

v-pong