asked Mar 12 '19 at 12:10 by sticklebrick (480)

edited Mar 14 '19 at 02:28

HI all,

Does anybody else find the Keytrack Modulator hard to use? I'm trying to set it up to modulate the Comb Filter so that the Frequency of the Comb Filter is tuned to the corresponding note that is pressed. I just can't seem to get it to map correctly across the whole keyboard. Any tips would be appreciated.


Main problem is that there's no grid lock to ease pining down right values (this modulator really needs external window mode for precise editing), but I guess you need to make the graph as diagonal as possible in Absolute mode.


answered Mar 12 '19 at 23:57 by xiso (76)

Hi @xiso,

Yeah I assumed that setting to Absolute Mode and as Diagonal as possible would do it, but it doesn't.... I'm either just not getting it or somethings not quite right with this Modulator....

  — (Mar 13 '19 at 12:16) sticklebrick

Did you set the frequency of the filter in the middle? When you adjust the value itself, a little helper shows value along with associated note, so you put it in C3 and it should align correctly. As far as I can tell it does work for me.

  — (Mar 13 '19 at 12:57) xiso

Also, Tried it in relative mode, when root set to default 60 and frequency to 261.625, seems to work fine as well, but it can't go below lower than 2 octaves. For that maybe you'll have to displace root in Keytrack to 48.

  — (Mar 13 '19 at 13:28) xiso

Hi xiso,

Thanks for your suggestions, much appreciated. I've just tried what you described and it's helped me to discover the following:

When I set the the Comb Filter frequency to "C3" or "261.625Hz", it does not sound like C3, it sounds closer to C#3. This is without even assigning the Keytrack Modulator yet. I think this may be the "root" of the problem (excuse the pun). I've checked the Comb Filter 'pitch' against other synths in Bitwig, it's definitely off.

With the Keytrack => Comb Filter Frequency modulation amount set to +1.5, I do get the correct pitch intervals (1 semitone) between each key. However, if/when you start to try and 'correct/tune' the initial value of the Comb Filter's frequency to compensate for the pitch offset, you loose the consistancy in the pitch interval. Which would make sense because the frequency difference between keys increases exponentially as you go high up the scale.

For instance:

C#3 (277.18 Hz) - C3 (261.63 Hz) = 15.55 Hz

Where as:

C#4(554.37 Hz) - C4(523.25 Hz) = 31.12 Hz

The weird thing is, that if you use Automation to set the frequency of the Comb Filter it is in tune!

I'd be most grateful if you or someone could confirm that the behaviour I'm experiencing is the same for everyone and not just me. Then I can let Tech Support know.

Many Thanks


answered Mar 13 '19 at 14:53 by sticklebrick (480)

I haven't found any difference if I'm setting Comb's frequency in automation lane or not, of course with Keytrack modulation still in place. I do hear that there are some resonance artifacts with some notes, but I suspect that it's because of nature of Comb filter or delay effect, resonance just not matching perfectly all the time, and slightest deviation causes to either resonances of actual note and Comb filter align and get louder, or miss slightly and it's not as loud. When I offset keytrack root by 1 (61 or 59 for example) I don't get those artifacts, but I'm guessing that's because resonances never perfectly align to begin with.

I don't have perfect pitch hearing, but it's difficult to tell if Comb filter is perfectly in tune (I think it's not perfect as I said earlier) because it kinda makes sound muddy to begin with.

EDIT: since it's especially muddy on lowest and highest frequencies, it was hard to tell what was going on exactly, but I think the culprit is the fact that min-max values for Comb filter's frequency doesn't match perfectly any single note, it's D#-1+45 (meaning +45 cents out of tune I suppose) for lowest and A6-26 for highest, so it wouldn't align with octaves or notes if it doesn't begin and end with same notes as keytrack is mapped. Given that max modulation index for frequency of the Comb is 2.240 which I suppose is 22,4 KHz, adjusting that may help, but it's quite a pain. Also a pain to make adjustments in Absolute mode of Keytrack, since you can't put in exact values for that odd range.


answered Mar 13 '19 at 15:21 by xiso (76)

edited Mar 13 '19 at 17:29

I've contacted Tech Support about the behaviour I'm experiencing. I will update this thread with any response I receive.


answered Mar 13 '19 at 16:01 by sticklebrick (480)

Follow this question

By Email:

Once you sign in you will be able to subscribe for any updates here

Markdown Basics

  • *italic* or __italic__
  • **bold** or __bold__
  • link:[text]( "title")
  • image?![alt text](/path/img.jpg "title")
  • numbered list: 1. Foo 2. Bar
  • to add a line break simply add two spaces to where you would like the new line to be.
  • basic HTML tags are also supported



Asked: Mar 12 '19 at 12:10

Seen: 333 times

Last updated: Mar 14 '19 at 02:28