Ambika Filter tracking

Hello, Is it possible to easily disable filter tracking?


from the manual
The filter cutoff frequency always tracks the note. Again, this can be disabled or attenuated by applying a negative modulation from note pitch to cutoff frequency. The rationale behind this choice is that most of the time, you want 1:1 tracking, so this frees up a slot in the modulation matrix for something more interesting!

so you have to set up a modulation slot for it. but it’s also not clear to me wich value exactly stops the tracking. or if you can set up negative filter tracking.

Ok, that’s smart!

I have problems with this. It seems that no value for key > cutoff modulation really disables the keyboard tracking on mine… I tried using -63 but there are still notes that jump out weirdly with that setting.

I wonder if it’s because keytracking might need calibration on the voice cards? EDIT: it could be, because I just set the voice mode to “cyclic” and played one key 6 times and with the same cut/res settings I got some different sounding notes from certain voicecards.

So how do I tune these filters? :slight_smile:

Bumping this, still curious on the keytrack question and how to tune the filters so they are in the ballpark across all 6 voices?

On the original SMR4 filter cards it’s only possible to tune the filter so that the octave interval is respected, but not so that all voice cards play in tune. For that a second trimmer is needed (which Tubeohm added in his version, and I in my works-in-progress SMR4X).

In the development notes for Shruthi Emilie wrote that “trimmers are evil” so this trimmer was deliberately eliminated.


We’ll that’s a huge bummer, I have a pretty big inconsistency on one voicecard (they’re all Pharmasonic SMR4). I should record that to showcase.

The other question still stands, though. How do I nullify filter keytracking, when setting it to -63 doesn’t work (using YAM firmware)?

Just a question: are you sure you’re verifying this (nullifying filter key tracking) when playing one single voice card? (If not, the varying tuning of different voice cards will come into play)

I’m currently not at home so I cannot verify this on my Ambika.


Yes, I tested this voicecard by voicecard by disabling all but one voice.

When I’m back home I’ll record something to showcase :slight_smile:

Alrighty. Turns out even regular keytracking is completely off on my Ambika, on every voicecard except maybe one :frowning:

Here’s all voicecards with self-resonating filter (cutoff 69, resonance max, both oscillators set to “none”, “organ” amp envelope, no modulation), going from C0 to C7 in octaves (C3 being middle C).

Ambika (1.6 MB)

One file for default (with keytracking), one file for supposed “no keytracking” (keytracking parameter in YAM firmware set to -64).

Looks like only voicecard 3 seems to keytrack properly, others are way off (thus destroying any unison sounds I’d want to ever do). And weirdly, voicecard 2 keytracks even in “no keytracking” situation, which I’m not sure what to think about - could it be a firmware bug?

Please advise what to do here. I’d like things to be in tune!

Hi @EvilDragon,

I’m pretty sure you haven’t calibrated your voicecards according to VCF tuning in

Just to repeat myself: With this tuning you will achieve the same note increments per voicecard, but they will not be in tune (because of the missing additional trimmer needed for this).

-64 is indeed the constant modulation needed to cancel the built in default key tracking for the filter (which is a little inconvenient because you need to use two modulation slots since only -63 is possible with one slot).

So, to sum up there is no way to achieve tuned filter resonance between voices without physical modifications.


I didn’t build my own Ambika, somebody else did. I see trimmers are not all in the middle, so I had assumed the guy who built it for me calibrated it as much as possible…

@Bjarne, I’ve played with the trimmers now and got them tuning to octaves as much as possible.

You don’t want to hear how 6 voice unison with heavy resonance on filters sounds! It’s unfortunately unusable for any pitched content, just beehive-like drones :frowning:

That said, I did confirm that 2nd voicecard over here completely doesn’t listen to the keytracking modulation. Even if I apply -64 by using two mod matrix slots, it doesn’t play the same note, but goes through the octaves as supposed to… Voicecard firmware busted?

@EvilDragon Hi, I’m unfortunately clueless. It sounds like a very unlikely effect from a corrupt firmware, but of course you could try to update the cards firmware. Cheers

@Bjarne just to let you know, I have upgraded the firmware to the latest YAM build you have on your github, and now 2nd voicecard behaves just fine when defeating the keytracking.

But man, I definitely do want new voicecards with second trimmer to tune the filters more accurately. It’s impossible to use unison sounds with any sort of keytracking with Ambika as is…