Ambika: Pedal Sustain, VCF offset and LED color

Hi everybody,

after finishing my 6-voice Ambika, I am enjoying to explore all the features of it.
By the way, I found some issues, do you experience the same?

  • Pressing the sustain pedal on my Kronos while playing some notes stops all of them. Even funnier, using a SY99 as master keyboard: play notes and hold them, releasing sustain pedal stops all notes which are still held by my hand. I think, this is a bug in the sustain logic of Ambika.

  • tuning VCF by the spread potentiometer is clear to me, but I am missing an offset value, so that each VCF plays the same note. Guess this could be implemented by software.

  • LED colors are wrong: notes on voicecards light in green, while the 6 note LEDs on the mainboard are yellow.

Robert

For the sustain pedal, it sounds like the polarity is wrong for the Ambika. Many sustain pedals have switches on the bottom to change the polarity and many synths check the polarity when they boot up now-a-days. Kinda odd 'though, consider this is being transmitted by MIDI. I’m not much of a fan of the Kronos but I’m pretty impressed that you have an SY99, I’d love to get one of those.

  • As piscione said, a pedal is a switch. Some pedals use the “switch closed” = pedal pressed convention, some pedals the “switch closed” = pedal released convention. Check if there is a switch to invert the polarity.
  • Which voicecard type are you using? Such an offset cannot be achieved in software since the cutoff CV controller has an 8-bit resolution.
  • This is normal. Note that in a future firmware revision, the group of 6 LEDs at the left of the switches will only be used to indicate the active part, not to indicate which voicecard is playing (orange indication).

I have analysed the Midi outputs of both keyboards:
SY99:
Sustain pressed: B0 40 7F, released: B0 40 00

Kronos:
pressed: B0 40 nn (nn depends how far Half-Damper pedal is pressed)
released: B0 40 00

I am using 6x SMR4 voice cards. With Resonance set to 63, each VCF sounds nearly at a different tune (with V/oct correctly set). I learned from other Midi-CV convertes, that it is meaningful to adjust V/oct and ofs seperately. Why not adding some constant offset to the 8-bit CV, to tune them individually to a common tone?

As for a futures firmware revision, it would be a sad to lose the voice indicators. But I guess, you have a better idea for the orange colors :slight_smile: Are you collecting a public wish list for future versions?

I’ll look into the sustain problem.

> Why not adding some constant offset to the 8-bit CV, to tune them individually to a common tone?

Because the offset that would be needed to put them to a common tone is smaller than what is permitted by the 8-bit resolution of the CV. How much detune do you observe?

Here is a fix for the sustain pedal problem. Previously I was releasing all held note when the pedal is released. Now, I am only releasing notes which have been tagged by a NoteOff message while the pedal was held.

It works great – thank u!

Sustain actually works now as it should.
Merci beaucoup!

>> Why not adding some constant offset to the 8-bit CV, to tune them individually to a common tone?

> Because the offset that would be needed to put them to a common tone is smaller than what is permitted by the 8-bit resolution of the CV. How much detune do you observe?

Some VCFs are detuned by a second, one by a third.

@rts
off topic do you still use the SY99? PM me if you want some banks of sounds i have created over the 20 (gulp) years I have had mine.
regards

Old thread… but I wonder if the issue of VCF tuning offset was ever addressed? I too would like to be able to tune my VCFs to the same frequency. It could potentially be a very beneficial effect sonically.

I’m glad to see that the Sustain problem is solved. I too stumbled upon filter differences between voices (in the order of 5 semitones differences between some voices), which can be heard even when the filter is not almost oscillating. A trimming solution for this in software would be great, unless it would me a sacrifice of the filter range or resolution.