Stairs in the knobs

[stiiiiiiive]

Hey Nordists.

I was tweaking the Nord Lead 2X and while being tremendoulsly rotating the cut-off knob, I noticed the sound had stairs.
Let me be clear:
- ok Clavia is digital
- ok parameters are almost always coded on 127 values in order to match with MIDI standard.
- ok the cut-off frequency is amongst the parameters for which that phenomenon is most audible.
When turning gently the knob, I ear it the way I'm expectiing it provided the points above.

My point is more about rapid rotations, hence my suspicion about a not-so-fast scan frequency of the knob values in the NL2X.

Does anybody knows what that frequency is?

BTW I haven't noticed this on the G2 so far. Different generations processors may explain that.

[mjbrands]

When you heard this, did you use the knob on the NL2X, or did you use some controller or a sequencer?

I don't have an NL2X anymore, but on the Nord Wave the cut-off knob seems to generate a higher precision (more than 7-bit) than via MIDI. If you record your playback via MIDI and then play it back, it is possible you hear stepping while you don't hear it if you turn the knob on the synth itself. If only the Clavia synths implemented 14-bit MIDI messages for stuff like cut-off (for example, the Moog Little/Slim Phatty now do so after a software upgrade).

Edit: Derp! You probably already know the stuff above. I should've read your question better. I have no idea how fast they scan it, but your description of the problem certainly makes sense. This problem should probably be worse when using the knob on the synth itself than when using a sequencer (or something like that).

[stiiiiiiive]

Hehe! No problem
It should be better through sequence as you said. However I don't use sequences but my fingers only...

I should have a look at te behaviour of the G2, just out of curiosity.

[mjbrands]

You might want to connect the synth via MIDI to your computer and use a utility to view the incoming MIDI messages (ideally with a time stamp). Something like MidiOx (Windows) or MIDI Monitor (Mac) would work.

I think that every time a controller is scanned (and the synth determines a new value was dialed in) a corresponding MIDI message is sent out. You might be able to figure out if, when you rapidly start turning the knob, the MIDI messages come in at a fixed rate (for example, 25 messages/sec) or at a more varying rate (up to 77 msg/sec). Ofcourse, there's no guarantee that the synth itself isn't picking up values faster than it sends out MIDI messages, but I cannot imagine the synth itself processes these values -slower- than the rate at which the MIDI messages are sent out (am I making sense here).

Also, I know some controllers (i.e. tempo) have a higher precision than MIDI allows (16-bit on the Wave, higher than both regular 7-bit and the more recent 14-bit MIDI messages). Cut-off is another likely culprit.

As far as I know, the Clavia synths send out 14-bit MIDI messages for the value of the pitch stick and regular 7-bit messages for everything else (even though their internal precision might be higher, as in the case of tempo).

[stiiiiiiive]

Yes, looking at the MIDI messages rate could give an idea.

[stiiiiiiive]

Ok guys. I feel idiot...

This week-end, I got nervous on the FM/RM knob again and could hear the stairs... while the RM is enabled. The cut-off knob does not produce any stairs.
So I guess the RM function involves a computation that is slower than the scanning frequency or something similar.

So to be clear: the cut-off knob of the Nord Lead 2X is ok and do not make any stairs in the sound, as well of the other knobs except the FM knob when setting the RM frequency.

It seemed very, very odd to me and I felt a bit disappointed but I'm happy again