Samba - Clock not accurate

Hardware NGEN
1

While recording 4-bar loops from the Samba generator into the Roland SP-404 MK2, I’ve noticed that NGEN’s clock is not completely accurate.

In order to get perfect loops on the sampler recorded at 130 BPM, I must set NGEN’s free clock to 132 BPM.

The Clock length is set to 4.
Both the Mod and the Swing parameters remain at 0.

The generator has the following parameters:

Rotate 0
Length 16
Density 3
Spread 5
Prob 10
Random 1
Note length Dynamic 1

Lastly, NGEN is sending the 4 midi notes to an Alesis D4 drum module, via a DOREMIDI midi interface, which then goes into a midi splitter. Although this should not have any kind of influence in the behavior that I am reporting.

Kindly let me know if further details are needed.

2

Thanks for the report @nzimas !

Quick question, what firmware version are you running?

I can confirm I’ve noticed this issue before but I didn’t get a chance to get it fixed for 1.2.
I do not believe this is related to Samba specifically but rather to Free Clock itself. My current understanding is that the calculations are correct but I believe the actual interrupt loop actual length ends up being slightly different from what it’s supposed to be. I just need to figure out if this difference happens to be fixed, linear or something else so I can compensate for it.
I will look deeper into this to see if I can get it fixed for the next update.

Yeah I do not think this would be an issue. It could affect latency but unlikely to cause that change in speed / tempo.

3

The unit is running the latest 1.2 version of the firmware.

I can confirm that it happens with other generators as well.
At least with ACDGEN.

4

I have connected my Circuit Rhythm to NGEN as a clock source and the tempo is absolutely spot on.
Meaning that there is most likely a bug in NGEN’s free clock.

If I set the free clock at 132 BPM, it nearly yields 130 BPM, but this trick doesn’t really work in certain situations that require absolute precision.

I hope this issue will be addressed soon.

Cheers!

5

Actually, the clock coming out of the Circuit Rhythm isn’t very stable either.

I can see that the tempo value received by NGEN’s MIDI clock is constantly drifting, instead of remaining fixed.

6

I noticed that the midi clock on NGEN also drifts when the clock is sent from the Arturia Keystep 37.

If I set the tempo on the KS 37 to 75 BPM, the MIDI clock animation on NGEN will display 74 BPM most of the time.

7

Another quick update.

The jittering that NGEN’s midi clock experiences is the result of unstable external clocks.

I tried to send clock from AUM, running on my iPad Mini, and the tempo value remains study throughout.

Still, it would be preferable to have a stable and accurate internal clock on NGEN.