Timing: Syncing Rack with External Synthesizer

I had not tried it before, so I loaded up a CC-MIDI module to see if I could control my Behringer Neutron with the SEQ-3. After some fiddling with the Neutron to get its oscillators in a usable range, it … worked.

Next, I loaded up a KNOCK drum module to add a bass thump, also triggered by a step on the SEQ-3. At this point I noticed that the KNOCK and Neutron were slightly out of SYNC. If I put a Bogaudio CV delay between the SEQ-3 and KNOCK, I can more or less dial in the timing.

Is there any way to know, upfront, the amount of time compensation Rack and an external device will need?

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Yes, try to set sample delay according to the buffer size selected in your Audio module.

I found these figures on Sweetwater’s website in an article about latency:

At 44.1kHz sample rate:

32 samples = 0.73ms delay
64 samples = 1.45ms delay
128 samples = 2.9ms delay
256 samples = 5.8ms delay
512 samples = 11.6ms delay
1,024 samples = 23.2ms delay

At 96kHz sample rate:

64 samples = 0.67ms delay
128 samples = 1.35ms delay
256 samples = 2.7ms delay
512 samples = 5.8ms delay
1,024 samples = 10.7ms delay

I’m running at 48kHz, so I guess I will extrapolate unless someone knows of a calculator.

Ehm, just do 1s/48000Hz*<numberOfSamples>.
No calculator needed…

OK, well this is not what I was expecting. At 48kHz/512 samples, I would have imagined that I would need to introduce about a 9 or 10ms delay to the gate going to the CC-MIDI and then to the Neutron to align it with the gate going to the KNOCK kick in Rack.

It actually takes about 10 times more delay, about 1/10 of a second.

Yes, the calculation you provided returns the expected ~1/100 of a second.

Yet it takes ~1/10 second delay to align the beats.

Then there must be something different introducing this large latency. Can you describe the whole signal flow out of Rack and back in again?
Are you using something like ASIO4All?

I’m using WASAPI on Windows 10 right now. I can try it with the ASIO driver that came with my PreSonus USB audio interface.

In Rack, I have a clock from CLOCKED going to the SEQ-3. From there, the GATE output is connected to both the GATE IN on KNOCK and the GATE jack on the CC-MIDI. The Neutron is connected to the computer via USB.

EDIT: Yes, the PreSonus ASIO is faster. About 30ms. Also, I should note that I am using a fairly ancient computer … if that matters. i7-3770 3.4GHz.

EDIT-EDIT: I guess I don’t actually care — I’ll just line 'em up by ear. :stuck_out_tongue_winking_eye: