Looper X Drifting with respect to a 4 bar Midi Drum Loop from Reaper

I’m using Looper X with a 4 bar Midi Drum loop in Reaper. The QC loop drifts with respect to the looping drum part from Reaper. The QC loop starts out in sync but slowly gets earlier and earlier. It seems like the QC loop is slightly shorter that the looping drum part and the sync only happens when the QC loop is first started.

Any ideas how to solve this or is it a bug?

Setup:

Quad Cortex:
-USB over MIDI is enabled
-Quantize - 4 Beats
-MIDI Clock start - ON

Reaper:
-Audio System - ASIO
-ASIO Drive - NeuralDSP USB Audio Device
-MIDI Device - Quad Cortex MIDI OUT, Mode - Enabled+Clock

Hi @GlenDSP and welcome to the community! Sorry to hear about the issues with loop sync etc., I think it would be best to contact support@neuraldsp.com and they should be able to get you sorted quickly. I’ll also leave the post up in case someone has run into this issue as well.

Hi Customer Support,

Would you be able to help with this issue (See below)?

Thanks,
Glen

Hi @GlenDSP , did you send an email to support@neuraldsp.com and if so, what response did they give you?

Hi,

I just sent the email today. I’ll forward their reply when it comes through.

Thanks for checking.
Glen

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I am experiencing the same issue with a BeatBuddy. I have written the support email.

I think I’ve found the problem with looper drift. If the length of the loop is a repeating number then the QC must round it which can make it a different length than the drum track. For example, the length of a QC loop with a tempo of 66 and a quantize of 4 is 60/66*4 = 3.63636363636363…. So, QC likely rounds it down which ends up being shorter than the drum track.

Tempos that work for me with a quantize of 4 are 50, 60, 64, 75, 80, 96, 100, 120, 125, 128 and 150. I’ve never had drift with these tempos. It does depend on the quantize you’re using. For example, a tempo of 72 doesn’t work for quantize of 4 (3.3333…) but does work for 3 (2.5).

Seems like the looper should be using floating point for these calculations.