# Looper won't stay in time with external clock

**URL:** https://unity.neuraldsp.com/t/looper-wont-stay-in-time-with-external-clock/8231
**Category:** Quad Cortex
**Created:** [September 24, 2022, 9:38am UTC](https://unity.neuraldsp.com/t/looper-wont-stay-in-time-with-external-clock/8231 "2022-09-24T09:38:04Z")
**Posts on this page:** 1
**Showing post:** 25

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### Author: ![MAEllis](https://avatars.discourse-cdn.com/v4/letter/m/ea5d25/32.png) [@MAEllis](https://unity.neuraldsp.com/u/MAEllis)
#### Post date: [April 18, 2024, 1:53am UTC](https://unity.neuraldsp.com/t/looper-wont-stay-in-time-with-external-clock/8231/25 "2024-04-18T01:53:23Z")

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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).

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