MOTU M2 Round Trip Latency And Driver Issues

[guitar2freak]

Round Trip Latency Measurements ---

I am writing this for those who would be interested in buying the M2 (or M4, M6) and were wondering the type of performance to be expected from it when using an M1 based MacBook Pro (or equivalent).

Please note that I did not use the driver supplied by Motu for the measurement because it did not work. When using the driver it lead to many audio artefacts irrespective of the buffer size used etc.... whereas using the default Mac driver lead to rock solid performance....


The propagation of sound in the air is about 343 m/s
This means that every 1ms the sound travels about 34.3 cm

So an audio interface with a round trip latency of 5.3ms would be equivalent of someone playing through a guitar amp where the amp is placed 5.3*34.3 = 1.8m

And if the audio interface has a round trip latency of 8ms, then the equivalent distance would be 2.7m

Even if you add the delay introduced by guitar modelling (maybe about 1ms) the numbers would be about 2m and 3m respectively.
On top of that, if you don't use headphones but monitors you may want to add another 0.6m...

MacBook Pro 16’ M1 Pro, MacOS Ventura, RTL Oblique, Motu M2, (latest FW as of Oct 2022).
No specific driver installed.

Sampling Frequency Buffer size RTL Equivalent speaker Distance
48kHz 32 6.98ms 2.4m
64 8.27ms 2.8m
128 10.96ms 3.8m
96kHz 64 6.30ms 2.2m
128 7.66ms 2.6m
256 10.3ms 3.5m
192kHz 64 5.28ms 1.8m
128 5.92ms 2m
256 7.26ms 2.5m

The higher the sampling frequency the higher the CPU will work. On a good machine that’s no issue but on older ones that may lead to glitches/pop noises.

Similarly a low buffer size requires a decent laptop and the value used may need to be higher on older laptop.

That being said, I used the Motu M2 on my M1 Pro at 192khz /32 samples (likely 5ms round trip) with no issues….

The above shows that using Motu’s driver is not necessary if you don’t need the loop back functionality.

It also shows the hardware behaves well as those numbers are actually quite good.

Everyone will have different sensitivity to latency. In my case, when playing guitar I only start noticing if I go above about 11ms... I would be surprised to see many people noticing anything that has a round trip of 8ms or below and as can be seen above, this can be achieved even at 48kHz without the need for a specific driver.

I am disappointed still that the driver has issues and I am clearly not the only one having those.... If they could address this, I would be willing to test it for them.... There is nothing worse than spending money on anything and only being able to exploit part of its potential.

Anyway, I hope the above will help people thinking of going for the M2 which is a good audio interface but could be even better with a working driver.

[HCMarkus]

Thanks for sharing that info, G2F.

In my studio, I rarely monitor audio thru the computer, preferring to use my very low latency 828ES hardware mixer. VIs are, of course, another story, but we are only concerned with MIDI + D to A latency in that application, about 1/2 f the round-trip.

The MOTU Pro Audio driver has been robust on my Macs when connected via either USB or Thunderbolt.