[jmoleParticipant]

32 tracks over USB is fine, there is enough bandwidth.

But I don’t think you can use the SQ drive at the same time.

[jmoleParticipant]

The latency on Windows is indeed lower than it is on Mac. I think the minimum RTL I saw on Windows was around 5ms, vs the 10ms for Mac.

[jmoleParticipant]

My plan is to use the focusrite as a low latency thunderbolt to Dante converter. Apparently the rednet PCIe cards only get you <3ms RTL, the thunderbolt interface will do 1.6ms @ 32 samples 96kHz.

The reason thunderbolt is faster is because it’s a different driver developed by focusrite, vs the PCIe card which is just a rebranded Audinate product.

The main use is for vocal effects like vocoding, hardtune etc, which need to be as close to real-time as possible.

[jmoleParticipant]

@steffenromeiss

The ASIO driver is supposed to report the latency to the DAW, which then uses this number for delay compensation between I/O tracks. Not only is the number reported *wrong*, but the measured round-trip latency *changes* each time you hit stop and play again.

It’s a broken ASIO driver, and a bug that needs to be fixed. This does not happen on mac, thankfully.

@keithjah

I have a Dante interface on the way, and will do some latency measurements of the system using Dante with VCS and also a thunderbolt connected Focusrite 4Pre /w Dante to see how it all shakes out.

The annoying thing about this is that with the extra cost of the SQ Dante card and the {Rednet PCIeR, RME Digiface Dante, or Focusrite Red 4Pre/8Pre/16Line interfaces} for the PC/Dante connection, I’m pretty much up to the cost of Waves’ new eMotion LV1 live mixer bundle, which will do most of the real-time processing I’m looking to do natively through my DAW.

[jmoleParticipant]

Just did more testing on macOS, with this handy little program: https://www.oblique-audio.com/tmp/beta.html

Here’s a table of results:

Note there are 2 samples taken at each buffer setting (32 & 128). One sample was taken via tie-line connection, the other sample was taken /w an XLR connecting input and output together.

So the path for one is:
pc -> USB out -> tie-line -> USB in -> pc
and the other is:
pc -> USB out -> XLR out -> XLR in -> USB in -> pc

The rows with the (-102.4) noise floor show the XLR connection, which adds about 50 samples to the latency for AD/DA conversion.

Anyway, this just goes to show that the best case RTL you will get will never be less than 10 ms on macOS.

[jmoleParticipant]

check out the USB latency post, where I’ve been doing some extensive testing of the USB interface on the SQ. Unless you have a Dante card, IMO, the SQ is totally unsuited to use with computer-based effects processing right now.

For Waves stuff, that means using Waves Native /w Dante, or using Soundgrid servers with the SQ Waves card.

[jmoleParticipant]

I repeated my latency testing process on windows. Same setup as before, but using the ASIO drivers. I found the oddest thing. The sample delay between playback and loopback recording was non-deterministic.

I made several recordings in a row, without changing the ASIO buffer size. Each recording had a different round trip latency.

Again, the signal flow is:

pc -> usb channel 1 OUT -> tie line on SQ -> usb channel 1 IN -> pc

It seems that when playback commences, the driver tries to establish sync with the SQ. This “point of sync” varies from recording to recording. That means, even with delay compensation enabled in Live, you will never be able to get phase coherent recording and playback, because the round-trip latency is non-deterministic from session to session.

What a crock!

[jmoleParticipant]

Just checked again on firmware 1.2.2, and the latency is actually a little worse, by some hundreds of microseconds. Not sure what’s going on here.

I really don’t want to have to buy a SQ Dante, RedNet PCIeR, and thunderbolt PCIe cage, just to use my computer for effects.

The other way to do it would be to buy a low latency audio interface and use some analog patching between the interface and the mixer to pull the channels I want into the computer, and patch the outputs into the mixer.

Both these solutions seem like a huge hack considering the mixer has a USB port and should be more than capable of ~3ms RTL @ a 64 sample buffer with 96kHz sampling. A&H, please get your act together and fix this problem.

[jmoleParticipant]

Hi, I recently acquired a SQ-5, upgraded the firmware to 1.3.2, and discovered that the latency over USB is terrible. Much worse than most dedicated USB audio interfaces.

This test was done on macOS 10.12.6, using Ableton Live. Delay compensation was turned off, and a sound was played out through the USB interface, and then returned via a Tie-Line back over the USB interface.

from pc —- USB output channel 1 —-> mixer tie-line —-> USB input channel 1 —> to pc.

We would expect the minimum round trip latency to be as follows:
( buffer_size * 2 ) * 1/96kHz + mixer_latency.

However, this is not the case. There’s an extra ~10ms of latency in the system, likely from A&H’s poor USB implementation. I also noticed in the firmware release notes that they fixed some bugs related to dropped samples over USB. My guess is they just increased the buffer size on the hardware side which added a bunch of latency, but I didn’t measure an earlier firmware version, so I can’t say for sure.

Check out the results I attached to this post. RTL was measured at:

32 samples: ~10ms RTL
64 samples: ~10ms RTL
128 samples: ~12ms RTL
256 samples: ~14ms RTL
512 samples: ~20ms RTL

For comparison, I ran this same test with a MOTU 624 thunderbolt interface, and the RTL at 64 samples/96kHz was ~2ms. I’m starting to regret returning the MOTU…

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