The attachments show the results that I obtained for latency tests/measurements with my Focusrite Scarlett 6i6. Since Focusrite is trying to modify their drivers to work properly with Pro Tools (PT), I used their latest (beta) drivers http://ift.tt/1m9Lem4 for these tests. Standard (non-HD) Pro Tools 12 was used with Windows 8.1.
With the current released version of the Scarlett ASIO driver/Control Panel (Scarlett Mix Control 1.8.128.0) buffer sizes need to be entered via Mix Control before PT starts/restarts. PT should then try to calculate an appropriate approximate buffer size when it starts – and it doesn’t do it very well or reliably! That Scarlett driver does not accept/reflect buffer size changes entered from PT. Using the mesaone/Sweetwater approach that attempts to do so (http://ift.tt/1JmzhpT) will likely cause PT to use a size that’s different from that used by the Scarlett driver - resulting in erroneous latency compensation. For example a Scarlett 1ms buffer size with a 96 kHz sample rate session equates to 96 samples. If anything different that 128 samples is selected as PT’s “H/W Buffer Size” (its closest option) significant errors in latency compensation will occur.
One of the Beta additions appears to be an attempt to make it possible to set the buffer sizes properly from PT. The first page of the attachments shows the newly added device control interface. This appears to be a good PT workaround and enables good (within ~ 1ms) loop-back latency compensation by Pro Tools 12. But, unfortunately, I think it has a long way to go before it will be ready for release.
As the attachments show, I did testing at 48k and 96k Samples/second with the default buffer size of 256 Samples. I did however change the USB Performance Mode to “High” from the default “Safe”. I tried “Safe” too - it adds 4.7 ms to both ASIO latencies, but didn’t really seem to improve reliability/stability. Note that operating with a 96 kHz sample rate causes far less distortion than does 48 kHz.
The basic test setup consisted of connecting the 6i6 as follows: The test signal imported into Track 1 was played on Output 1. Output 1 was externally connected to Input 1 for recording on Track 2. Track 2 was “monitored” on Output 2. Output 2 was externally connected to Input 2 and recorded on Track 3. (It’s important to have the “Low Latency Monitoring” “Option” off, “Delay Compensation” doesn’t matter).
I attempted to use the track labels and comments in the attachments to explain the test configuration and results adequately. I’m kind-of new to this stuff and its terminology so please let me know if there is something that requires clarification. :-)
With the current released version of the Scarlett ASIO driver/Control Panel (Scarlett Mix Control 1.8.128.0) buffer sizes need to be entered via Mix Control before PT starts/restarts. PT should then try to calculate an appropriate approximate buffer size when it starts – and it doesn’t do it very well or reliably! That Scarlett driver does not accept/reflect buffer size changes entered from PT. Using the mesaone/Sweetwater approach that attempts to do so (http://ift.tt/1JmzhpT) will likely cause PT to use a size that’s different from that used by the Scarlett driver - resulting in erroneous latency compensation. For example a Scarlett 1ms buffer size with a 96 kHz sample rate session equates to 96 samples. If anything different that 128 samples is selected as PT’s “H/W Buffer Size” (its closest option) significant errors in latency compensation will occur.
One of the Beta additions appears to be an attempt to make it possible to set the buffer sizes properly from PT. The first page of the attachments shows the newly added device control interface. This appears to be a good PT workaround and enables good (within ~ 1ms) loop-back latency compensation by Pro Tools 12. But, unfortunately, I think it has a long way to go before it will be ready for release.
As the attachments show, I did testing at 48k and 96k Samples/second with the default buffer size of 256 Samples. I did however change the USB Performance Mode to “High” from the default “Safe”. I tried “Safe” too - it adds 4.7 ms to both ASIO latencies, but didn’t really seem to improve reliability/stability. Note that operating with a 96 kHz sample rate causes far less distortion than does 48 kHz.
The basic test setup consisted of connecting the 6i6 as follows: The test signal imported into Track 1 was played on Output 1. Output 1 was externally connected to Input 1 for recording on Track 2. Track 2 was “monitored” on Output 2. Output 2 was externally connected to Input 2 and recorded on Track 3. (It’s important to have the “Low Latency Monitoring” “Option” off, “Delay Compensation” doesn’t matter).
I attempted to use the track labels and comments in the attachments to explain the test configuration and results adequately. I’m kind-of new to this stuff and its terminology so please let me know if there is something that requires clarification. :-)
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