1 (edited by chrbe 2019-02-03 10:00:18)

Topic: Which RME interface provides lowest latency for a given buffersize?

Hi all,

I would like to know which RME interface would give the lowest roundtrip latency at a given buffersize, lets say 64 samples, (at 48kHz). I am guessing the hdspe AIO or 9652? Yes, I understand that other things affect latency apart from the audio interface, like converters etc. I am not asking about the capacity to process many tracks etc, I am purely looking for the latency of streaming a stereo pair.

Thanks

2 (edited by ramses 2019-02-05 06:40:38)

Re: Which RME interface provides lowest latency for a given buffersize?

I wouldn't use a PCI card anymore, because the number of mainboards with PCI slots is very limited.

In general the RTT times are very low for every RME product, but to get really the lowest RTT times I recommend you to take a recording interface which has all required I/O ports already on board.

The reason for this is that when connecting AD/DA converters via digital ports such as MADI or ADAT, you need to add their AD/DA conversion time to the RTT.

The DAW only shows you the RTT up to the recording interface (what the ASIO driver reports to the DAW). This does not include the additional time required for AD/DA conversion from devices connected behind.

You can see this from the following table, which I put together some time ago.

I haven't had an AIO at hand, but the card will surely have very good values and you would have the advantage that the card is connected directly to the PCIe bus.

Times for AD/DA conversion depending on the sample frequency you can luckily find in the RME handbook.
It's great that RME delivers all these valuable informations :-)

https://www.tonstudio-forum.de/index.php/Attachment/2343-UFX-UFX-RayDAT-Latencies-v2-jpg/

You can nicely expand the AIO using digital I/O ports:

As the AIO offers 3 digital ports (ADAT, SPDIF, AES) you can easily expand this unit with i.e.
- ADI2 Pro FS get high end AD/DA conversion (via i.e. AES)
- either Preamps or AD/DA converter via ADAT

The AIO also allows analog expansion, see RME product page / handbook.

In regards to expanding the AIO with an ADI-2 Pro FS now or in the future:

1. This blog article shows, how nicely the ADI-2 Pro FS integrates into a RME recording environment: https://www.tonstudio-forum.de/blog/ind … our-Setup/

2. And in terms of RTT latencies you are also on the save side, because the ADI-2 Pro FS AD/DA converters
have a very low latencies:
- AD          : 0,11ms @44.1kHz, 0,10ms @48kHz, 0,06ms @96kHz, 0,026 @192kHz
- DA Sharp: 0,14ms @44.1kHz, 0,13ms @48kHz, 0,06ms @96kHz, 0,029 @192kHz
- DA Slow  : 0,12ms @44.1kHz, 0,11ms @48kHz, 0,05ms @96kHz, 0,024 @192kHz

Advantage of this combination is to have the AIO with TMFX for routing and the ADI-2 Pro FS on top for reference quality (speakers, phones).

BR
Ramses
X10SRi-F, Win7 Prof, Nuendo 8.3, UFX+, Octamic XTC, ADI-2 Pro FS BE/DAC, RayDAT, ARC USB

Re: Which RME interface provides lowest latency for a given buffersize?

As you do not respond ... is something unclear?

BR
Ramses
X10SRi-F, Win7 Prof, Nuendo 8.3, UFX+, Octamic XTC, ADI-2 Pro FS BE/DAC, RayDAT, ARC USB

Re: Which RME interface provides lowest latency for a given buffersize?

ramses wrote:

As you do not respond ... is something unclear?

No, it's very clear thank you!
I was mostly waiting for someone who had some (more) measurements from the series of cards I was interested in. The two measurement of the AIO card I have found are: https://www.gearslutz.com/board/music-c … hlight=rtl
at 5,283 ms at 64 samples 48kHz

and from the former DAW-bench forum which is offline now. Vince measured it at 4.263ms.

I have an ESI ESP1010 that I measured at 3.923ms. It's puzzling that low-cost cards perform "better" in this regard, but I also understand that the drivers for the AIO-interface is made to account for the much larger track count that it can handle simultaneously.

Re: Which RME interface provides lowest latency for a given buffersize?

Just curious, why are you interested in such minimal differences, of lets say 1ms?

Vincent, Amsterdam
https://soundcloud.com/thesecretworld
HDSP9652+ADI-8AE  2X HDSP9632
Cubase pro10

6 (edited by tzzsmk 2019-02-07 15:53:07)

Re: Which RME interface provides lowest latency for a given buffersize?

lowest latency will provide PCIexpress card without analog ADDA converters, as far as I remember, clear winner was HDSPe AES long time ago and nothing has changed smile

PCIexpress cards in general will provide lowest "reliable" latency due to being directly "plugged" into computer CPU (without additional bus controller drivers like USB, FW etc..), so HDSPe AIO would be best stereo balanced analog I/O solution

right now when I check reported latency in Reaper, stereo FLAC track (44.1kHz) played, HDSPe AIO, CoreAudio MacOS High Sierra hackintosh (6-core i7-5820K at 4.3GHz):
at requested buffer "16" I get 0.9/1.7ms (second number being roundtrip), reported realtime cpu usage around 10-11%
at buffer "8" (not even sure if it happens I can see 14spls latency, so I guess it cannot go lower than 14 by design, no crackling though) I get 0.9/1.6ms, RT cpu usage around 11.5%

HDSPe AIO, Fireface UFX, Octamic D, Octamic II
i7-5820K, X99-S, Eris E8
Reaper, High Sierra