Topic: Fireface UCX WDM audio dropouts

I have a Fireface UCX connected to a Windows PC:

CPU: Intel Core i7-5775C
Mainboard: Gigabyte GA-H97N-WIFI

The Fireface was running stably for years on Windows 8.1, connected via Firewire using a PCIe extension card.

A few weeks ago I updated to Windows 10. My Firewire card does not seem to work correctly with it, so I switched the Fireface connection to USB (using USB driver 1.167). Since this change, I encounter random audio dropouts when I play back audio via WDM (e.g. Spotify, YouTube). Audio via ASIO seems to work correctly (at least I did not have any dropouts there, yet).

When a dropout happens, the meter of the output channel in TotalMix FX drops as well. The error counter in the Fireface USB Settings dialog does not show any errors, though.

The manual suggests using a dedicated USB controller for the Fireface and connecting all other USB devices to a different controller. I downloaded USB device tree viewer (https://www.uwe-sieber.de/usbtreeview.html) and found out that I only have one single USB controller, so I cannot change it. I tried different USB ports, but this did not make any change.

Does anyone have an idea how to solve this?

2

Re: Fireface UCX WDM audio dropouts

Try buffer sizes 128 and 256 samples. All others are more critical for WDM operation.

Also download the Resplendence LatencyMon to check for system problems.

Regards
Matthias Carstens
RME

Re: Fireface UCX WDM audio dropouts

Make measuring with LatencyMon as suggested by MC. In properiert select method kernel latency timer and watch what the minimum and usual values are.
For an ideal system the min kernel latency timer is around <5 microseconds which should be reached by the system at least a few times during a 5 minute measuring interval. Usual values between 5 and 30 microseconds. Peaks should be low under 100 microseconds or something is blocking the CPU cores for too long, either:
- energy saving in the bios
- wrong energy settings in windows
- inefficient / bad drivers
- too many background tasks
Bad drivers you can identify also with LatencyMon. You can see it already during measuring with a higher number of ISR and DPC.

What other usb devices or hubs are connected to the systen besides mouse and keyboard? Disconnect all other and try all USB 2+3 ports whether one works better than the other.

What are your BIOS settings in terms of
- enervy saving ( c/p/t-states, c1n)
- Turbo
- speed step (EIST)
Disable Energy Saving and eventually also EIST and Turbo to get a fix cpu clock which is ideal for lowest system internal latencies to get a more agile reacting system.

Check whether Windows 10 is optimized for background tasks.

Use O&OWin10Shutup to reduce the amount of background tasks by disabling ie apps of the Start menu and telemetry data collecting  processes.

If you do nothing as user on your system then the system should be IDLE .. only very little background activity should happen. This needs to be reduced so that your CPU has full power and no lag fulfilling audio tasks which have near realtime requirements.

Therefore always disable automatic software updates.

Before making changes to your system make sure that you have a working backup and restore, best by using Macrium Reflect. It's fast and reliable and reduces the wear on your SSD because it changes only disk blocks during restore operation that need to be changed.

BR
Ramses
X10SRi-F, E5-1650v4, Win10Pro21H2, Cub11Pro, UFX+, XTC, 12Mic, ADI-2 Pro FS R BE, RayDAT

Re: Fireface UCX WDM audio dropouts

Thanks very much for your helpful replys.

MC wrote:

Try buffer sizes 128 and 256 samples. All others are more critical for WDM operation.

I have been using 64 samples buffer size for years, without problems. Does this make a difference between FireWire and USB? Why is WDM more critical than ASIO concerning the buffer size? Shouldn't I see buffer erros in the error counter if this is a buffer issue?

ramses wrote:

Make measuring with LatencyMon as suggested by MC. In properiert select method kernel latency timer and watch what the minimum and usual values are.
For an ideal system the min kernel latency timer is around <5 microseconds which should be reached by the system at least a few times during a 5 minute measuring interval. Usual values between 5 and 30 microseconds. Peaks should be low under 100 microseconds or something is blocking the CPU cores for too long, either:

I did that and measured a usual value of 995µs. Value drops to something between 50µs and 150µy regularly. I never saw values under 40µs, though. So this is obiously totally unusual and way too high, right?

Concerning other USB devices: Besides mouse and keyboard, I have two dongles (for Cubase and ProTools) connected via a USB hub and a USB MIDI keyboard. For the latency tests above I already removed the hub with the dongles.

I will check my energy settings later, but before there's something new I noticed: everytime a dropout happens, the host LED on the Fireface blinks shortly. So actually the Fireface seems to lose its connection to the PC, right? Does this bring any relevant news to the topic?

5

Re: Fireface UCX WDM audio dropouts

1. Yes, you talk about WDM and different drivers (USB/FW) and driver architecture. WDM is limited to buffer sizes of 256 samples, but somtimes that fails and one has to choose 128. 64 might work if the computer is capable for it.

2. Such are software errors which are not shown in the error display.

3. Yes, the FF blinking means complete loss of sync. That should be visible in the error display. Maybe only for a short moment as the automatic restart resets the error display.

Regards
Matthias Carstens
RME

Re: Fireface UCX WDM audio dropouts

Turning energy saving off and a stable maximum clock frequency are the fundament for getting an agile system without lag.

Measuring software alarms when kernel latency is over 1000 microseconds which is 1ms.

Everything which is over 100 microseconds on an IDLE system alarms me that the system doesn't deliver optimum performance.

The higher the lag of the system is the more you need to compensate by higher ASIO buffersizes which impacts RTL between recording device and pc through USB.

Therefore optimum performance is desirable to be able to have more stability/headroom that you can use lower ASIO buffersize's where needed when you need less than 10ms RTL ie when workin with VSTi''s like a virtual Guitar amp or drums.

BR
Ramses
X10SRi-F, E5-1650v4, Win10Pro21H2, Cub11Pro, UFX+, XTC, 12Mic, ADI-2 Pro FS R BE, RayDAT

Re: Fireface UCX WDM audio dropouts

MC wrote:

3. Yes, the FF blinking means complete loss of sync. That should be visible in the eror display. Maybe only for a short moment as the automatic restart resets the error display.

Thanks, that pointed me in a good direction. In fact, the loss of sync is not visible in the error display, because the USB settings dialog closes automatically in the moment the error happens. Using this information, I was able to do long-term tests without being present, because I could see if the error had appeared from the USB settings dialog being still open or not.

I noticed that I could reproduce the error by wiggling the USB plug on the PC side slightly. That made me think that maybe my USB cable is not that good. In fact, the only two USB cables I had lying around were ~12 years old. With both cables the error was reproducable.

So I ordered a new high-quality USB cable. I'm really not into cable voodoo, but I did not want to make a compromise here, so I chose an Oehlbach USB plus for ridiculous 20 Euros (while this is still cheap, as I also found USB cables for 900 Euros #wtf?!).
And this was it: the error is gone. I have been running my PC for 48 hours now playing audio non-stop without any loss of sync. Still using buffer size of 64 samples, so I am happy again.

Thank you very much for your help!

Re: Fireface UCX WDM audio dropouts

I think 20 Euro is well invested money, because you can get then cables which are good shielded.
I am using for example Lindy Cromo Line USB3 cable which has three shields and can be 5m long (IIRR  specification is only 3m) but without getting any USB transport errors.
Vodoo for USB cables start for me personally at much higher prices than 20 or 25 Euro.

BR
Ramses
X10SRi-F, E5-1650v4, Win10Pro21H2, Cub11Pro, UFX+, XTC, 12Mic, ADI-2 Pro FS R BE, RayDAT

9

Re: Fireface UCX WDM audio dropouts

The point is: did you do the wiggle test again? I had the same problem some time ago, my old test cable's connectors simply got too worn out...

Regards
Matthias Carstens
RME