Cannot get good data for card calibration

[tommyboy]

I cannot get a clean frequency response from my DAC. It contains data that has a "disturbance in The Force". This time it focused around 500 Hz but it moves around to land at different frequencies (200 to 9000 Hz) and intensity depending exactly how high I set the sweep volume. I tried different channels... same result. Same blip but in a different spot. DanDan said DAC cards aren't typically worth measuring and I'd like to forget about it... but now that I've seen it I can't move on until I know what this is. Is this something real that I need to know about? or just a malfunction of some kind? Anyone have an opinion?

Externally i connected the Ch 6 output to the Ch 5 input.

 

[John Mulcahy]

Looks like a dropout, try a larger ASIO buffer (or a higher latency setting if that's how it is configured). Bigger is generally better for the buffer setting for measurement reliability. Other factors can have an influence, WiFi can interfere sometimes, or background processes can take priority long enough to cause a dropout, depending on the buffer size.

 

[tommyboy]

Thank you. The image/data above was with the buffer at 256. Just tried a couple more at 1024, 4096, and 32. They all have the blip... just at different frequencies. If it's WiFi, would the frequency be consistent? My eventual goal is to measure my live/tracking room in my studio. I don't want to move forward if my DAC is out of whack. Do you think that perhaps I should ignore this? DAC is Lynx Aurora16 and computer card is Lynx AES16.

 

[DanDan]

Is it audible during the sweep?

 

[tommyboy]

The sweep is audible; sounds smooth. I do not hear any audible blip and it sweeps through. To be fair; it would be difficult to hear a 2 db change in a relatively fast sweep.

 

[DanDan]

Well you could slow it right down. I am trying to establish if the problem is in the sweep or the recording. Afaik it is possible to generate a sweep and play it from some other device, even a phone or such.

 

[John Mulcahy]

WiFi interference can happen anywhere during the sweep, try turning off WiFi. After you make a measurement the "Captured" graph shows the captured sweep, can see if there looks to be anything untoward there. It is only shown for the last measurement made.

I'm not following your reference to the Aurora16 DAC, your soundcard preferences show the AES16 is providing the output and the input, the DAC isn't in the path?

 

[tommyboy]

Sorry about the description. The Aurora16 is a stand-alone, rackmount 16-channel AD, 16-channel DA converter. In order for my DAW computer to use it I have a Lynx AES16e (PCIe) sound card that accepts all 16 in and out digital signals. Using ASIO drivers I arbitrarily chose Channel 6 as the output and Channel 5 as the input. When I run REW, Channel 6 output seems to get signal from it. I externally connected the output of Channel 6 to the input of Channel 5 (as the instruction imply) and so that Channel 5 input also shows the signal. I don't understand how or which signal gets recorded by REW... but it gets recorded. I will try 1) slowing the sweep down from the Tools | Measure screen, and 2) try turning off the WiFi. I will get back to you as it will take me a little while to set up and do it. Thank you both!

 

[tommyboy]

Had a chance to run a slower sweep. Played it back on a different computer using Microsoft Groove Music app. I can't really hear anything unusual. Below is a link to it (11M wav file).

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1drv.ms

I haven't had a chance yet to turn off the WiFi. Hope to do that today. (Waiting til everyone is off.)

 

[tommyboy]

As suggested by Mr. Mulachy, I tried sweeping REW measurements with and without the WiFi turned on. Both have the blip... but at different places. Nothing else was changed. Same connection. Same sweep. Same T-shirt I wore yesterday. If anyone can explain The Blip I would be most grateful. Maybe a better course of action is to use a different system - computer onboard A-D. Any thoughts?

 

[sm52]

If anyone can explain

maybe a switching power supply? Phone charging, sound card power supply, laptop fan. On the other hand, the amplitude of the noise is small. You can always keep it in mind and work on. There is also always a way to replace the components of the path one at a time.

 

[Bernard]

Hello,
Was the laptop connected to the AC power supply?
Sometimes, disabling Wi-Fi is not enough. You also need to work on battery to avoid AC interference (50 Hz in Europe) and even disable your antivirus.

Apart from that, REW works very well with Windows 11 since yesterday.

 

[tommyboy]

Thank you, sm52 and Bernard. Sorry for the late response, I didn't realize someone had answered. I'm using a desktop. In fact, two desktops. Swapping out the power supplies does have a significant hassle factor... or did you mean just use the battery? I've taken some time off because this and some closely related issues have worn me out. When I resurface I will try disconnecting the antivirus. Thank you for your assistance.

 

[sm52]

just use the battery

check if there is a difference between battery and mains power.

 

[tommyboy]

Unfortunately I cannot because I do not have a battery. It's a desktop computer. (Yeah, I'm one of those people.) Thanks for your thoughtfulness. This is a great forum. I think I'll give it a rest for a few days.

 

[ddude003]

Had a chance to run a slower sweep. Played it back on a different computer using Microsoft Groove Music app. I can't really hear anything unusual. Below is a link to it (11M wav file).

Share

Folder

1drv.ms

I haven't had a chance yet to turn off the WiFi. Hope to do that today. (Waiting til everyone is off.)

Your above sweep file looks fine... Used 2 other audio tools to look for the glitch and I could not spot any...

I am wondering if this is some kind of clock glitch when in loopback mode... Also, could be a system (windoz) tuning issue and there are utilities that can quiet your system processes or tutorials on how to strip down the system for more precise audio use...

As a reminder, are you running the latest software, drivers and firmware from Lynx? You might contact Lynx and see what they might have to say about this...

 

[tommyboy]

Thanks, ddude. Thanks for checking out the sweep on other tools. The blip that shows in the REW frequency report is semi-repeatable. It repeats in that there is always a blip. However, it appears at different frequencies, anywhere from 200-14000 Hz depending on the volume of input. As of an hour ago I am using the latest firmware from July 2021... still get the blips. Before that I was using a Feb 2020 firmware, which is still fairly recent seeing as how I bought this unit over 10 years ago and had updated the firmware at least three times. I may need to rethink my DAC choices. Hmmmm.

 

[ddude003]

Another thought would be some kind of contention on the PCI bus, maybe with a GFX/GPU card?

 

[jschwender]

I would try to find out if that an issue that is caused by signal input processing or signal output processing by checking with alternatively replacing the input and output device. An additional sound card for testing may be helpful.

 

[tommyboy]

Back in business! Thanks to my friend, Steve Allen. Turns out it was a clock syncing issue. MY FAULT. My PCIe card that talks to my ASIO drivers as well as my ADDA converter was using its own clock instead of syncing to my converter. Once we made the converter the slave, everything matched up. LIke I've said all along, the people on this forum are wonderful folks; and thanks to you all for hanging in there with me and giving me advice.

 

[John Mulcahy]

Phew!