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Gustard x16 roll off fast starting around 8khz

nrdjcb

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I have tested my new Gustard x16 using REW with loopback to behringer UMC404HD and I found that it starts roll off fast starting at 8khz, has anyone encouner this problem?
 

solderdude

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Most likely there is something wrong with the measurements.
 

Pdxwayne

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I have tested my new Gustard x16 using REW with loopback to behringer UMC404HD and I found that it starts roll off fast starting at 8khz, has anyone encouner this problem?
No. I did similar loopback using REW before and no such problem. I used Scarlett Solo as loopback device.
 
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nrdjcb

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When I loopback the behringer I get flat response
 
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nrdjcb

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Both connected via usb to Mac Book Pro, the gustard as output device and the behringer as input device and the gustard output to the behringer mic input
 

Pdxwayne

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Both connected via usb to Mac Book Pro, the gustard as output device and the behringer as input device and the gustard output to the behringer mic input
Interesting.....How long have you owned ithe Gustard?

Have you tried other DAC with your behringer to make sure it is not the mic input issue?

Also, what filter are you using on your Gustard? All three filters give same results?
 
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nrdjcb

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I have it for about a week. I have tested the behringer by loopback its main output to its mic input and I get flat response. The PCM filters should roll off around 18khz.
 

Pdxwayne

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I have it for about a week. I have tested the behringer by loopback its main output to its mic input and I get flat response. The PCM filters should roll off around 18khz.
I see. About how many hours you think it was on totally?

I have a thread about x16 burn in (which was received very negatively by many) and my first REW measurements (after weeks of usage) is at https://www.audiosciencereview.com/...my-gustard-x16-measurements.20679/post-688957

Filter 1 slopes more. As you can see in the next couple posts, filter 2 and 3 are flatter. Can you share yours?
 
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nrdjcb

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OP, do you think you could take some loopback measurements using RMAA and upload results by any chance (I think the forum should take a zipped .sav file or HTML report)? I am not entirely trusting REW for this type of measurement yet, although both programs have their quirks.
sorry, currently I can't but I attached my results:
 

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Pdxwayne

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sorry, currently I can't but I attached my results:
Wow, it is pretty steep drop. For me, my well used x16 with filter 1 only drop by less than 1db all the way to 18khz.

Which x16 filter do you use when doing this measurement?

Can you estimate how many total hours your x16 is actually powered on?

Also, what made you want to measure the frequency? The DAC sounds dull?
 
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nrdjcb

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Wow, it is pretty steep drop. For me, my well used x16 with filter 1 only drop by less than 1db all the way to 18khz.

Which x16 filter do you use when doing this measurement?

Can you estimate how many total hours your x16 is actually powered on?

Also, what made you want to measure the frequency? The DAC sounds dull?
Approx. 35 hours - l-fast
 

mdsimon2

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Not quite sure this is the source of the issue but I have seen similar issues if the DAC and ADC sample rate are mismatched as REW expects them to be the same (the one specified in REW). On a Mac this is very easy to change in "Audio MIDI Setup", I assume there is something equivalent on a PC.

Michael
 

solderdude

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I think the problem here is that different DAC and ADC is used. Might be a setting on REW.

You could try a really slow sweep as well in case it is a timing thing (most likely that's what's causing this)

The developper of REW ( @JohnPM) is also active here. He might have some pointers.

I would suggest you do the following test:

You play a white noise on the X16 and record it using the 0404 for at least 1min.
Then, using Audacity have a look at the spectrum.

I don't think there is anything wrong with the X16. A drop-off at 8kHz would be very audible when using it normally.
Doing a proper measurement isn't as easy as most think it is.
 
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nrdjcb

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Thank you all for your help,
I got the same results (even worse) when recording and analysing it with Audacity.
It seems that the problem was with the sample rate and the NOS mode. If I set both devices to 44.1 and NOS "off" then I get the expected FR for l-fast m-slow and h-fast.
 

solderdude

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Filter-less NOS is the silliest mode ever invented at 44.1 or 48. Some like the 'weird kind of roll-off'.
It does not adhere to the sampling theorem and is flawed.
Any measurements involving NOS will be horrible.
Even then... at 20kHz it should be about - a few dB at most not 20dB
Why not make the dB scale 0 to 90dB or so .. it shows a lack of experience with measurements.

Funny thing is that with music it isn't even that bad sounding and is a testimony about how poor and forgiving the hearing is.

Look at the waveform during the test (REW allows this). > 5kHz you cannot even recognize a sine wave in that signal.
 
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dsnyder0cnn

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I've been meaning to measure my X16 for a while. It just sounds so darn good, it's been tough to force myself to pull it out of the system long enough to run some tests.

I am hearing some clicking / distortion when playing DSD streams during silence or very low levels in the source material. This may be enough motivation for me to connect it up to the bench and see what's what. I'll share my results soon.
 

devopsprodude

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I've been meaning to measure my X16 for a while. It just sounds so darn good, it's been tough to force myself to pull it out of the system long enough to run some tests.

I am hearing some clicking / distortion when playing DSD streams during silence or very low levels in the source material. This may be enough motivation for me to connect it up to the bench and see what's what. I'll share my results soon.
I was having that problem when connected to Macbook Pro with high sample rates set. I don't have any issues at 96000 Hz.
 
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