Quick measurements with Topping E1x2 OTG: Your help is appreciated

[Guddu]

Dear FMs,

I borrowed this Topping E1x2 OTG from a FM who lived near me, I tried to take some measurements but could use help from you all for pointers to get it more accurately.

Topping E50 II > TRS out to XLR input on E1x2 OTG
Drivers: ASIO4ALL
REW: Output: Topping E50II USB, Input: Topping E1x2 OTG Analog IN

Basic noise/distortion with signal generator & RTA:

Does it make any sense?

 

[staticV3]

Drivers: ASIO4ALL

Don't use ASIO4All in REW.

Simply select Driver type: Java, then in the device drop-down, the EXCL versions of you DAC and ADC.

Regarding your measurements, while THD looks fine SNR is weirdly low.

What's the signal voltage coming from your DAC?

Edit:
Ah -12dBFS, sorry missed that.
Yeah looks fine considering, but you should be able to use almost 0dBFS with the E50II set to Low gain.

 

[Guddu]

Don't use ASIO4All in REW.

Simply select Driver type: Java, then in the device drop-down, the EXCL versions of you DAC and ADC.

Okay, will give it a try again.
When I did earlier, I got worse results and thought ASIO4ALL might be better option.

Regarding your measurements, while THD looks fine SNR is weirdly low.

Yes, SNR came low when I simply checked E1x2 Analog out to its XLR input. Tried a different settings and values but it didn’t improved.

 

[staticV3]

Okay, will give it a try again.
When I did earlier, I got worse results and thought ASIO4ALL might be better option.

Make sure you use EXCL.

If you do, you get bit-exact I/O and far greater stability than ASIO4All.

 

[Guddu]

Thanks @staticV3
Tried JAVA with exclusive mode again (I think I did the same before, but can't be sure) and now getting better results:

Now with these settings:
E50 II's volume set to -2.5 dB (above this interface shows clipping)

 

[Guddu]

Is it safe to say that its using close to 2V signal without a multimeter check on E50's cable out?
Here is quick Freq. sweep as well:

Any pointers on what else useful I can try to capture with REQ on this setup, for DAC?

 

[staticV3]

Is it safe to say that its using close to 2V signal without a multimeter check on E50's cable out?
Here is quick Freq. sweep as well:

View attachment 528161


Any pointers on what else useful I can try to capture with REQ on this setup, for DAC?

Best to use dBFS in the generator instead of dBV.

Then you can figure out the output voltage with some simple math.

With 0dBFS in REW and -0dB on the E50II, with the DAC's gain set to Low, you'll get ~5.6V via TRS out.

If you apply attenuation in REW or on the DAC, then you can calculate the output voltage via 5.6*10^(total attenuation in dB/20).

E.g. set REW to -6dBFS and the E50II to -1.5dB and you get 5.6*10^(-7.5/20)=2.36V out of the DAC.

In the same stroke you can calculate the total attenuation required to hit a certain target voltage via 20*log10(target voltage / 5.6).

E.g. to get 2.0V out of the E50 II's TRS port with the DAC set to Low gain, you need to apply 20*log10(2.0/5.6)= -8.94dB of signal attenuation.

 

[Guddu]

Best to use dBFS in the generator instead of dBV.

Then you can figure out the output voltage with some simple math.

With 0dBFS in REW and -0dB on the E50II, with the DAC's gain set to Low, you'll get ~5.6V via TRS out.

If you apply attenuation in REW or on the DAC, then you can calculate the output voltage via 5.6*10^(total attenuation in dB/20).

E.g. set REW to -6dBFS and the E50II to -1.5dB and you get 5.6*10^(-7.5/20)=2.36V out of the DAC.

In the same stroke you can calculate the total attenuation required to hit a certain target voltage via 20*log10(target voltage / 5.6).

E.g. to get 2.0V out of the E50 II's TRS port with the DAC set to Low gain, you need to apply 20*log10(2.0/5.6)= -8.94dB of signal attenuation.

Tried both, similar results

 

[staticV3]

Tried both, similar results

View attachment 528165

View attachment 528166

Input amplitude hardly changed, so did you mean you tried REW -6dB with DAC -0dB and REW -0dB with DAC -6dB when you wrote "tried both"?

 

[Sokel]

Some higher resolution and averaging helps as well.
Set 8 averages for example and 64k FFT.

You can also scale the dBFS range to 0dB to -150dB or so for better looks.

There is something strange though about levels, are you using Windows mixer to attenuate the ADC at some point? That would show abnormally low noise at some cases.
Check out the distortion panel and uncheck the Manual fundamental if it's checked.

 

[Guddu]

Input amplitude hardly changed, so did you mean you tried REW -6dB with DAC -0dB and REW -0dB with DAC -6dB when you wrote "tried both"?

Both screenshots have settings noted:
1st One: Generator -6.00 dBFS, E50 II TRS Out -1.5 dB
2nd One: Generator 0.00 dBFS, E50 II TRS Out -8.5 dB

 

[staticV3]

Both screenshots have settings noted:

Ah I see, the DAC part isn't visible as you've used black text color on a transparent background (PNG):


Besides that, yeah it's expected that the two perform the same.

 

[staticV3]

There is something strange though about levels, are you using Windows mixer to attenuate the ADC at some point?

OP uses EXCL input, so the Windows mixer is bypassed.

 

[Guddu]

Some higher resolution and averaging helps as well.
Set 8 averages for example and 64k FFT.

You can also scale the dBFS range to 0dB to 150dB or so for better looks.

RTA settings:

There is something strange though about levels, are you using Windows mixer to attenuate the ADC at some point? That would show abnormally low noise at some cases.
Check out the distortion panel and uncheck the Manual fundamental if it's checked.

I don't think I have changed or used any mixer settings. This is how Topping's app looks:

Do you think might be causing any issues and better to remove it?

 

[staticV3]

Do you think might be causing any issues and better to remove it?

Having the Control center installed does not cause any issues.

After all, you're already matching Amir's Audio Precision measurements of the E2x2 at 109dB SINAD, so all's good.

 

[Sokel]

OP uses EXCL input, so the Windows mixer is bypassed.

Not always, it depends how the VC is implemented.
Example:



Normal, attenuated by REW.



0dB at REW, -3dB by win mixer



and an extreme case just for the case here (-121dB noise! )

All done with java EXL (no way E-MU would have -110dB noise at shared mode)

We have talked about such VC at Multitone thread, and to pay attention about it as someone can game the results big time.
Same or similar with the manual fundamental.

 

[Guddu]

Not always, it depends how the VC is implemented.
Example:

View attachment 528173

Normal, attenuated by REW.

View attachment 528175

0dB at REW, -3dB by win mixer

View attachment 528177

and an extreme case just for the case here (-121dB noise! )

All done with java EXL (no way E-MU would have -110dB noise at shared mode)

We have talked about such VC at Multitone thread, and to pay attention about it as someone can game the results big time.
Same or similar with the manual fundamental.

Do you any of such errors in the my posted outputs as well?

 

[Sokel]

Do you any of such errors in the my posted outputs as well?

If you had levels at REW calibrated by a DMM you would see that each amount of attenuation by REW would result at the same level but at 0dB gain.

Your last chart shows 0dB at REW and about -8.5 dB for both level and gain, so it has to be somewhere before REW, your DAC if I understand well.
So many points of possible attenuation, the best you can do is to calibrate.

Get your DMM, measure DAC's output and fill the boxes at REW's generator and RTA window.

 

[Guddu]

If you had levels at REW calibrated by a DMM you would see that each amount of attenuation by REW would result at the same level but at 0dB gain.

Your last chart shows 0dB at REW and about -8.5 dB for both level and gain, so it has to be somewhere before REW, your DAC if I understand well.
So many points of possible attenuation, the best you can do is to calibrate.

That -8.5 dB and -1.5 dB earlier are the volume levels on E50 II DAC, I have printed that below generator snapshot as well.

I didn’t change any such settings like gain or mixer on Windows 11.

Get your DMM, measure DAC's output and fill the boxes at REW's generator and RTA window.

I had in mind to find output voltage levels with a few different volume levels, and I tried my DMM after long time and sadly that didn’t work, I am going to get a new one soon.
I thought there might be a way to find it on E1x2’s software or some other software tool but don’t know yet.

 

[Sokel]

That -8.5 dB and -1.5 dB earlier are the volume levels on E50 II DAC, I have printed that below generator snapshot as well.

I didn’t change any such settings like gain or mixer on Windows 11.



I had in mind to find output voltage levels with a few different volume levels, and I tried my DMM after long time and sadly that didn’t work, I am going to get a new one soon.
I thought there might be a way to find it on E1x2’s software or some other software tool but don’t know yet.

A DMM is the best buy you can do, ever, it comes handy in any occasion.
Use REW's "calibrate" button at generator and at RTA window and follow the instructions.

That way you will be able to also use voltage charts accurately, which is a great help at gain staging.