[Whit3Rav3n]

but then why would a ground loop exist between the 2 interfaces if they are both connected to the same computer. When connected by usb or coax then they share the same ground with the computer. Also balanced xlr would not solve a ground loop problem it only eliminates noise that the cable picks up. 

 

[frebs]

Cheers Tim
Thanks for the info.
I'm hoping to get a couple Muses 02 from a friend who says there is a definite noticeable difference then the 01's. 
Will let you know on how they sound.
I have had my E1 Plus for 2 weeks now. Not yet dived inside to play with the op-amp kit. Still letting it burn in.
I am planning on upgrading the caps in the audio stage and also the volume control, not looked at which audio grade caps yet and it would be nice to have a remote control volume (possibly TAIV VC-03), might need a bigger box for the volume control upgrade, if I go for it. I will probably change the wires to silver too. Not a clue on what I will settle for op-amps. I was told the chinese like brighter faster music and that all Muses would be a bit to bright. but that's a matter for my ears to decide, looks like a mix and match job. 
That's interesting to read about PSU cooling, I did notice mine a bit hot when I had it sat on top my PC at work.
I did think about off board power supplies may be power supply per channel also valve output stage.
But then how far do I go, am still sat back and enjoying the sound from a good DAC with the added pleasure of being able to use it late at night with headphones.

 

[frebs]

strange that link did not work for me too.
Try Google Hificollective.co.uk at the top in the grey bit click components and then semiconductors. this will take you to Dexa Technologies, NewClassD Op-amps & regulators Burson Audio Op-amps you might have seen these already. I am a bit new to digital. I still love the old valve stuff. Moving my music to laptop has taken me down the road of external DAC's. Thankfully the E1 Plus was a good buy & a good solid build to upgrade & play with.

 

[broke7224]

I am not a fan of asus xonar one but I can hear a distinct sound between upsampled and un-upsampled on my BDP-105 DAC.

 

[stv014]

Quote:

but then why would a ground loop exist between the 2 interfaces if they are both connected to the same computer. When connected by usb or coax then they share the same ground with the computer. Also balanced xlr would not solve a ground loop problem it only eliminates noise that the cable picks up. 

 
Even though they are connected to the same computer, their ground is not connected to exactly the same point of the computer, and since there is a non-zero resistance between the two ground points, a non-zero voltage can fall on that from the ground currents of the CPU, GPU, and other devices. Balanced interconnects, when implemented properly, do eliminate ground loops by not using ground as the reference for audio signals - ground noise (relative to pin 1) appears as common mode noise on both pin 2 and pin 3, and it gets rejected by the differential input.
 
To demonstrate this in practice, here are three RMAA measurements of the same sound card output, using three different configurations for recording:

 
The first case is a simple loopback, using the ADC is on the same card. There is no ground loop problem, and the results are quite decent.
 
In the second case, I used the Xonar Essence STX sound card installed in the same PC for the recording. Even though it has a better ADC than the Xonar D1, all the measurements are notably worse, and the noise in particular is dramatically worse, and is degraded to the level of typical onboard audio. The reason why this happens is that there is a ground loop between the two sound cards, even though their audio jacks are separated by the ground resistance of only about 5 centimeters of metal chassis.
 
The third case is similar to the second one, but this time I inserted a differential amplifier to the loopback to reject the ground noise. This configuration gives the best results - now taking advantage of the better ADC - except for crosstalk, which is slightly degraded by the extra cables, connectors, and amplifier circuit. Using a differential input improved the noise by 22 dB.
 
You may wonder why an RCA to XLR adapter does not necessarily work as well as the third test above, which essentially does the same. The potential problem is that the adapter may connect the ground wire to both pin 1 and pin 3 of the XLR connector so that there is a ground connection between the two devices, but that also prevents the differential input from being able to reject the ground noise.

 

[Archimago]

Quote:

 
Even though they are connected to the same computer, their ground is not connected to exactly the same point of the computer, and since there is a non-zero resistance between the two ground points, a non-zero voltage can fall on that from the ground currents of the CPU, GPU, and other devices. Balanced interconnects, when implemented properly, do eliminate ground loops by not using ground as the reference for audio signals - ground noise (relative to pin 1) appears as common mode noise on both pin 2 and pin 3, and it gets rejected by the differential input.
 
To demonstrate this in practice, here are three RMAA measurements of the same sound card output, using three different configurations for recording:

 
The first case is a simple loopback, using the ADC is on the same card. There is no ground loop problem, and the results are quite decent.
 
In the second case, I used the Xonar Essence STX sound card installed in the same PC for the recording. Even though it has a better ADC than the Xonar D1, all the measurements are notably worse, and the noise in particular is dramatically worse, and is degraded to the level of typical onboard audio. The reason why this happens is that there is a ground loop between the two sound cards, even though their audio jacks are separated by the ground resistance of only about 5 centimeters of metal chassis.
 
The third case is similar to the second one, but this time I inserted a differential amplifier to the loopback to reject the ground noise. This configuration gives the best results - now taking advantage of the better ADC - except for crosstalk, which is slightly degraded by the extra cables, connectors, and amplifier circuit. Using a differential input improved the noise by 22 dB.
 
You may wonder why an RCA to XLR adapter does not necessarily work as well as the third test above, which essentially does the same. The potential problem is that the adapter may connect the ground wire to both pin 1 and pin 3 of the XLR connector so that there is a ground connection between the two devices, but that also prevents the differential input from being able to reject the ground noise.

Thanks stv014! Nice measurements and discussion.  I'll have a better look at the setup later this week and your detailed results when I have some time.
 
The MAIN thing I remain concerned about is that frequency response issue with upsampling at 44kHz (and probably 48). I hope ASUS takes this seriously as it's a clear "defect" in an otherwise excellent product IMO!

 

[hotsauce81]

Hi All
I got my E1 today and i have it running with ASIO/bitperfect from Foobar. If i press the upsampling-button the led's for Hz indication goes dark. Is this normal?

 

[Archimago]

Quote:

Hi All
I got my E1 today and i have it running with ASIO/bitperfect from Foobar. If i press the upsampling-button the led's for Hz indication goes dark. Is this normal?

Yes. It'll do that...

 

[hotsauce81]

Ah. OK.
Thanks for the reply

 

[Archimago]

ASUS:
If you guys are looking into this frequency response issue with upsampling, why not just implement a minimum phase filter with slow roll off from about 18kHz for the 44/48kHz sampling rates? This is of course a bit of what the big boys like Esoteric, Ayre and Meridian have been doing over the years.
 
That would be something many of us can conceivably use and potentially beneficial from the sound quality perspective (lets turn this defect into something potentially good!). It should be quite easy to implement with the SHARC DSP - open source software like SOX can easily do this already for years...
 
In fact, all my 16/44 music is minimal phase upsampled to 24/88 on the server side when I listen to the Transporter to get rid of that pre-ringing...
 
http://archimago.blogspot.ca/2013/02/measurement-asus-xonar-essence-one.html

 

[Whit3Rav3n]

Quote:

 
Even though they are connected to the same computer, their ground is not connected to exactly the same point of the computer, and since there is a non-zero resistance between the two ground points, a non-zero voltage can fall on that from the ground currents of the CPU, GPU, and other devices. Balanced interconnects, when implemented properly, do eliminate ground loops by not using ground as the reference for audio signals - ground noise (relative to pin 1) appears as common mode noise on both pin 2 and pin 3, and it gets rejected by the differential input.
 
To demonstrate this in practice, here are three RMAA measurements of the same sound card output, using three different configurations for recording:

 
The first case is a simple loopback, using the ADC is on the same card. There is no ground loop problem, and the results are quite decent.
 
In the second case, I used the Xonar Essence STX sound card installed in the same PC for the recording. Even though it has a better ADC than the Xonar D1, all the measurements are notably worse, and the noise in particular is dramatically worse, and is degraded to the level of typical onboard audio. The reason why this happens is that there is a ground loop between the two sound cards, even though their audio jacks are separated by the ground resistance of only about 5 centimeters of metal chassis.
 
The third case is similar to the second one, but this time I inserted a differential amplifier to the loopback to reject the ground noise. This configuration gives the best results - now taking advantage of the better ADC - except for crosstalk, which is slightly degraded by the extra cables, connectors, and amplifier circuit. Using a differential input improved the noise by 22 dB.
 
You may wonder why an RCA to XLR adapter does not necessarily work as well as the third test above, which essentially does the same. The potential problem is that the adapter may connect the ground wire to both pin 1 and pin 3 of the XLR connector so that there is a ground connection between the two devices, but that also prevents the differential input from being able to reject the ground noise.

In this case both interfaces should be connected to the same power outlet so they are grounded the same way or one of them should not be grounded at all. Most XLR connectors i have seen just re-invert the inverted signal and add it together with the non inverted signal. I am pretty sure that all of the cheaper AD interfaces work that way.

 

[stv014]

Quote:

In this case both interfaces should be connected to the same power outlet so they are grounded the same way or one of them should not be grounded at all.

 
That is not relevant here, because the ground loop is created in the computer, and not through the power outlets. The above example used two internal sound cards in the same PC, but even if they were external (like in the case of Archimago's measurements), the effect would be the same.
 
Quote:

Most XLR connectors i have seen just re-invert the inverted signal and add it together with the non inverted signal.

 
Which works for its intended purpose of rejecting common mode noise.

 

[Whit3Rav3n]

Quote:

 
That is not relevant here, because the ground loop is created in the computer, and not through the power outlets. The above example used two internal sound cards in the same PC, but even if they were external (like in the case of Archimago's measurements), the effect would be the same.
 
 
Which works for its intended purpose of rejecting common mode noise.

It is relevant since they are not exclusively grounded to the computer but also to the outlet, so if both interfaces are grounded to the same outlet there should be no ground loop in the signal.
 
It works for rejecting noise in the cable but it would not work for ground loops since the ground is still the reference level for the signal.

 

[stv014]

Quote:

so if both interfaces are grounded to the same outlet there should be no ground loop in the signal.

 
That can fix AC hum resulting from potential differences between the outlets, but not noise between different ground points of the same computer. You can frequently see people complaining on this forum about "computer noise" they get in the audio signal when using a grounded external amplifier, and it does not go away when both the computer and the amplifier are grounded to the same outlet.
 
Quote:

It works for rejecting noise in the cable but it would not work for ground loops since the ground is still the reference level for the signal.

 
The noise resulting from the ground potential difference is the same on both the inverting and the non-inverting input, therefore it can be canceled out. What do you think is responsible for the 22 dB drop in the noise floor when I added the differential amplifier in the example above ?

 

[Whit3Rav3n]

Yes but that is with analog signal, these interfaces would be connected via digital cable to the computer. But then i don´t really belive that the reason for the noise is really the grounding, since the resistance differences are so small that it would be really difficult to even measure it. It is far more likely that the noises come from ripples in the power supply caused by the pc components.