"Audiophile" motherboards

[DonR]

If the supplied power is insufficient to drive a DAC, it is most likely the DAC that is running too close to the top of the spec (or over it) rather than the MB not meeting the power spec. Most decent USB DACs that require larger amounts of power, relatively speaking, have a separate USB power port usually of type C.

 

[phrwn]

One thing where all PC motherboards fail, even the Apple ones, is low output impedance for IEMs.
I always get lots of hiss.
I wonder if the new Mac Studio which promises "3.5 mm headphone jack with advanced support for high-impedance headphones" is any better.

I've been using my ER4XR's too; no background noise at all. I just plugged them in and pushed the volume up to 100 to check. Nothing.

Background hiss was why I got into external DAC/amps in the first place, several years ago, but it seems to have been resolved on this board at least.

Don't get me wrong I like wasting money as much as the rest of us. I'm still unclear on whether an L30 II would give me better dynamics and more competent handling of voltage swings and so it's tempting...

 

[Sokel]

I'm really not sure what is shown here or what setup is behind this. But USB is a digital connection by design. If this were a digital connection, there would be no difference in the results. So it looks to me like there is an analog step in there with different noise levels. If so, that would be totally different from a USB-connected DAC, which relies solely on digital audio transmission and doesn't care about USB noise (up until the point where the connection fails, that is).

It's the same USB interface (E-MU ,the ones DIYAudio uses) loopback with the exact same settings through 2 different PC's.
No voltage dividers,same cabling,same everything.
Of course there are analog steps between but its the same ADC-DAC measured a million times with the same repeatable results to the last db (you can see it on Multitone thread,hundreds of measurements).
Only PC changes and noise floor with it.
Both connected to power grid,not laptops.

 

[antcollinet]

It's the same USB interface (E-MU ,the ones DIYAudio uses) loopback with the exact same settings through 2 different PC's.
No voltage dividers,same cabling,same everything.
Of course there are analog steps between but its the same ADC-DAC measured a million times with the same repeatable results to the last db (you can see it on Multitone thread,hundreds of measurements).
Only PC changes and noise floor with it.
Both connected to power grid,not laptops.

The three possibilities I see:

1 - You have a ground loop but with very low coupling of noise, different between the two PC's. I find this unlikely. Ground loops normally couple specific frequencies, such as mains frequency, or the frequencies associated with switching power supplies or graphics hardware, from the magnetic fields these noise sources create. These would show up as spikes in your plots rather than a shift in the wideband noise floor.

2 - There is wideband noise coming from the USB connection (possibly through the power connections), that is coupling into the analogue electronics of the DAC.

3 - The different motherboards output slightly different power supply voltages. The dac noise floor level is influenced a tiny amount by power supply voltage.

Possibly other mechanisms but I can't think of any right now.

I think the important point is neither of your PC's are worsening the noise floor in any audible way. I don't know if either have an "audiophile" motherboard - but even if one were used, it would make no audible improvement, in exactly the same way there is no audible improvement going from a Dac that can achieve 110dB Sinad to one with 120dB.

This just confirms the basis for my statement "So no, audiophile motherboards will do nothing for USB connections"

 

[valerianf]

"So no, audiophile motherboards will do nothing for USB connections"
In theory, that is correct.
But practically the end result could differ.
The computer is receiving the music from a digital source (streaming, file on the hard disk...), do some digital format manipulation and send the
digital file to USB.
USB is sending the 5V from the computer to the DAC.
I would strongly recommend sending a clean 5V (additional filtering) to avoid increasing the noise at the DAC level.
Could somebody try to measure the external DAC noise when the computer is playing a game full speed?
It would be interesting to see if the noise floor is increasing.

 

[Sokel]

The three possibilities I see:

1 - You have a ground loop but with very low coupling of noise, different between the two PC's. I find this unlikely. Ground loops normally couple specific frequencies, such as mains frequency, or the frequencies associated with switching power supplies or graphics hardware, from the magnetic fields these noise sources create. These would show up as spikes in your plots rather than a shift in the wideband noise floor.

2 - There is wideband noise coming from the USB connection (possibly through the power connections), that is coupling into the analogue electronics of the DAC.

3 - The different motherboards output slightly different power supply voltages. The dac noise floor level is influenced a tiny amount by power supply voltage.

Possibly other mechanisms but I can't think of any right now.

I think the important point is neither of your PC's are worsening the noise floor in any audible way. I don't know if either have an "audiophile" motherboard - but even if one were used, it would make no audible improvement, in exactly the same way there is no audible improvement going from a Dac that can achieve 110dB Sinad to one with 120dB.

This just confirms the basis for my statement "So no, audiophile motherboards will do nothing for USB connections"

My thoughts exactly.
No,none of the two is "audiophile",just decent although one of them is nearly 10yo.
I will keep measuring everyone falls in my hands,hopefully maybe an "audiophile" one too.

"So no, audiophile motherboards will do nothing for USB connections"
In theory, that is correct.
But practically the end result could differ.
The computer is receiving the music from a digital source (streaming, file on the hard disk...), do some digital format manipulation and send the
digital file to USB.
USB is sending the 5V from the computer to the DAC.
I would strongly recommend sending a clean 5V (additional filtering) to avoid increasing the noise at the DAC level.
Could somebody try to measure the external DAC noise when the computer is playing a game full speed?
It would be interesting to see if the noise floor is increasing.

For good or bad I don't play games but I can try measuring the same measurement (and more) while under heavy load.
Stay tuned!

 

[Sokel]

Could somebody try to measure the external DAC noise when the computer is playing a game full speed?
It would be interesting to see if the noise floor is increasing.

Ok,that was easy,I measured with no load and under load running the CPUID Stress Test.
Not much of a difference:
(note the bandwidth )

Edit:
Did the same with GPU under heavy load,not much of a difference.

 

[antcollinet]

Ok,that was easy,I measured with no load and under load running the CPUID Stress Test.
Not much of a difference:
(note the bandwidth )

View attachment 235522


Edit:
Did the same with GPU under heavy load,not much of a difference.

I love this @Sokel, exactly what ASR is about. Actual real world measurements to counter a world of supposition, guesswork, and worst of all: marketing.

 

[valerianf]

Excellent @Sokel, it means that we do not have to worry about the noise on the USB coming from the motherboard.
The argument from Gigabyte seems to be pure marketing...
Running an external DAC seems the best way to get a very low noise floor whatever the computer load is.
Thank you for this useful measurement.

 

[antcollinet]

Excellent @Sokel, it means that we do not have to worry about the noise on the USB coming from the motherboard.
The argument from Gigabyte seems to be pure marketing...
Running an external DAC seems the best way to get a very low noise floor whatever the computer load is.
Thank you for this useful measurement.

With caveats of course.

@Sokel 's measurements apply to the PC's and Dac he has tested with. It is possible to imagine a much worse motherboard, and a dac incapable of rejecting power supply noise.

In that case a motherboard that outputs much less noise might result in an audible improvement.


However, even in that case I'd argue that a more cost effective solution than an "audiophile" motherboard would be just a basic "good" one, combined with a competenetly designed DAC that performs at least as well the one @Sokel uses. These are not hard to find.

 

[Sokel]

With caveats of course.

@Sokel 's measurements apply to the PC's and Dac he has tested with. It is possible to imagine a much worse motherboard, and a dac incapable of rejecting power supply noise.

In that case a motherboard that outputs much less noise might result in an audible improvement.


However, even in that case I'd argue that a more cost effective solution than an "audiophile" motherboard would be just a basic "good" one, combined with a competenetly designed DAC that performs at least as well the one @Sokel uses. These are not hard to find.

And just for clarity,the dac I use (audio interface to be precise) is the 10-12 years old E-MU 0204,( about 100 euro in it's time) USB powered and no isolators or other stuff between.
The above PC is also 10 years old,mid to high at it's time,vastly inferior to the new ones of course.Just adequate for the task,is doing ok.
I expect both dac's and PC to be a lot more decent at this time.
All we have to do is use common sense.

As a comparator there's a measurement from the Khadas tone1 who many people know as an index of the limitations of that combination (measurement in dbr,no weighting so you can do the math):

(many thanks to @pkane for his time,effort,knowledge and generosity to offer us Multitone)