Topping D10s noise via Mac mini

[BKDad]

Folks - there is a reason an audio precision costs 10's of thousands. Don't for one minute think you are going to get results as good as it using a couple of hundred £ ADC (No matter how good that ADC may be), combined with consumer grade PC, power systems and interconnects.

Well, you probably can come close. At least, close enough for hobbyist purposes. The problem is that it takes real effort to get it all right. Optimization of those PCs, power systems, and interconnects takes time and often money. Most owners of AP test systems value the time it takes to get it right more than hobbyists do. And, they should. Many hobbyists demand plug and play perfection.

I think the big point this all highlights is that in a real system, you can't just plug in any piece of gear and expect to get system performance that matches the idealized test results. The good news is that this may not matter so much in a practical sense.

 

[Tangband]

What problem? Noise spikes at -120dB? It is incredibly difficult to get system noise down at this level. What on earth makes you assume this is a problem with the device being tested, rather than the much more likely test setup?

Folks - there is a reason an audio precision costs 10's of thousands. Don't for one minute think you are going to get results as good as it using a couple of hundred £ ADC (No matter how good that ADC may be), combined with consumer grade PC, power systems and interconnects.

What youre saying here is that one cant expect much from a consumer grade PC, true - but this dac is made to be connected to such a computer . Maybe more measurements is needed using a crappy PC to show the real noise numbers ?

 

[Sokel]

A lesson learned from this might be that If one connects a computer thats not running on batterys, one can not expect a SINAD higher than 100 with a dac.

No,that's not true,all the measurements that I posted here is from a full tower PC,with GPU's and everything,connected to el.grid and I get 105 SINAD from the Khadas despite all that.
You can get even better with proper gear (mine is next to vintage,it's a wonder they still work! ).

 

[BKDad]

A lesson learned from this might be that If one connects a computer thats not running on batterys, one can not expect a SINAD higher than 100 with a dac.

The lesson really probably is that how things are connected together matters. Powering by battery certainly eliminates one or more connections in the current mesh.

 

[antcollinet]

You can see my #32 post for a similar (and much worst in terms of conditions) test with different devices.
I'm trying to point out that everything is specific to the measured system,essentially we're saying the same thing.

Ah! Im good at being in violent agreement with people.

 

[antcollinet]

The problem is that Thomas bought a dac with a reallity SINAD of 98 when he expected 110.
Even if you cant hear such a difference, the selling points of this cheap dacs are a low price combined with spectacular measurement results. People expect to get highend results for almost no money.

A lesson learned from this might be that If one connects a computer thats not running on batterys, one can not expect a SINAD higher than 100 with a dac.

No, he still has a dac with 110 sinad. But his system sinad is lower. it will always be the case that system sinad is worse than the worst rated individual component In the chain.

and you can have as grumpy a pc as you like. Connect it to the system only with toslink and it will be like it is not there.

 

[BKDad]

No, he still has a dac with 110 sinad. But his system sinad is lower. it will always be the case that system sinad is worse than the worst rated individual component In the chain.

and you can have as grumpy a pc as you like. Connect it to the system only with toslink and it will be like it is not there.

Toslink has its own limitations, unfortunately. You can make great USB isolators these days, though. Pick your poison...

 

[antcollinet]

Toslink has its own limitations,

Not many though. More than capable of being totally transparent.

 

[Thomas_A]

Have not had time today for more experiments. But I previously disconnected everything to the Macmini except for the USB to D10s but no change:

E1DA Cosmos ADC

What sample rate did you try?Olimex may to allow you to do more that 44.1/48K. This was 44.1 and 24 bit. I tried both through REW and Audacity. Got some intermittent messages as well; not possible to write to device. Software froze as well.

www.audiosciencereview.com

 

[Zek]

1st measurement. PC > USB2 port > E-MU0204 DAC > 20cm cable >E-MU0204 ADC > (same) USB2 > PC.
2nd measurement.PC > USB3 port > E-MU0204 DAC > 20cm cable >E-MU0204 ADC > (same) USB3 > >PC.

This confirms what was said earlier that USB3 ports are worse for audio transfer than USB2 ports.

 

[Sokel]

This confirms what was said earlier that USB3 ports are worse for audio transfer than USB2 ports.

Not necessarily,this only happens to E-MU.
The Khadas DAC I measured in #32 post has similar performance either on USB2 or USB3.

Difference is that Khadas is powered by a Salas Reflektor-D PSU,not the port itself.
I will measure it stock though some time and compare,I'm curious.

What is more important is that we're blind without a way to measure and see,there to many variables that can mess things up.

 

[AnalogSteph]

In the first one:
Mac mini->D10s->E1DA->Macbook (battery). Result is exactly the same if I have an USB isolator with prong inserted or not.

There is no difference between having the USB isolator between the Mac mini and D10s? Hmm. Well, I mean, the Macbook technically is already floating, so you wouldn't expect any ground loop action.

I suspect the root of your problem may be the difference between audio ground and surrounding earth potential, in conjunction with capacitive coupling vias cables and whatnot. Try giving the D10s an explicit ground connection.

Besides, how exactly did you hook up the unbalanced outputs of the D10s to the balanced inputs on the Cosmos ADC? Is it a properly balanced connection? Impedance balance is kind of critical since common-mode input impedance on the ADC is quite low. It also scales with selected input level, being directly tied to differential mode input impedance. In other words, the effect should reduce at higher nominal input level. Ideally, the Cosmos ADC requires a high-performance buffer of sorts.

 

[Thomas_A]

There is no difference between having the USB isolator between the Mac mini and D10s? Hmm. Well, I mean, the Macbook technically is already floating, so you wouldn't expect any ground loop action.

I suspect the root of your problem may be the difference between audio ground and surrounding earth potential, in conjunction with capacitive coupling vias cables and whatnot. Try giving the D10s an explicit ground connection.

Besides, how exactly did you hook up the unbalanced outputs of the D10s to the balanced inputs on the Cosmos ADC? Is it a properly balanced connection? Impedance balance is kind of critical since common-mode input impedance on the ADC is quite low. It also scales with selected input level, being directly tied to differential mode input impedance. In other words, the effect should reduce at higher nominal input level. Ideally, the Cosmos ADC requires a high-performance buffer of sorts.

As per the Cosmos thread I soldered short RCA to XLR cables. They are correctly made. Shown in the Cosmos thread.

Will try get time for some more trials today

 

[antcollinet]

As per the Cosmos thread I soldered short RCA to XLR cables. They are correctly made. Shown in the Cosmos thread.

Will try get time for some more trials today

Theres more than one way to create an RCA to XLR cable. None of them are particularly correct, though some are better than others. Which one did you use? (I"m not prepared to browse through pages of the other thread to find it)

 

[Zek]

Difference is that Khadas is powered by a Salas Reflektor-D PSU,not the port itself.

This is a very significant difference.

 

[Thomas_A]

Theres more than one way to create an RCA to XLR cable. None of them are particularly correct, though some are better than others. Which one did you use? (I"m not prepared to browse through pages of the other thread to find it)

As recommended here

E1DA Cosmos ADC

Thanks, so this is GND/USB noise between mac mini and the D10s and not looped through the Cosmos USB? Using the macbook (battery) only gave even worse noise, so the USB/GNDs are really noisy. Much worse than my cheap old Transit DAC/ADC. (I will make an order another day - going for heart...

www.audiosciencereview.com

 

[Thomas_A]

I think there is just no way to solve this with the Mac mini to DAC. Here are three connections, all other connections removed from the Mac mini:

Mac mini to D10s:

Mac mini to Transit DAC:

Macmini analogue out:

As you see the 100 Hz noise is there from the analogue out from the Mac mini. So it pollutes the signal no matter if I use analogue out or USB. There is no ground loop here, but just a noisy computer.

So I get around 10 dB better THD+N with the D10s (-98 dB) than the other connections, but I don't get the -110 to -112 that I can get with the Macbook. What I win over the Mac mini output is lower THD.

Perhaps this performance degradation is specific for Mac mini and this model, or perhaps it is exists with other computers as well. Who knows?

 

[Tangband]

I think there is just no way to solve this with the Mac mini to DAC. Here are three connections, all other connections removed from the Mac mini:

Mac mini to D10s:
View attachment 303685

Mac mini to Transit DAC:
View attachment 303686
Macmini analogue out:
View attachment 303687

As you see the 100 Hz noise is there from the analogue out from the Mac mini. So it pollutes the signal no matter if I use analogue out or USB. There is no ground loop here, but just a noisy computer.

So I get around 10 dB better THD+N with the D10s (98 dB) than the other connections, but I don't get the 110-112 that I can get with the Macbook. What I win over the Mac mini output is lower THD.

Perhaps this performance degradation is specific for Mac mini and this model, or perhaps it is exists with other computers as well. Who knows?

I believe noisy computers are very common If they are connected to the powergrid. Because they are not made for hifi in specific and the powersupply is probably very cheap , only good enough for daily use of the computer ( non music ).

Here you can read about how your topping is constructed, very interesting .

Topping D10 balanced DAC review

Website of Nathalie Beimler.

nathaliebeimler.com

 

[gvl]

@Thomas_A is this a full scale signal you’re looking at and if so what are the output voltages in those 3 cases?

 

[antcollinet]

I believe noisy computers are very common If they are connected to the powergrid. Because they are not made for hifi in specific and the powersupply is probably very cheap , only good enough for daily use of the computer ( non music ).

Here you can read about how your topping is constructed, very interesting .

Topping D10 balanced DAC review

Website of Nathalie Beimler.

nathaliebeimler.com

Like I say - connect your PC (as noisy as you like) to your audio system with Toslink - and it will be as though it is not there - except for the pure sweet music.