Topping D10s noise via Mac mini

[Thomas_A]

I did some initial experiments with the D10s and Cosmos in the Cosmos thread, and got some weird 100 Hz noise when D10s was connected to Mac mini. Since this seems to be related more to the D10s and Mac mini I made a separate thread.

The noise profile, measured with macbook/E1DA on battery. Thus no ground loop. It was the same whether or not connected through the Topping HS01 isolator, powered with a separate USB/telehone charging PSU (it did not work without).

Looping the thing only via the Macbook looked like it should (with isolator):

So my question: is this what you can expect in "real use" - that measured performance drops significantly? Or is it anyway to fix this with the Mac mini to D10s?

 

[gvl]

The level of those spikes is very low, there’s nothing to worry about.

 

[Thomas_A]

The level of those spikes is very low, there’s nothing to worry about.

Agreed, but I still don't like the results. And I wonder why it happens and if it is fixable.

 

[Sokel]

The level of those spikes is very low, there’s nothing to worry about.

That's for sure.
Problem is that he payed for a 2023 114 SINAD DAC not a 2007 noisy interface (still inaudible).

 

[gvl]

Agreed, but I still don't like the results. And I wonder why it happens and if it is fixable.

There’s some elevated noise it seems but it’s not because of what you see in this chart. Try to power the Mac from the wall maybe. If you don’t hear the hiss through your speakers the noise is not really an issue.

 

[Thomas_A]

There’s some elevated noise it seems but it’s not because of what you see in this chart. Try to power the Mac from the wall maybe. If you don’t hear the hiss through your speakers the noise is not really an issue.

The Mac mini is powered from wall. It is used as center for music storage and other small things so it is connected to my Marantz AVR. Having a separate DAC to the AVR improves performance - at least I thought so.

The results raise some questions regarding performance in "optimal measurement conditions" and in "real-life use". High-end results and praised reviews but not getting that performance in practice is quite disappointing.

 

[Thomas_A]

That's for sure.
Problem is that he payed for a 2023 114 SINAD DAC not a 2007 noisy interface (still inaudible).

Exactly.

 

[CedarX]

Not sure if it can help… I remember reading reports of weird hiss or statics caused by the total absence of ground on the Mac Mini. Most of the time, the Mini is grounded through the HDMI monitor cable, but not always, and not with a D10S that is only USB-connected.
A simple test is to plug a 3.5 cable into the Mini audio output and connect the other end to some ground to see if the noise on the D10S remains or not…

 

[Thomas_A]

Not sure if it can help… I remember reading reports of weird hiss or statics caused by the total absence of ground on the Mac Mini. Most of the time, the Mini is grounded through the HDMI monitor cable, but not always, and not with a D10S that is only USB-connected.
A simple test is to plug a 3.5 cable into the Mini audio output and connect the other end to some ground to see if the noise on the D10S remains or not…

Thanks,

the Mac mini is hooked up against my AVR (HDMI, in/otrput), and to external HD through USB. It should, as it is centre for storage and I make use of real-time click repair (RIAA stage) through the Mac mini etc.

Why and how the 100 Hz noise comes in through the USB->D10s is a bit of mystery. There is no return path from the measurememt loop, so no ground issue.

 

[gvl]

Why and how the 100 Hz noise comes in through the USB->D10s is a bit of mystery.

Why are you picking on the 100Hz? Its level lies at close to -130dB and is utterly inconsequential. Yes 98dB Sinad is a bit low but it’s not because of the 100Hz spike or its harmonics. What am I missing?

 

[Sokel]

How does it looks like when you only measure noise floor with digital silence?

 

[holla]

Why are you picking on the 100Hz? Its level lies at close to -130dB and is utterly inconsequential. Yes 98dB Sinad is a bit low but it’s not because of the 100Hz spike or its harmonics. What am I missing?

It's a bit hard to see at the higher frequencies but at least up to 3kHz it looks like most of the non-harmonic noise is on multiples of 100Hz so perhaps that's the reason for concern over the 100Hz?

 

[Thomas_A]

Why are you picking on the 100Hz? Its level lies at close to -130dB and is utterly inconsequential. Yes 98dB Sinad is a bit low but it’s not because of the 100Hz spike or its harmonics. What am I missing?

I bought the D10s and E1DA for two reasons; one for upgrading my 20 year old Transit DAC used for measurements and second to use the D10s as add-on DAC between Mac mini and AVR.

You are completely correct that the noise is below audible level. What annoys me is that I bought the unit based on good reviews/measurements for the purposes above, and it fails to deliver the performance unless I use it in my Macbook loop. In the Mac mini/AVR connection the approx. -98 dB THD+N is barely an improvement from my 20 year old Transit DAC. It's a disappointment.

 

[Thomas_A]

How does it looks like when you only measure noise floor with digital silence?

I'll see if I do the RCA short experiment with silence today.

 

[BKDad]

The noise profile, measured with macbook/E1DA on battery. Thus no ground loop. It was the same whether or not connected through the Topping HS01 isolator, powered with a separate USB/telehone charging PSU (it did not work without).

And, there's your ground loop. Maybe.

The HS01 also isn't universally applicable, since it doesn't consistently operate well above USB Full Speed data rates. Wasn't designed to.

Here is what I measure, using an iMac and both the D10s and the E1DA ADC connected to the same USB hub. Guess which trace is with the isolator in place.

Naturally, my power supply related spikes are at multiples of 60 Hz instead of 50 Hz.

Results are similar with the E1DA connected to a battery operated MacBook Air and the D10s connected to the iMac or with the USB devices plugged directly into the iMac instead of through a hub. I also got similar results with a Topping HS02 and with an Olimex USB-ISO, although the latter was limited to Full Speed use.

Connecting the D10s to one iMac on the lab bench and the E1DA ADC to another iMac plugged into a different AC mains connection across the room gives quantitatively similar icky results. The ground loop is just longer, so the spectrum is different.

Perhaps Mac Minis are different. Is there a monitor plugged into it? How about an Ethernet connection? With the iMac, the monitor is built in, so there's no separate AC mains connection. My iMac doesn't use an Ethernet connection.

Forget the measurements for a second. Does the D10s sound OK to you in actual use while playing music? If so, then there's no problem. I'm hardly dismissing measurements, but at some point the rest of the system's imperfections - like noise - will mask whatever is coming out of the D10s. Plus, there's also a point where imperfections are inaudible. We often tend to forget all that when passionately arguing about whether a DAC with a SINAD of 121.3 dB is superior to one with 120.9 dB. In actual use, there's so many systemic effects that although measurements like that are probably accurate they don't come close to telling the entire story.

 

[Thomas_A]

And, there's your ground loop. Maybe.

The HS01 also isn't universally applicable, since it doesn't consistently operate well above USB Full Speed data rates. Wasn't designed to.

Here is what I measure, using an iMac and both the D10s and the E1DA ADC connected to the same USB hub. Guess which trace is with the isolator in place.

View attachment 303049

Naturally, my power supply related spikes are at multiples of 60 Hz instead of 50 Hz.

Results are similar with the E1DA connected to a battery operated MacBook Air and the D10s connected to the iMac or with the USB devices plugged directly into the iMac instead of through a hub. I also got similar results with a Topping HS02 and with an Olimex USB-ISO, although the latter was limited to Full Speed use.

Connecting the D10s to one iMac on the lab bench and the E1DA ADC to another iMac plugged into a different AC mains connection across the room gives quantitatively similar icky results. The ground loop is just longer, so the spectrum is different.

Perhaps Mac Minis are different. Is there a monitor plugged into it? How about an Ethernet connection? With the iMac, the monitor is built in, so there's no separate AC mains connection. My iMac doesn't use an Ethernet connection.

Forget the measurements for a second. Does the D10s sound OK to you in actual use while playing music? If so, then there's no problem. I'm hardly dismissing measurements, but at some point the rest of the system's imperfections - like noise - will mask whatever is coming out of the D10s. Plus, there's also a point where imperfections are inaudible. We often tend to forget all that when passionately arguing about whether a DAC with a SINAD of 121.3 dB is superior to one with 120.9 dB. In actual use, there's so many systemic effects that although measurements like that are probably accurate they don't come close to telling the entire story.

Yes, I get that measurement with and without isolator using Macbook only in the loop. The isolator was powered by a two-prong telephone charger, no ground loop there ( as seen in my second Macbook measurement).

Mac mini is connected to the AVR (HDMI), RIAA (analogue in), ethernet and to external HDs. I had a connection from Mac mini, analogue or optical to AVR. Plan was to go Mac mini -> D10s ->AVR analogue in, for 2-channel music sources. It will work of course - but as it is now I just won a few dB over my 20 year old M-audio Transit DAC. The second use of it will be measurements together with the E1DA - as for now I have to go for the Macbook as measurement centre to get good performance. Strange that I cannot get the same performance from the Mac mini.

 

[BKDad]

The isolator was powered by a two-prong telephone charger, no ground loop there ( as seen in my second Macbook measurement).

That certainly looks to me like a ground loop connection. It happens to be modulated at a 50 Hz rate (in Europe - 60 Hz here) as the diodes conduct to turn the AC mains signal into DC 50 times each second. 100 times if a bridge rectifier is used. There's no question that no chassis ground can simplify the overall mesh, though.

Probably a better name is "common mode current connection." Most everybody gets messed up by the term ground. Actual ground connection implies dirt...

 

[gvl]

I bought the D10s and E1DA for two reasons; one for upgrading my 20 year old Transit DAC used for measurements and second to use the D10s as add-on DAC between Mac mini and AVR.

You are completely correct that the noise is below audible level. What annoys me is that I bought the unit based on good reviews/measurements for the purposes above, and it fails to deliver the performance unless I use it in my Macbook loop. In the Mac mini/AVR connection the approx. -98 dB THD+N is barely an improvement from my 20 year old Transit DAC. It's a disappointment.

I understand your disappointment, What I don’t understand is why you think 100kHz and its harmonics are the reason for the decreased performance.

 

[Thomas_A]

That certainly looks to me like a ground loop connection. It happens to be modulated at a 50 Hz rate (in Europe - 60 Hz here) as the diodes conduct to turn the AC mains signal into DC 50 times each second. 100 times if a bridge rectifier is used. There's no question that no chassis ground can simplify the overall mesh, though.

Probably a better name is "common mode current connection." Most everybody gets messed up by the term ground. Actual ground connection implies dirt...

Do you see 50/100 Hz signal in the second graph?

 

[Thomas_A]

I understand your disappointment, What I don’t understand is why you think 100kHz and its harmonics are the reason for the decreased performance.

What can it be that differs graph 1 to graph 2?