Is their any evidence that the SMPS in a Mac Mini audibly degrades sound quality?

[wgscott]

Title pretty much says it all.

Briefly, I've been taken to task (elsewhere) for suggesting to someone that there is no need to "upgrade" the internal SMPS in a mac mini in order to produce high-quality sound.

As a qualitative/subjective observation, I hear no difference between USB or optical input from this computer, and internet streaming of copies of these same files I store on a NAS 15 miles away, and stream directly to the DAC (Teac NT-503) via DNLA. (I was told in response that the SMPS on that NAS and every network router/switch between it and my DAC is also degrading sound quality, and the only way I can escape this is to unplug and install a costly boutique linear power supply. Also, unless I have tried it for myself, I have no business making such claims, etc. The usual.)

 

[solderdude]

One should realize that inside a PC/Mac there are lots of other, non replaceable SMPS present for various CPU voltages and other stuff. Not just the main power supply.

The ones making the claims may buy fancy smancy linear power supplies all day long and tell folks how great it is.
After all that has been replaced your cables are the next hurdle, and the fuses, and the mains cords, and the ethernet cables .. and ... and.
Perhaps put those folks on ignore.

 

[vitalii427]

Here you can find some info: https://www.audiosciencereview.com/...ar-power-supply-review-and-measurements.1849/

 

[Hugo9000]

Here you can find some info: https://www.audiosciencereview.com/...ar-power-supply-review-and-measurements.1849/

Just finished reading the whole thread. Very interesting in a number of ways, thanks very much for linking it!

 

[Blumlein 88]

I have proof of it. It was arrived at with total subjective listening methodology. And the fix was evaluated the same way. I never used so much as a multi-meter.

My good audiophile friend complains that something may have happened to his tubed phono stage. It is distorting especially on peaks. So a few days later I get by there. Sure enough it seems okay at first, but high levels cause an odd distortion, sometimes even warbling and motor boating. I suspect a bad tube or a capacitor having gone bad. But it is neither of these. I'm thinking about and noticed when I came in he had re-arranged the gear on his shelf. Sitting next to it about 6-8 inches away is the 2011 Mac Mini he uses for computer based audio. The PS side of the Mini is next to the phono side of the preamp.

Okay so on a hunch, I shut down and unplug the Mini. Distortion is gone. Everything is beautiful. Just messing with things now, I have him plug it back up and bring it online. Where once again we get the distortion. I rigged a temporary fix by taping some aluminum foil to the back of a legal pad. I connect an alligator clip to one corner and the other to a neutral ground lead on a power strip. I can stick the foil shield between the devices and distortion is gone completely. Pull it away and distortion returns. So the SMPS in the Mini can sound worse than if the Mini had an LPS instead.

Now the line stage was not bothered. A phono stage is supplying 50 db or so of gain into a relatively high impedance so picking up garbage is much easier than most other components in a home hifi rig. So would this create noise and issues with digital based gear? I doubt it. You could do a simple shield like I did between it and all the rest of your gear. Compare sound both ways. No need to buy an LPS. I know from experimentation that balanced leads could be wrapped around the Mini without any pickup of the noise.

My friend moved his phono and Mini apart by 3 feet and all was well. So distance or shielding or both would work without an LPS being needed.

Is some of this getting into the USB and traveling downstream to cause trouble? I wouldn't doubt that within the smaller confines of a Mini the USB might actually have a little more noise pickup though without measuring I don't know. I don't think it will get thru and cause issues with the analog output of the DAC until someone shows me measures that it does. The radiated interference is taken care of by distance or shielding.

 

[wgscott]

Gosh, I wish there were more posters like you on ComputerAudiophool.

I'm a bit surprised that a Mac Mini case wouldn't be an adequate Faraday cage.

Presumably if contamination of the USB datastream was a thing, comparing to that delivered via optical could be revealing.

 

[rebbiputzmaker]

Gosh, I wish there were more posters like you on ComputerAudiophool.

I'm a bit surprised that a Mac Mini case wouldn't be an adequate Faraday cage.

Presumably if contamination of the USB datastream was a thing, comparing to that delivered via optical could be revealing.

Maybe he needs to wear a dress when he posts there, you would feel better.

 

[Thomas savage]

Could @amirm measure a Mac mini? I’d like to know just how good a device for Audio it is.

 

[svart-hvitt]

Could @amirm measure a Mac mini? I’d like to know just how good a device for Audio it is.

Could he (@amirm ) lose his golden pension benefits?

 

[rebbiputzmaker]

Could @amirm measure a Mac mini? I’d like to know just how good a device for Audio it is.

As we already know all computers are the same.

 

[rebbiputzmaker]

Could he (@amirm ) lose his golden pension benefits?

Were they a golden parachute , or golden showers (of cash)?

 

[amirm]

Could @amirm measure a Mac mini? I’d like to know just how good a device for Audio it is.

I don't have one to measure unfortunately.

 

[amirm]

Could he (@amirm ) lose his golden pension benefits?

No worries. I have a macbook pro...

 

[Sylafari]

I had a possibly similar issue but with an Apple TV 4K. It was right next to my RME ADI-2 DAC, and the headphone output had static in the background. Moved the Apple TV 4K like two feet away and the issue was resolved.

 

[wgscott]

I don't have one to measure unfortunately.

I have an under-used 2010 mini I could send you if you would be willing.

 

[Don Hills]

... So the SMPS in the Mini can sound worse than if the Mini had an LPS instead. ...

It possibly can, but your test didn't show it either way. You'd need an LPS to prove / disprove it. It's possible that whatever was upsetting the phono preamp was being generated by other circuitry in the Mac Mini rather than its SMPS. It also has limited relevance to the original issue, where it was claimed that the SMPS had an audible effect on the audio being played from the Mac Mini.

(Just observations by the way, no criticism expressed or implied. I've had my own battles with EMI in phono stages over the years. The worst was when I was living in a house with a 2 KW AM broadcast transmitter antenna in the back yard. It was so bad I had to ground myself when using my computer, otherwise if I hovered my hands over the keyboard it would type random characters. With my amp, the EMI was actually getting in via the speaker cables. I had to fit bifilar wound chokes close to the amp.)

 

[Old Listener]

I have proof of it. It was arrived at with total subjective listening methodology. And the fix was evaluated the same way. I never used so much as a multi-meter.

My good audiophile friend complains that something may have happened to his tubed phono stage. It is distorting especially on peaks. So a few days later I get by there. Sure enough it seems okay at first, but high levels cause an odd distortion, sometimes even warbling and motor boating. I suspect a bad tube or a capacitor having gone bad. But it is neither of these. I'm thinking about and noticed when I came in he had re-arranged the gear on his shelf. Sitting next to it about 6-8 inches away is the 2011 Mac Mini he uses for computer based audio. The PS side of the Mini is next to the phono side of the preamp.

Okay so on a hunch, I shut down and unplug the Mini. Distortion is gone. Everything is beautiful. Just messing with things now, I have him plug it back up and bring it online. Where once again we get the distortion. I rigged a temporary fix by taping some aluminum foil to the back of a legal pad. I connect an alligator clip to one corner and the other to a neutral ground lead on a power strip. I can stick the foil shield between the devices and distortion is gone completely. Pull it away and distortion returns. So the SMPS in the Mini can sound worse than if the Mini had an LPS instead.

Now the line stage was not bothered. A phono stage is supplying 50 db or so of gain into a relatively high impedance so picking up garbage is much easier than most other components in a home hifi rig. So would this create noise and issues with digital based gear? I doubt it. You could do a simple shield like I did between it and all the rest of your gear. Compare sound both ways. No need to buy an LPS. I know from experimentation that balanced leads could be wrapped around the Mini without any pickup of the noise.

My friend moved his phono and Mini apart by 3 feet and all was well. So distance or shielding or both would work without an LPS being needed.

Is some of this getting into the USB and traveling downstream to cause trouble? I wouldn't doubt that within the smaller confines of a Mini the USB might actually have a little more noise pickup though without measuring I don't know. I don't think it will get thru and cause issues with the analog output of the DAC until someone shows me measures that it does. The radiated interference is taken care of by distance or shielding.

A first rate post.

Audiophiles often think about a theoretical problem with audio playback and immediately buy gear billed as a solution. Then they listen and usually hear a significant improvement in sound quality. There is no attempt to verify that the theoretical problem has a real, audible effect before buying additional gear and no valid experiment after the new gear is in hand to verify that there was a real difference.

Your experience was quite different. The start was an actual problem with sound quality: repeatable, easily heard sounds foreign to the music. You went through a troubleshooting process to identify the cause of the problem. You did simple but valid experiments and then verified the cause with a couple of additional experiments. It didn't require buying gear to solve the problem.

You contrasted the effect of fields from the Mac on a phono stage cable vs. the effect on a line stage cable. You rarely find any sense that quantity matters in audiophile discussions.

I lived with LPs and turntables for a few decades before bidding them good riddance and good bye.

 

[Reddy]

is a distortion from the mains audible??!! i think it is worthwhile to see what happens before the smps

 

[Hybride]

Hi all, i just joined this great forum! At this time Mac Mini is my favorite toslink streamer for my toslink DAC. In the past i experienced that streaming audio over LAN gives a lot of jitter related problems, especially in case of using USB(2). Tried LAN filters, usb filters, super clean PSU's, LAN>Toslink converters, dedicated lan cables, routers etc. Every change was audible. In that case; everything matters imo. To avoid most of these problems i now prefer streaming directly from HDD (with VLC) Toslink out, with VLC remote app over LAN. The mac mini 2014 is powered through a SEEC HQSN-4U mainsfilter. Ok, max 96khz, but i do not find that a problem.

 

[AnalogSteph]

In the past i experienced that streaming audio over LAN gives a lot of jitter related problems, especially in case of using USB(2).

Jitter? From what you write I'd rather suspect a ground loop related problem. (Your Ethernet wiring is some sort of shielded twisted pair, I bet?) Any USB DAC with plainly audible jitter would measure pretty terrible.

Toslink out, with VLC remote app over LAN.

If it was a ground loop, it has now been eliminated. Well, assuming the DAC's power supply is well-behaved.