Mac Mini power supply

[usblues]

Hi Chris.There's a cat from So Cal who, is apparently out of his garage building power supplies for the mac mini.Its 400$ and I have no tech details but he thinks some other customers will be posting on the Gon fairly soon.Just wondering if you have any thoughts or is it a little early on?Thanks,Bob

 

[silverlight]

Is this the one? Looks pretty cool

 

 

 

 

 

 

[usblues]

I have not seen unit from him.Just mail back and forth today with general ramblings.That one from you is a beauty.Is it yours?Do you have an upgraded PS for the MM?Thanks for the tip,Bob

 

[silverlight]

This is the one I use. Doesn't look as sexy, but did much for the sound in my setup (and don't forget to add a Furutech fuse )

 

 

[usblues]

Not nearly as sexy.That other was almost Zanden-like.More like a 4K unit rather than a 400$ piece.Ah well,I see another fellow this weekend is going to audition 2 different PS for the mac mini.Should be interesting.Nice system you have,good to hear from you,thanks,Bob

 

[earflappin]

I'm eager to try a linear power supply for my MM as well. I bought a lab bench linear power supply which is adjustable between 2-32V and have tried it on my LIO-8. On the LIO-8 I could not hear an improvement. I bought a MM cable and will use it to connect to my linear PSU. I also bought on trial an optical FireWire extender which provides complete electrical isolation between my LIO-8 and the MM. I could not hear an improvement with it and sent it back. The question in my mind is how would a linear PSU improve sonic performance in an asynchronous interface application? My experimentation tends to show that the LIO-8 at least is not susceptible to electrical noise transfer from the MM....so....how then?

 

Do you have a link to the guy who is offering the MM linear PSU for $400? It looks great.

 

[barrows]

I will only speculate here: a linear power supply will be relatively quiet in terms of the amount the amount of high frequency noise it produces compared with a stock switching supply (there are those who will point out that sophisticated low noise switching supplies can be built, like those custom supplies used in Linn and Chord products). I doubt that a low noise external supply will make any difference to the audio performance of a computer, because the computer will still produce a huge amount of high frequency noise internally, due to DC-DC converters, processing chips, spinning hard drives, etc.

But, using a linear supply will put less noise back on the AC line. Any improvements in performance from using a linear supply is very likely the result of lowering the noise level on the AC line (which can get in to other components in the audio system and produce sonic problems). Additionally, the switching supplies can also broadcast airborne RFI, which could get into the audio system as well (picked up through cables acting as antennas, or by the components themselves).

The MH DAC/ADCs use internal DC-DC converters as well, but I believe that the designer has gone to great lengths in the board layout of these units to reduce any problems that could be caused by internal power supply(ies) noise, this may explain why a linear supply may not improve the performance of the MH products.

 

[earflappin]

Barrows, many thanks for your thoughtful post. I think you add a lot of value to the CA forum.

 

After my last post I decided to do a comparison of my Macbook Pro on battery versus my Mac Mini on it's stock SMPS. I used Pure Music on both machines and the same FW cable. Dang if the MB Pro doesn't sound better - there is a notable increase in clarity across the frequency spectrum. Now that I hear the diffence I cannot go back to the MM with SMPS.

 

As a side note....I have been following the Pure Music thread and while I have had zero issues with v1.45 on my Mac Mini I am getting periodic drop outs on the MB Pro running on battery mode. Same configuration. Perhaps related to battery operation?

 

As I noted in my other post, when I tried an optical FW extender with the Mac Mini I did not hear an audible difference. I even tried a linear power supply with it versus the stock SMPS wall wart. Would this device have allowed HF noise to pass through?

 

The big question for me now is this....what is the optimal FireWire music server? A Mac Mini on linear PSU, a MB Pro on battery or something else? I thought with FireWire bits would be bits....a

 

[The Computer Audiophile]

"The big question for me now is this....what is the optimal FireWire music server? A Mac Mini on linear PSU, a MB Pro on battery or something else? "

 

 

 

Hi Barrows - Your experience and "big question" mirror my thoughts lately. This is part of the reason I've been looking into isolation so much (bus powered hard drives, USB optical isolation, etc...). All of this combined with running a MacBook Pro from batteries is a very compelling proposition.

 

[earflappin]

Actually Chris, that was my post....earflappin. I'm eager to progress this topic now that I have heard what a significant impact it has on sonics. Perhaps Daniel could weigh in on this subject?

 

[The Computer Audiophile]

Thanks for the correction!

 

[barrows]

Thanks for your article about the battery supplies, I think that is a good way to go. What makes me most uneasy about the wall wart Apple supplies is the fact that you then have a cable running from the supply to the computer; it hard for me to not think that this wire is a nice broadcast antenna for RFI produced in the wall wart. Unlike in audio components, where there are usually some drawbacks to using batteries, I cannot imagine that a computer would perform any differently when powered by battery.

Ear: I am not an engineer, and do not know enough about optical transmission (or the use of optocouplers for isolation) to understand exactly how this works. In any case, even if no RFI gets into the audio system via the link to the computer, one must remember, we are talking about Radio Frequencies, so these can be airborne and then be picked up by components. I have noticed at shows that Gordon Rankin often places computers on carbon fiber damping shelves. Carbon Fiber couples with RF and damps it, and probably helps to reduce the airborne RFI out of the computer. It is also wise to think about where the computer is placed in relation to other components.

 

[earflappin]

Barrows, the optical FireWire repeater I tried is shown below and is one of the devices Chris mentioned in his recent article on isolation:

 

http://industrialcomponent.com/opticis/m4200.html

 

One hypothesis as to why I didn't hear an improvement with it is that it simply passed the EMI/RFI noise generated by the Mini by converting the electrical firewire signal to optical and back again. Is this plausible?

 

Regarding the comment about Gordon using carbon fiber shelves for his computers at shows this makes sense. I'll have to get out my ERS paper and wrap the Mini's SMPS and the Mini itself to see if I can get an improvement. ERS has similar properties to carbon fiber as I understand it.

 

Regarding your inference that the use of a linear power supply for the Mini helps improve sonics by reducing noise on the in home electrical grid I find this doubtful. There are just too many other devices in the typical home generating noise on the grid IMO. Things such as other computers, A/V equipment, wireless phones, etc. In my case my DAC and amps are completely isolated electrically from my Mini. The only connection is the Firewire interface.

 

This still begs the question as to what configuration will give the best sonic results....a battery powered MB Pro, battery powered Mini, linear power supplied Mini, etc. Does one get cumulative benefits by using battery/linear power and SSD's? I believe Gordon has inferred this to be the case by some of his posts as regards async USB.

 

Would be nice if an expert in this area could weigh in....

 

[barrows]

"One hypothesis as to why I didn't hear an improvement with it is that it simply passed the EMI/RFI noise generated by the Mini by converting the electrical firewire signal to optical and back again. Is this plausible?"

 

I do not know the answer, I think this question needs to be answered by someone with a better understanding than myself.

ERS paper uses suspended carbon fibers, plated with metals-essentially lots of little antennas, of different sizes (apparently corresponding to different frequencies), the paper converts RF energy into vibration/heat in the "little antennas".

RE, the Firewire link: do you think you have sonic degradation caused by RF coming over the link? Depending on how the MH LIO-8 is designed it may decouple the firewire input internally from the rest of the circuitry-I would not be surprised if it does deal with this internally, as these MH ADC/DACs have a great reputation for good design.

BTW: as an example, the Ayre QB-9 decouples the USB receiver stage from the rest of the circuitry by using optocouplers (no electrical link between the stages).

RE RF on your home AC, yes, you are correct, and this why good power conditioning can be so effective at improving performance. I have a moderate home, and I live with one other person, so I can keep most "bad" devices powered down when listening (and I am lucky to live in a rural area which is relatively "clean" from an RF point of view). I try to have as little RFI around as I can (no wifi, no cordless phone, other computers off, and plugged into power conditioners when on, TV plugged into power conditioning, PS Audio Noise Harvesters plugged into various outlets around the home lowering noise levels) for both audio quality and health reasons.

 

"battery powered Mini, linear power supplied Mini, etc. Does one get cumulative benefits by using battery/linear power and SSD's? I believe Gordon has inferred this to be the case by some of his posts as regards async USB."

 

I think the answer to this question has to be to try it, as systems are going to be affected differently. I would expect benefits of these things to be cumulative, but some of them may be so small as to be insignificant in many systems.

 

[barrows]

"One hypothesis as to why I didn't hear an improvement with it is that it simply passed the EMI/RFI noise generated by the Mini by converting the electrical firewire signal to optical and back again. Is this plausible?"

 

I do not know the answer, I think this question needs to be answered by someone with a better understanding than myself.

ERS paper uses suspended carbon fibers, plated with metals-essentially lots of little antennas, of different sizes (apparently corresponding to different frequencies), the paper converts RF energy into vibration/heat in the "little antennas".

RE, the Firewire link: do you think you have sonic degradation caused by RF coming over the link? Depending on how the MH LIO-8 is designed it may decouple the firewire input internally from the rest of the circuitry-I would not be surprised if it does deal with this internally, as these MH ADC/DACs have a great reputation for good design.

BTW: as an example, the Ayre QB-9 decouples the USB receiver stage from the rest of the circuitry by using optocouplers (no electrical link between the stages).

RE RF on your home AC, yes, you are correct, and this why good power conditioning can be so effective at improving performance. I have a moderate home, and I live with one other person, so I can keep most "bad" devices powered down when listening (and I am lucky to live in a rural area which is relatively "clean" from an RF point of view). I try to have as little RFI around as I can (no wifi, no cordless phone, other computers off, and plugged into power conditioners when on, TV plugged into power conditioning, PS Audio Noise Harvesters plugged into various outlets around the home lowering noise levels) for both audio quality and health reasons.

 

"battery powered Mini, linear power supplied Mini, etc. Does one get cumulative benefits by using battery/linear power and SSD's? I believe Gordon has inferred this to be the case by some of his posts as regards async USB."

 

I think the answer to this question has to be to try it, as systems are going to be affected differently. I would expect benefits of these things to be cumulative, but some of them may be so small as to be insignificant in many systems.

 

[earflappin]

Thanks to Barrows and the others for contributing to this thread. Being a bit OCD, having spare time and being an audiophile is not always a good combination...:-)....anyway, today I decided to pursue this aspect of my system a bit further.

 

First, to summarize the various threads I've read on LPSU's (linear power supply) for the Mini there appears to the following schools of thought in terms of how they impact sonic performance:

 

(1) LPSU reduces HF noise back onto the home electrical grid. This noise decreases as function of distance from the outlet you have your other audio equipment plugged into (e.g. amplifiers, DAC, pre-amp) due to the inherent resistance of the wiring and other factors.

 

(2) LPSU reduces airborne HF noise that is picked up by your audio system's cables and other components.

 

(3) LPSU reduces HF noise on the USB/Firewire interface cable to one's DAC which degrades sonic performance.

 

As a baseline, I plugged my Mini/SMPS, LIO-8 (with its own LPSU) and Atma-Sphere M60 amps into a PP2000 (PurePower 2000). The PP2000 was unplugged from the wall - not that it matters as this unit regenerates power from its internal battery - just to be sure I was completely decoupled from the rest of my home's grid.

 

Next, I inserted an isolation transformer (iso xfer) between the MM/SMPS and the PP2000. I realize from Clay's friend's recent post about the complexities and interactiveness of the power grid that my iso xfer might not have completely isolation the MM's noisy SMPS from the PP2000....but, the improvement was very audible (note: the PP2000 has no HF filtering of its outlets).

 

Dang....Clay's (and Happy's) hypothesis was right - check off #1 above. If others are plugging their MM/SMPS into the same circuit as the rest of their equipment you are most likely compromising sound quality - even if you have it plugged into a power conditioner with HF filtering.

 

So I get why a LPSU for the Mini would yield improvements. Less clear, however, is what incremental benefits a LPSU provides over an iso xfer? If the iso xfer is substantially (if not completely) isolating the SMPS from polluting the rest of your grid, then one would have to be convinced that the SMPS's HF noise is polluting your USB/Firewire interface. This is something I have yet to see definitively answered on the various forums I follow...seems pretty key...perhaps Gordon could chime in...

 

As I noted in another post, I tried an optical Firewire extender - found it made no audible improvement - then learned after I sent it back from the manufacturer (should have checked in advance...oh well) that it simply re-transmits the electrical signal so any HF noise on the line before the optical transmitter/receivers passes through. Do the optocouplers on the Ayre and Weiss DAC202 function the same way? This would eliminate potential ground loop issues....perhaps there is other circuitry which ensures no HF noise can pass?

 

So for now the iso xfer is staying. It has made a very BIG improvement in sound quality and only cost $100. I hope to get definitive clarification on the USB/Firewire HF noise issue before plunking down an incremental $600 for a high quality LPSU. BTW, as someone else noted I am not inferring that HF noise could/would corrupt the transmission of the music data stream...if this were true than Firewire would not be the robust comm link that it is. Rather I am questioning whether this noise could pollute the digital/analog circuitry of the DAC itself to an extent that would audibly deteriorate sound quality....

 

[cfmsp]

 

 

"So for now the iso xfer is staying. It has made a very BIG improvement in sound quality and only cost $100."

 

Earflappin'

 

perhaps you should share this with the folks on the other Mac Mini Linear PS thread.

 

GIven that the BOlder PS cost 4-5 times what you spent on the isolation device, I consider this good evidence in support of my contention that isolating the SMPS from AC is MORE COST EFFECTIVE than adding an expensive Linear Power Supply to a computer.

 

OTOH, everyone's situation is different.

What iso transformer did you use?

 

clay

 

PS, did you get your cables from Franck yet?

 

 

 

 

[4est]

I think he is talking about an ultra isolation transformer ( something like a .005 picofarad). They are common in the medical field, and can be found surplus for cheap on ebay.

 

[earflappin]

Clay, the iso xfer I used was a hospital grade Tripp Lite IS250 250W I bought on Amazon. I have to thank Happy who posts here on CA forum for turning me on to this idea. Yes, I got my ASI XLR cables and they are fantastic...but I opted at the last minute to not do the TRS plugs in the event I get a new DAC with standard XLR jacks. It took 4-5 days for them to hit their stride...the first 96 hours was not pretty.

 

Now if I can get some clarity on how/if EMI/RFI HF noise impacts the Firewire interface to my LIO-8 I will be all set....for now.... :-)

 

[B.J. Buchalter]

earflappin,

you said: As I noted in another post, I tried an optical Firewire extender - found it made no audible improvement - then learned after I sent it back from the manufacturer (should have checked in advance...oh well) that it simply re-transmits the electrical signal so any HF noise on the line before the optical transmitter/receivers passes through.

 

Any noise that would "re-transmitted" over the optical link is irrelevant to the phenomena that you are investigating. I actually don't really believe that it is "re-transmitted" anyway, since optical Firewire is fully regenerated via a PHY from a local clock in the repeater. Any noise that would be injected in the data lines would either be irrelevant or sufficient to corrupt the data. If it corrupted the data, there would not be subtle changes in the sound -- you would just have substantial dropouts. The only mechanism I can see that would have an effect on sound quality would be noise injection onto the ground of the converter via the FW ground line, but in any case, the optical connection would have isolated any potential ground contamination going between the MM and the LIO-8 via FireWire, so it would have isolated any relevant noise source that was transmitted via the FW connection. Since it had no effect on your system, that tends to indicate that the source of the issue that you have identified is not entering the system via FireWire, but rather through the AC power distribution system and is probably occurring at your power amp.

 

You could try using your iso tranformer on individual components rather than the MM and see if it has an impact with some specific component (e.g. amp or LIO, etc.)

 

Best regards,

 

B.J. Buchalter

Metric Halo

 

[earflappin]

B.J., many thanks for taking the time to weigh in on this thread. The clarity on the FireWire interface is greatly appreciated. This is what I was hoping to hear. I'll try using the iso xfer on the LIO-8 and report back. Thanks again.

 

[cfmsp]

 

BJ

 

welcome to CA!

 

clay

 

[cfmsp]

 

http://arraysolutions.com/Products/nqnaclinefilter.htm

 

 

Here's another inexpensive device you might want to try.

 

$106 plus shipping.

 

clay

 

[silverlight]

If Chris is okay with it, I'll post up a link from another forum that provides another account of the linear PSU with the Mini, and draws comparisons to conditioning/filters, etc. It's very relevant to this and the other ongoing Mac Mini power discussion and other Mac tweaks referred to in other threads.

 

http://www.audiocircle.com/index.php?topic=72497.msg816864#msg816864

 

"First I would like to Thank Wayne for sending me the power supply to audition. I received the power supply and then brought it over to a fellow Chicago Audio Society members place.

 

I will briefly describe his system and then what we heard.

 

'09 Apple Mac Mini w/ Amarra software

Amarra DAC

External hard drive is a Drobo hooked up via firewire

Speakers are Peter Gunn modified Magnepan 1.6's

Monoblock amps are by Atma Sphere. I believe they are the M-60's but not sure

which version.

All cabling by Reality Cables

 

 

Previous to receiving the Power Supply I had heard from a friend that in their listening the PS did make a difference but not huge. So I had that preconceived notion going into it.

I brought the Bolder Cable PS over on Thursday. We listened and my first impressions were very favorable. A larger change than what I was expecting. We could hear an immediate tightening of the bass with better dynamic attack. You could hear individual instruments more easily and better defined in space. There was a greater sense of air around the instruments. There more "life" to the music. It was more enjoyable to listen to.

I left the unit with him over the weekend. I went back last evening along with another fellow CAS member. When I arrived I was told that Amarra had just introduced a software upgrade and they also had a firmware update to the DAC. He downloaded them prior to arriving. We listened and I could easily tell that the updates were increasing the resolution of his system. His system sounded even better after the updates.

After doing some listening and becoming more familiar with the new updates and the Bolder PS in his system we put the stock Apple PS back into the system. The main thing that we picked up on is that his system now lost a lot of it's musicality. It was no longer enjoyable to listen to his system.

We left the stock PS in and did the changes to the Apple Mini that are listed in the DB Tranquility DAC thread. We made the changes to the Mini per the detailed instructions. I have to say that the changes brought the Mini to a level that equaled or surpassed in some ways the PS upgrade. It was much more enjoyable to listen to again. Even with the stock PS. I was awe struck that the modified Magnepan speakers could have the dynamic attack in the bass that they now had. Every ribbon type of speaker that I have ever heard before could not do the slam that these speakers were doing. Maggies (in general) do not do bass dynamics well as compared to dynamic speakers. So for all Apple computer owners that use them for audio it is imperative that you do the changes. Even is you are not using a Mini. After doing the changes to the Mini and listening we started up the computer in 64 bit mode. More icing on the cake which I will not get into detail but I would highly recommend it.

After becoming acclimated to the stock PS with the changes to the Mini we went back and put the Bolder Cable PS back in. All that I can say is that it just improves the sound. The bass even got more tighter and better defined. We were able to hear individual instruments easier. It became even more enjoyable to listen to.

We had a Hi Rez download that we were listening to. Not sure the name but it is a number of singers that some are also making sounds in the background. I would call it Beatbox like. Without the Bolder PS you could hear a main singer and others harmonizing in the background. Your could hear the Beatbox rhythm but it was less defined. With the Bolder PS you could now distinguish 3 other singers individually along with the Beatbox rhythm more distinctly. You could pick up on the individual type of sound that the Beatbox sound was making.

When it comes to ultra high end audio this is the types of things that you are striving to improve to. If you are going for high end audio computer and are using a Mini this Bolder Cable power supply is a must to go to the next level. We have tried things like isolation and power conditioning into the mini along with other tweaks. Those are smaller in comparison to this. The Bolder PS and the internal changes to the Apple computers will bring you to another level that you have not heard before in your computer audio system.

That said these kinds of changes that I am referring to may not be audible with mid fi type of systems. If your speakers are right up against the back wall you will not be able to pick up on the instruments in there 3 dimensional space. If your system does not have the resolution you may not be able to hear as easily each singer as easily as we did..."

 

[The Computer Audiophile]

"If Chris is okay with it, I'll post up a link from another forum..."

 

No worries. All well intentioned links elsewhere benefit all of us :~)