[werd]

I am using a Chapter 400 watt Class D that will not work plugged into my Torus. It only works plugged into the
wall? It might have to do with the 16amp fuse, or it's adjustable grounding scheme. You can toggle between the chassis or the ground pin on xlr.

[dBe]

Yeah, you can tell everyone is selling them by the way all the audio classifieds are just jammed with them....

Some of the most respected names in audio use them. It is, like many other things, about implementation. Of course there are still those confined by their out of date dogma...they can't be helped.

Like I said in my circle, Bruno is one smart guy.  The SMPS used is a very, very good one and is part of the voicing for the amp.  The only real issue that I have with it is the use of polyester coupling caps.  That I'd pretty easy to fix, if a bit kludgey. I would say that if the builder does not follow the build instructions to the letter EMI "could" be a problem.

I have build several of them for customers and did a bit more in the noise mitigation mode and they sounded very good.  I'm still a tube guy though.  A dogmatic toobular lemming 

[cab]

To each his own. At least your opinion is based on experience...

[dBe]

To each his own. At least your opinion is based on experience...

Thanks.  I have spent way too much money on this addiction . Slow learner, I guess.

[db audio labs]

Interesting thread here. There's a couple of tests we did ourselves to determine the best sonics of a Mac Mini into our DAC that support some of the posters here and their experiences with Switch Mode supplies:

Firstly, I'd say that its very hard to get better sound from the switch mode supply with any power conditioning. We've tested (in blind A/B tests) and tried quite a few different offerings by various respected high end manufacturers. To this day we haven't found any conditioners we would say -  "use this one and your Mini will sound much better'. In fact, in our 25+ recommendations for tweaks with the Mini for our DAC customers to try, we've always told them to avoid any power conditioners entirely and plug their Mini directly into the wall. 

There have been other non-digital components that I myself have owned over the years with SMPS designed within. That design choice always seemed to be the weakest part of the design (once I started tweaking, changing and improving the internals). From a high end manufacturer's view these SMPS are very cheap as all get out as compared to linear, so I guess it makes good business sense to design them in? As for making an outstanding sounding product though, I myself would never consider using SMPS. The downward sonic detriment is just too great IMHO.

As to other direct analysis of the SMPS and what happens when it is removed or replaced in a Mini. We now feel it's better to completely remove and replace the Mac Mini's switch mode supply with direct battery power or a linear power supply. This removal / replacement of the SMPS has been fairly popular with Mini modifiers beyond just my own company's recommendation mind you and seems to be universally accepted as a major improvement sonically by those audiophiles who have done it to their Mini. Hence, we are not alone with our findings 

Another tweak we call out for our customers is the "try both plug orientations on your Mini's power cord, turning it 180 degrees, one way will sound better". This surprised many a customer and even more technical guys when I told them to try it. I can only suspect that the internal ground noise must be finding a better path to the neutral side of the power in a customer's outlet than the other way. Perhaps its something different entirely? Regardless, it remains an eye opener for every Mini owner who tries it...at least with our DAC hooked up to the Mini mind you 

Cheers to the people with ears!

Eric Hider - dB Audio Labs    www.dbaudiolabs.com

[rdsu]

Using a SMPS after the Power Conditioner only helps to prevent that noise go back to AC and contaminate the other components...

The Power Conditioner can't do nothing about noise after SMPS...

[Folsom]

I'm sorry but I believe you're both wrong on this, somewhat, db and rdsu.

First off it's more likely that the orientation of the Mac Mini's plug is breaking a connection from neutral to ground at the service panel, from making a connection through your system. You've eliminated multiple paths at that point, to anything you're connected to. Perhaps I'm wrong and it's 100% internal to the Mac Mini's grounding scheme causing a loop, but generally speaking I've seen computers making loops with other devices pretty indiscriminately.

Power conditioners can actually lower the noise in a SMPS depending on it's design. There's some things happening with change of reactance in frequency ranges they operate in, and the ability to provide a shunt to some of the noise. Some SMPS units have weak, interfering, input filters, others do not.

Again this may be best seen originally with the Felix applied to the Squeezebox stock SMPS (junky). It didn't have to be on the same power distribution as the rest of the system to see the benefit.

Well, of course I assume a linear is the upgrade to have for a Mac Mini, despite that I think depending on the SMPS design it could benefit. I haven't cracked one open but I've got a guess, and it wouldn't surprise me if while fixing one thing it causes another. My apologies that I don't want to discuss it too much more, as I don't feel it's to my personal benefit as an Industry Participant, to share every least thing in the world.

[rdsu]

Power conditioners can actually lower the noise in a SMPS depending on it's design. There's some things happening with change of reactance in frequency ranges they operate in, and the ability to provide a shunt to some of the noise. Some SMPS units have weak, interfering, input filters, others do not.

I fully agree!

[werd]

Mac Minis are 2 prong no ground. I think they charge the battery while plugged and run off the battery?

[jarcher]

Your thinking MacBook (laptop). Mac mini are desktop and  have no battery (other than bios).

[werd]

Ok thanks.   

[Folsom]

Mac Minis are 2 prong no ground. I think they charge the battery while plugged and run off the battery?

I made a terrible drawing of a path that shows how a Mac Mini can have a path taken out of the equation if the plug is reversed, if it's interacting with other equipment in this manner. You can see how this loop won't form if you switch hot/neutral. SMPS's vary on how this works; there's numerous wiring configurations. As you can see it might be possible to have a path on the neutral as well, depending on your other equipment.

[dBe]

I made a terrible drawing of a path that shows how a Mac Mini can have a path taken out of the equation if the plug is reversed, if it's interacting with other equipment in this manner. You can see how this loop won't form if you switch hot/neutral. SMPS's vary on how this works; there's numerous wiring configurations. As you can see it might be possible to have a path on the neutral as well, depending on your other equipment.

I don't want to start a holy war here, but I don't think you are misunderstanding our experience with the Minis and the successes we have with them. A lot of our experience deals with the Mini being used in a battery powered system... Yep, pre, amps and DAC.  The Mini will exhibit the same polarity characteristics on an otherwise battery powered system.

Bottom line is that it is characteristic of those particular power supplies.

It is easy to talk about subjects with words like : might ; could ; perhaps ; depends and probably.  This make for good discussion, but 4+ years of experience has to count for something.

[dBe]

Fat fingers

[Folsom]

Really, on battery power? Hm.. well that's interesting. Seperate or same batteries?

[db audio labs]

Hey guys,

Everyone in our group here (doing true actual blind A/B testing) and now hundreds of our customers throughout the world (in 22 countries) are all experiencing the same dramatic sonic improvements with either a battery power replacement of the SMPS or the replacement of the SMPS linear supplies. Not a singular audiophile power conditioner that any of my customers have tried (thus far) matches the sonic improvement of the removal and replacement of the SMPS comparably. Not even close.

It certainly would make my life as an Audiophile Digital Provider much, much easier to point to some sort of conditioner than the alternative of recommending the complete removal of the SMPS and the inclusion of an internal harness for battery or linear power comparably. Are there any "Audiophile Conditioner Providers" watching this thread who have yet to respond?  if you can create such a conditioner that magically improves the Mini's SMPS? I have hundreds of customers for you! Hint, hint 

I myself don't really have a concrete technical hypothesis to why the SMPS seems to suck sonically in the Mini. And thus far why no conditioners connected to make it sound any better. I can only speculate to the technical reasons. But at this point it is pure speculation for me. Perhaps someone that really understands the Mini's SMPS implementation could explain why the Mini doesn't seemingly respond positively to any power conditioning? Hmmm, anyone care to guess?

Cheers,

Eric Hider - dB Audio Labs  www.dbaudiolabs.com

[werd]

Why not use a parallel conditioner on the same outlet? What is the forseable improvement that you are talking about that isn't happening?

[werd]

I currently have this amp (400watt) on borrow.  http://www.chapteraudio.co.uk/products/reference/couplet-1000s/

Can some one give me a good answer why this amp will not play using my Torus rm20 240V? It will turn on but i can't get music. It works flawlessly plugged into the wall. It does have a toggle between the ground pin xlr or chassis ground. Can't get music on either toggle select, but turns on, lights up when plugged into my Torus. This appears to be a problem with all conditioners not just a Torus.

[jarcher]

Last night was trying a Torus RM20 w/ a 300WPC Hegel 4HSE amp.  It worked, but totally killed the dynamics (slow slow slow).  Not qualified to try to explain why a big isolation transformer like that won't work (rated power is greater than the one in the Hegel).  What I will say is that convention audiophile wisdom is to never plug power amps into power conditioners, and particularly not high power amps.  Just chokes the power delivery too much.

So I guess the simple answer is : plug that amp into the wall!

[dBe]

Really, on battery power? Hm.. well that's interesting. Seperate or same batteries?

The Mac Mini is on a 55AH AGM through a BatteryBUSS.  The Mini is a little noise generator and other gear is much happier with it on a separate source.  Pre and power amp are on a 100AH with proprietary output impedance correction for the battery to get the output impedance very, very low and with noise reduction to get the sulfation noise out of the line.  DACs will vary, but are generally battery powered.  Just like running dedicated circuits for gear...