[Quiet Earth]

I realize that the best SMPS is no SMPS, but many of us have that one piece of gear with a SMPS inside and we don't want to modify it. Maybe it's a dedicated streamer or a computer. Perhaps it's a universal disc player or CD burner. Whatever it is, there it is and how do we treat it when we connect it to the main power strip of our linear powered audio equipment?

Many of these SMPS equipped devices already have some pre-AC noise filtering built inside. So do we just plug the SMPS device straight in to the main power strip and leave it at that?

Would additional power conditioning dedicated to the SMPS device eliminate the switching noise that goes back into the main power strip?

And last but not least, can power conditioning actually improve the performance of a SMPS powered device and make it sound better?

Thanks for sharing your thoughts on this subject.

[Folsom]

They benefit in a huge way. In fact it's almost the only way they're worth anything barring some very high end ones like Paul Hynes (which can probably benefit anyway).

[Speedskater]

Well some SMPSs can get very unhappy with some power conditioners.
Let me look for the info.

[Folsom]

Well some SMPSs can get very unhappy with some power conditioners.
Let me look for the info.

Please do.

Many people years ago found that SqueezeBoxes stock power supply was very good but only with some conditioning, otherwise replacing it was sort of manditory for a decent source.

[Speedskater]

Well it's in the Henry W. Ott book 'Electromagnetic Compatibility Engineering' book.  It's section '13.6 Power Supply Instability' and it's only 5 paragraphs long.  But putting it online might be a trick.

http://www.hottconsultants.com/EMCE_book_files/emce_book.html

Mr. Ott references another book:

"Power Line Filter Design for Switched-Mode Power Supplies"
by Mark Nave    see Chapter 6

[Folsom]

It says that when a SMPS has a constant output, it can compensate for voltage loss by drawing more current (due to the switching nature). If the current draw is to much then the filter may become inefficient and cause even more of the problem.

This is only an issue if you use higher resistance power conditioners or improperly sized current devices. It may even be a likely problem with some junk sold by less than audiophile companies.

This is just another reason for using CMC's twice the size of the load (or more). Well that's what I do and recommend. And yet another reasoning to stay away from cheap low current junk like those little IEC "filters" for power inlet.

The book also discredits those things for a variety of reasons that don't even cover how they totally muck up ground and sometimes have ferrite trash in them.

Audience
Pi
Running Springs
Blue Circle
And myself are a few to name that don't experience this under any normal operation. You'd have to plug in an impeccably large (15-20a depending on power conditioner) or inappropriately sized device for the socket to have this issue.

This problem could be replicated by just having too small of wire or anything that limits current. Generally audiophile companies far exceed current need capability.

Personally I'd consider it a non-issue with any quality company. It's an engineering problem for those that build SMPS's that have input filters, and those who want to buy trash expecting non-trash results.

[dBe]

SMPS are the bane of a music lovers and they are everywhere.  I posted a picture of the new receptacles with built-in USB chargers.  Smart grids have telemetry powered by small SMPS.  Coffee pots have SMPS in them... Like ChickenMan: "they're everywhere, they're everywhere".

They suck.  They suck any semblance of true musicality out of reproduction because of the grungy haze and grit that gets passed by power supplies that are built to price points.  A properly designed linear power supply is very expensive to manufacture. 

One of the difficulties in designing a filter for a SMPS is that the differences in their input characteristics.  They get very finicky when plugged into AC.  A good example is the power supply in the unibody Mac Mini computers.  When used as a music server you will find that it sounds very different depending upon the orientation of the IEC C7 plug into the back of the Mini.  Why?  I have no clue.  I dislike SMPS so much that I have no interest in finding out why.  They are banned from my system.

Some SMPS work very well with my BUSSes.  Some do not.  I have been trying to develop a one size fits all conditioner that works as well as the BUSSes do feeding transformer input supplies.  I am convinced that there is no such animal.  There are ways to mitigate the deleterious effects of the SMPS on the rest of the system and that is much more important than finding the best way to treat a particular SMPS.

Keep the EMI/RFI out of the system is imperative IME.

[Folsom]

I have no problem with them and conditioning. But as I said maybe Paul Haynes would work, but as is I prefer linear (of my own design). They can still sound good and there's no other choice with the world's most expensive DAC...

I'm sure the Apples are just as simple as an either complete or not circuit. In fact one original orientation may eliminate a ground loop, as an example of potential. It depends how it's grounded internally and what it's connected to probably.

I've been toying with the idea of a linear for NC400s.... NO ONE thinks it's a good idea but perhaps it's the ears and not the brain that needs coercion.

[Quiet Earth]

  There are ways to mitigate the deleterious effects of the SMPS on the rest of the system and that is much more important than finding the best way to treat a particular SMPS.

When you have some free time, perhaps you can list some of the ways to reduce the deleterious effects of SMPS on the rest of the system. That could be helpful for many of us.

Thanks!
 

[dBe]

I'm sure the Apples are just as simple as an either complete or not circuit. In fact one original orientation may eliminate a ground loop, as an example of potential. It depends how it's grounded internally and what it's connected to probably.

[dBe]

When you have some free time, perhaps you can list some of the ways to reduce the deleterious effects of SMPS on the rest of the system. That could be helpful for many of us.

Thanks!
 

Here is an easy one.  Plug system SMPS into a small isolation transformer with an adequate capacitive input filter.  There are a lot of small ISO TX available on the used/salvage market.

Having a home run to your system it makes EMI/RFI treatment much easier, too.

[jarcher]

In my amateur and unprofessional opinion, I'd just make sure any cheap external switching power supplies are as much as practically possible kept on a different circuit from your nice high end linear power supplied gear.  I've heard it myself muck up the sound of the other components unless it's on an isolated receptacle into a power conditioner, and even then I don't trust em.  I make sure to keep all those devices on their own power strip plugged into a separate receptacle that's on a circuit separate from my audio dedicated lines.  Thats my switching power supply isolation / containment policy......

[Folsom]

Here is an easy one.  Plug system SMPS into a small isolation transformer with an adequate capacitive input filter.  There are a lot of small ISO TX available on the used/salvage market.

Having a home run to your system it makes EMI/RFI treatment much easier, too.

Meh, they don't offer a benefit to the SMPS itself. But I guess it's one way to deal.

The Apples orientation could mean a connection to safety ground or not. (In your service panel)

[dBe]

Meh, they don't offer a benefit to the SMPS itself. But I guess it's one way to deal.

The Apples orientation could mean a connection to safety ground or not. (In your service panel)

The question to me was about how to mitigate the bad juju from a SMPS.  Hence my answer.

An IEC C7 is a non polarized connector.  There is no connection to safety ground except through the neutral which is normally bonded.  I guess I am just missing what you are talking about.  It's late and I have a head cold.  Snot must have crowded out my brain.

[Wayner]

My 2 Emotiva phono stages (XPS-1) have SMPS that I was always concerned with. However, I have plugged them into the outlets on the back of my preamps and they haven't been a problem, at least that I have noticed.

To be honest, I really don't know what a SMPS does or why some engineer would use it over a conventional power supply.....

[rdsu]

I use two SMPS(each are isolated from other connections) after my DIY Power Conditioner (PC), for my Cable TV and AudioPC, and they works really well.
The other components works much better than if I don't use them in the PC, so the noise that get back to AC is very reduced or almost none...

If you can't get a LPS, try to buy a better SMPS, like the medical ones, with low ripple noise, and then make a good CLC filter to improve it even more, and the component that you want to feed will thank you for that...

Currently, I'm removing a SMPS(<150mV) for a Medical SMPS(<22.8mV), with one more electrolytic cap 120uF400V before the transformer to improve the transient filter, and after the transformer a very good CLC to remove the rest between it and my AudioPC.

[cab]

Like most things, it depends on the design of the smps. There are cheap, poorly designed units and properly designed smps'. Those from Hypex are very good and actually work best without anything between them and the outlet.

[DaveC113]

..........

[Folsom]

Like most things, it depends on the design of the smps. There are cheap, poorly designed units and properly designed smps'. Those from Hypex are very good and actually work best without anything between them and the outlet.

And yet everyone sells their Hypex's and goes back to A/AB all the time. I'd argue they may not be much more intelligent than being a relic from the distortion wars with today's best learned lessons on quality engineering. You can quality engineer a paper cup, but you won't find them in an archeological dig hundreds of thousands of years from now like with ceramics.

Honestly I think SMPS's could serve as more efficient constant current devices, but not a lot else.

[cab]

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.