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SMPS for Audio vs Linears... my 2 cents (long, of course!)

Of course, I'll have an opinion on this... and it may not be the one you expect.

I've had several experiences with SMPS's in audio eq over the last 6 years or so, starting with a Panasonic S47 DVD player modified by one of the serious modifying houses. He did quite a bit to the SMPS in the unit... and having an un-modified unit to compare to, I could hear a significant improvement over the stock player and it competed very well against my fully-outfitted Njoe Tjoeb player with upsampler, beating it in some ways, equaling it in others, and doing so for 1/3 or so of the price (and the Tjoeb was fully linear-supplied).

Couple of years later, I read about the Sony Playstation PS-1 as CDP mini-craze and picked up a couple to play with. They were promising enough to dig into and mod... and because I was deep into my then-business and model airplanes, I didn't try to do custom linear supplies, but instead modified their standard SMPS's (see attached pix). My mods, inspired by the ones on the S-47 and information gleaned from other modifiers, included replacing the rectifiers with supposedly good-sounding soft-recovery diodes, the main cap with a Jensen 4-pole (first time I used one), and most of the other electrolytics with Rubycon's (I hadn't tried Black Gates then... they seemed really expensive to me back then). Very nice improvement, it preserved the liquidity and analog-ness of that game console when used as a CD player while improving the resolution and definition. While it didn't have the level of resolution of the S47, it was very fun and listenable and also a good platform for modifications.

Modified Sony Playstation PS-1 SMPS:









One year later, I get a real job again and celebrate by purchasing a pair of serious amplifiers, built-up by the same modifier who did the S-47. These were based on the B&O 1000ASP IcePower modules (over 500 WPC into 8 ohms, over 1000 WPC into 4 ohms), which of course had SERIOUS SMPS's. They worked very well in my system, surplanting an extremely-modified Counterpoint SA-12 and decisively beating it in every parameter... and worked very well with the S47, which became my main CDP again.

And another year or so later, I picked up a used Oppo 970 modified by the same guy who did the S47... another SMPS-powered piece of gear and it was a good step up from the S47.

So far, SMPS audio gear is holding up well.

Next step in my audio evolution was to build a Shigaclone and feed it into a Peter Daniel NOS DAC. That beat the Oppo 970 (altho it didn't play DVD movies like the Oppo and Panny) AND was all linear supplies. I don't think that was the key reason that setup beat the Oppo, but it contributed... and I got to see how people were making linear supplies nowadays (the last ones I built were back in the early nineties before people started using anything but garden-variety diodes).

Then enter the cMP. I put it together and liked it... sound quality in the same realm as the Shigaclone/PD NOS DAC combo with a bit of convenience thrown in (Remember, that PS-1 had NO screen, just a set of controls... and the Shigaclone was a step up with a screen, but just as rudimentary controls).

As I moved forward in implementing the standard tweaks to my cMP, I looked long and hard at the insides of the Antec SMPS when I was disconnecting the fan and un-needed wires... Hmmm, maybe I could do some mods in here. But then I saw the sub-threads about adding caps at the output of the Antec... and then I saw Peter Daniel's PicoPSU implementation... and started trying these tweaks to my cMP... and the rest is history (for me).

What did I learn from all of this (and also reading about SMPS-powered gear that reviewed and sounded good)?

1. SMPS's can be made to sound good (Heck, I knew that back in the late '80s when I got to hear several times a Berning TF-10 tube preamp with SMPS owned by a friend of mine!).

2. Most SMPS's are not designed and/or built for good sound.

3. You can improved the sound quality produced by those SMPS's with some mods.

4. But it's simpler in most cases just to build good linear supplies than modify a SMPS... and it likely will produce a better result.

IMHO, computer power supplies are EXTREME examples of SMPS's that are not designed and/or built for good sound. The ones in the B&O 1000ASPs are designed for and built for good sound. The ones in the Linn gear are too. The ones in the Nagra amps are too and likely better than either of these (although they seem to be more of a hybrid power supply with that large transformer before the power supply board than a classical SMPS setup). The ones in moderately-good-sounding-when-stock DVD players like the S47 and Oppo 970 (and some of the Toshiba models, one of which is playing a movie for my wife right now) are... somewhat. Ditto with the one in the PS-1... and the SMPS's in these game consoles and DVD players responded pretty well to mods designed to improve their sound quality. This was helped by their simplicity (at least compared to a computer SMPS). On the other hand though, the guy who had modified the S47 and Oppo is now offering a linear supply add-on to his latest DVD mod offering.

Given all of this, I believe that modifying the standard computer supplies, even the 'good' ones like the Antecs, are like putting lipstick on a pit bull. They are so far from what is needed to produce good sound that while you can make them better, you'll never make them good. And my experiences with minor changes to my cMP's power supplies, even the motherboard and 'dirty' (USB, screen, HDD) supplies, making a noticable-to-large difference, has told me that power supplies are critical to getting the best sound out of a cMP-type of source, even when the sound card (and DAC and output stages) has it's own power supply.

But of course, I'm very curious to hear what you report. I hope it'll make a significant improvement in your setup. I hope at least that it works ok... I'm not sure it will. If you removed your fan from your computer supply, you may want to add it back at first... I can see some ways where the chokes may cause the supply to work a lot harder and the fan may be what saves your supply until you can power it down.

Looking forward to your report!

Later!

Greg in Mississippi

P.S. Thanks for keeping this all so interesting!

P.P.S. I forgot to mention I used a Panasonic receiver with SMPS for awhile in the last couple of years as I moved into our house down here and it made a better account of itself than I expected.
Everything matters!

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