[eclein]

Jim-I think its great idea!!...and boy do I hope I'm right and don't have to slowly, calming, RUN AWAY!!!.
What kind of SB?? My results come from a stock Duet with Parts Exp. power supply...but I would think any version would work.

[bpape]

Sounds like a good test to me.

Don't get me wrong Jim.  The differences were not as pronounced with the digital output but they were there in the same areas. 

Bryan

[Nuance]

Not really. A CD sector is 2,352 bytes.

For data CDs, this is split in 12 bytes sync, 4 bytes sector id, 2,048 bytes real data, 4 bytes error detection, 8 bytes zero and 276 bytes of error correcting code.

For audio CDs, all the 2,352 bytes are used for real (audio) data with no ECC. If there are errors there's no level 3 ECC to help correct them.

Nap.

I have the option to use C2 Error COrrection with both of my DVD-RW drives on my main computer.  The option is in Exact Audio Copy, and it runs a test to verify that your CD-ROM's or DVD drives support it, which both mine do.  So I am confused - are you saying with Audio CD's that error correction isn't supported with DVD and CD-ROM drives?

Jim,

That's a terrific idea!  You'd need to have at least two people, each with biases in both camps (one that believes he/she will hear SQ differences, and one that doesn't believe the improvements will be heard), else certain individuals will cry foul...well, they'll probably do that anyway; just ignore them.   I wish I lived closer, as I'd love to volunteer to participate.

[eclein]

Nuance- I personally would never cry fowl...its all for fun and better sound is always fun!! Its all Good!!!
Jim- Where is the proposed test site??
 Ed L.

[coke]

OK.  Some posters seem to feel that a high quality power supply on a squeezebox can improve the resulting sound quality of the digital output when fed to an outboard DAC.

I have been thinking about conducting a blind test to determine if this is the case.  (I would imagine that it could have a postive impact on the analog outputs and we can test that too.)

Here is a possible setup for the test:

Frank's AVA Vision DAC has a pair of coax digital inputs and you can switch between them.  If we set up two identical SB units, one with the supplied power supply and one with an "improved" power supply (or even a battery power supply), we can sync the SB's and run each to a separate input on the Vision DAC.

Someone who would not be involved in the listening test could flip a coin to determine which of the SB's would be connected to which input.  Then a cloth of some sort could be placed over the wiring so no one would be able to see which SB was connected to which input.  That way, no one participating in the listening test would know which was which.

Switching back and forth between the inputs while listening to various musical selections would allow listeners to judge whether they were able to hear any difference between the two and which, if either, was superior.

Does this sound like a reasonable approach?  If so, what upgraded power supply should be used to maximize any potential difference?

We could do a similar test with the analog outputs by simply running the SB outputs to two inputs on the preamp.

- Jim

I would do the test twice.  On the 2nd test, put the better quality power supply on the other squeezebox.  I doubt there are any differences, but it removes a variable.

[fsimms]

The double blind test sounds like it would be interesting.  I don’t think it would be definitive as people could say that RF frequencies could ride the grounds of one of the power supplies and ride the shields, of the interconnects, of one of the units all the way to the DAC.   Leaving a potential bad supply hooked up for the whole test would add a small level of uncertainty.

Bob

[Nuance]

Nuance- I personally would never cry fowl...its all for fun and better sound is always fun!! Its all Good!!!
Jim- Where is the proposed test site??
 Ed L.

I certainly didn't mean you.  Sorry if it came across that way.

[eclein]

Nuance-No problem-Its all good!!

Bob pointed out something regarding RF frequencies and shields and all...thats something to consider I guess but if we don't over
technify the test, and just do it simply. I mean no disrespect at all to anyone but it would be as easy as taking one SB and just have someone unplug one supply and plug in the other supply without the subject knowing, same SB used for both PS just manually switch plugs. I don't know maybe thats over simplified..hmmm...
 We'll have this all planned out and Jim will log on here and go "what did I start here."!!  LOL

[srb]

..... but it would be as easy as taking one SB and just have someone unplug one supply and plug in the other supply without the subject knowing, same SB used for both PS just manually switch plugs.

I am guessing (?) that powering off and back on would require some small amount of time for initialization and not give that instantaneous A/B that works so much better.
 
Steve

[eclein]

I just tried it...its not instaneous...you have to restart the file being played. I was ready to jump in my car and do a road trip then I remembered I have Duet receiver only-no controller to configure it to a different network. I was able to semi-hack it using perl scripts and make it work with my ipod touch via ipeng but if I disconnect and try and reconfigure for the network wherever it ain't gonna happen.

[cacophony777]

The blind test sounds like a great idea! Perhaps if it goes well, simple blind tests could be done with various other components as well (cheap vs expensive speaker wire, $125 receiver vs expensive integrated amp).

[jsalk]

I have two standard Sqeezebox units (SB3's as I recall) we could use for the test.  I would have to have BRM bring the "upgraded" power supply or purchase one for the test. (We could even run a control test swapping only the SB units to eliminate any possible variation related to differences in the SB units themselves.)

Changing power supplies on a single SB will not provide an immediate A/B comparison and the time delay would introduce far more variability than RF (in my opinion).  Switching at the DAC would provide almost instantaneous comparisons.

When we made the final SoundScape driver selections, having Dennis Murphy's magic comparo box made a huge difference.  When switching speaker cables (before using the comparo box), everyone THOUGHT they had an idea of which drivers were better.  But with the remote-controlled A/B switch, the differences in sound quality were immediately evident and unequivocal.  In that case, the elimination of switching time showed how dramatic the differences were (greater than I would have thought listening to both individually)and made the analysis easy.

As for RF, perhaps we can run them so that each SB unit is 3ft on either side of the DAC and their respective power supplies are as far to the right and left of the SB's as possible.  This should put the power supplies almost 6 feet from any other components and the closest the power supply cables would be to any other system cable where they connect to the SB units themselves.  Did that make sense?

As for location, we can do it in my listening room.  I have a pair of SoundScape 10's hooked up right now and they should surely be able to resolve any possible sound quality difference.

While amps, speakers wires, etc, could also be tested at the same session, it would be more difficult as the tests would not be totally blind and there would be time delays between each component being tested.

- Jim

[mchuckp]

I think trying to take out as many variables as you can (cables,level matching, etc) is obviously the best approach.  But if one has to go to over extremes to hear a splitting hair difference then what is the point?  To me if you have to try that hard to hear a difference, one could consider them basically the same.  If what I read about power supply upgrades is true on SB's than hopefully the difference (or lack of) will be pretty apparent.

Based on my reading on power supplies from other users, I've taken the plunge and anxiously awaiting mine.  I have a SB Touch being worked on by Wayne at Bolder currently getting analog and digital mods and and his new "Deluxe" power supply.  I'll have a stock Touch to compare it to so I can easily test the difference Wayne's mods and/or power supply make.  I'll can easily run both into my Wyred4Soud DAC.  One might ask why I got the analog mod as well if I have the DAC.  I'm curious how good it can be.  It would be interesting if I felt the sound quality of the analog mod/power supply rivaled my DAC.

Jim:  Hopefully you follow through with this.  I have a lot of faith in your opinions and your opinion would hold a lot of weight with me.

[cacophony777]

While amps, speakers wires, etc, could also be tested at the same session, it would be more difficult as the tests would not be totally blind and there would be time delays between each component being tested.

Maybe some participants could be blindfolded for the entire duration of the test. 

Or perhaps Dennis just needs to make a reverse magic comparo box 
(A/B remote switch where the input is two pairs of speaker cables, and the output is just one pair)

[srb]

Dennis just needs to make a reverse magic comparo box 
(A/B remote switch where the input is two pairs of speaker cables, and the output is just one pair)

And what speaker wire would the output wire be?   
 
Steve

[cacophony777]

And what speaker wire would the output wire be?   
 
Steve

Something from The Shack, obviously.

[Wayne1]

Hello all and Happy Father's Day.

I was referred to this post. I do have an interest in power supplies so I will try to keep this without any blatant ads.

The power supply comparison suggested by Jim sounds like a good idea, but unfortunately it will not give a true comparison between the stock switcher and a linear power supply. The stock switcher is always an and always is polluting the AC line whenever it is plugged in. It also transmits a fair amount of RFI. The only fair way to judge the difference is to unplug the stock switcher from the wall.

This can be done with an A/B comparison but it will complicate things. You can run the switcher and when you switch to the linear, you would have to unplug the switching supply. Then you would have to plug the switcher back in 30 seconds or so before you switch back. This would make AB/X type of testing impossible. It also would make it very hard to do double blind testing.

I think this is part of the reason many people have had problems comparing the stock to linear supplies. The stock switcher was left plugged in and it's noise was so bad it rendered any
comparison invalid.

For some more information and the linear vs switcher I would like to refer you to an article written by AC's own Scott Faller some years ago. It is a review on one of my older products, so please take that into consideration. The facts he states will refer to most linear PS.

SB power supplies

[cacophony777]

The stock switcher is always an and always is polluting the AC line whenever it is plugged in. It also transmits a fair amount of RFI. The only fair way to judge the difference is to unplug the stock switcher from the wall.

Couldn't he just plug the stock supply into a different circuit to prevent the pollution of the AC line? Also, if the RFI and AC pollution from any cheap power supply can invalidate the advantage of this upgrade, then how does anybody see the advantage of the linear power supply? Do they have to upgrade *every* nearby power supply (TV, dvd player, dvr, etc), make sure cell phones aren't plugged in, etc?

[srb]

The stock switcher is always an [on] and always is polluting the AC line whenever it is plugged in. It also transmits a fair amount of RFI. The only fair way to judge the difference is to unplug the stock switcher from the wall.

If the problem of AC line pollution is present even if on a different circuit, then the linear supply will always be polluted as I would guess the average household has a half dozen SMPS throughout the house.
 
If being on a different circuit makes the difference, then a beefy extension cord could be plugged into another circuit, in another room if necessary.  And a metal box could be placed over the switching supply for shielding.
 
Steve

[werd]

Hello

What amp and preamp would you use in this test Jim?