[Occam]

But Serengeti, bits is bits! 
One of the most disconcerting revelations of my Feliciating phase was finding out how critical mains conditioning is on the digital transport, whether a cd player, SB, Olive or computer. It doesn't matter whether you use a toslink or coaxial (within limits, the stock SB ps is a AM transmitter and toslink does help). In the general scheme of things, I'd take a good $300 'transport' with proper power conditioning over many $2,000 transports without.
Yea, I know 'a proper power supply shouldn't require power conditioning', but its hard to find the room for it in and existing component. And there are those electrochemical thingamabobs, which can be quite spiffy if implemented wisely, but aren't noiseless anyway and have their own inherent problems.

[serengetiplains]

Wouldn't you know, clean bit-server-computer AC = cleaner, better-sounding bits!     Yet another observation that'll no doubt get the Can't-Be community in a flap.

Occam, I'm right with you on AC conditioning.  In a stereo store the other day I sat down and listened to their premium system ... Sonus Faber Superspeakers + super-pricey electronics probably totaling $150K.  Didn't like it, no doubt due to the lack of 1) premium capacitors anywhere in the system and 2) AC conditioning.  But j'digress.

[serengetiplains]

I've spent an extra few hours casually listening at some distance, in the room, out of the room, etc.  I perform intensive listening at close range to identify minute particulars.  Though near-field listening of this sort requires greater concentration and attention, it has the side effect of losing the forest for the trees.  Casual listening allows a more holistic, impressionistic perception.  My sum conclusion is that a power conditioned computer is significantly better than one not, more so than I estimated above.

[audioengr]

"You cannot remove the USB Ground.  It is part of the circuit.  The 5V line is already isolated (disconnected)."

Disconnected where ?

At the input to the Off-Ramp.

Steve N.

[welwynnick]

This is all really interesting.

Firstly it suggests that well-established audiophile measures may benefit HTPCs.

Secondly, it confimrs to me that all digital signals are not the same, and specifically that the differences are down to bit errors rather than jitter, which AIUI would largely be taken out of the equation by the USB to I2S convertor.

This is a bee I've had in my bonnet for a while.  People ofen assume that every bit is correct, but I'm convinced that there are usually enough error bits to make an audible difference. So you have to minimise bit errors as well as jitter.

Nick

[serengetiplains]

Nick, the difference I experience between clean and dirty AC fed to my computer is about the same as the difference between a moderately priced CD player and an expensive high res player.  Not subtle indeed, with improvements across the board in listenability.  Your speculations are worth testing, I would think.

[audioengr]

This is all really interesting.

Firstly it suggests that well-established audiophile measures may benefit HTPCs.

Secondly, it confimrs to me that all digital signals are not the same, and specifically that the differences are down to bit errors rather than jitter, which AIUI would largely be taken out of the equation by the USB to I2S convertor.

This is a bee I've had in my bonnet for a while.  People ofen assume that every bit is correct, but I'm convinced that there are usually enough error bits to make an audible difference. So you have to minimise bit errors as well as jitter.

Nick

The error rates on transports are very low if non-existant.  The audible stuff is due to jitter in the clock.  It is the low jitter possible with computer audio that makes it intrinsically superior.

Steve N.

[serengetiplains]

Steve, what's your read on my results?  Looks to me that the supply chain feeding digital data down the USB cable is its own source of jitter.

[audioengr]

Steve, what's your read on my results?  Looks to me that the supply chain feeding digital data down the USB cable is its own source of jitter.

It's certainly possible.  The jitter in this signal may impact the PLL in the Off-Ramp.  However, the USB signals really have a lot of jitter, so I think most of this is filtered out.  I recently did another laptop for a customer and I was trying to decide if it sounded any different from my laptop.  If there was a difference, it was small...

[LightFire]

Tex, I'm not surprised by your observations. 

Wow, what interesting, far-from-subtle differences between the two computers in my setup.  Listening to The K&D Sessions, Kruder & Dorfmeister, the song "Gotta Jazz" begins with a synth sound to which is added a cymbal and bass.  The bass begins with an echo-like staccato blurp, and the blurp trails the bass line a few times.  That blurp is almost entirely missing --- absent, gone --- on the desktop.  A difference of that kind and magnitude suggests, at least to my mind, that the digital data is somehow subtly different, and rendered so in the ripping process (all ripping done to wav with error correction on).  If the difference attributes purely to electrical and/or hardware, it suggests significant room for improvement on either or both those fronts.

This makes no sense at all. If the digital signals are the same they will sound identical. This is a fact. Power supply and battery will have no effect on it unless they were of extreme bad quality and, still, errors would be 100% corrected when the digital signal is transmitted. Other explanation is necessary: different media players in each computer, different digital equalizer and digital sound "enhancement" settings in each computer, and/or listener biased towards believing that a computer with battery will sound better just because somebody else said so.

[Doublej]

Sure it does. It's all in the timing of the bits. If two people are playing the same music on identical instruments, can it sound different?

[LightFire]

Sure it does. It's all in the timing of the bits. If two people are playing the same music on identical instruments, can it sound different?

Sure it does not.

The above comparison is not valid.

If two people are playing the same music on identical instruments it will sound different.
If two computers are playing the same computer file in identical hardware/software setups it will sound exactly the same.

There is no such a thing as "timing of the bits".

[serengetiplains]

This makes no sense at all. If the digital signals are the same they will sound identical. This is a fact. Power supply and battery will have no effect on it unless they were of extreme bad quality and, still, errors would be 100% corrected when the digital signal is transmitted. Other explanation is necessary: different media players in each computer, different digital equalizer and digital sound "enhancement" settings in each computer, and/or listener biased towards believing that a computer with battery will sound better just because somebody else said so.

Why the surprise as if it should make sense?  Many things don't make sense.  At a general level, anything "makes no sense" because the person trying to make sense of the something 1) has an incorrect observation that doesn't accord with a correct and adequate theory or 2) has an incorrect or inadequate theory that doesn't accord with a correct observation.  I suspect your don't-make-sense confusion is mostly variety #2.  The operating system is the same, the player software is the same, the player settings are the same, the source cd data is the same, the source music data (ripped) is presumably the same.  The one thing possibly different in the setup is the audio hardware, though the laptop and desktop are both Macs of the same generation purchased at the same time.  A difference in hardware, if there is a difference, might not be the cause of the different sound because I noticed distinct differences changing the electricity feeding the desktop.  The type of electricity makes a difference; I assume battery electricity thus has its own sound.

[audioengr]

Sure it does. It's all in the timing of the bits. If two people are playing the same music on identical instruments, can it sound different?

Sure it does not.

The above comparison is not valid.

If two people are playing the same music on identical instruments it will sound different.
If two computers are playing the same computer file in identical hardware/software setups it will sound exactly the same.

There is no such a thing as "timing of the bits".

I'm sorry but the comparison is valid.  The timing of the bits is all-important with real-time playback.  Any timing variations or jitter in the clock can be audible.

Batteries, cable and even the choice of drivers can affect this jitter and be audible.  Batteries and power sources have noise and so does the ground-return.

Steve N.

[LightFire]

This makes no sense at all. If the digital signals are the same they will sound identical. This is a fact. Power supply and battery will have no effect on it unless they were of extreme bad quality and, still, errors would be 100% corrected when the digital signal is transmitted. Other explanation is necessary: different media players in each computer, different digital equalizer and digital sound "enhancement" settings in each computer, and/or listener biased towards believing that a computer with battery will sound better just because somebody else said so.

Why the surprise as if it should make sense?  Many things don't make sense.  At a general level, anything "makes no sense" because the person trying to make sense of the something 1) has an incorrect observation that doesn't accord with a correct and adequate theory or 2) has an incorrect or inadequate theory that doesn't accord with a correct observation.  I suspect your don't-make-sense confusion is mostly variety #2.  The operating system is the same, the player software is the same, the player settings are the same, the source cd data is the same, the source music data (ripped) is presumably the same.  The one thing possibly different in the setup is the audio hardware, though the laptop and desktop are both Macs of the same generation purchased at the same time.  A difference in hardware, if there is a difference, might not be the cause of the different sound because I noticed distinct differences changing the electricity feeding the desktop.  The type of electricity makes a difference; I assume battery electricity thus has its own sound.

If the computers are feeding digital signals to the same decoder and subsequent audio pre-amp, amp, speakers. Then the sound will be EXACTLY the same. Because there is no sound being fed but a code, a set of information that tells the DAC how to make the sound properly. If an error occurs during the transmission of this information the DAC will (in 100% of the cases) detect it and correct it perfectly. If it can't be corrected perfectly it will send a message back to the computer telling it to re-send the missed part. And the process will be repeated until it gets it right. This entire process takes fractions of seconds and is imperceptible because the information is buffered before it starts playing.

Welcome to the world of Boolean Algebra and digital electronics. A technology light years ahead of: tube amps, chariots, turntables, arrow and bow making, vinyl LPs, you name it.

[serengetiplains]

Did somebody transport me back to 1982?  Say, anyone seen that new film "E.T."?  I hear it's good.

[texendo]

This makes no sense at all. If the digital signals are the same they will sound identical. This is a fact. Power supply and battery will have no effect on it unless they were of extreme bad quality and, still, errors would be 100% corrected when the digital signal is transmitted. Other explanation is necessary: different media players in each computer, different digital equalizer and digital sound "enhancement" settings in each computer, and/or listener biased towards believing that a computer with battery will sound better just because somebody else said so.

Why the surprise as if it should make sense?  Many things don't make sense.  At a general level, anything "makes no sense" because the person trying to make sense of the something 1) has an incorrect observation that doesn't accord with a correct and adequate theory or 2) has an incorrect or inadequate theory that doesn't accord with a correct observation.  I suspect your don't-make-sense confusion is mostly variety #2.  The operating system is the same, the player software is the same, the player settings are the same, the source cd data is the same, the source music data (ripped) is presumably the same.  The one thing possibly different in the setup is the audio hardware, though the laptop and desktop are both Macs of the same generation purchased at the same time.  A difference in hardware, if there is a difference, might not be the cause of the different sound because I noticed distinct differences changing the electricity feeding the desktop.  The type of electricity makes a difference; I assume battery electricity thus has its own sound.

If the computers are feeding digital signals to the same decoder and subsequent audio pre-amp, amp, speakers. Then the sound will be EXACTLY the same. Because there is no sound being fed but a code, a set of information that tells the DAC how to make the sound properly. If an error occurs during the transmission of this information the DAC will (in 100% of the cases) detect it and correct it perfectly. If it can't be corrected perfectly it will send a message back to the computer telling it to re-send the missed part. And the process will be repeated until it gets it right. This entire process takes fractions of seconds and is imperceptible because the information is buffered before it starts playing.

Welcome to the world of Boolean Algebra and digital electronics. A technology light years ahead of: tube amps, chariots, turntables, arrow and bow making, vinyl LPs, you name it.

Man, I totally feel your pain.  I certainly felt the same way about it.  IT'S FRIGGIN ZEROS AND ONES!!  Then I tried it for myself.  You can read my post earlier in this thread about simply changing power cable and ac outlet supplying my iMac feeding a battery powered usb dac.  Granted, it's not a randomized double blinded trial, but the differences in sound were so stark, an average iPoder off the street could have immediately noticed the difference.  I won't pretend to be an EE and give some sort of reasoning why this is, but it is.  I might add that I'm not a seasoned tubed and vinyl guy either; I grew up on computers and CDs.  Don't knock it till you've tried it!!

[Occam]

Did somebody transport me back to 1982?  Say, anyone seen that new film "E.T."?  I hear it's good.

No, more like 1482 and the Papal Inquisition. Before that time that folks realized that it might be more appropriate to empirically verify rather than conduct an ill formed thought experiment.

[Doublej]

I am confident that you can play the same track with the computer on A/C power and on battery power and see a difference in the analog waveform coming out of the DAC.

I guess ears and brains do not count as devices of measurement.

By the way, what determines sufficient proof to say god does or does not exist? How do we measure it?

[CSMR]

I am confident that you can play the same track with the computer on A/C power and on battery power and see a difference in the analog waveform coming out of the DAC.

I guess ears and brains do not count as devices of measurement.

Please do:
http://audio.rightmark.org/products/rmaa.shtml