Audiophilleo 1 and 2 USB to S/PDIF transport - Page 57

Quote:

Originally Posted by DaveBSC 

The more you can get away from computer supplied USB power, the better.

Which is why you add a Hynes on the USB...oh wait, this isn't the Empirical thread;):))

You got it right.  Pure Power is onto something obviously beneficial, and should only get better and better shall Philip REALLY go far with it.

Posted in error.

The impact on SQ by adding the Vaunix on the processor/USB side of the AP+PP was significant for me. I believe Phillip is looking into it.  

Quote:

Originally Posted by Audioexcels 

Which is why you add a Hynes on the USB...oh wait, this isn't the Empirical thread;):))

 

You got it right.  Pure Power is onto something obviously beneficial, and should only get better and better shall Philip REALLY go far with it.

Looking on the Audiophilleo website, it appears that new as-built Pure Power A2 units are not available yet? All I see is the retro-fit option and the original A2 for $579.

Quote:

Originally Posted by pigmode 

Looking on the Audiophilleo website, it appears that new as-built Pure Power A2 units are not available yet? All I see is the retro-fit option and the original A2 for $579.

You're looking for the option to buy a new AP2 with the PP upgrade already done?  It's in the drop-down menu.

A2PP is $579? Cool!

Re the iPad, if I'm typing more than a few sentences, I connect the BT keyboard.  

X2 re the power conditioning, especially for digital audio. Even in my big rig, power conditioning made a significant difference. Due to the intimate nature of headphones, I find the differences easier to detect. 

Look forward to hearing more about your AP+PP+Vaunix experience. I believe my system is fairly resolving as well, and the Vaunix stays. 

Quote:

Originally Posted by Currawong 

Quick thoughts, because I'm on my iPad and typing sucks...
I have a very resolving system, so the small improvements are very important to me. The Vaunix hub resolved an issue with harshness in the treble when listening which I didn't like. I'm sold on power upgrades because all of my experiences with audio since I joined Head-Fi have proven the benefits to me. Improvements in the digital transport have too, ever since I found out that upgrading the clocks in a DAC made for significant benefits in sound quality, even in cheaper gear.
That being said, while I don't understand why it should make any difference, I keep finding different players on my Mac sound very *very* slightly different. I am very sensitive to the sound of instruments in jazz and classical so I notice, though now it is at the point of splitting hairs.
I haven't noticed any difference in USB cable quality. The current thoughts about them seem to be related to noise and the cable's characterisitic impedance being correct.
One of the reasons, incidentally, I use the Vaunix hub is that I can connect more than one DAC/transport to my rack without having to use multiple long cables and I can test the sensitivity of DACs to differences in USB power.

Quote:

Originally Posted by dailydoseofdaly 

Quote:

Originally Posted by pigmode 

A2PP is $579? Cool!

That is just for the ap2, if you go to the drop down menu it says
Standard + Pure Power $999.00 USD

Thanks. Hard decision then compared to a couple others at +$1k.

Quote:

Originally Posted by Currawong 


That being said, while I don't understand why it should make any difference, I keep finding different players on my Mac sound very *very* slightly different. I am very sensitive to the sound of instruments in jazz and classical so I notice, though now it is at the point of splitting hairs.
I haven't noticed any difference in USB cable quality. The current thoughts about them seem to be related to noise and the cable's characterisitic impedance being correct.

The same is true on Windows. JRiver with RAM playback enabled and WASAPI output (bit-perfect) sounds quite different than JPlay with RAM playback and WASAPI output.

Quote:

Originally Posted by Trogdor 


How? Right now the problem I see with all of this is that if the Vaunix is improving the AP2 wPP there is either an issue with Phillip's design or some other phenomenon occurring.
I'd like to understand more on WHY there is any audible differences.
So far no one has given me a technical reason that makes sense (at least to me!). I can only suspect that its placebo (no offense) without listening to it myself (anybody got a spare Vaunix laying around for me to borrow for a week?).
I understand that AP is now looking into it to see if there is indeed an issue, so I await Phillip's analysis.
Floating point arithmetic would be my guess (perhaps 32 vs 64-bit). Same comment goes to DaveBSC.
In the end Currawong, most of it is placebo. There were some USB audio bugs in 10.6 that caused issues with various devices (clicking noise mainly). AFAIK, Lion+, the players should sound the same.
Setting up a DBT with a friend or significant others is easy if you truly believe you can tell the difference between players. Try it! Its a lot of fun! :-)
That's a nice idea.

If I had a dollar every time I heard that one.  Like I said before if you try to figure out why gear sounds a certain way before listening to it you have  hard task ahead of you.  Best not to get into sound science here as it will spawn a lot of off-topic nonsense.  I best leave it at that.  We can revive another thread to discuss computer side tweaking etc. or something and about 15 sound science folks can come and get all uppity etc etc.  Or not...

Quote:

Originally Posted by Currawong 

Quick thoughts, because I'm on my iPad and typing sucks...
I have a very resolving system, so the small improvements are very important to me. The Vaunix hub resolved an issue with harshness in the treble when listening which I didn't like. I'm sold on power upgrades because all of my experiences with audio since I joined Head-Fi have proven the benefits to me. Improvements in the digital transport have too, ever since I found out that upgrading the clocks in a DAC made for significant benefits in sound quality, even in cheaper gear.
That being said, while I don't understand why it should make any difference, I keep finding different players on my Mac sound very *very* slightly different. I am very sensitive to the sound of instruments in jazz and classical so I notice, though now it is at the point of splitting hairs.
I haven't noticed any difference in USB cable quality. The current thoughts about them seem to be related to noise and the cable's characteristic impedance being correct.
One of the reasons, incidentally, I use the Vaunix hub is that I can connect more than one DAC/transport to my rack without having to use multiple long cables and I can test the sensitivity of DACs to differences in USB power.

The first issue is that many players either are not bit-prefect themselves, or cause the operating system to not be bit-perfect. Once you have the player changing bits then you would expect each one to change the bits in different ways, and so sound different. Likewise, the player may interact with the O/S to cause (or allow) changes to the bit-stream there. Some of the drivers themselves may not be bit-perfect. Luckily, if you have an AP1, you can verify once and for all that you're getting bit-perfect output.

The second issue is that every player (and every other program) interacts with the operating system itself, which is bound to affect the timing - which will end up causing or aggravating jitter. I don't think that, in this context, the jitter issue is as straightforward as we tend to believe. Assuming that each sample arrives approximately when it should (let's say "before the next one is due to arrive"), then removing jitter is simply a matter of re-clocking. But, what if the player (or the O/S) causes enough delay that we get several samples behind? In that case, we MUST have some sort of buffer; simply being able to adjust the timing of each individual sample isn't going to be enough. In the first case, a reclocking scheme (like that included internally in the Sabre DAC) will fix the jitter on the individual samples; in the second case, since it doesn't have a real buffer, it won't be able to replace the samples that are unavailable when they are needed - and the result will be a dropped sample (which could well be audible if it happens enough). Some USB converters have actual buffers while others do not. (A buffer in the driver may or may not eliminate this problem - depending on exactly where the bottleneck is.) The upshot is that, for a given USB-S/PDIF converter, the player could well influence whether the signal is or is not too badly damaged to "be made perfect". It is also true that many converters use various methods to reduce jitter, and different types of jitter will respond more or less to different methods. For example, a specific PLL will eliminate jitter at certain frequencies very well, but work very poorly with jitter at different frequencies. And, yes, the cable could influence this as well. As far as I know, in this context, the AP has buffering, and responds very well to any and all types of jitter.

The third issue is power supply noise. The actual operation of the processor in the computer adds noise to the power and ground lines which is related to the power the computer is using - and what it is doing. If you connect a bad USB DAC to your computer, you can usually actually "hear" what program is running - the noise changes when you switch programs, or when a given program is "working harder". This is obviously going to extend to music player programs as well as other applications. A converter (or DAC) connected to a USB output on a computer is using both the +5V supply and ground. The +5v supply on most computers is really noisy (computers don't care), so something like the Vaunix hub should make an improvement for devices that use that power supply. However, something like the AP (especially with PP), which doesn't use either the +5 or the ground from the computer, shouldn't be affected. Presumably a badly designed cable could also allow the data itself to "bleed" into the supply lines, where it would appear as noise.

Another (related) issue is that there may well be noise on the USB data lines themselves. (The data is ones and zeroes, but minor variations in those levels caused by noise, even though they're ignored by the digital circuitry, may "bleed through" and end up finding their way into the DAC and interfering with things.) With a device like the AP, which has galvanic isolation, both the ground and +5 supply are NOT passed through to the DAC, nor allowed to affect the output data, and the data is totally "rebuilt" by the output USB sender (also running off the isolated power), so this should also be eliminated. The real problem with "galvanic isolation" is that, while it's pretty simple to isolate the DC path, it's much more difficult to ensure that absolutely NO high-frequency noise can leak through. (At a dead minimum, with a single-box solution, you have the possibility that a minute bit of noise will be radiated by the wires coming in, and picked up by the wire going out.... therefore, it's POSSIBLE that reducing the noise going in will make a minute difference. Considering how well designed the AP is, though, I wouldn't be all that worried.

After all, at some level, having the computer within a few hundred feet of the DAC risks the possibility that noise being radiated through the air by the computer will be picked up by the DAC. Perfect isolation isn't even theoretically possible, so we'll have to settle for "inaudible" :) )

From an engineering point of view, the AP with PP seems to cover all the bases, and it seems difficult to conceive of how anything else would improve matters further.

Quote:

Originally Posted by drez 

If I had a dollar every time I heard that one.  Like I said before if you try to figure out why gear sounds a certain way before listening to it you have  hard task ahead of you.  Best not to get into sound science here as it will spawn a lot of off-topic nonsense.  I best leave it at that.  We can revive another thread to discuss computer side tweaking etc. or something and about 15 sound science folks can come and get all uppity etc etc.  Or not...

There's a huge problem with your statement - actually two of them.

The first problem is that "expectation bias" will tend to incline us (myself included) to hear what we expect to hear - often leading us to hear things that aren't there. Worse, we may attribute things that are indeed present to the wrong causes. (Did DAC b actually have an ever-so-slightly cleaner high end, or was it just that the humidity was 5% lower when we listened to it?)

The second problem is that there are a huge number of products (and DIY options) out there - and very little opportunity to audition most of them in proper surroundings. Since we won't ever have an opportunity to hear even a minute fraction of them, we need some way to pre-screen the ones that are at least likely to be worthwhile. (And, yes, this often directly conflicts with the first problem.) As far as I'm concerned, the best screening method we have is to consider the scientific (engineering) justification of the product or technique.

In this particular case, the theory is that the AP is NOT insensitive to poor quality power (on the USB side).

If this is indeed true, then the Vaunix Hub, and several other alternatives, can be tried and would be expected

to produce similar results.

At least we can avoid wasting time on things that don't seem to have "legitimate justification" for our expecting them to work. (Is it possible that some dolt, whose scientific explanation is obviously pure drivel, somehow lucked onto something useful? Yes. Is it likely?)

In the case of the Vaunix Hub, I'm pretty sure that there's nothing magical about it in particular, so the engineering question becomes that of whether running the computer-powered-side of the AP off of cleaner power affects the output or not. If it really does, then there is some flaw in the design (since it theoretically should not). If so, then the Vaunix may help, but a better solution would probably be to identify and eliminate the weakness in the AP. If no such flaw exists, then we had best move on to other tweaks.......

The easiest way to find out if we're chasing our tails or not would be to cut up a USB wire and use it to supply clean power to the PP (on the computer side).