Audiophilleo 1 and 2 USB to S/PDIF transport - Page 55

If they are not bit perfect you have a MUCH BIGGER problem (just imagine you were transferring files).

I don't want to rain on anyone's parade, but so far it doesn't make sense. I will await Audiophilleo's comments on this issue.

Why doesn't it? The data stream depends on a precise impedance to combat reflections, and both data and power legs will benefit from reduced interference by differential and common mode noise. The AP+PP is not totally isolated from the power provided by the computer, but take a converter that is, like the Off-Ramp. It sounds better through the Short-Block than straight from the computer. Why would that be? There is no effect on the signal being bit-perfect. The input is isolated, and is not powered by the computer at all - everything comes from the wall-wart.

 

The Vaunix could have a similar effect with the OR, even if the power provided is completely ignored.

I don't think you have differential mode noise since the pair of D wires are grounded as per USB spec (yes, I looked that up).

Now let's talk common mode...

Reflection occurs due to impedance mismatch between sender and receiver. Reflections are typically very small and the USB spec accounts for it. The level of reflection you are going to see should not create common mode where you incur an unrecoverable BER.

Moreover, the AP2 is totally isolated from any noise generated on the USB bus. The stage that is responsible for generating the signal is external and fed by the PurePower. The data I believe is buffered in the PurePower unit and then fed into the AP2 unit. So even if you incurred an uncorrectable BER, the PP unit could re-fetch provided the buffer was large enough. This is speculation on my part but I believe the PP unit houses the data and then using async USB the AP2 module fetches the data (its now master, powered by an external supply). Think of the PP unit as a data and power source through two discrete channels, i.e. the PP is already acting like a Vaunix with respect to power. That's why I have two cables from the PP to the AP2 unit, one for power and one for data.

Wait, are you sticking the Vaunix between the PP and AP2 data path or between the Vaunix and PP unit? I have been speaking about the later. The former should not be necessary, see async USB.

Unless you are claiming the USB bus noise is some how seaping into the data path provided by the PP -> AP2, why would the Vaunix help again?

Not trying to be combative, just trying to understand whether $200 will really help here (I'm all for it, if it will) and better understand this new toy in front of me.

Now on topic, so far the AP2 has performed magic on my JH3A system compared to the HiFace.

Deeper bass (I literally had to turn down the JH3A bass adjust), wider sound stage, and just overall better dynamics/impact. The attack/decay is utterly fantastic and at the same time, not bright feeling or SS cold ("too digitals"). Its definitely on par from when I owned the Qualia's. It has that kind of speed.
Edited by Trogdor - 7/14/12 at 5:08pm

The purepower is pretty much just a battery pack - the two modules Audiophilleo refer to are within the AP2 itself.

 

I don't know how AP2 clocks are set up eg I think the dual clocks for the asynch decoding are needed at the USB receiver or at the ARM CPU, and the SPDIF output stage just has an adaptive pll data filter and maybe a separate single frequency clock.  This is just my guess of whats happening inside that wondrous little grey box.

 

Obviously Audiophilleo don't think the quality of power and ground being fed to the USB input and ARM CPU are critical to the performance - then again they also say USB cable doesn't matter much at all with the AP2 and probably would have a hard time believing that music player and settings would affect audio quality.  In fact the hardware buffered asynch USB setup is meant to be a silver bullet that makes everything upstream completely irrelevant, but this is definitely not my experience.  AP2 is good at making these things less important, but its not able to make them completely irrelevant.

 

Regarding the Vaunix I can't say for sure how it might be affecting the performance of the USB input and ARM CPU, or how in turn this would affect the quality of SPDIF signal being produced.  Even if I did understand it, chances are I would not predict any change from using the Vaunix, or different cable, computer setup etc.  In fact I'm not even sure why Audiophilleo thought the purepower would have an influence in the first place if it doesn't affect the jitter performance (maybe noise getting to the DAC chip?) but again this is not something that is necessarily predictable.

 

To add another layer of complexity not all changes vaunted as "improvements" by computer audiophools are actually improvments per se - I tend to disagree with at least a couple of people about specific hardware components and the effect they have on  USB audio performance.  Vaunix could be the same - a change that is perceived by some as in improvement and by others as detrimental to performance.  Because of this I am always looking for specific and articulate impressions to deliver a more informative impression of what the performance differences might be.

That's what I thought too... until I tried it. There's something else going on here, and it's not clear to me what it is. It's another one of those, "Huh? " moments. If I had stuck with the diagrams on the Audiophilleo site, and just used logic, I'd not be enjoying all this music so much!  

 

My buddy with the same DAC, AP1+PP just ordered his. It arrives next week, and we'll see what his results are. 

I understand that there are some inexpensive USB cables with a  similar configuration as the Wire World stuff. Belkin? I don't recall. 

 

Re impedance, per one of the designers from Vaunix, they designed hub for balanced impedance:

 

"3.  The data lines on the PC board are matched to a balanced 90 ohms impedance. The best cables in the world won't help you if the data lines are not properly matched on the PCB. The use of balanced, properly matched lines provides common-mode rejection of noise resulting in a cleaner output."

 

 

Right, I misread that section in my haste.

Again though from the site:

"Total isolation from USB power, gound, and data. When running off battery, relays are used to physically disconnect the PurePower from the noisy USB power source (the PC) so that lowest possible power noise levels are achieved when feeding the Audiophilleo1 and Audiophilleo2 output stages."

Still scratching my head on where the Vaunix comes into play here.

Well I am not discounting anything. My bottom line is what technical benefits do you gain with say a Vaunix in addition to the PP unit. Right now, I don't see any.

Per Phillip, adding the PP battery supply does not appreciably change the jitter results of the AP1 or AP2. 

So that everyone knows how things are set up in my system:

 

 

BEFORE:

MacBook Pro -->USB cable --> AP2 --> DAC

PP powered via the included USB cable

 

AFTER:

MacBook Pro --> USB cable --> vaunix --> USB cable --> AP2 --> DAC

PP powered via the included USB cable 

 

I have written to Phillip too. It would be interesting to hear his thoughts on what might be happening. 

X2. Couldn't agree more. I'm writing up my observations about the AP2+PP. Now, having experienced the Vaunix, I'm going to add it to the write-up as an addendum. However, at this point, I can't imagine using the AP+PP without the Vaunix, the trinity is just too compelling.

 

I am looking forward to Phillips explanation of all of this!

Thought it worth chiming in. I've used my AP2/PP's through Vaunix (similar to Rdr. Seraphim) for quite awhile. I don't claim to understand why, but found it to make an incremental improvement is blackness, dynamics and detail. While I don't have AP2/PP anymore (just finished the second of two Buffalo DAC's, with eXD USB -> I2S (PCM/DSD) , Paul Hynes regs, etc.) I concur with the general consensus - it's a hell of a device(s).

Anybody here used the A1 or A2 with the Anedio D2?

It uses the U2 (xmos) inside. Trying to find out if it would be worth it to try the Audiophilleo.

Read the D2 thread, there's plenty of info on using converters with it.

Welp, just bought the PurePower upgrade and boxed my AP1 to send out tomorrow.  Hopefully the turnaround time isn't as brutal as it was when the upgrade was first introduced.