[slim.a]

Quote:

Originally Posted by audioengr /img/forum/go_quote.gif This assumption assumes that the power to the USB converter is good and not dependent on the cable or USB port. Power on a USB port is never high-quality, therefore improving the power feed to a device that is powered from the USB port may help. Steve N. Empirical Audio

Quote:

Originally Posted by rosgr63 /img/forum/go_quote.gif Thanks Steve. That means as I understand it, that improving/upgrading the USB cable would not improve the power supply as the USB port has poor quality power to start with. I am thinking about standard type USB cables without external power supply and asynchronous DAC's, Transports.

The way I understand what Steve said is slightly different:
Scenario1: If the async usb converter doesn't draw power from the usb port (like his Pace car), then the usb cable doesn't matter
Scenario 2: if the usb converter draws its power from the usb port (such as the stock hiface), then the usb cable might impact the sonic performance.

In scenario 2 a good usb extender cable can help get rid of some high frequency distortion in the usb power lines. If the usb cable is set to act as a low pass filter, it can improve (a little bit) the power from the usb port. Of course, such a low pass filter won't get rid of all the "junk" (ripples, spikes, ...) but it could at least in theory get rid of the high frequency content.

To my knowledge, there at least 2 cable companies that apply that concept for their power cables: Wireworld and Hifi Cables & Cie (a small French mannufacturer). I am currently using Hifi Cables & Cie's Powertrans Plus cable that apply the principle of increasing the capacitance (among other things) in order to filter out some of the junk in the power supply.
The result is that the Powertrans Plus power cord works very well with all equipments (it is not system dependant). It provided improvement for different equipement I tried it on: DACs, headphone amps, big tube power amps, powered subwoofers... and even for my TV set.
That it is to say that a good usb cable extender should improve (to some extent) the performance of the stock hiface.

Hiface, jkeny's idea is more elegant. Instead of trying to cure the usb power supply, one can just bypass the usb power from the computer and use an external 5V power supply.
I wonder why nobody has thought before of building such an "audiophile" usb cable. Such a cable would not only work with the hiface but with any usb converter that draws its power from the usb port.

 

[mmerrill99]

One other possibility is that the USB power running alongside the USB signal wires in the same cable has a detrimental effect on the quality of those signals. I've also removed this possible source of signal interference.

 

[mmerrill99]

Quote:

Originally Posted by ironmine /img/forum/go_quote.gif Why nobody can make a reasonably priced ($100-150) asynchronous USB-SPDIF converter with an external power?

That's pretty much what my modded HiFace is except in Euros

 

[rosgr63]

Quote:

Originally Posted by jkeny /img/forum/go_quote.gif One other possibility is that the USB power running alongside the USB signal wires in the same cable has a detrimental effect on the quality of those signals. I've also removed this possible source of signal interference.

So are we back to square one as far as USB cables are concerned?

 

[mmerrill99]

Quote:

Originally Posted by rosgr63 /img/forum/go_quote.gif So are we back to square one as far as USB cables are concerned?

How do you mean? Do you mean that we can't ignore the USb cable? In scenario 1 of slim.a you can by & large as long as the USB signal is being transmitted without distortion - what this implies & how sensitive the USB receiver is, I'm not sure. Is it as sensitive as a SPDIF receiver where impedance matching & transmission Line reflections come into play?

 

[rosgr63]

An external PS may be more beneficial to hiface than an expensive USB cable.

 

[t/sound]

Quote:

Originally Posted by rosgr63 /img/forum/go_quote.gif So are we back to square one as far as USB cables are concerned?

As I see it usb has always been a computer application, in an audio world all that convenience has to have some shortcommings. Imagine a top preamp performing well from a computer ps as power source while the signal wires are wrapped up around the power line in one cable.

See it as going seperates with power, cleaner, carried away from sensitive signal information. Seems reasonable, tolerances in audio is just that more precise.

Powershade.

 

[mmerrill99]

Quote:

Originally Posted by rosgr63 /img/forum/go_quote.gif An external PS may be more beneficial to hiface than an expensive USB cable.

I would think so & you can control the quality of that 5V supply - go for Paul Hynes supplies or battery supply or wallwart supply, etc & see just what effect this PS has on the SQ.

 

[slim.a]

Quote:

Originally Posted by jkeny /img/forum/go_quote.gif How do you mean? Do you mean that we can't ignore the USb cable? In scenario 1 of slim.a you can by & large as long as the USB signal is being transmitted without distortion - what this implies & how sensitive the USB receiver is, I'm not sure. Is it as sensitive as a SPDIF receiver where impedance matching & transmission Line reflections come into play?

I remember that Dan Lavry mentioned somewhere that impedance and line reflections would also affect usb cables. However, I believe that it might only be a problem for adaptive usb converters.

If the usb converter is designed properly (Empirical Audio's Pace car based on the hiface for example), the quality of the usb cable won't matter at all. The usb converter will only use the transmitted data and will act as the master clock. Any jitter will be generated by the usb converter only and it wouldn't matter what kind of PC/notebook is used. As long as it is fast enough to play the files, it should be fine.
This wasn't the case before where many settings in the computer (battery vs. mains, memory, brand of computer, ...) and including the usb cable seemed to matter.

Quote:

Originally Posted by rosgr63 /img/forum/go_quote.gif An external PS may be more beneficial to hiface than an expensive USB cable.

You are right, an external PS would more cost effective than an expensive usb cable.
I have seen some "audiophile" usb cables sell for insane prices. But it would probably be better to use a decent usb cable + an external 5V power supply in the case of async converters.

 

[regal]

Quote:

Originally Posted by rosgr63 /img/forum/go_quote.gif An external PS may be more beneficial to hiface than an expensive USB cable.

I think we need to look for that ideal external powersupply. The typical LM series regulator has a poor reputation with digital. I'm not well versed in this but know that Tentlabs makes very good digital power-supplies, albeit very expensive. The Salas LV Shunt reg may be a good one to look at. People have had good results with AMB's S1 for powering the slim devices transport.

 

[mmerrill99]

Paul Hynes does very well regarded shunt & series replacements for 3 leg regulators at 30 - 36Euro, I think.

 

[regal]

Quote:

Originally Posted by jkeny /img/forum/go_quote.gif Paul Hynes does very well regarded shunt & series replacements for 3 leg regulators at 30 - 36Euro, I think.

Thing about it in my limited knowledge on this area is the regulator ideally needs to have very low ripple but also I think a very wide bandwidth because the clocks run at such high frequency, in other words a typical great for audio regulator isn't what we are after. Its been a while since I researched this topic

 

[waterlogic]

I have Aqvox DAC. The dealer borrowed me all cables that Aqvox makes (USB ext. USB coax, Y bal. etc.)

People, cables make no audiable difference, nothing, zero ...
(auditioned through reference speaker setup , through Sennheiser HD 800).

Do not spend your money on rubish, because it looks nice !

 

[slim.a]

Quote:

Originally Posted by jkeny /img/forum/go_quote.gif Paul Hynes does very well regarded shunt & series replacements for 3 leg regulators at 30 - 36Euro, I think.

Quote:

Originally Posted by regal /img/forum/go_quote.gif Thing about it in my limited knowledge on this area is the regulator ideally needs to have very low ripple but also I think a very wide bandwidth because the clocks run at such high frequency, in other words a typical great for audio regulator isn't what we are after. Its been a while since I researched this topic

Do you know any good and affordable 5V power supply for digital? Russ Andrews seems to be making SMPS power supplies for DACs, squeezbox, ... Do you think it is a good idea?

ps: people, please ignore waterlogic's post. There is no point in going into another debate about cables.

 

[mmerrill99]

Quote:

Originally Posted by regal /img/forum/go_quote.gif Thing about it in my limited knowledge on this area is the regulator ideally needs to have very low ripple but also I think a very wide bandwidth because the clocks run at such high frequency, in other words a typical great for audio regulator isn't what we are after. Its been a while since I researched this topic

You haven't looked at his site 3 Terminal Regulator Replacements
Look at those specs Quote:

Error amplifiers in regulators above 12 volts have a slew rate over 2,000 volts per microsecond and a minimum bandwidth of 150 MHz. Error amplifiers in shunt regulators up to 12 volts have a slew rate of 5,000 volts per microsecond and a bandwidth of 1 GHz. Settling time in all error amplifiers is < 10 nanoseconds and wideband noise spec 2 nanovolts root HZ. Typical output impedance from DC to 200 KHz for the Shunt regulator is less than 0.001 ohm and the series regulator is less than 0.005 ohm. Regulator dropout voltage is 1.5v for shunt and 3v for series.

These are used by a number of people in both analogue & digital supplies on the Buffalo and report a major improvement in sonics. I've just received one of them today & will be testing it out on both 3.3V & 5V HiFace supplies.