[nicholars]

I am cynical with things like this and try to be "objective" about it.... but I had my D1050 connected to my PC with a cheap 3m printer cable I found lying around, I wanted to use USB async on my DAC but was a bit disappointed that the USB connection sounded worse than the SPDIF coaxial from my Xonar STX.... I bought a £20 QED graphite 2m audio USB cable and plugged it in expecting probably nothing.... Surprisingly no grain in the sound and the USB async connection sounds the same or better than the SPDIF connection. I am not imagining it either there is definitely harshness / grain / sibilance on the cheapo 3m cable whereas the QED 2m audio cable sounds clean and a lot better (like the coaxial SPDIF from Xonar STX does). I wouldn't expect a USB cable to change the frequency response or anything like that, but it seems a decent cable vs a crap one can clean up the sound, I have no desire to spend any more than £20 or try any other cables as I think a decent, short as possible, audio USB cable is all you need compared to a £1 3m printer cable.

 

[Kane Williams]

What about Y cables that split the data and 5V power, so one can disconnect the power going to the DAC altogether (after handshake) if the DAC runs on battery or another PSU? Is there any scientific proof that USB Bus power can degrade the audio?
 
So why does everyone rave on about asynchronous USB for audio if isochronous transfer was designed for audio etc?

 

[nicholars]

  What about Y cables that split the data and 5V power, so one can disconnect the power going to the DAC altogether (after handshake) if the DAC runs on battery or another PSU? Is there any scientific proof that USB Bus power can degrade the audio?
 
So why does everyone rave on about asynchronous USB for audio if isochronous transfer was designed for audio etc?

 
Basically because async is controlled by the DAC and then a very short distance from USB chip > DAC chip so it will have less jitter whereas isochronous is controlled by the clock in the PC which is obviously not going to be as good as the DAC.

 

[Kane Williams]

I knew that Asynchronous was to do with the DAC doing the clocking but having read this following statement, it sounds like isochronous, was designed with audio in mind too?

"I have oppo-ha 1 that uses isochronous transfer mode. The main purpose of isochronous transfer is for applications such as audio data transfer, where it is important to maintain the data flow, but not so important if some data gets missed or corrupted. If a USB cable is made according to USB 2.0 specs, the PC and the DAC both use USB 2.0 interfaces, then the will be no corruption to the transmitted square wave, no data loss, it will be bit perfect, it will be recovered correctly by the receiver".

 

[nicholars]

I knew that Asynchronous was to do with the DAC doing the clocking but having read this following statement, it sounds like isochronous, was designed with audio in mind too?

"I have oppo-ha 1 that uses isochronous transfer mode. The main purpose of isochronous transfer is for applications such as audio data transfer, where it is important to maintain the data flow, but not so important if some data gets missed or corrupted. If a USB cable is made according to USB 2.0 specs, the PC and the DAC both use USB 2.0 interfaces, then the will be no corruption to the transmitted square wave, no data loss, it will be bit perfect, it will be recovered correctly by the receiver".

 
Everything I have read says that well implemented async USB is the best out of all digital connections to DAC.
 
I think that is a typo.... On the oppo website it says "Asynchronous USB DAC"

 

[x838nwy]

Isn't a step change a bunch of sines? So if we're talking a very abrupt step, then it can be approximated into a number of high freq. sines. So "the bits are high freq." or whstever is not entirely incorrect.

 

[Chris J]

Isn't a step change a bunch of sines? So if we're talking a very abrupt step, then it can be approximated into a number of high freq. sines. So "the bits are high freq." or whstever is not entirely incorrect.

Well you are correct, the step waves are really just a bunch of sine waves.

But the original statement which was quoted way back when made it sound like the small bits are high frequencies, the wide bits are low frequncies. That part is not true.

 

[Kane Williams]

So anyone tried the Audiocadabra Optimus USB cable? I like the idea of a split power/data cable like the ifi one but would cheaper.

 

[Kane Williams]

I ended up buying a Y style (split power/data)  USB cable from Achtung Audio on Ebay. I was hoping that I would be able to disconnect the power leg of the Y cable altogether once the initial handshake between my MBP and Ifi Nano had been made, but unfortunately, this just results in the laptop disconnecting from the DAC. Bummer!

 

[cablepro98]

I'd say that the difference in usb is not really about pcocc silver and all that "voodoo" but rather what makes the biggest difference is capacitance low for data to reduce jitter but high on power side for usb powered dacs because high frequency roll off would be good considering how noisy the power most computer usb ports have.

 

[dmbr]

I got good results from the iFi Gemini cable.

Anyone compared it to alternatives?