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Specific question for BADA USB converter users.

What lengths of USB and SDPIF cables do you use? I'm trying to decide between the BADA and the Audiophilleo w/PurePower converters. One of the issues is how much will i have to spend in cables to get optimum sound. BADA advises 1.5 meters for both cables, which contradicts conventional wisdom with regard to having the USB cable as short as possible. If I ignore BADA's advice, I could buy a 0.3m USB cable with a 0.5 meter AES/EBU cable, which would be more comparable in price to the two 0.3m USB cables I could use on the Audiophilleo.

I'd rather have higher quality shorter cables than longer less effective cables. I would also prefer the shorter cables because they would be easier to install in my planned setup. For those who use shorter lengths on the BADA than what they advise, have you tried the 1.5m lengths before deciding on the shorter cables? I'd like to get the impressions of those who have used/are using the BADA USB converter and have used shorter lengths than advised. This is not a general question about cable lengths, about which there are already several threads on various websites.
asindc
audioengr
3,282 posts
 
All digital cables that are used in jitter sensitive applications should be around 1.25-1.5m in length. Read this:

http://www.positive-feedback.com/Issue14/spdif.htm

Digital is not like analog. Shorter is not always better, unless it is really short like 4 inches.

Steve N.
Empirical Audio
mesch
3,394 posts
 
Thanks Steve for the link. Very informative.

A couple questions come to mind.
1) Does the impedance issue pertain equally to USB transmission as SPDIF transmission?

2) With use of purepower with the audiophillieo. How much of the benefit is due to the ellimination of the problem of 5V transmission along side the audio signal through the USB cable?
audioengr
3,282 posts
 
"1) Does the impedance issue pertain equally to USB transmission as SPDIF transmission?"

You bet.

"2) With use of purepower with the audiophillieo. How much of the benefit is due to the elimination of the problem of 5V transmission along side the audio signal through the USB cable?"

Its not that the 5V is in the same cable that makes it particularly bad, although the return current in the ground wire can make the common-mode noise worse.

Its that the 5V power is poor to begin with from the computer and then a long cable to transfer it makes it even worse. Replacing this with a better local 5V power is a beneficial thing.

Even without the 5V in the cable, there is still a ground as well as two signal wires. The ground is still a problem because unwanted loop currents flow on this wire causeing common-mode noise at the receiver. The best options are to filter this using a Short-Block or use a USB interface that is galvanically isolated.

Steve N.
Empirical Audio
almarg's avatar
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almarg
9,670 posts
 
Steve, I certainly agree with everything you have said, except that I'm curious as to why the optimal cable length for USB would be similar to what is optimal for S/PDIF. The rationale for 1.5 meters that is presented in your paper is based on the presumption that signal risetimes and falltimes are in the vicinity of 25 ns. Aren't risetimes and falltimes far faster than that for USB 2.0, and therefore why would the optimal cable length for the two kinds of interfaces be similar?

Regards,
-- Al
cerrot's avatar
cerrot
1,700 posts
 
Why not just spend $150 for an ESI Juli@ soundcard? It sounds much better than either USB converter at a fraction of the price. USB is NOT ready for prime time.
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