How long a USB cord is too long?

[djtek]

Hey all,

 

Been thinking quite a bit about how to move to a computer audiophile solution the past few monthes and this is what I would like to do. My listening room also doubles as my office. I want to use my iMac + a firewire raid device to a USB DAC. I believe the maximum USB cable length is 16'. I measure it and without completely rearranging everything I need about 18' from my computer to my audio rack. I believe there is some repeater tech I can buy, but I'm not sure if that is a good idea or not? Also not sure how important the quality of a USB cable (and whether or not it is practical to buy 'audiophile' cable of this length).

 

Any advice/suggestions?

 

[Max]

Hi djtek

 

I had exactly the same issue: I don't want a computer, even one as quiet as a mac mini, next to my speakers. The maximum allowable length of a USB cable is 5m - this is set by the the maximum time allowed for a device to respond to the first stage of bus enumeration. I was also just over the maximum length: in addition, I was using a built-in CAT5 cable between the computer & the DAC. I chopped a USB cable in half & fitted RJ-45 connectors (in a spirit of experiment). It did work, but not reliably. Sometimes the link would drop out, and need to be disconnected & reconnected to recover.

 

In the end I bought a Chinese no-name 'USB extender/4 port hub' for about £45 which works perfectly. This is only USB 1.1, but that is all that is needed for a DAC (though I think that one USB 2.0 DAC is about to come to market). It also allows me to connect the remote control receiver as well.

 

Max

 

[djtek]

Thanks for the response.

 

Anyone know if using a USB extender can adversely affect the sound quality? I could also go the Toslink route. It seems that the maximum length for toslink is much longer then 5m.

 

[GemMoth]

Thanks for the response.

 

Anyone know if using a USB extender can adversely affect the sound quality? I could also go the Toslink route. It seems that the maximum length for toslink is much longer then 5m.

 

I does degrades quality. I get hiss and noise. Too noticeable that I don't want to keep the current arrangement (computer -> 16 feet USB repeater cable -> 15 feet USB cable -> DAC)

[wgscott]

Any advice/suggestions?

 

Wireless (eg Audioengine D2, or Airport Express if you don't mind the limitations).

 

USB/coax converter, and use coax to span that length.

 

If you haven't already read this thread:

http://www.computeraudiophile.com/f6-dac-digital-analog-conversion/usb-extender-solves-cable-length-limitation-6750/

[Snowmonkey]

I had a similar problem (21 feet from PC to amp). On advice from my local audio shop, I kept the DAC with the PC and ran a 21 foot Audioquest interconnect cable from the DAC to the amp. Sounds fine, to my imperfect ears.