what exactly is digital coax? [Archive] - Audio & Video Forums

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mohakky
05-06-2005, 05:55 AM
Does anyone know the difference between a digital audio coax cable and say a standard audio cable with phono plugs?

Can you even use a regular audio cable in place of a digital coax cable? does it sound the same? etc...

hermanv
05-06-2005, 11:08 AM
Coax cable is a controlled impedance cable usually either 52 Ohms or 75 Ohms. What coax cable does that regular shileded cable does not do is propagate all frequencies at the same speed and attenuate all frequencies by the same amount relatively regardless of length. (Within some upper frequency limit often in the GHz.)

Regular audio cables even the shielded ones are quite acceptable for passing the 20Hz to 20KHz traditional audio spectrum but they become problematical above one Mega Hertz or so.

Compact Disk (CD) digital audio has a 1.4 MHz bit rate. This requires the cable to carry information to at least 7 MHz for any reliable transfer. Since a square wave (any digital signal) is a wave comprised of an very large number of odd harmonics (3rd, 5th, 7th, 9th etc) the ability to maintain "squareness" is quite dependent on the properties of coax.

Now the other hidden question, what is the difference between "digital" coax and "ordinary" coax I can not answer, I'm reasonably sure there isn't any.

Coax is made by having a controlled diameter wire suspended with an insulator in the center of a controlled inner diameter hollow conductor. Often the outer conductor is a briaded wire sometimes foil wrapped around the outside of the insulator . Flexibility varies.

For short distances regular wire appears to work but coax is so cheap it's not worth avoiding and could provide benefits in sound quality you might not know is missing if you use a regular interconnect. You can try it, at these signal levels nothing will be damaged by the attempt.

JBMAudio.com
05-24-2005, 05:44 PM
Does anyone know the difference between a digital audio coax cable and say a standard audio cable with phono plugs?

Can you even use a regular audio cable in place of a digital coax cable? does it sound the same? etc...

This depends on which two cables you are comparing. Some companies, there are none, others their digital coax are 75 ohms, while there analog are not. If you are unsure on which to use, a good rule of thumb is use a 75 ohm coax for everything, they can be used for analog, digital and video with very good results