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Microphone cable suitable for digital signals? (1 Viewer)

Reggie_F

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Is inexpensive microphone cable good enough for digital audio use? I assume it must be able to transmit at 75ohms. I've got an old microphone cable lying around with the words OFC stamped on it and I'm wondering if I could just attach some RCA connectors on it and use it for digi. audio use.
Any comments?

Thanks. Reg.
 

Phil A

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Signal will pass. The digital audio spec is for 75 ohms. I've played with cables other than 75 ohms. The microphone is likely not 75 ohms, might be 110 or who knows. Why bother buying connectors. If you want something cheap use the RG-59 you noted in the other thread. It is 75 ohms. I've used Belden 89259 among many other things as digital cables. It is RG-59 and makes very good analog cables too. Personally. if you want something cheap and decent get a reasonbably (e.g. AR or lots of others) priced RCA to RCA composite video cable. If you feel like experimenting later with other things more expensive, that's OK. Get something basic that will work well for now.
 

Reggie_F

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Phil,

So something with a higher ohm rated is not recommended? You mention that a signal will pass, isn't that enough considering a digital signal is binary and as long as the the signal is passed, then it should be fine, right?

Thanks.
 

Phil A

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Reggie, the signal carried over the wire is not in digital form (not 1s and 0s floating thru the cable). A coaxial (RCA digital) able sends an electric signal with its voltage or lack there of representing the digital bits. It is an analog transmission and therefore subject to any of the problems of interference that an analog cable can have. The spec designed for a digital coaxial cable was done by those with engineering skills (far in excess of my minimal overview technical knowledge) so as to minimize any corruption of the bits. Dolby Digital stuff is sent in packets along the cable and corruption of the bits can result in errors. PCM (on CDs) can have jitter and other problems induced via a poor transmission between the source and the DAC. You will get sound, assuming you do the connectors right, but it may not be as accurate or trouble free as a proper cable. As I say to anyone, try if you must. A reasoanble decent composite video cable is not all that expensive. Blue Jeans cable, a forum sponsor has decent quality digital cables that won't break the bank (probably under $15) so why worry so much?
 

Leo Kerr

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...or, what kind of digital?

AES/EBU digital audio is generally shipped over 3-wire mic cable.. but it's also balanced with a +/-5 volt differential..

Leo Kerr
 

Phil A

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Yes Leo that is correct. I believe a commom std. output from an analog XLR connector on most equipment is 8V vs. 2V for an analog RCA output device. Digital RCA outputs I believe have an even smaller std. output. The cable it itself has of course no add'l output and a balanced digital cable would be 110 ohms impedence. Very little consumer equipment has that type of digital connector (and some are not true balanced connections either). I bought the pro version of the Bryston SP 1.7 pre/pro that has one (instead of 2 toslinks on the std. version) as my old DVD transport I sold had a balanced digital out. I figured it would always be nice to have as I can alway get a digital switcher for toslink or coax if I really needed it.
 

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