[kajohndet]

Hi,

Some one please help me clarifying these 2 questions.

1. Is there ant differences between Coaxial Digital Cable and RCA IC? , since they cosmetically look the same. Can RCA IC be used as digital cable?

2. When we use digital out from home CD player, will they still be a signal output from analog part?

Thanks in advance for your help.

John

 

[zzz]

1. Analog ICs have near-zero impedance. On the other hand, digital ICs are supposed to have impedance of 75 Ohm. No clue how it affects anything, but I guess somehow it does

. (btw, standard RCA video cables are 75 Ohm too)

2. Yes.

 

[gaineso]

Quote:

Originally posted by zzz 1. Analog ICs have near-zero impedance. On the other hand, digital ICs are supposed to have impedance of 75 Ohm. No clue how it affects anything, but I guess somehow it does . (btw, standard RCA video cables are 75 Ohm too) 2. Yes.

They may be 75 Ohm, but I don't have a clue how that's measured. If you hook a meter between the center pins, end to end, they'll measure nearly 0. Same with outer shield. Center to shield should measure about infinity, so WHAT THE HELL IS A "75 OHM" CABLE?????

 

[Richard Berg]

1) there's more to impedance than DC resistance, though I'd hope an interconnect wouldn't be too reactive

2) pretty much all the resistance comes from the connectors, not the wire -- consider that "75 ohm" cables can be a wide variety of lengths

 

[kajohndet]

So can RCA interconnect be used as digital cable?

Thanks

John

 

[Nezer]

Quote:

Originally posted by kajohndet So can RCA interconnect be used as digital cable? Thanks John

Yes but they aren't designed for it. It will probably work but there will be an increase in errors. If the errors get to be too many you will have drop-outs in the audio. I have used standard cheap RCA analog ICs as a digital IC in the past and it did work. I don't do it anymore as I doubt it's any good for the line driver.

75 Ohm refers to the resistance at RF frequencies. This wouldn't be measurable with a standard meter. Just trust the cable manufacturers on the specs.

On my home theater setup I wouldn't be able to tell the difference between expensive digital ICs vs. cheap video ICs so I use video ICs there.

If your rig is mid-fi I would just go the video cable route and upgrade your components first.

If you want something better but for not a lot of money Outlaw makes a decent digital IC.

 

[kajohndet]

Hi,

My setup will be like this:

AMC CD8B --> ART DI/O (awaiting) --> MG Head --> HD580

What digital cable would you guys suggest?

Thanks

John

 

[Ricky]

75 ohm is just the characteristic impedance of the cable, and it has not much to do with the "common" or "regular" impedance of a cable, at DC or at high frequencies. It cannot be measured with a multimeter. It is related to transmission line effects at cables.

Characteristic impedance Z is calculated:

Z=square root of (L/C)

Where L and C are the inductance and capacitance per meter of the cable.

Some more info at:

http://www.kentech.co.uk/transmissio...l#anchor869219

and

http://www.tpub.com/neets/book10/41.htm

 

[Anders]

Ricky,
Thank you for this useful answer.

 

[gaineso]

Quote:

Originally posted by Richard Berg 1) there's more to impedance than DC resistance, though I'd hope an interconnect wouldn't be too reactive 2) pretty much all the resistance comes from the connectors, not the wire -- consider that "75 ohm" cables can be a wide variety of lengths

Question.

Isn't this impedance, which I realize is not actually DC resistance, frequency dependent?

I always thought it was anyway, just like the impedance of a speaker system varies all over hell and half of Georgia depending on frequency.

 

[andrzejpw]

Personally, I use video rcas for my dvd player > reciever link. I know I won't be able to tell the difference. . .

 

[dvw]

In general, there is no detrimental effect on using video cable as digital cable or audio cable. But you can't use audio cable for digital cable unless you are certain that the cable is 75 ohm.

All coax are not the same, e.g. thin Ethernet coax cable is 50 ohm.

Also some video cable are not very well made,i have experienced bad cable. If you can find a good cheap cable, that will be good enough. Exotic construction doesn't really matter in this case. IMO, exotic construction is more likely to screw up impednace than a well made coax cable.