2. cables
  3. 1242221206

1.5m for 75ohm digital coax?

Hey everybody.

I am going to upgrade my RCA coax cable connection between my Monarchy DIP (re-clocker)and Musiland MD10 DAC. I'm upgrading from copper to silver.

I have read numerous posts on this and other forums that one should use at least a 1.5 meter length to prevent signal reflections(or something like that). Is this length really necessary? I only need a .5m cable and these silver cables are expensive.

Mike
mmarvin19
tobias
1,534 posts
 
There are quite a lot of very good digital cables that don't cost very much more in a 1.5m length than they do for a meter. Atlas Opus and Compass, VH Audio cryo Pulsar, Apogee Wyde Eye are examples. All these are at or near the top of their price class.
sidssp
1,077 posts
 
Mike, you are talking about digital cable here. For digital cable, impedance is important but length is not, unless you are talking about very long length in which signal degradation becomes a factor. Signal reflection is caused by impedance mismatch, not length. You shouldn't have to spend more than $30 to $40 for a good digital cable, silver or copper makes no difference. Don't spend too much on it.
kijanki's avatar
kijanki
4,450 posts
 
Sidssp - Signal reflections are caused by length. For very short distance there is no transmission line effect. We have transmission line at about <8x ratio between signal travel time and rise/fall time. Signal travels 0.5m at about 2ns and rise/fall times are often in range of 20ns - we don't even have transmission line. If cable in question would be 1m or slew rate would be higher (good transport) then go with 1.5m to make impedance boundaries reflections (if any) come after transition.

Mike - at these frequencies signal travels on the surface only (skin effect) and many copper cables are already silver plated for that reason. I would pay more attention to shielding (braid and foil) and connectors. If you build cable yourself and one side has RCA connector then find one that is 75 ohm.
More to discover