Digital or Analog cables from Pre-Amp to Amp.


Digital or Analog interconnect cables from Pre-Amp to Amp.
comments, inputs, feedbacks, thx u much.
rlew
Hi Rlew.

Just taking your question at face value, you want analog I/Cs. Even when one is running I/Cs from a CDP or DAC to a preamp, you would want to use analog I/Cs.

A digital I/C is commonly defined as an I/C whose characteristic impedance, not resistance, is set at an industry standard: 75 Ohms for Single Ended/RCA S/PDIF or 110 Ohms for Balanced/XLR AES/EBU. A digital I/C is a single I/C used between a transport and DAC whose output and input respectively is supposed to be either an 75 or 110 Ohm impedance. The signal between a Transport and DAC is still in the digital domain. Hence, it's name: Digital I/C.

Analog I/Cs are just that; they are a left and right channel stereo pair that carries an analog signal that starts at the output of the CDP or DAC and runs throughout the rest of the system. For many reasons, there is no industry standard as to what analog I/C's characteristic impedance is. It's fairly all over the place from maybe 50 to 200 Ohms. Any I/Cs that are used between a CDP or DAC to a preamp, or from a preamp to amp that a manufacturer says are digital is probably saying they are "Digital Ready" which is simply marketing hype....like loudspeakers some years ago when CD playback was offering "Perfect Sound Forever" and a ton of speakers were marketed as "Digital Ready".

Finally, a bit of clarification. Impedance and resistance are not synonymous. Resistance is a DC characteristic while Impedance is an AC characteristic. Kind of a simple clarification but if that distinction isn't understood, all kinds of confusion can and usually does result.

Cheers!

Robert
RSAD
Thanks for that clarification Robert! When it comes to electrical info, my synapses are not firing on all cylinders...or, er,...my elevator doesn't quite get to the top floor...you get what I mean!

So, out of curiosity, when you do mis-match the impedance in those specific applications, what are the likely results?

Marco
Hi 'x2.

Despends on how the impedances are mismatched. Predominately, the cable's contribution will be dull or bright or, noisy or blunted transients. Whether the mismatch is on either side of the required impedance, efficient energy transmission is wasted.

When the impedances are correct, everything simply snaps into place.

Cheers!

Robert
RSAD
Robert

Thanks for your explanation of impedance in digital interconnects.

I want to be clear about what causes a mis-match of impedance with respect to digital interconnects. The mis-match of impedance most often talked about in audio involves the output impedance and input impedance of two components connnected to each other. I gather that is not true for impedance mis-match in digital cables, because you said the proper impedance is established by the type of termination on the interconnect. That means the proper impedance does not depend on the output impedance of the transport/CD player or the input impedance of the DAC. From what you said, the only way an impedance mis-match could result would be the design of the interconnect itself. Is that right? For example, a cable that yields an impedance of 86 ohms instead of 75 or 110 ohms.