You are fine.
Hi...I don't know if we can hear a difference between the two. But a coaxial digital cable was designed to have an impedence of 75 ohms. Where as a RCA cable should have a impedence of 50 ohms as per design. Iam not sure if I can hear a difference between the two if I swapped them. So if you are fine with the sound, then absolutely no harm
Please use Special 75 coaxial digital canle only for spdif. These will have special shielding to safegaurd the digital signal. RCA is meant to carry Analog signals and analog signals are not prone to outside noise, hence they don't have impedance matching shield
True but can you pass a blind test comparing the two ?
I can't
Why would that be ? Why would analogue signals not be prone to noise ?
The noise if from reflections in the cable due to wave transmission and if there is impedance mismatch. Even analogue signals should experience the same IMHO. All are EM waves
Analog is also susceptible to noise I don't deny that but in case of digital any impedance misatch from external environment could result in bit error.
These reflections are governed by Fresnel equations and where first developed for optics. But EM radiation also follow the same pattern. The refection that happens depends on the angle of incidence and the refractive index of the material. These become significant for high frequency when the cable starts acting like a transmission line. As the S/PDIF digital signal contains fundamental frequencies of 1.5 and 3 MHz, even quite short S/PDIF cables behave like transmission lines. The same effect also occurs at audio frequencies, but only if the cables are massively long — as in, long like overhead telephone wires between cities!
resources.pcb.cadence.com
Thank you sir for that wonderful technical background.These reflections are governed by Fresnel equations and where first developed for optics. But EM radiation also follow the same pattern. The refection that happens depends on the angle of incidence and the refractive index of the material. These become significant for high frequency when the cable starts acting like a transmission line. As the S/PDIF digital signal contains fundamental frequencies of 1.5 and 3 MHz, even quite short S/PDIF cables behave like transmission lines. The same effect also occurs at audio frequencies, but only if the cables are massively long — as in, long like overhead telephone wires between cities!
Q. Why are S/PDIF cables specified at 75Ω?
In a digital S/PDIF cable, what exactly is the 75Ω specification a resistance measurement of?www.soundonsound.com
A signal travelling along an electrical transmission line will be partly, or wholly, reflected back in the opposite direction when the travelling signal encounters a discontinuity in the characteristic impedance of the line, or if the far end of the line is not terminated in its characteristic impedance. This can happen, for instance, if two lengths of dissimilar transmission lines are joined together.
If you are dealing with high frequencies then understanding these reflections become very important.
How to Use a Transmission Line Reflection Coefficient Correctly
There is more than one way to examine how the transmission line reflection coefficient affects your signals.
Indeed. The reflections become troublesome only for frequencies in few MHz or when very long.
I use DIY cat5 cables for all my interconnects because they give lower capacitance then most top of the line manufactured cables. I now have a graveyard of manufactured cables which I'm using to harvest the RCA plugs. The RCA made by some company named DAC were the one with highest capacitance.
Just put back my copper coax.
A perfect cable will have zero resistance, zero inductance and zero capacitance. Consider resistance and inductance in series and capacitor in parallel. The most difficult part is getting very low capacitance. The moment you bring two conductors close to each other, the become a capacitor.
