Using a short coax cable?


I've read in the past that using a coax cable at least 1.5 m is necessary to prevent Jitter between a CD transport and a DAC. Does the same hold true for using coax cables between a streamer and a DAC? I have a 0.75 m audioquest cinnamon coax cable that I'd like to use between my bluesound node 2i and an external DAC. Should I sell this cable on eBay  and buy a longer one?,  Or, are stories like I read just neurotic rumors and theory that can never really be heard when enjoying music?
Thanks!
4342b7d3 d980 4bec aac0 282f8da1ee60labguy
labguy, Idea of min 1.5m cable comes from assumption that transition of digital signal is in order of 25ns. In ideal case DAC has exactly the same characteristic impedance as cable, but in reality there might be slight mismatch causing reflection from the DAC. Since signal travels at about 5ns/m reflection will come back in 15ns (5ns/m x 1.5m x 2) after beginning of transition. It will distort the shape of transition, but it will happen after 12.5ns mid point, (assumed threshold of the DAC) and won't produce any time jitter. As you can see there are many unknowns. Signal can travel faster or slower - dependent on dielectric, transport can swing faster or slower etc. It is almost impossible to measure and what works in one system won't work with another. With high quality transport edges might be as short as 5ns and much shorter cable will be still OK.  Only very short cables are free from reflections from impedance change. Time of signal propagation through such cable would have to be shorter than 1/8 of transition time. 25ns/8=3.125ns equivalent to about 2 feet counting wires or traces inside of transport and the DAC. Because of that I wouldn't risk going more than 1 foot, but even with one foot faster transitions (like mentioned 5ns) will still cause reflections on impedance boundaries.   There are so many assumptions or unknowns, that I would just try and compare the sound.  Cheaper cable might sound better than expensive one in one system and worse in another. Since it is system dependent reviews don't make any sense. I would still compare your 0.75m cable with another possibly 1.5m and even 2m cable. There is no way of knowing what is transition time of your streamer digital output.
Holy cow!  Thank you! That was the most educational and informative explanation I could have ever imagined. You relayed that knowledge very logically and without undue complication. I appreciate you providing an answer and the Logical reason of why you arrived at that answer. I honestly have no idea what that reflection would sound like or if I would even be able to notice it if it was there, but if a longer cable would reduce the odds of me encountering it it seems to be the logical choice.
-Kijanki, Thumbs up to you my good man!
As a general method for anything, and this cable specifically:

I suggest keeping your existing cable until you decide to either return or keep the new longer one. Hear no difference, you learned something, send the new one back.
due to how the impedance of the liquid metal alloy occurs, in the moment or in situ, the liquid metal has the least issues of any cable type, re the shaping of the edges of a square wave. atomic and quantum function of the impedance actually occurs differently in the liquid metal vs that of wire.

The casual eye and casual analysis says they seem to be the same or very similar. But when it comes to defining transient edge and the dynamic aspects of impedance, with the liquid metal we get into living QED (quantum electrodynamics), not LCR, per se. (LCR is the day to day usage & simplification of quantum, in the more correct way of thinking. Like a slide rule averaging for the complexities of QED. Even though LCR came first, it is still the illiterate child of QED)

QED analysis can be done with wire, but it is pretty well useless, so we use just LCR, as an entrenched dogma that functions in the very vast number of ways and casual cases. With the liquid metal, the QED is actually a functional working analysis pathway.

If a physicist that is familiar with QED and transmission lines (as a way of life) looks at our patent, they might mutter to themselves ’holy mother of god’, as there are some interesting things in it ....that very few know what they can do (why they are in the patent) -or be used for....
due to how the impedance of the liquid metal alloy occurs, in the moment or in situ, the liquid metal has the least issues of any cable type, re the shaping of the edges of a square wave. atomic and quantum function of the impedance actually occurs differently in the liquid metal vs that of wire.
teo_audio, Impedance of the melted metal (resistance) or solid wire has very little to do with it.  Characteristic impedance of the cable, in simplification, is a square root of L/C, both being function of cable geometry and dielectric.  Edges of the square wave are shaped by multiple reflections in the cable and there were methods to even determine shape of distorted edges (staircases).  One of them known for at least 50 years, a Bergeron Diagrams, allows for geometric analysis of edge distortion.  Texas Instrument published primer on it:  http://www.ti.com/lit/an/sdya014/sdya014.pdf

Welp, ya'll lost me right after the post by Elliotbnewcombjr.
May as well be speaking Klingon, but impressive nonetheless.