Digital And Analogue Cables

@pegolea Digital cables transmit a digital, binary signal (0’s and 1’s) before a digital to analog converter (DAC) converts the signal into an analog signal.

Generally different types of digital cables have required specifications to enable the effective delivery of the digital signal to its destination. Coax, for example needs to have a 75ohm impedance while AES (digital XLR) needs to be a 110ohm impedance cable.

@blisshifi 

Digital cables transmit a digital, binary signal (0’s and 1’s) before a digital to analog converter (DAC) converts the signal into an analog signal.

Its actually an analog waveform which represents a voltage for a one and a different voltage for a zero...I realize I'm splitting hairs but unfortunately too many people (not you, your posts demonstrate an expertise) believe the digital signal is infallable..."its just sending ones and zeros"..."if that were the case then financial transactions would be fraught with errors and they arent"...when I read that stuff from some on Audiogon I just roll my eyes...its usually from an IT/networking "expert".

@ghasley Digital cables are basically intended to transmit square waves of sorts, right, and not a full analog audio signal (despite whether you classify those signals as analog, they do not contain the analog representation of the music)? Yes, all cables have conductors that can send either type of signal, but the interfaces in which they connect and the spec that they need to transmit the information effectively determine their classification.

@Op I may be simplifying too much.

Analog cables

• Speaker cables
• Interconnects - RCAs or XLRs carrying analog signals between components (analog outputs from a DAC, phono stage, preamp)

Digital cables move digital signals - I have a network player/preamp so it’s all in one box. And many folks have separate components for streamer, DAC, Clock and music libraries connected using digital connections.

• This is where I think it gets confusing because there are a variety of USB, Optical, Coaxial, HDMI, AES and I’m sure there are others

@blisshifi

I was trying, rather poorly I might add, to communicate that the analog representation of the digital waveform is a pretty fragile thing. Subject to noise, induced jitter, reflection, etc. Too many in our hobby believe its transmitting EITHER a one or a zero. It is transmitting a representation of but it isn’t like say a ribbon cable between a hard drive and a mother board. The cable quality and specifications matter and can positively/negatively affect sound quality...in short, all cables aren’t equal.

Again, your exemplary reputation precedes you and I know you counsel your clients accordingly, I was just trying to make certain that a budding audiophile wouldn’t make incorrect assumptions. Regards.

So… a digital “cable” the wire part, not speaking on the connector, does not need carry but minimal voltages in a narrow range, but noise (interference) is of much higher concern because, as the signal is “low”, any interference is going to be “high” relative to the signal.

With a full spectrum, higher voltage signal, “analog”, the density and power of signal is higher and so the “interference” is vanishingly small (given the same interfering signal as above).  

Increasing the signal value relative to the interference value is a different beast depending on what type of “information” and at what “strength” and “density” that signal is.

Analog signal carrying fat pipes with some shielding (impedance as low as possible) vs digital signal carrying thin “pipes” with heavier shielding with specific line impedances per specs for the transmitters and receivers depending on what they are doing.

which is why optical cable is superior as shielding that from anything that can interfere with the light stream in the cable is much easier than shielding “regular” signal from emf interference. (And the specifications for optical is a .. more dense… info stream)

also why interference coming in on the power input is of concern.. there is no information, so any interference signal that is picked up has an outsized influence on signal as that interfering signal becomes part of the base of the carrying wave produced in the audio stream.

at least that is my layman’s conceptual understanding.

@blisshifi you hit the nail on the head. "Digital cables" transmit packets that are mapped to 0's and 1's with a different voltage levels and those voltage levels vary continuously during the transmission, due to power fluctuation, EMI, and various other influences. RCA single ended interconnect does the same (in all honesty it is questionable whether RCA cables can do sine wave without distortion, no jagged edges), transmits voltage variation. I haven't heard that someone is referring to Ethernet cable as digital, and it does exactly the same thing. It seems that it was pushed through via cable manufacturers to market cables as digital and sell them for digital music easier. In technical terms, probably the closest to a digital cable is optic cable, light=1 no_light=0. Another bone for us HiFi hobbyist to chew on.🫣

@ghasley I appreciate your respect, and no offense is taken. I’ll be the first to admit that I myself still have much to learn about the engineering side of audio. I am at least lucky to consider myself curious and want to gain experience and expertise wherever possible!

Thank you for your clarification and coaching. :)

@pegolea @blisshifi

@pegolea it isn’t that simple. Google the AES3 (AES/EBU = Audio Engineering Society/European Broadcast Union) standard. As they say, timing is everything. The consumer standard is called Spdif. Virtually identical although most anyone with ears will tell you that even though the data fed through AES/EBU, BNC, RCA SPDIF and Toslink Spdif are identical at the source, they ABSOLUTELY will NOT sound the same. Not close. Toslink carries lower noise but is more susceptible to jitter induced problems. AES/EBU via 110 ohms (xlr) in many cases presents the best opportunity for the fewest compromises. BNC is best for longer distances.

There are no absolutes because it depends on the individual dac’s optimation of how it accepts the data and of course, USB and Ethernet is different because packets, error correction and clocking happens differently, usually at the receiver whereas AES/EBU-SPDIF most often happens at the source.

In summary though, most dacs are quite good. Some however, really lock in and exploit their strengths. Some engineers are quite a bit more advanced in their thinking. Read up but more than anything, trust your ears by optimizing your streaming chain. Matching the strengths of a particular streamer with the strengths of a particular dac maximizes your oppotunities for success.

@ghasley Nicely said! And many times the audible differences in those interfaces are due to differences (improvements and fallacies in signal preservation, impedance, shielding, and grounding) in cable designs (e.g. one Coax can sound vastly different from the next), or that the destination’s handles something a bit different from one interface to the other, even if they are all using SPDIF. 

@blisshifi indeed.

My Audio education taught me that a “digital coaxial” cable was just another name for the once commonly used “composite video” cable. Both operated in the same frequency spectrum and both were 75 Ohms. The chief Monster marketed the exact same cables as video, or, with herpetologic lubricant as Coax for more $$…because…greed. Bill Low at Audioquest had a line called VDM…signifying they were suitable for video, digital, or monaural analog audio.