analog or digital cables??? - Page 1
Forum section: electronics / beginners

author: Unknown
author_rank: Unknown
timestamp: January 24, 2019, 09:23:36 am
content: Hi.Is there any reason to choose analog over digital cables,or vice versa?Thanks.

author: Zero999
author_rank: Super Contributor
timestamp: January 24, 2019, 09:46:49 am
content: Please provide more information.Cable is inherently analogue.Are you talking about sending audio via Ethernet vs analogue?

author: Brumby
author_rank: Unknown
timestamp: January 24, 2019, 09:56:29 am
content: Quote from: Zero999 on January 24, 2019, 09:46:49 amThis ^ ^ ^ ... but there's more to it.QuoteYes, more information is necessary before we can offer any sort of useful response.

author: spec
author_rank: Frequent Contributor
timestamp: January 24, 2019, 10:47:47 am
content: Quote from: ddmeltzer8 on January 24, 2019, 09:23:36 amDefinitely ddmeltzer8Like any other component in a design, you must choose the appropriate cable for the job.But in many cases the cable is relatively unimportant- if you are just sending a few switch closures to an MPU, for example.In some cases the cable must match a very strict specification, like Ethernet, USB, RS485, LVDS, etc.Then you get cabling for handling power, like your house wiring or car wiring, which has completely different requirements.At the very extreme there are microwaves where coaxial cable and connectors are mandatory and must be of the highest quality.

author: ataradov
author_rank: Super Contributor
timestamp: January 24, 2019, 07:21:29 pm
content: Quote from: ddmeltzer8 on January 24, 2019, 05:54:42 pmThis is BS to extract money from suckers.

author: Mr.B
author_rank: Unknown
timestamp: January 24, 2019, 07:31:07 pm
content: I agree with Alex - assuming the well known context of audiophool websites.However, there is a valid argument that, in certain types of installations, a fibre cable carrying digital audio may be superior to a copper cable carrying analog audio.

author: Gyro
author_rank: Super Contributor
timestamp: January 24, 2019, 07:37:33 pm
content: If, by digital audio, you mean an S/PDIF connection, then its impedance specification is 75 ohms. Using a 75R impedance coax cable will result in minimum reflections and best edge transitions. This is the only case where it will make a difference - on an actual high frequency digital data stream.If you are talking about any other sort of audio connection, then the impedance of the cable makes no difference at audio frequencies. Really poor cable, with just a few strands of wire forming the screen might be more susceptible to noise pickup but that's about it.General 'Digital audio' type hype on standard audio interconnects is just that - hype!

author: Benta
author_rank: Super Contributor
timestamp: January 24, 2019, 07:38:01 pm
content: Quote from: ataradov on January 24, 2019, 07:21:29 pm+++1

author: ArthurDent
author_rank: Super Contributor
timestamp: January 24, 2019, 10:44:58 pm
content: I cycle all my audio cables through a liquid nitrogen bath to align the crystals in the 100% pure copper to be inline with the current flow. Further improvement is realized by orienting the tube amplifier to be facing the left side of the flat earth.

author: Brumby
author_rank: Unknown
timestamp: January 24, 2019, 10:53:23 pm
content: I like this answer as a general comment:Quote from: Gyro on January 24, 2019, 07:37:33 pmWith this adding some specifics in differentiation of various uses:Quote from: spec on January 24, 2019, 10:47:47 amIf you could find that link, we could address what it says more precisely.

author: bson
author_rank: Unknown
timestamp: January 24, 2019, 11:25:56 pm
content: The problem with AES/EBU and derived signal standards (SPDIF for consumer price points) is that the sample clock is embedded in the bit stream. This means waveform integrity is everything since, well, it's the sample clock. The consumer coax variety is single-ended, meaning the shield braid or foil is also the signal return path, which degrades its ability to act as a shield. AES/EBU runs over XLR, so is both differential and has a shield separate from the signal return lead. TOSlink had the potential to be totally immune to noise and reflections, but the transceivers were made to be as cheap as humanly possible for the consumer market, and never performed well. Toshiba never targeted anything past a consumer audience for whom cost is everything.Impedance matching is also critical, at 100Ω. Even though short runs will have trivial reflections,anyreflection will manifest itself as sample clock jitter. This is simply unavoidable since the waveform contains the sample clock. (Not only that, but it will also be signal self-modulated!) SPDIF can be done perfectly well in this regard; however an AES/EBU or I2S (over USB 3, HDMI, or CAT5) interface from a reputable brand (not talking eBay kit stuff here) is almostguaranteedto do it right. (Even Chinese ones, like Audio-GD or Yulong Audio will design for proper termination.) And if it has an AES/EBU interface,use it!The reason the sample clock is in the bitstream is that AES/EBU was intended as a digital replacement for analog interconnects; this means if the source plays a little faster, the clocking is sped up a little; if plays slower the clocking is slowed down. This is required for uses like maintaining frame-accurate sync with video (especially for transfers, or splicing between cameras or audio sources), between multiple channels, or trick play. For a purely home audio application it's obviously superior in every way to have a packet format that specifies the nominal sample rate and then flow-control the transfer to the playback device and let it clock it locally from a low jitter XO. But that doesn't work for many professional applications.