Last week I saw an advert by a well-known electronics shop advertising digital HDMI cables – you know, the sort you use to plug your DVD player into your TV. They had them listed under the headings: Good at $150, Better for $200 and Best for over $250. So what? Analogue cables vary hugely in price. Why not digital cables?
Digital is not Analogue!
That may sound like an obvious statement but people keep getting sucked in and think the old arguments which worked for analogue still work for digital. They don’t. Trust me. OK, don’t trust me … read on instead.
In the Angry Young Man column in Tone 62, Brett Gideon wrote how people neglect their speaker cables and that the cable quality can affect audio sound. That’s true, in the same way that translating the physical grooves on a vinyl record into an analogue electric signal has virtually an infinite number of ways of coming up with a slightly different sound from the same record.
This is due to the various wires, stylus needle, tone arm, electronics and physical construction all contributing to make the varying electric signal which represents the audio slightly different. This is because the audio is represented by a continuously changing electrical voltage which is quite susceptible to alteration.
Digital is not analogue!
Things are quite different in the digital domain. Digital is just numbers, ones & zeros, voltage or no voltage.
A CD has a smooth reflective surface with holes in it. The CD’s laser reads the surface and converts the holes and smooth bits (called lands) into ones and zeros. There are no ‘almost ones’ or ‘almost zeros’. Because CDs are essentially stamped out like a record, there is a lot of redundant information on them to recover from the odd wrong hole or a scratch on the disc.
This error correction will either work, or it will fail. When it works, the numbers read off the disc are identical to the numbers from the original source. When it fails (maybe due to a scratch) the player skips, doing the du-du-du-du-du-du thing, or it inserts a tiny bit of silence, which is less noticeable than the noise-like buzz of bad data.
It was crazy when, no so long ago, people were selling special pens, claiming that when you coloured in the edge of your CDs, it made them sound better by stopping internal laser reflections. Nope, sorry. The laser is designed to read those holes and smoothes bits fine by itself thank you very much. You don’t think the people who designed CD players wouldn’t have accounted for internal reflections if it going to jeopardise reading the disc?
I once bought a second hand CD that someone had attached one of those sticky plastic rings to the outer edge. It was claimed that they smoothed out and improved the performance of the disc. Nope, sorry. CDs often need to have their rotation speed changed very quickly and sticking extra weight on them makes them less able to do so. Manually attaching something to the disc also upsets the balance of a disc, making it vibrate a hell of a lot more and, if anything, making things more difficult for the laser to read.
You can sell anything if you wave your hands around and spout enough techno-babble. But I digress.
Where was I going with all of this? Well, once you have that string of digital numbers, ones & zeros, voltage & no voltage representing some audio and send them down a cable to another device, the ‘quality’ of that cable CAN’T SUBTLY CHANGE THE TONE OR QUALITY OF THE AUDIO THOSE NUMBERS REPRESENT.
They just can’t. Whether you post a letter in a standard size or an A4 envelope makes no difference to the contents of the letter (it’s just more expensive). Cables can’t subtly alter digital video either.
The numbers that go in one end of a cable are the same that come out the other end, so it doesn’t matter whether you connect your CD player to your amp via digital coaxial, optical or HDMI cable; if it’s digital they will all faithfully transmit the same correct data. If theydo change the data, then they are actually faulty and you will hear periods of silence, dropouts or possibly noise. Take the cable back and get a replacement.
But finish reading this first…
So why did that retailer advertise three different qualities of cable for three different prices?
Did you every hear of anyone buying a new computer and throwing the keyboard away, going out and buying the most expensivekeyboard they could find, just because it made their writing better? No. You press a key and the digital numbers representing that letter gets sent to the computer exactly as you type them.
Did you ever hear of anyone buying a printer and throwing away the USB cable, going out and buying the most expensive USB cable they could find, because it made the pages they print look better? No. The quality of a printer has nothing to do with the cable.
So one HDMI cable should be pretty much as good as another HDMI cable. The only way an expensive cable is ‘better’ is that it’s better for the retailer because they can charge more money for it. It was ironic that the expensive cables were one third of the length of the cheaper one. 60% less length for 70% more cost. Wow – a bargain!
Digital is not analogue!
So don’t let anyone pull the wool over your eyezkg(#DG4kdo@djs+-…
Damn those cheap USB cables!