Does length matter

Cables!

Digital, analogue, mains, speaker.

Does the length of the cable really make any noticeable difference?

Does anyone out there think they could really tell the difference between different lengths of cables? For example 1m v's 10m pair of speaker cables? etc....

I'm talking within *sensible* lengths.

They say shorter is better ("they" say quite a bit don't they?), and this would seem obvious enough with it meaning less distance for the signals to travel etc.... Which is nice, because that tends to mean cheaper and neater too

Strange how cable companies don't state the need for a minimum length (£$£$£$). I think cables like CAT5 has a min' recomended length in industrial use.

So, does it really make a noticable audible difference?

 

MO! FYI CAT5 can be any length under 100M

 

this is really close to i thought i was having a couple of days ago. to whit...
it is often said that it's better to have a long run of line level cable between pre and seperate monoblocks with short runs of speaker cable than a short run of line level and long runs of speaker. i would have thought this is the wrong way round with any rfi or other distortions picked up by the long line level i/c being amplified by the amps in the former situation whereas in the latter the already amplified signal would swamp the same rfi etc. distortions. or am i once again arse / elbow blind.

cheers

julian

 

Re: Re: Does length matter

I thought there was a minimum reccomended length for CAT5? Just a couple of meters or something, but still a minimum.

 

I've come across minimum lengths for speaker cable which I think is based on "amp load" rather than sonic qualities. Similarly there is the odd interconnect which has a minimum length (0.5m?) which I find strange considering amp designers often talk about keeping the signal path as short as possible.

But what do I know?

 

You shouldn't have I/Cs less than 0.8-1m, becasue as the signal passes through the plug/socket/medium, you get an immpedence drop. Impedence recovery will bring this back up to the original value (ish) and so at least 0.8/1m is required for this. If you don't allow it to get back to the original ohmage, you'll get reflection and alsorts. The point is don't buy I/C cables of less than a meter really.

 

I think there's much sense in what you say here.

The shorter speaker cable argument is based (I think) on the power amps having greater control of the speakers if the cables are shorter.

 

Very long speaker cables increase the impedance the speaker 'sees' consisting of the output impedance of the amp and the impedance of the cable. The damping factor is the impedance of the speaker divided by the impedance of the amp. Thus if the speaker 'sees' a higher impedance the damping factor is decreased. In the end this might lead to bass being less 'tight'.

Damping factors amp manufacturers specify mostly are calculated using a nominal impedance of 8 ohms (8/(output impedance).)

 

Slightly off topic, but i noticed this guy on ebay sells alot of 0.5m Nordost hi end cables.. if the above is true me thinks he's chopping 1m cables in half to sell? especially as they all appear to be 'lovingly updated with new plugs' or am i just too synical??? either way could these be bad news??

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=3065684565&category=295

 

WHAT???! I think your equipment is unmatched, sir.

 

onno i thinks youve got it back to front,the speaker couldnt care less wot impedance is down line from it,as long as it gets enough power to move backwards and fallward its happy.the idea with a short speaker cables is theres less power lost in the cable.if a cable has an impedance of 1 ohm and the speakers are 8 ohm 1/8 of the power will be lost in the cable,on low level signals the circuit impedance is much higher and even a 10 ohm cable will olny lose around 1/1000 of the origanal signal

 

so how common are 1 ohm speaker cables and why do they have such a low impedance?
cheers


julian

 

A speaker moves because a magnetic field is generated by the coil that interacts with a permanent magnet. This proces can also be reversed. If the speaker moves this will generate a current in its coil. If the current can flow freely this will dampen this movement. the smaller the resistance of this current the better.

Energy dissipation in cables is so low it's allmost never a problem except in very large lenghts. For example a 10 meter 2,5 mm^2 cable has a resistance of about 0.2 Ohm so only 1/40 of the energy is lost.

 

You need minimum .75 for digital ICs, at least with most players,or the reflections will "mix" with the signal, so I have been told...

Also shielded PCs need a minimum lenght to work, I thought it was 2 meters, but my VDH come in 1.5...

 

No - but then, you wouldn't have expected me to say otherwise, would you? My domestic situation obliges me to have the boxes with speakers at one end of the room and the boxes without speakers at the other, joined by cable runs of 11M. And it doesn't sound any different to what it sounded like before. And while we're at it, the fact that cable length is different also doesn't matter - I once ran a pair to speakers, one of which was 1.5M long and the other 4.5 M long (the speakers were on either side of a fireplace and the equipment was all on one side).

 

Re: Re: Does length matter

One of the few advantages I can see so far in building my own speakers [I haven't heard them yet, so I can't comment on the final benefits] is that you can design the box for a particular 'extra' resistance [added to the crossover inductor].
This means that I can predict what various lengths of cable will do to the bass [yes, I am assuming that it all works as planned, of course...]
The speakers are designed for 5m of 1mm² solid core, or the equiv. DC resistance of another length/thickness, thus giving plenty space for movement.

 

Que?

 

"SPM goes a long way, so 0.5m is more than enough with most racks."

As the guy seems to think 0.5m of one cable might stretch further than 0.5m of any other cable, I'd suggest steering well clear.

I imagine his reference to SPM 'going a long way' is more an indication of how he views what can be done with 1m of cable to make twice as much money.

 

CAbles

One of the biggest affects you can have on the sound of your amp is capacitence. And considering that the largest changes that cable length changes bring is capacitence then yes, it does affect your sound. (Hence the Townsend keeping resistivity to 8ohm with their caps, so length brings no chagne to capacitence)
Most cables are designed within safe bounderies so length changes the sound very little and within the "known" family sound. Hence "I doubled the length and detected no change", I bet your amp did.
That excellent sounding flat Geortz cable is a good example of the capacitence effect though, just try and drive more than 15m, or even 5m with a Naim.

The 100m cat5 limit is the design limit in the digital domian with standard 12 volt repeaters. As the amplifiers got better the speed also went up. Todays 1 gig standard really requires sheilded wire to protect the delicate signal, and often cannot reach 100m.

I really wouldn't use it for domestic hi-fi speaker cable runs especially over 5m, it simply isn't designed to take the current and is designed to handle a voltage you can put your tongue across.

 

A1000

Townsend Cable is the same cable as Goertz (except for cryogenic treatment and a zobel device).

They are both 8 ohm cable IME.