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2.5mm vs 4mm speaker cable

foxwelljsly

Me too, I ate one sour too.
I am loathe to bring up any discussion of speaker cable, but I need to knock up some new runs and am considering whether I should use 4mm instead of my usual 2.5mm cable. Cable will be Van Damme Blue Studio series.

The 2.5mm is rated at 7.65r/km and the 4mm at 4.6r/km

The max length of my runs will be about 7m.

I would prefer to use the 2.5mm as it far less obtrusive and easier to route.

Is there any scientific reason why the 4mm will be better in this application than the 2.5mm? I would have thought the resistance difference in such a short run would be negligible.

cheers
 
Depending upon how loud you play, into eight ohms I think there will not be much between them, at four ohms the thicker cable is probably the better choice - because over 5m length. If you never exceed one watt peak then use the thinner/cheaper/easier anyway.
 
That's quite long speaker cables but not long enough for it to be a clear cut "definitely get the 4mm". The loop resistance with 7m of the thinner stuff will be around 0.1R which will mean a damping factor of 80 being imposed by the cable itself with 8R speakers (40 with 4R speakers) no matter what the DF of the amplifier. That's a pretty high DF (low resistance) and reasonably acceptable. It has nothing to do with how loud you play.
If using 4R speakers then there is more reason to go 4mm but it's still not "mandatory".
 
I was in a similar situation except debating 4-versus-6mm over 10-12m runs. I ‘cheaped out’ with 4mm but it’s absolutely fine. My speakers are 8ohm/93dB though...
 
10m runs into 15 inch Tannoys. Different cables but 2.5 v 4mm here and I am sure that my hearing would have to be at least 30 years younger or equivalent to that of a bat to hear any significant difference.

If there isn't a simple calculator online that does what Jez just did, there ******* well ought to be.
 
Power = I^2 * R.
If the current is more than not much then you need enough cable to take it. Depending on how loud you play... ;)
8W into 8 ohms is 1A, most anything will do at a pinch, especially if the run is short. 1W peak is nothing. :)
32W into 8 ohms is 2A, skinny two-core lamp flex is still ok for a few metres. :cool:
100W into 4 ohms is 5A (I have been known to do this from time to time :eek:)...
Having established that you are not going to turn your amplifier's output extension leads into heating elements, you can now worry about damping factor etc. if you so wish. And then you can ponder what happens to damping due to the almost certainly present low pass inductor in series with the bass driver. If your speaker has no such element then lucky you, some of mine don't either. :D
 
Nobody is likely in domestic circumstances to have any worry at all about the current rating of the cable unless they are daft enough to use DNM single core and have >100WPC that's actually thrashed.
 
QED 79 strand sounds better, looks better (in white) and is 2/3rds the cost.
 
Power = I^2 * R.
If the current is more than not much then you need enough cable to take it. Depending on how loud you play... ;)
8W into 8 ohms is 1A, most anything will do at a pinch, especially if the run is short. 1W peak is nothing. :)
32W into 8 ohms is 2A, skinny two-core lamp flex is still ok for a few metres. :cool:
100W into 4 ohms is 5A (I have been known to do this from time to time :eek:)...
Having established that you are not going to turn your amplifier's output extension leads into heating elements, you can now worry about damping factor etc. if you so wish. And then you can ponder what happens to damping due to the almost certainly present low pass inductor in series with the bass driver. If your speaker has no such element then lucky you, some of mine don't either. :D

The speakers in question are Kef 104/2s, which present a constant 4r. I run them with a Quad QSP, probably peaking around 200w into 4r. This setup is capable of going biblically loud and does on the rare occasion I get the house to myself.

For now I've prepared some 2.5mm cables with some z-plugs.

Would shortening the cables by 150cm make any difference?
 
but just in case you remains curious - chopping 1.5m off the cable you propose might save 0.01ohm at most, and into a pretty-linear 4ohm speaker load as the 104/2s offer ...as such the extra costs you at most, a theoretical drop of 0.02dB in max output. Good luck ascertaining that difference howsoever you try. The excellent KEF driver matching employed on 104/2s - between pairs of mids or side to side - will be at least 200x worse in level for a start.

Since the ear has logarithmic response, and actually pretty darn insensitive long before you start to go where these KEFs will go with 200w behind them : the answer remains : NO


;)
 
Only tweak now might be to get some spade connectors for the binding plugs on the Kefs. The z plugs poke out a mile and I can see them being trashed by a careless hooverer.
 
Fork rather than spade?

Forks always make me nervous - I am always in fear that they will come adrift and short.

I'd be happier with bare wire into a through hole in the terminal. Shame that no binding post clamp (that I have come across), comes off completely so that you can use an eyelet.
 
I have 8m runs and use the 6mm VD blue, best cable I ever used
Alan
Hope you have that well supported at the amp and speaker terminals or have stripped the outer jacket back a fair bit, Alan, 'cos the 6mm VD Blue is as thick and heavy as plumbing! :D
 
Hope you have that well supported at the amp and speaker terminals or have stripped the outer jacket back a fair bit, Alan, 'cos the 6mm VD Blue is as thick and heavy as plumbing! :D
That's almost as large as what comes into a house from a utility pole. So it must be better! :rolleyes:
 


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