Extending/re-routing speaker cables

[Jimk]

Stagger the joints and the potential for shorts is hugely decreased...

[Bert Coules]

I'm helping a friend make changes to his audio-video system, principally moving a main AV equipment rack to a different location. This involves rerouting a good deal of speaker wiring, almost all of it running in the loft under insulation and in some areas chipboard flooring.

The "correct" way would be to uncover the existing cables and relocate them. Given the necessary disruption and severely limited headroom, a far more attractive idea is to connect new cables to the accessible ends of the current ones and run them across the top of the loft floors and areas of exposed insulation then down through to ceiling to a new AV hub.

The maximum extension would be in the region of sixteen feet, resulting in a cable run some thirty feet from amplifier to loudspeaker; would that make any material difference to the sound or the loading on the amp? This is a decent mid-price hifi setup but nothing really ultra-high-end.

We can of course experiment with extending the cables on just a pair of speakers in order to assess the sound, but it would be useful to know in advance if a run of such a length is pushing things a bit.

Many thanks.

[Brian Gaff (Sofa)]

So much depends on the speakers and amp in use. I've heard amps that seem to sound leaden on long speaker runs, which I'd consider bad design really. I think the best you can do is use decent cables, ie that can handle the current and suck it and see. I'd have thought in the current state of the art all these strange effects should be sorted out by now. My one issue would be pick up of interference being fed back to the amp. I had an issue with the local Sea Cadets some time ago, but never did get it sorted even with ferrite beads. I sold the amp and got a different make and there was no issue. One of the problems of having too wide a bandwidth and long cables. Brian

[Bert Coules]

Brian,

Thanks for that. The existing cabling is hefty (and expensive-looking) specialist speaker wiring: matching it exactly for new runs is going to be pretty pricey, not that that's necessarily a problem, but it's also pretty inflexible. I might suggest experimenting with something of similar weight but easier to work with: if it functions OK for the longest necessary run then it should be fine for the rest, if my friend is willing to ignore the extreme high-end audiophile insistence on having all speaker cables the same length.

The possibility of picking up radiated interference hadn't occurred to me at all: that would liven up his listening no end.

[spuorgelgoog]

10 metres is nothing for any reasonable amp, speakers and sensible cable.

Owain

[Dave Liquorice]

It really depends on how much power you need to shift to the speakers and how much electrical damping the speakers require.

Is this just for "background music" or to have 110 dB SPL flat 20 Hz to 20 kHz cinema/disco "sound experience"?

From personal experience changing 5 m speaker leads from 72 strand "heavy duty bell wire" to 1024 strand 2.5 mm^2 "speaker cable" made a noticeable difference to the bottom end when driven hard. The bass was much tighter and controlled as the lower cable resistance electrically damped the 10" paper cone woofers much better. The voltage drop along each wire went from 5 or 6 V to less than 2, with

100W RMS being delivered to the speakers.

If I was putting in a "whole house system" I'd either go for active speakers or an amp with sperate speakers (on decent cable...) in each room and distrubute at line level balanced not speaker level. Amp/speakers is probably more convient to control.

[Bert Coules]

Dave,

For some reason the centre of your message appears as blank white space on my screen, but enough remains legible to get your points, I think. I don't know the full tech details of the installation but I do know that the speakers are part of a home cinema setup: three front, two side, two rear, and a separate subwoofer. The amp is a fairly high-end domestic Marantz. Not sure about the speakers.

[Bert Coules]

Owain,

Thanks.

[Robin]

If messages appear odd it's worth looking at Google Groups

[The Natural Philosopher]

It will loosen the bass slightly. Use very fat cables

[Brian Gaff (Sofa 2)]

Yes I have a sub woofer here with internal amp which used to pick up Radio China till a friend put in some capacitors to stop it. It was coming in via the input terminals. Bah humbug. There is of course a person who makes loads of money out of unproven audio cables called Russ Andrews who seems to make unsubstantiated claims for anything he sells at huge mark ups. To me this is a simple LF transmission line issue. So the losses matter since the amp low impedance needs to be seen by the speaker to make them have the right damping. Apart from that, all this talk of oxygen free and the like is fiddling about at the edges of things.

Brian

[Brian Gaff (Sofa 2)]

Yes well, he did say it was not top of the line, and as such I think most cables with a decent low resistance are probably OK. The effect you mention on bass is one reason why so many sub woofers have their own inbuilt amplifiers I'd suggest. The problem with active speakers fed wirelessly is you still need a mains supply and as such you then need wires for that instead! Brian

[Brian Gaff (Sofa 2)]

His message was OK here, must be something on the client you are using. Is the sub amplified in its own right? Brian

[Brian Gaff (Sofa 2)]

Yes but as all Usenet messages are plain text there seems no reason for any one particular message to be an issue, unless the client is having issues of some type. Brian

[Brian Gaff (Sofa 2)]

Most people with surround set ups spend more time deciding which profile they should use for each track, than listening to it. Ahem. Brian

[Brian Gaff (Sofa 2)]

And make the joins accessible for goodness sake. I used to find soldering them together beat most other ways generally, but of course make sure they don't short. Keep out of reach of Squirrels too. Brian

[Bill Wright]

I got involved with the audio system in a big old house that was being renovated. I can't remember what sorts of amp and speakers it was but the speakers were big buggers that weighed a ton and were on wheels and the amp was a monster thing. Actually there was a pre-amp feeding two black boxes that had fans. For some stupid reason the amps had to be in a little room that was at one end of a gigantic long room and the speakers were at the other end of this big room. The cable route had to be circuitous. I used 81 strand auto cable. Bought two 100m drums, one red and one black, and made up lengths of 'twin' feeder. The speakers had great big binding posts for connectors, which was fine. The connections to the amps were a bit faffy though. It all sounded absolutely fine when it was done and it was incredibly loud. I played some fairground organ music and it sounded awesome.

Bill

[Bert Coules]

Curiously, when I went to respond to the partially-blank message it was reproduced complete and intact in the reply box. Possibly a glitch at my end, I think.

The subwoofer in the installation in question is indeed powered.

[Bert Coules]

Yes, that should be possible. And so should soldering, which I know is the ideal method. On that topic, can heat-shrink sleeving be tightened with a hair dryer on a high setting? Neither of us has a hot-air gun and I've never had much success with matches or a lighter.

Undoubtedly a valuable piece of advice for life in general.

[Bert Coules]

Thanks for that, Bill. This setup is considerably more modest, but sounded good to me in its current layout and hopefully will do so again once we've finished shifting bits of it about.