routing speaker cable in chipboard floors

[NC]

I am trying to think of the easiest way to route cable in a house we are looking to buy. When we move in, there will be no carpet on the floors - and the bare chipboard under-flooring will be exposed. Can I route a channel about 1cm wide and about .5cm deep in this to lay speaker cable ? Skirting boards will also be missing, making it easy to fit banana posts on wall plates in the desired speaker locations (easy to poke the cable from the channels and up behind the plasterboard). 'Normal' routing is difficult behind the plasterboards as I dont want to have to re-decorate, feeding cable through using rods is also very difficult due to doorways getting in the way.

We will be laying underlay then laminate over the chipboards. I could try and put the cable ontop of the chipboards and under the underlay (ie not cut a channel). Would 'flat' speaker cable allow this without causing problems for the laminate ?

Help and advise much appreciated....

[tony sayer]

In article , NC writes

Just cut a small grove the thickness of the cable...

Seems fine to me;), but don't post this over on uk.rec.audio unless you want a 1000 plus posting on how the cables need laying after soaking in snake oil, and must only be laid when the planets Venus and Uranus are in conjunction, and all must be done by a high priestess of hi-fi whilst sacrificing two virgins to the god of audio etc,,etc,,etc.....

[ben]

The speaker cable is normally flat anyway and will cause no discrepencies under the laminate, in fact you could trail it around the perimeter of the laminate, the gap your supposed to leave for flexing/expansion of the laminate.

[NC]

Good plan. Should be easy to go across the living room / kitchen doorway too - using the expansion gap between laminate and tile; and around the fireplace too.

[Picker]

Make sure you are not contravening "part P" ;0)

[Dave Liquorice]

I wouldn't mess with the flooring boards, their strength relies to a certain extent on a dense "skin" on the faces the cores are not so strong. A groove will break this skin...

As the skirtings are off why not construct cable ducting with that, either routed grooves in the rear face but dificult to fit as the cable will drop out or battens and a thin cover to allow access at a later date for network, AV, RF etc cables.

[Ian Stirling]

Probably a bad idea - unless you do it directly over the joists. If it's 18mm ply, you've only got 13mm left, which is very significantly weaker. If you have to do this, use a snaking line going back and forward 3" or so every 12". This will be much stronger.

"Flat" speaker cable, (I use 0.1" IDC cable*50) routed in 1mm deep wouldn't make a significant difference.

[Chip]

On Mon, 18 Jul 2005 07:21:33 +0000 (UTC),it is alleged that NC spake thusly in uk.d-i-y:

My suggestion which audiophiles would kill me for is much the same as Ian Stirling's. 0.1" pitch ribbon cable would be ideal for this, depending on the thickness of the underlay beneath the laminate you may even be able to get away without routing the floor at all.

Another possibility would be 25mmx16mm minitrunking under the level of the baseboards (which you say are being temporarily removed). It's roughly the same depth as skirting board, and then that would just leave you doors to cross, which you may be able to do on a join in the floor boarding, where weakening it wouldn't be so bad. If you can and do do this, make sure you put something over the cable to protect it from when they fit the thresholds and make the installers aware it's there.

[bigcat]

Everyones making life difficult here. The solution is enamelled copper wire. It has almost no insulation, the 2 cores will need to be laid not touching. You can lay it behind or under skirting, or on top of the chip when you cover it, and wont need any grooving. Great stuff. Also very cheap.

BTW never try to refit and reuse it, its a fit once only item.

NT

[Mike Dodd]

Along with all the other suggestions to date...

Why not use those fibre-board mats, in place of the underlay (basically, around 3' square, and about 5-8mm thick, some dense fibre type material, as an underlay to the laminate (it is sold as such).

Then, just leave a gap between the boards to allow whatever cable runs you need.

[The Natural Philosopher]

Trouble is, for decent resistance it has to be quite thick and stiff...its useable though..

[bigcat]

I'm assuming it would be treated like cable rather than flex. Speaker use doesnt need anything particularly big.

Enamelled is no use if you want to use it like flex tho.

NT

[Dave Liquorice]

IMHO anything with less than 2.5mm^2 CSA is to small.

20W into 4 ohms is over 2A... but it's not just the abilty to carry the required current. The extra resistance reduces the damping on the loudspeaker affecting the LF response.

[Andy Luckman (AJL Electronics)]

Au contraire. The more copper you can get in line, the better. Too little and the bass goes all wooly.

[PC Paul]

Thirded. Ribbon cables are very very flat, and easy to get in many widths (or run several strips!).

Each conductor in typical 0.1" cable is capable of carrying 2A and since the cores all have good heat dissipation this doesn't really go down much with number of conductors, as a round cable would.

Just pick a size you can get cheaply and bundle together as many conductors as you want for each side of the speaker connection.

[The Natural Philosopher]

Yes. I laid some cheap car loudspeaker (pretty fat stuff) into a chased channel in concrete floor.

Its good - beter than T & G.

[bigcat]

Lets see.

Typical 8 ohm speaker, voice coil R typically 6 ohms.

5 meters of 2 core 1.29mm dia cu wire, tot 10m, 0.0128 ohm/metre, total R 0.128 ohms.

Cable's R increase as a percentage of total speaker R: 2%. Ie a non issue.

NT

[tony sayer]

Its not as simple as that. Take into account the effects of the crossover unit in most all speakers and then post that to uk.rec.audio and wait for the 1000 odd posts.

They won't be long 'a coming;)....

[The Natural Philosopher]

Current carrying capacity is not the issue: It's resistance. You will get a very woolly bass sound from ribbon cable of that dimension. Lousdpeakers rely on a low presented impedance to damp out cone and enclosure resonances at low frequencies. The amplifier manufacturers go to extreme lengths to get this well below 50 millohms: ruining all their good work with high resistance cable will not get the best out of the kit.

[The Natural Philosopher]

Cable R as a percentage of amplifier output impedance (say .05ohms)

250%

A little knowledge is a dengerous thing.

Normal ampplifiers would have a damping factor (ratio of loudspeaker to effective amplifier impedance) of 50:1 or better. Your 1/8 ohm has limited that to at best 32 on a 4ohms system.