ECN Forum Forums General Topics of the Trade Voice - Data - Video Discussion question about speaker wire

Just my point. The increased length of conductors running parallel to each other increases the capacitance (in some R.F. applications very small values of capacitance can be made with two short lengths of insulated wire which are twisted or untwisted to adjust), and the transmission-line effects of combined capacitance and inductance are insignificant at <20kHz for the length of cable runs involved.

The cable capacitance could start to become significant and attenuate higher audio frequencies if we were talking about a high-impedance circuit, but in this application the sourece impedance is simply far too low for it be an issue.

Yes Paul,
That thing is called a Radio Ham's "gimmick" capacitor, very handy when you are "bread-boarding" a new circuit design.

Yep, certainly done that a few times!

very handy when you are "bread-boarding" a new circuit design

And for those manufacturers who feel a real trimmer cap would be way too expensive.

-Hal

Hbiss
Please explain my false impressions. Maybe I am applying transmission priciples but I know High voltage transmission wires rotate their position on long runs to cancel capacitive reactance. At least the local transmission engineer told me that. The twist is supposed to add inductive reactance to offset or cancel capacitive reactance.
What else is totaly false? the surface area. Are you saying that high frequencies are not benifitted by greater surface area? My Physics teacher and all my electrical teachers told me that High frequencies and higher voltages tend to travel on the surface of the conductor and certainly there are High voltage conductors that are hollow for this reason. I understood the surface effect started to matter around 1000 hz and that is in the Audio range. I know solid wire will drive a speaker and I probably would not hear any attenuation.
Another benifit of stranded wire relates to vibration but maybe I am wrong there too??
I don't mind you telling me I am wrong but now you need to elaborate so I can correct my mis-understandings. Just telling me I am wrong is totally wrong and tends to get my back up.
Thanks

Skin effect is measurable at audio frequencies but at those frequencies the small difference in surface area between solid and stranded is an insignificant factor. Non-listening tests have born out the fact that a wire with a given cross section of copper and the same length, whether solid or any configuration of stranding or braiding, will conduct audio frequencies measurably the same.

Another benefit of stranded wire relates to vibration but maybe I am wrong there too?

Stranded is certainly more flexible and will tolerate bending and vibration much better than sold, yes. How that would relate to a speaker installation I don't know unless you are talking about a portable setup or where speakers will be moved about. Nothing wrong with using stranded wire for those reasons or just because you want to use it. But don't think one or the other is going to make your speakers sound any different.

-Hal

With regards to the twisting you both seem to be correct, but you are talking apples and oranges.

The transmission line twist and the twist to make a cheap trimming capacitor are essentially different in that with the cheap trimming capacitor you are looking at the surface area of the one wire near the other wire, capacitance being caused by having a charged plate near a second plate (the twisting of the wires together create far more capacitive surface area than laying two wires next to each other - look at the surface areas exposed). The inductance created by the twisting is negligible in this case (but not always) as the wire ends are not connected to comnplete the loop.

With a transmission line over long distances, the twisting does add inductive reactance (it is a closed loop) The surface area between the two exposed wires is virtually unchanged (look at the distance between the wires).

Some days your the boot and some days you are the goat. I guess my facts about speaker wire are well mostly wrong.
I found this article from Belden about audio wiring.

http://www.belden.com/pdfs/techpprs/wcfsbetp.htm

After reading it I realize that when it comes to speaker wire most of the things I have heard don't really apply to speaker wire.
By the way the reason for twisting is to create a balanced line and the twist helps noise rejection for RFI and EMI. The other reason is to give the cable a round profile which makes it easier to handle. After this maybe I'll stick to power wires. Sometimes knowledge comes from being mistaken.

Don't get me started there Hal.
What ever happened to the old aluminium ganged tuning capacitors you USED to be able to buy?.

Oh sorry, I forgot, people don't BUILD anything themselves anymore, just buy it out of a store.

A LOT of electronics stores have forgotten where it was they came from and only offer cheap appliances.

Those that used to supply the "hobbyist" are quickly getting rid of their stocks of electronic components, even switches and the like, in favour of laptops, iPods and anything else to pander to the kids of the now.

Try this one for the laughs, go into your favourite electronics store and ask them for a "DPST switch with a contact rating of 20A per contact and a Neon indicator, in that switch"
I'd like to hear the result.

I still have a big box full of assorted types.

The famous (in the U.K. at least) Jackson brand is still made here, but they'll cost you an arm and a leg. You might want to pour yourself a stiff drink before looking at the prices of some of these:

http://www.mainlinegroup.co.uk/jacksonbrothers/index.htm