DIY speaker: braid vs twist vs straight

CDC, if you don't have some room in the tubing you will never get the wire through it. You will be very frustrated with the trouble you are going to have as it is. Do not "kink" the wire by pushing too hard on it. If you do, the kink will make it even harder to push the wire through from that point on. The best way I found is to stretch out the tubing totally straight, and clamp the end, so there are no bends or curls. Then carefully push the wire through. When you get to the end, then unclamp the tip of the tubing and push the last inch of wire through it, or cut last bit of the tubing off and grab the tip of the wire with a needle nose plier. It's not as easy as you think. Definitely straighten out the tubing and hold it straight!

CDC: 18 gauge may involve using a more complex design in order to get it to sound good (it will also never sound like, or as realistic, IMO, as the smaller gauge wire, when used as speaker cable, which is what I was attempting to coax you to try:-).

TWL is "right on" about feeding wire through Teflon tubing (it is not an easy task).

Yes, vibration is a concern when using oversized tubing in longer runs, but such tubing is not required with magnet wire. Magnet wire is coated with lacquer which serves the same purpose as the Teflon tubing and which also has similar (favorable) dialectic characteristics.

The best insulation is "air" and what I try to achieve in cable design is the next best thing (@ a reasonable cost) which is either lacquer or Teflon.

The good thing about the RS spool of magnet wire is that you get two useable gauges to experiment with (in regard to speaker cable), plus the 30 gauge can make decent IC's. The M-C wire may be of the same quality as the RS stuff (which is not HQ cable), but you don't need nearly that much, plus you should be experimenting with various gauges. Once the gauge is determined, then purchase high quality magnet wire from a source such as Michael Percy. HQ magnet wire (with a boutique "name") can run as much as $8/ft from other sources, but Percy (and I assume other sources as well) carry HQ oxygen free magnet wire for "much" less than $1/ft in the 22-26 gauge range.

End of rant.

Dekay, the magnet wire I found has a clear enamel coating. So you're saying I don't need ANY tubing to protection it?

* Would this wire configuration have any funky inductance or capacitance like the Goertz stuff? Probably not, but I want to make sure.
* Should I separate the runs by 1/4" or more? Or can the 4 bi-wire runs be bundled together?
* I found the Radio Shack wire. It too is enamel-covered copper and has 40 ft) 22 Ga / 75 ft) 26 Ga / 200 ft) 30 Ga. Not sure about enamel vs. lacquer coating.
I guess it couldn't hurt to try thinner stuff. I am bi-wiring and could do 26 for the top and 22 gauge on the bottom.
Southwire (800) 444-3600 sells round, rectangular, and square magnet wire with nomex, kapton, or paper insulation. MWS (888) 697-9473 sells MULTIFILAR parallel bonded magnet wire said to offer consistent capacitance and impedance. Phelps Dodge Magnet Wire co sells coaings to apply to magnet wire. I couldn't find Michael Percy.

Going to http://www.sundial.net/~rogerr/wire.htm they recommend:
Wire Size 2 ohm 4 ohm 6 ohm
22 ga 3 ft max 6 ft max 9 ft max
20 ga 5 ft max 10 ft max 15 ft max
18 ga 8 ft max 15 ft max 23 ft max

This site also says when resistance gets too high it makes the amplifier look like a current source. "This means the speaker frequency response will tend to follow the rise and fall of the speaker's impedance curve. The impedance of most speakers is not constant with frequency". This could cause frequency response inconsistencies.

So since my speakers are 4 ohm and the run is 12 feet I felt safe with 18 ga. However since I'm bi-wiring I guess the 22 ga may work.
==>I don't want to burn the house down from overheating some micro-thin copper wire! <== Hence the thought on using teflon tubing.
If people have been using 26 ga with50 watts or more, I would wonder how long a run they had.

Cdc, I used the 22ga radio shack magnet wire on my 3 meter speaker runs. You can go without the tubing because of the protective enamel, but the enamel can get rubbed off and there is a small chance of shorting the wires together. For this reason I used tubing on mine. I also separated the runs by 2 1/2" all the way. With single-conductor runs, capacitance is really not an issue. With wires separated beyond the distance where the fields can interact, inductance is not an issue. I used 3/8" tubing around my wires in order to get mostly air-dielectric, except for the few small contact areas where the wire occasionally touches the tubing. In this case, even the dielectric is not an issue. The tubing provides a sound-wave barrier for the wire, so it will get less vibration, than if it was bare. Since the wire hardly touches the tubing, the tranferred vibration is minimal.
You will not heat up the speaker wires or damage anything. The tables you looked at are about 1% loss tables, and they really bear no relevence to this discussion, where the cable length is under 4 meters. The resistance difference at 4 meters is negligable. There is no risk of damage or fire with this type of wire and a 50 watt amp.

Twisting is usually a better performer because it locates the forwards and return wires in close proximity and creates some field cancellation. When the forward and return paths are in parallel or twisted, this lowers the inductance substantially over separated wires. Braiding is really only for convenience to hold multiple pairs together. Braiding actually degrades the performance. If you select a braid that mostly makes the pairs orthogonal to each other, this will help. I would recommend using enough twisted-pairs to equal 10-12 gauge.