I came upon a few good lengths of old 300 Ohm TV antenna wire, which I picked up intending to use a speaker cable. Since there's no Analog / Digital / Speaker "connectivity" forum, it was here or the Lounge...
The spacing of the wire is something I've seen in a commercial offering, which makes sense to me as to offer lower capacitance than the type of wire where the conductors are running as close to one another as is manufacturable.
My question is around the quality of copper in these things. One hunk was definitely copper plated steel, verified being magnetic. Another feels a little stiff, is non-magnetic and perhaps some alloy with a bit more tensile strength...as that seems to be desirable for the intended application. Another pair of lengths as a foam-core arrangement the conductors feel more "coppery" in how it bends.
Wire gauge? No problem, at the few if any Watt levels I listen to these days. Just curious if my not quite 99.9999% pure, not single crystal annealed, not Litz braided stuff could be doing me any imaginable disservice. Thanks!
The spacing of the wire is something I've seen in a commercial offering, which makes sense to me as to offer lower capacitance than the type of wire where the conductors are running as close to one another as is manufacturable.
My question is around the quality of copper in these things. One hunk was definitely copper plated steel, verified being magnetic. Another feels a little stiff, is non-magnetic and perhaps some alloy with a bit more tensile strength...as that seems to be desirable for the intended application. Another pair of lengths as a foam-core arrangement the conductors feel more "coppery" in how it bends.
Wire gauge? No problem, at the few if any Watt levels I listen to these days. Just curious if my not quite 99.9999% pure, not single crystal annealed, not Litz braided stuff could be doing me any imaginable disservice. Thanks!
As long as the resistance of the wires will be less than 1/50 of the impedance of the speakers, everything will be OK.
You want to steer clear of those cables if the conductors are copperweld (copper plated steel) rather than pure copper. A magnet will tell you in an instant. Manufacturers often cheap out in this fashion, because at high frequencies, the copper plating is doing most of the conducting. I'd just use 16-18 AWG zip cord instead
Uh, yeah - I already weeded out that particular cable. Understandably, if this is "accidently" hanging down unsupported from an antenna mast, you'd want the tensile strength steel offers.
I'm already using zip on the woofers. Not much there above 300 Hz, as it's a DSP amp. It's the FRs carrying the rest of the range that I've wired with this type of cable.
Looking in my old Belden catalog, the 300 Ohm Twin Lead TV antenna cables use:
20 or 22AWG copper or Copper Clad Steel conductors.
Notes:
a] while the cable capacitance is low the inductance is high. In a speaker cable inductance is more important than capacitance, because high total inductance may reduce high frequency response. On the other hand, some old legacy or boutique amplifiers might have problems with high capacitance.
b] these cables will have no problems carrying a great deal of audio power. But the high end-to-end resistance can impact the frequency response of some multi-driver loudspeakers.
20 or 22AWG copper or Copper Clad Steel conductors.
Notes:
a] while the cable capacitance is low the inductance is high. In a speaker cable inductance is more important than capacitance, because high total inductance may reduce high frequency response. On the other hand, some old legacy or boutique amplifiers might have problems with high capacitance.
b] these cables will have no problems carrying a great deal of audio power. But the high end-to-end resistance can impact the frequency response of some multi-driver loudspeakers.
Bad idea! What are you trying to achieve? The attributes of 300 flat antenna cable (long since obsolete) are tailored to RF issues. They have no practical effect at audio frequencies. And depending on the length, 22awg is not up to HiFi standards for speaker wire. The minimum is 18awg IMO.
Note the reason some RF cables are copper clad steel is for mechanical strength. At RF frequencies, skin effect is very real so they only need good conductivity on the surface of the wire. And steel is also cheaper than copper! But none of this applies to audio signals.
Copper clad steel coax is also no good for satellite dishes. Why? Skin effect is even greater at the 1ghz signal coming out of the dish? The reason is DC power. The microwave amplifier and the 17 to 1 ghz block converter needs several hundred milliamps of DC power.
Note the reason some RF cables are copper clad steel is for mechanical strength. At RF frequencies, skin effect is very real so they only need good conductivity on the surface of the wire. And steel is also cheaper than copper! But none of this applies to audio signals.
Copper clad steel coax is also no good for satellite dishes. Why? Skin effect is even greater at the 1ghz signal coming out of the dish? The reason is DC power. The microwave amplifier and the 17 to 1 ghz block converter needs several hundred milliamps of DC power.
Last edited:
300 ohm antenna lead is actually not bad as an interconnect cable from preamp to amp etc.. is is at best 18ga so not the best for high powered speakers.
300 Ohm TV twin-lead is a terrible RCA unbalanced interconnect cable! and a bad XLR balanced cable.
Back in the 90's I experimented with using 300Ω twinlead as balanced cable wih dynamic mics, due to its low capacitance. I poked holes in the middle of the insulation and threaded a 3rd wire for Pin 1. The upper freqs definitely sounded cleaner/smoother, but placement was way too critical to avoid picking up noise from whatever. Impractical, but illuminating.
It will work. As other posters mentioned, there are some issues. But it will work. Perhaps a 100nF in series with a couple of Ohm in series over the output if your amplifier is tricky.
Sure it will work. But why bother when you can get the proper shielded cable for pennies a foot? I mean now we propose adding resistors and caps to make the improper cable work better in the wrong application? Electrical issues aside, how do you terminate flat cable into an RCA connector in a professional, workman like manner?
I once came across a normal gauge speaker cable with a ~3/4" wire to wire spacing and was curious why the manufacturer did it that way. I still have some of that in lengths too short, but just too lazy at the moment to walk out to the garage to see what brand it is; I believe it's recognizable. They must have been going after reduced capacitance, for a run length...
There's no issue with added wire resistance; as I can listen (at my volume levels...) with 4 Ohms in series with the amp output - as a DIY experiment - no problem.
It's simply another DIY experiment; no need for availability, manufacturability or addressing a particular market. Been listening to them for a week and they seem no different than the flattened multi-strand (someone's commercial attempt at two thick flat ribbons running edge-to-edge) I replaced with this 300 Ohm stuff.
I had some Monster cable like that. This was in the early 1990s when "oxygen free" copper was all the rage. That Monster cable turned green with time as the chlorine in the PVC insulation would ... oxidize the copper. Yeah. Marketing fail!
I'm sure the spacing was just a marketing thing. There's no technical reason for it that I can think of.
Tom
Nordost?
I picked a very long run eons ago for a song and still use them in my office as speaker cables. I believe they still make them, they call them Superflatline speaker cables.
They are flat, with sixteen conductors, eight per side... each side is composed of a pair of four flat 1/16" "wires" bundled alongside each about 1/16" apart for a bit over half an inch span... the two sides are then also separated by a gap of 1/8" of an inch. The total cable cross section is about two inches wide and very flat.
Conductors are copper, still shiny all of these years.
The termination is sort of strange, since it was a raw cable I terminated them in eight "wires" crimped into a banana.
The speakers are 16 ohms so I don't think they much care about the cables.
For my application, they were the right price ( like 50 bucks for 100 feet ) and I was able to snake them easily between the wall and the shelves. The manufacturer claims a very low impedance. I just know they are easy to layout. Once I had them in the living room with a run under a rug...
My experience with 300 ohm is different, as I still have some for the indoor antennas. They tend to be RF sensitive... but then, I've never hooked up the Nordost to an FM antenna.
Last edited: