Got Shielded Cable? GOAT coax for amps?

BSG1

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Maybe you all know about this shielded cable source, but if you did you're keeping it a secret. Because I didn't find it here or on TGP either.

I have been searching for good shielded cable for my amps. I have tried everything from old school fender external braided reverb wire with it's always present short hazards to Mogami high tech (read expensive) with super fine strands and some weird fiber crap intertwined making soldering very difficult. And, of course, I started with what it seems everyone recommends, RG 174. That stuff is easier to work with but won't hold a bend and you dare not bend the soldered center conductor or it will snap off the terminal to which it had been soldered. Oh, and those super fine copper strands, if you aren't stripping carefully, I mean really careful you will end up with little bits of them floating around inside the chassis just waiting to short something out!

Anyone else have these issues, or am I the only clutz who can't manage coax in the tight spaces of an amp chassis?

My father was a private pilot later in life, he learned to fly at age 50 and we grounded him at age 90. He made it to 97 but might have lived forever had we let him continue flying. He was still passing his flight physicals so the FAA wouldn't ground him. I helped him work on his plane once in a while, his plane was a budget item - dad hated spending money. But, I did see some great looking wiring. I wired Boeing 747's during my college years, I know great wiring and I know really bad wiring too.

Okay, here's the punch line. I found a mil-spec shielded wire with tinned 20 AWG stranded single center conductor not super fine strands of raw copper. It has braided shielding. The outside diameter of the insulating jacket is just 2.53mm or 13/128th inch. It is a little stiff, but will hold a moderate bend. And even a clutz like me can solder that center conductor to a terminal and count on it to be there for years to come.

If you want to give it a try go to: SteinAir in Faribault, MN. Their service was amazingly fast, I had my wire in a matter of days and shipping was reasonable and reliable - USPS. Oh, and they had some great grommets both snap-in nylon style and rubber donuts in many sizes. They were reasonably priced so I bought a bunch.
 

tubedude

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I had a several rolls of similar coax left over from a mod I installed on Cobra gunships in the '70's. It had a Teflon insulation and silver coated copper conductor with a silver color braid insulation.
As I recall, the capacitance was very low.
 

King Fan

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Nice idea, looks like a nice outfit. Here's a link for those interested.

https://www.steinair.com/product/20-ga-single-conductor-shielded/

Is this the wire you got?

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I see they also have this 22ga, which might be fine for amp work.

1674772903872.png
 

chas.wahl

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schmee

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I have an old spool of grey fine core coax I use for inputs etc on amps or in guitar outputs etc. It's probably 22 ga but might be 24 ga. I figure for a 6" run it's fine and has been. No idea where I got it. I also have some nice but more rigid black covered stuff a bit bigger.
 

Jon Snell

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I had a several rolls of similar coax left over from a mod I installed on Cobra gunships in the '70's. It had a Teflon insulation and silver coated copper conductor with a silver color braid insulation.
As I recall, the capacitance was very low.
On short runs <3 Metres or 10 feet, the capacitance has no real effect.
Most coax is rated at a stated impedance and around 100pF per Metre, so in the grand scale of amplifier building and patch lead making, 100pF is just useful at blocking unwanted HF interference at radio frequencies.
PTFE is not good at going around tight corners as it tends to allow, over time, the conductors to slide through small rips in the insulation.
RG58 coax is rated at 50 Ohms impedance, around 100pF at usually 100MHZ or above.
Use as internal wiring is OK but difficult to dress as RG58 has a solid conductor.
VanDamme XKE Super Flexible microphone/instrument cable has a capacitance of around 150pF at 1 Metre, so there again, no issues and very nice to work with.
 

Kevin Wolfe

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I bought some similar mil-spec (MIL-C-27500) coax from Aircraft Spruce a couple years ago. They have single-conductor coax in gauges from 24 to 6, and also multi-conductor types. More expensive than the Steinair source, granted, but more types available. Both conductor and braid (85% coverage) are tin plated, and the insulation is ETFE.
This is what I’ve been using. Makes you want to throw rocks at RG174.
 

sudogeek

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In the last several years, I’ve used shielded plenum cable which is available in 18-22Ga. The metal foil shield has a convenient integrated wire which makes soldering the ground points easier. For a single channel, I run one wire as signal, one as ground and ground the shield on one end of that run. For dual inputs, you can run the ground through the shield and have 2 signal wires, or you can use 3 or 4 wire cable as needed. You can even run balanced signal. IMO, it’s easier to work than RG174.

For example, see this product.
 
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King Fan

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Excellent point, I've found shielded cables with a 'drain' wire *way* easier than braided shield. You made me look up an old thread, full of good products, including a new fave I stole from one of the contributors: Belden 8451. This is the two conductor version, great for two-way signal runs. Nominal 22ga, strips like 24ga, but so much easier to solder than my old favorite RG-174.

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BSG1

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rdjones

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I got a few end-of-reel remnants of several types of Belden audio/instrumentation cable, 8760, 8761, 8762.
Two conductor, Beldfoil shield plus drain in 18, 20 and 22ga sizes. I use it for multiple uses such as unbalanced, balanced or stereo unbalanced.
The conductors and drain are stranded but the cable is not designed for flexibility so I don't use it for guitar or mic cords where motion is involved.
I have used the 22g inside chassis' and the heavier stuff for pedal jumpers.

OI000044_SC226.jpg
 

Nicko_Lps

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with super fine strands and some weird fiber crap intertwined making soldering very difficult.
I love this mogami wire. You must be talking about the 2330.

Twist the center core, grab a lighter and burn it for 1 second or less. That fiber goes away and the wire is easy to solder. Dont overheat it because then it will be difficult to solder again.

In my humble opinion, Mogami for tube amps should be an overkill but i bought some a long time ago and still have plenty. There are cheaper wires that will do the job just fine just like the white one linked in pictures above.
 
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