Chassis wire

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I wired (signal) a tube diy preamp with Teflon jacket, silver plated, shielded twisted pair. Probably used 60' +/-. The stuff is bulky, inflexible, & hard to work. More important, it's not as quiet as I had hoped. Thinking about re-wiring with Mogami 2330 mini coax. Twenty five cents per foot at Markertek.

Any thoughts?
 
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it's not as quiet as I had hoped. Thinking about re-wiring with Mogami 2330 mini coax.

All I can tell you and hope is encouraging is that "practice makes perfect". :)

Keep building stuff and progresively this kind of problems will minimize.

Not FULLY disappear of course, you will lways have * a little* background noise one kind or the other, but way less than today.

FWIW when I started with this (47 years ago) , I had the exact same problem, and tried the exact same solutions, including use of solid core wire so it stayed where I wanted it to, also used shielded wire for everything, including filaments, used tight and even twisting, bus bar grounding (then the state of the art technology ;) ) , etc.

All of my friends complained that their SS amp projects oscillated like crazy, usually into self destruction.

Nowadays?: I use standard plain PVC wire, twist only some connections, hardly use any shielded/coax wire, ... and stuff does not hum/buzz/oscillate/catch radio , etc.

Not doing any special effort, just some wiring paths or grounding "do not look right" and simply are avoided.

No black magic involved, simply practice/experience.

Just keep building and you´ll see these problems minimize :)

Feel free to experiment with layout and grounding, you´l find better ways to do it.

Often if you ground something "there" instead of "here", just an inch away , makes all the dfference.

It´s not a *parts* problem if you know what I mean :)

A practical example: just yesterday, Saturday night, a Musician friend came worried because his Acoustic guitar amplifier hummed slightly.

Never noticed or worried about that because he always used it live, which implies a certain ambient noise level, but yesterdy, a *cold* day, (we are in Buenos Aires, Argentina, and Polar South wind has been blowing for a couple days) he stayed at home and in the silence of his bedroom he started recording a couple songs on his PC ... and background hum/buzz, although slight, now became *annoying*.

After some testing I noticed slightly flexing the preamp PCB, noise level changed a little.

Traced it to a brass mounting post to which the PCB was bolted to, which grounded it to chassis.

I replaced it with a plastic one so as to insulate it and put it out of the picture, soldered a short piece of wire to the PCB ground plane and started touching the chassis to different points until I found a spot, about 2 inches away, where hum/buzz fully disappeared.

Scratched the chassis until I got bright shiny metal and soldered the new grounding wire there, end of the problem.

This is an example of problems which can not be attributed to parts but to the way things are made.
 
I have fallen foul of layout problems with valve amps.
1/ Keep wiring as short as possible.
2/ Keep valves and audio away from transformers and high VAC.
3/ If using a pcb use copper pours connected to ground.
4/ Beware of nasty charging impulses going into smoothing capacitors, if they get into the ground you will have huge hum. Keep the power supply separate and only connect to audio via output of smoothing capacitor not the other side where the rectifier is.

Its a good idea to use the classic metal chassis with transformers on one side and components on the other side.
The chassis acts as a shield.
 
I use copper, shielded, PVC insulation. Twisted pair is for balanced connections. In any case, getting the grounding right is the thing to concentrate on.

DF96,

You know the history of things.

Why was silver plated teflon insulated wire specified for aerospace?

I recall reading a post of yours that said that silver plated teflon insulated wire does not benifit audio but has application for UF.

Yesterday I came across half a dozen partial 1000 foot rolls i purchased for $5 a spool.

DT
 
Fun to read this old thread again. FWIW, I did rewire using the mini coax. In the process I was meticulous in soldering and wire management. Finally got the grounding right too. Took a couple of months to get it right, but it’s dead quiet and has been flawless for over a year. Knock on wood.
 
I would need to Google to find out, but my guess is that teflon is fire-resistant - useful in areospace; possibly PVC can creep if put under pressure. Silver plating good for VHF and above. Certainly nothing to do with audio quality!

I took you suggestion and went to Google.

PTFE vs. PVC has greater resistance to heat or melting, is less flammable and generates less smoke.

Silver vs. copper has ~ 6% greater conductivity or conversely copper has ~ 6% greater resistance than silver.

Proponents of PTFE insulated silver plated wire claim sonic improvements over copper wire due to skin effect.

For a discussion of skin effect at audio frequencies see this Belden link. Understanding Skin Effect and Frequency

Skin effect does not come into play at audio frequencies.

DT
 
When Teflon insulation is used, silver plating on the copper is necessary to prevent oxidation.

Is that because of the potential reaction between copper and PTFE. Or that both PTFE and silver are both better suited to harsh environments than PVC insulated bare copper.

In air plenums where fire and smoke are the primary issue PTFE insulated copper cables are not uncommon.

DT
 
So the only reason to use teflon coated silver plated wiring in audio is to get less smoke under serious fault conditions. Even aerospace doesn't use silver plating for electrical reasons. As SY used to point out (he is an expert on these things), teflon on silver is a bad combination for triboelectricity so such cables might be microphonic or suffer from handling noise - so a poor choice for audio, especially low level signals.
 
Has anyone tested silver plated Teflon insulated hookup wire?

Hello,

I am not ready to trash my newly found stash of silver plated copper Teflon insulated hookup wire.

Has anyone tested the claimed possible negative effects of silver vs Teflon or on the other side the claimed brighter effect of silver plated copper vs copper alone?

DT
 
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I've noticed that under higher than room temperature, copper wire near well biased tubes within a PVC insulation tends to develop a greenish, copper chloride patina. The resulting copper wire appears to be more mechanically fragile.

A possible explanation is that PVC tends to break down at higher temperatures, releasing chlorine and the later reacts with the copper metal. It's used as a chlorine donor in colored pyrotechnic mixtures after all.

Teflon on the other end, can release fluorine gas which is not a lesser evil, but this happens at higher temperatures than PVC.

As for the silver coated copper wire, lots of us folks subjectively detest it for the known, brightly harsh sound in the midrange domain.
 
Physics says that silver wiring will sound exactly the same as copper wiring. I am not aware of any tests (electrical measurements or ears-only listening) which show anything else. However, there are lots of anecdotes about silver wiring sounding bright and copper sounding dull; the correlation between these descriptions and the surface appearance of the metal may be pure coincidence.
 
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