Re: Twisted Pairs - how tightly should I be twisting the wire?



Chief_Billy@xxxxxxxxxxx wrote:

On Jan 28, 1:59 pm, Lord Valve <detri...@xxxxxxxxxxxxx> wrote:
KingofTone wrote:
Building a 5F4 Super clone (my first build complete from scratch, I've
just been fixing/modding my amps for years), and was thinking about
wiring the filaments. I was just planning on twisting two 18 AWG
wires to form a twisted pair, then the thought of using shielded
twisted pair (I really despise hum) seemed like a decent idea as it's
not so expensive and I wouldn't need that much for one build. I found
some Belden 8719 (overkill, I know, but I can buy it by the foot) 16
AWG shielded twisted pair and reading the spec *** it only has 4.4
twists of wire per foot. I thought maybe it wasn't twisted so tightly
because it's got the shielding. I googled some more and found a few
samples:

Belden 8719 16 AWG (Shielded) twisted pair - 4.4 twists per foot:
http://tinyurl.com/2twezk

Belden 8760 18 AWG (Shielded) twisted pair - 8 twists per foot:
http://tinyurl.com/332ybv

Ebay 16 AWG twisted pair (Unshielded) - not many twists per foot as
you can see in the description and photos:
http://tinyurl.com/2k5okc

Alessandro High-End Guitar Amp Wire 18 AWG twisted pair (Unshielded) -
not many twists per foot visible in the photos:
http://tinyurl.com/3d9dlo

So I guess my question is have I been wasting my time all these years
tightly twisting wire into twisted pairs? In my repairs I can count
twists per inch not twists per foot. Not to mention all that twisting
takes a lot more wire. Should I just be twisting the pairs loosely?

The question also begs the question regarding all those transformer
wires, etc. that need to be twisted into a twisted pair before they
got soldered onto their destination. This needs to be done by the
tech, I've never seen a transformer with sheilded pre-twisted wires
coming out of it. How much twisting is really necessary?

Belden and Alessandro are both high quality products. Even if these
are their "low end" offerings I bet they'd sell two grades of twisted
pairs if it mattered. But look at the guts of some of those vintage
HiWatt builds, they twist their pairs like there's no tomorrow. Look
at Rich K's work - a Rich K twisted pair is a hell of a lot more than
4 twists per foot.

For the moment I'm going to keep twisting them tightly, maybe wasting
my time but at least it looks pretty, and I'll sleep better at night.

Please let me know what you all think - do twisted pairs need to be
that tightly twisted or is a twist every couple of inches OK?

Sean - the hum despiser

....

One of the best (and easiest) things you can do to a SF Fender is
unsolder the filament wires from one side of every other preamp tube
and twist the pairs much more tightly. (You leave the other wire in the
pair still soldered in place - easier that way.) Once you have them
tight (3 turns per inch or so) dress them straight up in the air and
square the corners. Anyone who's done this can attest to the
fact that there is an audible reduction in the hum level at even
soft playing levels. Tighter is better, within reason., When I'm
doing a ground-up build, I use cloth-covered 18G solid, and I
chuck one end of the pair in a 3/8" VSR drill, with the other
end squeezed tight in a bench vise. When I have the twist
pitch I'm looking for, I run the drill backwards for a half second
to lossen the twist slightly. I only do around six feet at a time,
since the stuff is much easier to work with if you leave it
straight rather than coiling it up for storage.

Lord Valve
Expert- Hide quoted text -

- Show quoted text -

Why is this a good thing for SF Fenders, and yet with Mashalls they
lay them down against the back of the chassis. Seems that it would be
best for all if it reduces hum....

It's good for SF Fenders because the lead dress in those is horrible.

BF Fenders usually have tight wiring. No reason not to put the
filament string up in the air on Marshalls; it's a Brit thing, I
guess. Most Marshalls benefit from having the grid leads
stuck up into the air, away from the chassis-hugging filament
leads. Try it and see. ;-)

LV




.

Loading