Modem Cable experiments on my line.

I have been experimenting with modem cables for a few days. I got a Tandy one quite a while ago which is twisted pair and shielded. I also got another Cat 6 twisted pair through the post today. I have a couple more on order with different cables and plugs. Ideally, I would like a cable that provides the highest sync speed with an RJ11 at one end and an RJ45 at the other that is 2m long.
So far the speed tests
Tandy Cable 72/17
Cat 6 cable 76/17
Flat Billion modem cable 78½/17
So nothing beats the flat untwisted Billion cable so have ordered an RJ11 to RJ45 with flat cable hoping it is as good as the Billion modem cable.
All the experts say that twisted pair cable should be the best but my experiments prove otherwise so far and this is repeatable.
How strange.

More experiments with Billion 8800 R2 modem lead has given me another half a meg. Could be just the time of day but this cable is slightly shorter and round.
Current sync with 8800 cable 79112.

Even more experimenting. Tried the ZyXel VMG1312-B10A modem cable and sync is 77. Back to the Billion 8800 R2 cable and back to 79 with 80 attainable. It seems not all modem cables are equal.

You could also experiment with hard wiring one end onto the filtered faceplate's terminals A&B and a rj11 plug at the other end of a cat5e 2 metre cable - guess you don't like the idea of a rj11 plug wobbling about in the faceplate's rj45 socket

guess you don't like the idea of a rj11 plug wobbling about in the faceplate's rj45 socket

Yes that is the main reason for ordering Cat 6 cables with RJ45 and RJ11 plugs but it seems the cable isnt up to it. Tonight I ordered a standard modem cable with RJ45 and RJ11 so will test that when it arrives.

But so far the best syncing modem cable is the round Billion 8800NL R2 closeley followed by the Billion 7800 flat modem cable. More experiments to be conducted.

Don�t care for the flat 7800 cable myself - seems a bit long and flimsy, although having said that, for me, differing filtered faceplates seem to result in more noticeable changes in line stats than differing good quality cables. However that is with ADSL and a Mk3 faceplate seems about the best on my line.

Edited by 4M2 (Wed 16-Aug-17 01:24:28)

I have an MK4 5C box on my wall fitted by OR. At least I think it's a Mk4 but it is definitely a 5c as it just snaps on.

In reply to a post by Banger:

I have an MK4 5C box on my wall fitted by OR. At least I think it's a Mk4 but it is definitely a 5c as it just snaps on.

Yes I think the Mk4's internals are pretty much the same as a Mk3, just a different unique fitting. Certainly the Mk3 has only two contacts into the NTE5A test socket which may be advantageous.

Given the distance the signal has to travel I'm quite surprised that the modem cable makes any difference at all, however...

Twisted pair has benefits in multi-circuit systems:
Increased immunity to external interference and reduced leakage
Reduced crosstalk in multi-circuit systems but only if the twist is properly randomised
Paired wires held together give a consistent impedance
And of course there's the fact that they are clearly identifiable as pairs reducing wiring errors

On a single pair system the benefits of twisting don't really apply.
You probably don't have interference sources nearby
There's only one circuit so nothing to crosstalk to. This is especially true for "cheap" bundled leads whichfrequently have only two conductors, the outer wires are left off.
The insulation holds the wires at a fixed spacing.
There's really only one way to wire it.

It is possible that the simple flat cable could be better.

There might even be a slight benefit to a longer lead. The added loss should be trivial but all junctions introduce unwanted reflections and there may be a benefit to separating them so the reflections are less likely to add.

Whether the metal core is copper to just copper coated Al plus its gauge will be a factor too

In reply to a post by MrSaffron:

Whether the metal core is copper to just copper coated Al plus its gauge will be a factor too

Don't forget copper coated steel ... or even sliver, or silver coated copper.