Running from the test socket, faceplate removed, makes no difference that I can discern. I even ran it with a flexible extension lead into the master socket, just a splitter but no telephone connected; this reduced the sync speed and increased the attenuation as one would expect, so although I thought that the fixed extension lines were flat, as you supposed, they are actually performing very well, so are probably twisted.

Not sure where this leaves me. You seem to suggest that noise is being picked up, which makes me wonder from where? While I can get the ISP to raise the target SNR, I should be getting a better speed - as you correctly point out. I guess the only option now is to bite the bullet and book an engineer(!) visit.

Edited by Mygri (Tue 13-Aug-13 11:53:13)

Noise that affects ADSL comes from many sources, some of which are:

AM radio masts
Plasma TV's
Misbehaving switched mode power supplies, e.g. mobile phone chargers
Florescent lights
i.e. anything that can cause noise that you would hear on an AM radio.

If the phone line is crystal clear when all ADSL kit is unplugged, then likely an engineer visit will produce little result, and you'll probably find the ISP just say the speed is reasonable.

Hmmm...

Within the house, I can't identify any obvious sources of interference. I have accessed the master socket, again, and plugged a splitter and just the phone into it. If I call the number from my mobile and wind the volume on the landline handset right up, I can just hear a low level white noise static. This is the best I can do in the circumstances as I can't get hold of a Talktalk Business quiet line number. (The BT number doesn't work.)

I note your comment about the ISP saying the speed is reasonable, although they did originally quote a speed of 5.7 MB, which is an awful lot better than I've ever had. That was back in October 2010.

So I'm just left to weigh up the likely success of an engineer(!) callout. Ho hum....

Btw, thank you for your prompt responses; despite my gloomy tone, you have helped me considerably.

In reply to a post by Mygri:

Within the house, I can't identify any obvious sources of interference. I have accessed the master socket, again, and plugged a splitter and just the phone into it.

Try it without the splitter, as that is filtering things out from the phone side. Also use the test socket behind the master.

Try it without the splitter, as that is filtering things out from the phone side. Also use the test socket behind the master.

Hello James, firstly, I have unwittingly mislead you and all those who have read and responded to this thread: when I said master socket, I should have said test socket, ie the one exposed with the faceplate off. My apologies for any confusion this has caused.

Secondly, thanks for your suggestion - I'm currently running from the test socket without the splitter, and I'll post the results a bit later on.

Cheers

Secondly, thanks for your suggestion - I'm currently running from the test socket without the splitter, and I'll post the results a bit later on.

Got some results, but no time to collate and post now - will update in the morning...

In reply to a post by Mygri:

Secondly, thanks for your suggestion - I'm currently running from the test socket without the splitter, and I'll post the results a bit later on.

The phone on its own in the test socket, and do the quiet line test.

You can't use the internet like this

The phone on its own in the test socket, and do the quiet line test.

Yessss.... I should have realised - Dohhhhh...

You can't use the internet like this

I can confirm this...

I've now done the phone test, using the test socket, and I can hear a distinct hum although it is at a low level. Any thoughts?