Long line/speed issues

Hi everyone.
I've got the double misfortune of having a long line of about 6km and Virgin as an ISP(I am on Virgin bundle 2,only 2 months into a 12 month contract) and I've accepted all of this fairly stoically,achieving d/l speeds of around 450kbps at most.
My router (BT voyager 205) stats are:
Local line atten: 61db
Local SNR margin 12db
AS0 (downstream interleaved) 896kbps
LS0 (upstream interleaved) 448 kbps
Obviously I see a deterioration in evening speeds, but at least my connection is fairly steady with few disconnects. I have read on the forums about how to maximise my connection, and have an ADSL nation faceplate on the master socket, with no extensions wired in,no Sky box connected and no electrical apparatus close by.

My query is that on testing with speedtester.bt.com, I got the following result:

Test1 comprises of Best Effort Test: -provides background information.
IP profile for your line is - 500 kbps
DSL connection rate: 448 kbps(UP-STREAM) 896 kbps(DOWN-STREAM)
Actual IP throughput achieved during the test was - 452 kbps

If you wish to discuss these results please contact your ISP.

I decided to try a live chat with Virgin and the transcript is as follows:

Hi, Welcome to Virgin Media Chat and Remote Assistance. My name is neil. How may I help you?
14:24 Hi,can you give me an idea of why my speeds seem slow,I have a BT speedtester result
14:25 Can I send it to you somehow?
13:25 Okay and how was it run under your normal virgin username and password connecting to the internet?
14:25 Yes
13:27 They need to be done connecting to the internet under username peedtest@speedtest_domain and password: testing
14:28 OK,on the www.speedtester.bt.com site do you mean?
13:29 Yes thats the correct site, although you need to connect to the internet with username and password given above we need 6 tests done in 48 hours.
14:31 OK,I'll try.Why does the speedtest I've just done say the IP profile is 500kbps,DSL connection rate downstream 896kbps yet actual IP throughput is only 452 kbps?
13:33 Well 500kbps is the set rate for your line.
13:33 Your synching at 452kbps.
13:33 With downstream sync at 896kbps.
13:34 But basically your 48kbps under your speed which is not alot at all.
14:35 Right, but what I don't understand is the difference between the 896 and 452 synch speeds,should I not get the higher of the two?
14:36 Is my IP profile therefore stuck at a low rate?
13:36 It is set to the best your line can take.
14:37 Can you explain why the 896 speed is quoted on the speedtest?
13:38 This is your current speed 896 kbps, this is what your downloading at 452kbps and 500kbps is your ip profile.
14:41 OK,so if you're saying the IP profile of 500kbps is the best my line can take, then why is the "current speed" quoted as 896? This seems to make no sense to me
13:42 Ip profile is what your meant to be synch'd at with a stable connection although it can go higher or lower.
14:45 My query is, if a speedtest seems to show the higher, 896 speed,then why can't I get this speed.Is there anything you as my ISP can do to help? Obviously slow speeds are rather a problem to me and anything to help would be welcome.
13:53 Okay make sure that you are connected in the main bt socket with no extention leads, also make sure you dont have backround programs running as this will all slow your connection down.
14:55 Yes, I've done all of that,I even have an ADSL nation faceplate with integral filters, and no extension wiring nor any electrical source interfering with the connection. I was wondering if a simple solution could be a reset of my IP profile to a higher one, or are there risks with this approach?
13:58 To get this reset done you would have to call in to the technical helpline on 0906 217 0001 to raise a fault firstly, advise the agent that you are raising the fault to get your ip profile reset.
14:59 Ok thanks for your help.If this doesn't work, what next?
14:00 Well failing all that the only thing left to try if you have the according speedtests is raise to bt although i can see them rejecting the fault as your downstream is above 400kbps.
15:01 Ok thanks again
14:02 Not a problem thanks for your time.

Judging by people's comments on the Virgin forum about the technical knowledge of these people,I have no idea if he's talking rubbish or not, and would appreciate comments on whether there is anything I can do to increase my download speeds.

Thanks in advance,
Rob

Look here, towards the end, about data rates.

http://www.dslzoneuk.net/adslmax_explained.php

Read John2007's reply first, the link explains how it all works. The Virgin guy is right, just lousy at explaining it to you.

But he is wrong on a very important point.

"13:25 Okay and how was it run under your normal virgin username and password connecting to the internet?
14:25 Yes
13:27 They need to be done connecting to the internet under username speedtest@speedtest_domain and password: testing
14:28 OK,on the www.speedtester.bt.com site do you mean?
13:29 Yes thats the correct site, although you need to connect to the internet with username and password given above we need 6 tests done in 48 hours."

The facility to do the speed test with that user name and password was withdrawn by BT weeks ago. You can only get to Test 1 initially, which is what you did. If the test itself doesn't like the result (which I think means you get a throughput of under 400) then it lets you do Test 2 (logon bt_user@your_usual_signon. Finally if it isn't happy it lets you do Test 3, which I think is the one he is asking for. BT require 3 bad results taken at different times of day before they accept a fault from the ISP.

Which is all irrelevant because you are getting the right sort of speed.

What you can do is look fairly high on this page and see if your modem/router is listed under any of the versions (versions handle different ones, they are not in functionality order like we are used to). If it is, download it (DMT).

That lets you look at what is happening on your line in some detail. Once you get to understand it you can alter the figure in your stats "Local SNR margin 12db". With luck you could lower it to get a sync of 1152 or more, which would give you a profile of 1Mb and should about double you actual speed.

As a matter of interest what speed is the OP likely to get with a line att of 61db, that does seem quite high?
Thanks,
Mike.

Hi, Thanks for your advice, I've downloaded DMT and will give it a try-once I work it out, that is!

Rob

Thanks, John, I think I understand it better now.I'll try some tweaking with DMT also.

Rob

61db isn't so long, I was on a 73db line today.....now that sucks. The 12db snr would indicate a raised target snr, it is possible that the OP might *just* squeeze 1meg if the profile were 9db...maybe more if 6, the issue here is that long lines can be just as noisy as the short ones, so maybe DLM has had to raise the target to provide stability ?

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I was on a 73db line today.....now that sucks
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Nah, that's a nice short line

I had one today, 78.5dB att & 3.5dB margin at the SCP. I couldn't get sync at the nte5, but the customers Billion would sync every time. Woosh just said >63dB but the Billion said 6dB margin.

Yeah, who needs FTTC anyways ?