7 - Replace your filters

16 Jun 2008

ADSL filters are a surprisingly common point of failure for home broadband connections. These seemingly innocuous little devices separate the low-end frequencies required for voice calls from the high-end frequencies needed for your ADSL connection. However, the poorly made freebies dished out by some ISPs are prone to fail, leading to excessive noise interfering with the speed of your connection.

But before you pop down to Currys and buy a job lot of filters, there are a few basic checks to perform first. Make sure there's a filter fitted to every socket in the house where there's telephony equipment attached - be that the telephone in the back bedroom, the Sky box or a fax machine. The filter should plug directly into the wall socket. If you have a two-way splitter coming off the wall socket (to serve a phone and a fax machine, for example), make sure the filter is plugged in before the splitter.

A tell-tale sign that one of your filters has gone wonky is noise on the line when you're making voice calls. Zen Internet provides a comprehensive guide to testing your ADSL filters at www.pcpro.co.uk /links/165broad1, but it essentially involves plugging each filter into your master socket in turn to eliminate the faulty unit.

If you've ever wondered what the inside of an ADSL microfilter looks like and why some are better than others, the ADSL nation website provides a terrifyingly detailed example. Zen Internet says the SpeedTouch filters it supplies to new broadband customers are "highly reliable".

Alternatively, you could do away with filters altogether and buy an ADSL faceplate for around £17. Like the iPlate in Step 2, this fits over your master NTE5 telephone socket, and provides separate voice and ADSL connectors, instead of the single connector. It also does away with the need to fit dedicated filters on extensions, meaning you can plug all your equipment in as normal. Clarity has decidedly no-nonsense advice on fitting and buying these devices.

Next: 8 - Watch out for AR7 routers

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