DSL Micro Filter

Micro Filter: Use or Not?

First of all what is a Micro Filter? Basically its installed between your phone line and your DSL modem with the goal to make internet connections more stable. The typical DSL Micro Filters I know has an RJ-11 tip on one end which you plug in your telephone socket and an RJ-11 socket on the other which you will use to connect your ADSL Modem. Other variants comes as a splitter--for telephone and DSL.

DSL connections can come in two forms, Naked and Bundled. The first one (Naked) is a dedicated line for DSL connection only. Whereas Bundled connections is one line which services both voice (telephone) and data (internet). From what I have read it is advised to use Micro Filters for Bundled connections to prevent interference from either of the two frequencies (voice and data). I believe the explanation is sound, however I have no way of testing that since I only have Naked connections.

Last night I installed a Micro Filter in our office. I placed it between the telephone socket and the ADSL. Connection was okay and maintained to be stable. Well, it was already like that, so just no complain here. Until I tested it with speedtest.net. I was randomly getting the results from speedtest the whole day and to my surprise the Micro Filter instead of improving performance actually reduced my Download speed by a few Kbps. Our connection in the office is a stable 5Mbps, with the Micro Filter installed it could not really hit 5Mbps. So this evening I took out the Micro Filter and immediately did a test and right there and then speedtest registered over 5Mbps. To verify the results I conducted the test over and over again among several servers and the results were conclusive.

Again I have not tested the performance of a Micro Filter over a Bundled line, but its purpose is to protect each frequency running in the wires against radio interference. In my setup I did not need the Micro Filter since their was only one (1) radio frequency running through the wires.

The nature of the Micro Filter is not directly the cause of my setup's reduced performance. In other words filtering the connection doesn't do any damage. However as you increase the number of Hops (devices where data passes) data travel naturally increases and performance diminishes.

Note: PLDT is my ISP