Raw Bandwidth Communications - ADSL Filtering Choices

ADSL Filtering Choices

Filtering of the ADSL signal off of voice jacks in your home or business is critical to the proper functioning of ADSL service, not only so you don't have problems with voice service, but to protect the ADSL connection from the voice. Improper filtering typically results in flaky ADSL service. Every single device plugged into the phone line besides the ADSL modem itself must be filtered. Note that it is not okay simply to not use a phone device--if it's plugged in, it needs to be filtered even if it's on-hook or it can cause problems.

There are two main ways to filter the voice side of your service. In-line microfilters are small filters that filter each device plugged into the line, except the ADSL bridge/modem itself. You'll generally have one filter at each jack throughout your premise where a device is plugged in. Alternatively, you can use an ADSL 'splitter' which is basically a centralized filter--all voice jacks in your house are filtered by the splitter at your phone box, while a separate jack dedicated to ADSL is connected by a dedicated pair from your phone box and is not filtered. Generally a splitter installation will result in a better ADSL signal and potentially allow you to work at a faster speed profile, though often when the site is close enough to the ADSL equipment at the phone company and/or the inside wire is in decent shape, there is no practical difference (basically anytime you already are working fine at the top profile for the service you ordered). Sometimes however, when the inside wire is bad, there is a monitored alarm system sharing the line, or the distance from the serving DSL equipment at the phone company is great, then a splitter installation can become critical. Unless you know one of these factors applies in your situation, we recommend you start with in-line filters for ease of installation, and you can always switch to a splitter later if it proves necessary. If you are trying for 6Mbps service, and are even modestly far from the serving telephone office (say 8Kft or farther), you may want to use a splitter just to be sure.

Microfilters

This is Excelsus's Z-D230TJ filter.

. It has two ports, one labeled phone which is filtered, and one for DSL, which is not. It is used when you want to plug both the ADSL modem, as well as a regular telephone, or dialup modem, fax, or other device, into the same jack. It can also be used just to filter the phone device and ignore the DSL jack on it. Here is Excelsus's installation instructions.

Next is Excelus's Z-200SM filter.. This filter is used on ALL other devices on the line, at jacks other than where you want to plug in the ADSL modem (ie. only filtered devices on the jacks). Sometimes we may send you a Z-200SM and a T-adapter (aka 'jack doubler') instead of a Z-D230TJ, because the pair is functionally equivalent to D-230TJ to allow both the ADSL modem and filtered devices to be plugged in at the same jack. Here is Excelsus's installation instructions.

Last is the Z-D250CW which is used to filter wall-mount phones which have the jack immediately behind the phone (ie. there is no cord dangling from the phone to plug into a jack elsewhere). These phones are commonly found in kitchens, but rarely anywhere else. These filters have a DSL port on the side which allows you to plug the DSL modem into the same jack, but if you don't want to use your DSL modem in the kitchen, then just ignore it. Here is Excelsus's installation instructions.

Raw Bandwidth offers two options for filter packs:

Five (5) In-line Filters: This choice comes with 1 D-230TJ or equivalent, and 4 D-250SM.
Four (4) In-line plus One (1) Wall-mount Filter: This choice comes with 1 D-230TJ or equivalent, 3 D-250SM, and 1 D-250CW.

Basically if you have a wall-mount phone, pick the second one, otherwise pick the first one.

ADSL Splitters

Raw Bandwidth offers two choices for centralized ADSL splitters typically installed at the phone box ('demarcation') where the wires come to your home from the street, or the wiring closet of larger apartment buildings and offices. While these are intended for technicians to install, many of our customers are savvy enough to do it themselves. If you are unsure, you should start with filters and switch to a splitter only if necessary. It's definately more work, even for a pro.

The first choice for a splitter has its own weather-housing ('Splitter with Weather Housing') and must be mounted near your phone box or existing termination blocks. It looks like this... Splitter with Housing and is wired to the existing box, with inside wires moved from the existing phone box to terminate on the filtered voice terminals on the splitter.

The second choice for a splitter is designed to go in an open position of a network interface device ('Splitter for NID box') with test-jacks. Typically such a modern phone box has either two or six positions for modules with test jacks. Part of the box is sealed such that only telephone company personnel can get inside, and the other part is customer accessable. Inside the customer accessable part you'll find test-jacks which can be unplugged to isolate the inside wire, and a regular phone or other device can be plugged into the test jack to see if any problem being experienced is gone at this jack (indicating there's a problem with inside wiring), or still exists there (indicating it is a phone company problem). If you have open positions in such a modern NID (that is, with no test jack module installed), then we have splitter modules that look like this... and can go into one of the open positions, eliminating the need for an additional box mounted on your home. Note that if all positions in your existing NID have test jacks installed, you will need to use one of the first splitter's above with its own housing anyway. Note these splitters are made by Keptel, and may not fit NID's made by other vendors. They fit many of the Keptel NIDs Pacbell is using, but we've seen at least one NID used by Pacbell that this splitter will not snap into properly, though a little hot-glue took care of that and it still was usable.

Additional Notes

We may substitute functionally equivalent parts from other vendors, so the parts we send may not be exactly as pictured above.

If you want to use in-line microfilters, but need more than the five included with the two options we give above, then you can order more for $5/ea--simply note what you need in the Comments field of our order form (remember, you need to filter all devices on your DSL line, including computer dialup modems, fax machines, cable and satellite TV pay-per-view boxes, etc.). If you need more than five filters though, you may want to consider a splitter since all those inside wire jacks could present a problem, though you still may be okay.

If you have more than one phone number coming to your home, then only devices on the DSL line need to be filtered, however the inline filters provided only filter 'line 1' of the jack. If your DSL phone number appears as the second line on any jack wiring, then please contact us for assistance prior to ordering to get those jacks filtered properly. Note also that if your DSL line appears as the second line on a jack, even if you are not using it at that jack but have a single-line device plugged in there on the line 1, it still could present a problem for the DSL. You may want to unwire the DSL line from that jack in that case.

All filtering options come with a twisted-pair phone cord. You should use this cord to connect the ADSL modem to the wall jack or unfiltered DSL connection of one of the D-230TJ or D-250CW filters. The typical phone cord is flat/untwisted 'silver satin' and may not work, or may cause flakiness--you should always use a twisted pair cord with your DSL modem.