 M3TL Transmission Line Speakers Here are some photos of a pair of HiFi loudspeakers that I recently built from a kit supplied by IPL acoustics. The M3TL is the smallest (and cheapest) of IPL's transmission line speakers. The drivers are a Morel MW142 5½" mid bass unit and an Audax TW025M1 soft dome tweeter. All parts, except for the wood (18mm MDF), were supplied with the kit along with detailed plans, photos and construction guide. The MDF was bought from a local DIY store and most major panels were cut to size on the premesis (for free!). This is a great help as construction is made a lot easier when all panel edges are cut straight and square.
Construction was straightforward and was completed within a week of evenings. Here the tapering transmission line, corner deflectors and front & rear panel bracing can be quite easily seen. The line is `lagged' with acoustic sound absorbing foam throughout it's length. The crossover is constructed on a small MDF panel and mounted together with the binding posts on the rear panel of the cabinet. No wadding is placed in the line.
IPL Acoustic M3TL Here the cabinets are finished with the drivers installed. Iron-on ash veneer was used, with a coating of clear finishing wax. The speakers are mounted on a pair of simple spiked stands made from MDF. Fabric grilles have yet to be constructed. So how do they sound? Well, simply superb! (To my ears at least). They are smooth with no harshness in the high frequencies, and of course, being a transmission line design, the bass response is well extended and `tight'. Bass notes exhibit a degree of `bite' and detail not previously heard on my old bookshelf speakers, but with none of the `boomyness' that is associated with infinate baffle designs. I would certainly reccommend these loudspeakers to anyone contemplating replacing their current bookshelf units with a decent pair of floor standers. I wonder what the larger IPL transmission line units sound like? No.... I must stop now and be content with these wonderful speakers! A Second Opinion? Geoff Husband has built a pair of M3TLs too! His review can be found at HiFidelity.co.uk. (I think he liked them! :-) DIY Speaker Links
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