The arrival of the Abyss means that MartinLogan knows when it’s onto a winner.
After first introducing the radical new concept of the ‘dual orientation subwoofer’ with the tiny Dynamo, that little subwoofer’s enormous success right around the world encouraged MartinLogan’s CEO, Gayle Martin Sanders, to up the ante by adding a larger and more powerful model, the Abyss.
There are two ways of orienting the bass driver in a subwoofer. The designer can align it vertically, so it fires forward (fixing it to a panel either inside or outside the cabinet) or horizontally, so it fires downwards, at the floor (again, either inside or outside the cabinet). (So far as I’m aware, no designer has yet put a driver in the top of a subwoofer, facing upwards, but I wouldn’t be surprised to be corrected!) As you’d expect, each approach has its advantages and its disadvantages and so when audiophiles get together, they can often be heard arguing the relative merits of down-firing vs front-firing subwoofers, along with valve vs solid-state, single-ended vs push-pull and so on…push-pull and so on… To summarise these, the chief advantage of a down-firing subwoofer is the increased flexibility of placement in the room, while its primary disadvantage is that the forces on the cone are not equal, so that during each ‘up and down’ cycle—irrespective of the frequency being reproduced— the cone will move further on the ‘down’ half of the cycle than it will on the ‘up’ half, due to gravity hindering it in one direction and helping it along in the other. Frontfiring subwoofers, on the other hand, are a little harder to position effectively in a room (though corner placement usually works pretty well) and have the technical disadvantage that their cones are sometimes so heavy they can ‘sag’ over time, which then has the effect of displacing the voicecoil in the magnetic gap, which can in turn lead to non-linearities, or even voice-coil scraping. It is for this reason that many experts recommend physically removing a subwoofer’s driver every year and rotating it by one ‘bolt-hole’ to equalise the forces. (You need to keep track of how far the driver has been rotated. After one complete revolution, you start back in the opposite direction, in order to avoid over-twisting the wires connecting the speaker to the internal amplifier.)
There’s no need to argue if you buy MartinLogan’s Abyss, because you can choose to orient the Abyss cabinet so that its 308mm aluminium-coned bass driver is firing forward, or downwards (or even upwards, if you’d prefer—but I wouldn’t recommend it). You’re able to do this because MartinLogan provides a special removable base that has four mounting lugs located in the same positions as the lugs on the Abyss’s grille. If you want the Abyss to fire forwards, you fit the grille over the bass driver as you would any subwoofer, and attach the base over the amplifier plate. If you’d rather a down-firing subwoofer, you simply replace the grille with the special base, then place the subwoofer on the base. The whole ‘switcheroo’ operation takes only a minute or two.
MartinLogan’s manual makes it fairly clear that the company intends the Abyss to be in down-firing mode if it’s used freestanding, and only converted to front-firing operation in situations where it is to be installed in a cabinet or enclosure. Actually, if you use Abyss in its front-firing mode, all the controls and connections end up being underneath the subwoofer—which makes access difficult, to say the least! It also makes connecting the all-essential wires more than a little tricky, so MartinLogan helpfully includes a set of 90° right-angle RCA adaptors so you won’t stress your cables.