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Description. The GT 1 is a very compact attractive two-way bass reflex monitor. Compared to previous models this Atohm draws particular attention to its cabinet which purposefully conveys how very decisively the GT series belongs to the high-end segment. Available finishes include white and black lacquer and the ‘Rosewood’ skins of my loaner pair. To acquire anything more prestigious in such a small enclosure would require reaching for a Sonus Faber Guarneri where price tag and required amplification completely alter the game. Make no mistake, for the money asked even the toughest critic wouldn’t find fault with Atohm’s fit and finish. Thierry Compte decided on a double grill system to meet the demands of different owners. You have the choice of a simple circular grill which fits directly atop the woofer—the tweeter already sports an integral metal perf protection—or a more traditional complete coverage grill magnetically held in place. Both are provided standard. In my opinion the only aesthetic detail that might still be perfected are the three visible magnets which could have been concealed beneath the surface.

Although compact the GT 1 includes a type of plinth which serves multiple functions. It strengthens the overall structure’s rigidity, supports the crossover and contributes to the progressive damping of the rear wave. The cabinet is internally lined with cotton felt and filled with Dacron patches to optimize internal absorption of reflections. The rear port sits behind and just below the tweeter and as such just above the two WBT binding posts and an unusually large aluminium knob which acts as 3-position switch to modify the speaker’s response by +/-1.5dB in the 1500Hz – 30kHz band referred to as soft, linear and high definition settings.

The GT1 is fitted with two drivers of Atohm’s top Absolute Series. The upper frequencies from 2.000 – 30.000Hz are handled by a new direct-radiating tweeter, a 28mm silk dome equipped with a very powerful neodymium ring motor to achieve 98dB/2.83V/1m sensitivity without any horn loading or compression chamber.

This equates to a greater than 17.000 gauss magnetic field for high dynamics with very limited thermal compression. The voice coil is made from an aluminium/copper alloy. Parasitic voice coil behavior was taking into account to achieve very low inductance regardless of coil position in the gap. For significant distortion reduction it is also an underhung voice coil design whose coil is a lot shorter than the magnetic gap to insure consistent application of electromotive force whereby the coil regardless of excursion never leaves the gap. The tweeter mounting plate is cast dimpled aluminium for high rigidity and anamorphic dispersion patterns or ADP™, Atohm’s term for improved off-axis dispersion and limited spurious reflections at very high frequencies.

The mid/woofer is a 13cm unit with special alloy membrane and non-conductive Nomex/Kapton former on the 25mm voice coil for pistonic behavior over the required bandwidth. The preference for a more rigid membrane than paper or Kevlar reflects the desire for manufacturing consistency over driver to driver precision. Bandwidth here covers 30 to 4.000Hz. This 4Ω version (the same driver in the GT2 tower operates as 8Ω) has a sensitivity level of 91dB/2.83V/1m. It was carefully engineered to minimize distortion, unwanted resonances and guarantee high power handling. It also uses patented ADP™ technology. The basket is made from cast aluminium with a very high stiffness index. And the suspensions on Atohm drivers provide progressive compliance particularly over the critical range between 700 and 1.800Hz.

Thierry Comte employs numerous simulations and laser interferometry measurements to determine and optimize the geometry of all mechanical and moving parts. The chief goal is to achieve highest linearity over the entire bandwidth before employing secondary filter optimization. This design capability and engineering focus differentiates Atohm from other small speaker houses who must rely on OEM drivers where the only variables they may truly manipulate or 'personalize' are the enclosure geometry and crossover.  A further example of Atohm’s seriousness is 0.8dB matching of each pair of these monitors which isn’t common in this price range.

Many investigations in the field of mechanics have led Thierry Comte to believe that while the physical properties of the membrane certainly influence the frequency response, the overall result is very much conditioned by the rigidity and length of the voice coil former, coil winding features, type and amount of glue used for driver assembly and cabinet joints as well as the geometry, weight and viscoelastic properties of the driver suspensions. All moving parts interact as a "whole unique entity" as he put it. For best results it thus becomes necessary to optimize each contributor to this picture whilst remaining focused on reliability and manufacturability.