Atohm is a brand better known than people know about. If that sounds like a contradiction, think on this: when it’s not making drive units (already a rarity) for its own loudspeakers like the GT1, Athom’s parent company makes drive units for fellow French loudspeaker brands, such as Triangle, Elipson and Waterfall.
Atohm is the brain-child of Thierry Comte, one-time technical director of Triangle, who used those years of driver design skills to go it alone and create one of France’s premier OEM and DIY suppliers of drive units. More recently, however, Atohm has made its own complete loudspeakers. The great advantage driver makers have is generally they bring a highly scientific approach to the loudspeaker building craft. If you make loudspeaker drivers by the thousand both for your company and others, you need a thorough background in the physics and engineering involved in the task, and the ‘fairy dust’ element that permeates some loudspeaker designs never makes it to the drawing board. The downside is this can result in loudspeakers designed by engineers for engineers, that real people cannot or will not take to. With one notable caveat, Atohm has avoided the engineer’s folly elements of design.
The smallest of three models, the GT1 is an elegant rear-ported two-way standmount loudspeaker, finished in either a rich rosewood, black or white lacquer. The drivers in the GT1 are from Atohm’s Absolute Series, meaning they are the best specification it’s possible to get from the company. The tweeter is the company’s SD28 ND 04RD model, a 28mm soft-dome design. Unlike most tweeters, this is a direct radiating design that relies on sheer magnet (17,000 gauss, apparently) – rather than horn loading or compression chambering – to deliver a very high sensitivity driver. The dimples in the tweeter surround – where the horn usually resides – is designed to improve off-axis performance while limiting stray HF reflections. It’s partnered with the LD150 CR 04, a 150mm mid-bass unit using a light but stiff alloy cone with a nomex/kapton former on the 25mm voice coil and a rigid aluminium basket. It too achieves high sensitivity, and as the GT1 uses a relatively simple first order crossover, the GT1 is conservatively rated at 89dB sensitivity and a comfy six ohm impedance load. Because of the nature of the drivers, Atohm puts the crossover point at a relatively high 2.5kHz.