Hardware Reviews

Atohm GT1-HD


Atohm may not be a familiar name to many readers, but when we couple Atohm to Devialet and mention that these two companies brought us the Devialet Ensemble 120/GT1 it might a ring a bell. Atohm is a French company that was chosen to supply loudspeakers for a Devialet package that is sold worldwide under the name Ensemble. But Atohm has more to offer, they make several ranges of loudspeakers, produce loudspeaker kits for DIY and supply drive units to other French manufacturers. The GT (or Grand Thrill) range consists of two floorstanding loudspeakers and one monitor, the GT1-HD, which has a lot in common with the Ensemble GT1, but they are not the same, in fact the HD is the newer  version of the GT1. Now that they are being distributed in the USA, Atohm products are even more worthy of investigation.

GT Series
The Grand Thrill series is Atohm’s top line and uses the best drivers they offer. The 28mm soft dome tweeter comes from the Absolute Series and is big enough to handle everything from two to 30 kHz. It has very high sensitivity of 98dB which has a lot to do with the neodymium magnet and high flux inside the ferrofluid filled magnetic gap. The voice coil support is made of aluminium and the coil wire is copper clad aluminium. Aluminium is also used to form the chassis. The woofer has a coated aluminium cone with a copper voice coil on a Kapton-Nomex former. It has been optimized to cover the full frequency range between 20Hz and 2500Hz with very low distortion even at high volume levels. Another Atohm speciality is the Time Coherent Crossover, this has a 6dB, first order slope but is complicated by a time delay circuit for the tweeter to optimize the phase response. Instead of using a cabinet with a recessed tweeter, Atohm uses coils, resistors and capacitors to make sure integration between tweeter and woofer is phase coherent. The GT1-HD has adjustable output on the tweeter in three steps, with a switch on the back of the cabinet. The ‘linear’ mid position gives a flat response, ‘smooth’ offers a -2dB reduction in output and finally ‘high definition’ offers a +3dB gain. Acoustic loading of the bass unit is done with a bass reflex port, with its opening at the bottom of the loudspeaker. This is why there’s a baseplate with a 12mm gap under the cabinet. A solution normally only seen on floor standing loudspeakers.

The cabinet is made out of several layers of MDF that are bent into shape and glued. This is covered with rosewood veneer or black or white gloss lacquer. The cabinets are polished to obtain perfect transparency and shine. The grilles warrant a mention, there is a traditional cloth on MDF frame grille that’s held in place by magnets but take this off and there is metal protection over both the tweeter and the woofer. The modern look I would call it. Remove the metal grille from the woofer (very carefully!) and you have a high tech look. Note that the tweeter grill cannot be removed. The GT1-HD’s impedance is a moderate six Ohms and the load for the amplifier is quite easy.


GT1 HD tweeter terminals


The loudspeakers are positioned on Custom Design FS104 stands, about 80cm away from the back wall and toed-in to point almost directly at the listening position for the best stereo image. More and less toe-in was tried, but to get the sound free from the cabinets they should almost face you. I started with some lovely jazz performed by Sarah McKenzie on her album We Could Be Lovers. This 96kHz FLAC download is of excellent quality and brings us a singer who plays piano accompanied by drums, bass, xylophone and brass. The Atohm GT1-HDs keep it small and intimate with her clear voice against the rest of the band, on the title track I experimented with the three position switch on the back of the speaker, only to find that the mid position is fine. Reducing treble makes the music less inspiring, more treble opens up a bit more detail but I soon get tired of the higher notes. It is a useful extra if you have to compensate for room acoustics and your amplifier lacks tone controls, but for me the GT1-HD is very well balanced as is. That also shows in the way music from the album is presented, bass is tighter than I would expect from a reflex design, brass is never too harsh, and the xylophone adds dynamics while piano and voice reach a high level of realism. Moving on to Enya and her latest album Dark Sky Island revealed a limitation of the GT1-HD that I could not change with positioning or equipment, somehow the loudspeakers never fully disappear from the stage like others have done in the same setting. The soundstage is wide enough, has excellent in height, reasonable depth and positions well, but I am always aware of the loudspeaker position even with my eyes closed. They sound more like big floor loudspeakers in this respect than monitors often do.


atohm mid bass



Speaking of sound balance I tried to find a weakness using Patricia Barber’s A Fortnight In France, recorded live in 2004. Barber tends to put too much bass in her recordings and this upsets many loudspeakers. Well not the GT1-HD, the marvellous track ‘Norwegian Wood’ results in some truly deep bass notes coming from the loudspeakers. Again I feel like I’m listening to a floorstanding system, this time because of the bass depth. Percussion is fast and thrown around in front of me, albeit at a comfortable distance, the soundstage is positioned on and behind the virtual line between the loudspeakers. Winding up the volume on ‘Call Me’ brings Barber a little closer, this doesn’t upset the Atohms, they handle the extra power with ease and make the music even more intimate. Hall acoustics are clear in the background, guitar is fast and the piano rich in tone. This speaker shows it French roots with restricted but deep and controlled bass, a wide open midrange and detailed but never over the top highs. More live music, this time from John Mayer recorded in Los Angeles in 2008. The GT1-HD has no problem handling the power in the music, the ear blowing drums, the hammering bass and guitar strings that endure serious abuse at Mayer’s hand. Thus far the Atohm handled all kinds of music without a preference. Could these capabilities continue with classical music?

Joshua Bell made his Kreisler Album in 1996, inspired by the late Fritz Kreisler, an Austrian born violin player and composer. The music is cosy and light in tone, it brings me joy every time I hear it. It has that romantic Vienna swing that makes me feel like I am back in the last century, sipping a coffee (not schnapps? – Ed) in an ancient restaurant surrounded by elegant people. I enjoy the way the piano and the violin play together, it’s a truly easy on the ear sound. Maybe not as perfect in tone as the best of the British loudspeakers, but if you seek a little more joy and presence from a loudspeaker it was always the French you had to turn to. They capture life in their products, they even seem to capture ‘le soleil’. Putting on oboe concerts composed by Georg Philipp Telemann I enjoy his table music (Tafelmusik) played by an orchestra and not two soloists. Again I try the different treble settings the GT1-HD has to offer, and reach the same conclusion that the neutral (middle) position is the best for me in my room. That way musicians are individuals on the GT1-HD, the sound is lively but never overly bright and bass is balanced against the midrange and high notes. Atohm’s excellent tweeter is smooth enough to let me listen for extended periods without getting tired, at the same time it keeps me awake and holds my attention.


SD28ND04RD coupe1


I have been listening to a number of small and very affordable loudspeakers of late and I often wondered how manufacturers could produce such great speakers at such low prices. Afterwards I always return to my own costly monitors to find more enjoyment, precision and neutrality. The same is true of the Atohm GT1-HD, spending more always pays off. Cheaper systems are often excellent in certain respects, maybe bass, midrange, dynamics etc. But it takes more to be good, better or excellent in all respects. It takes money too, which is a pity. The Atohm proves that research, craftsmanship, a lot of testing and listening pay off in a product worth finding even if that means travelling abroad.  The GT1-HD shows that modern monitor loudspeakers can work without a subwoofer in most listening environments. Bass is no longer a serious issue and bass reflex ports are nowadays used to deepen bass and not to add quantity. The mid is fast and responds to the amplifier without colouring the sound in any nasty way. The tweeter, which is very good, takes over smoothly in the upper frequencies. Add to these points the beautiful finish of the cabinets, the looks, the clever placement of the bass reflex port on the bottom and you have a winner. You won’t need a French amplifier with tone controls to make a GT1-HD sing, but you will need a decent amp, these loudspeakers are worthy of that. They’re also worthy of being enjoyed with or without a glass of the best Bordeaux in your hand.


Two-way bass reflex system
Max power handling: 100W
Short term power handling:  200W
Impedance: 6 ohms
Sensitivity:  89 dB/2.83V/1M
Frequency response:  45Hz-30kHz
Crossover frequency:  2.5kHz
Mid-bass driver: 150mm coated aluminium
Tweeter:   28mm soft dome
Crossover: Time Coherent, first order, with 3-position tweeter adjustment
Dimensions HxWxD:  330 x 200 x 265mm

Price when tested:
Manufacturer Details:

Welcohm Technology
T +33 3 81 47 91 01


standmount loudspeakers


René van Es

Notify of
Inline Feedbacks
View all comments