If the Atohm Sirocco 1.24 two-way bookshelf speaker was unveiled last May at the High End show in Munich, it was at the Paris Audio Video Show, on October 26 and 27, that the Atohm Sirocco 2.24 2.5-way column was presented to the world. And it was on this occasion that we were able to listen to them both, to get a clear idea of their great qualities. There is no doubt that with the Sirocco 2024, the French manufacturer Atohm once again demonstrates its expertise and mastery of the loudspeaker (Atohm designs and manufactures its own speakers), but also of cabinetmaking with a new internal structure. Presentation.
Atohm Sirocco 2024, new tweeter speaker Atohm WSD20 DND 04F££££
The Atohm Sirocco 1.24 and 2.24 speakers each feature a new high-efficiency [abc]tweeter[/abc] called WSD20 DND 04F and equipped with an optimized waveguide in injected aluminum to annihilate vibrations and align its time origin with that of the [abc]midrange[/abc]-[abc]boomer[/abc] C150 which also equips the speakers. The 20 mm dome of the tweeter is made of silk. Its motor is made of a double ring in very high grade neodymium (ND52H), within an air gap treated with ferrofluid for great linearity and optimal heat dissipation. The rear chamber, also made of injected aluminum, is calibrated to absorb the rear wave and limit excursions, in addition to the distortion of the lowest frequencies of the sound spectrum covered by the tweeter.
Namely, the level of the tweeter is deliberately attenuated once mounted in the enclosure via the filter to match that of the mid-woofer speaker. And each tweeter carefully manufactured in the Atohm workshops undergoes a battery of five measurements in an anechoic chamber in order to perfectly know their sensitivity and then associate them as finely as possible with a mid-woofer speaker. Everything was developed using the FEA process of advanced electromagnetic simulations.
Atohm Sirocco 2024, new Atohm C150 midrange-woofer££££
The C150 midrange-woofer is directly inspired by the LD130 speaker, one of the first specimens developed by Atohm in the early 2000s. Its diameter, its attachment to the basket, the type of its membrane or its motor structured from a ferrite magnet, these are all elements largely influenced by the LD130. However, with the help of technological progress and almost 25 additional years of experience, these have been redesigned and optimized for significantly higher final performance.
A paper composed of short oriented fibers was chosen to make up the membrane. A specific treatment on the back is present to dampen the splitting of the membrane in the highest frequencies of its response for greater linearity. This greatly facilitated the development of the speaker's filtering. The membrane suspension used LDS (Low Diffraction Surrounding) technology, again for a more linear frequency response. In addition, its adjusted geometry offers perfect symmetrical stiffness during the largest excursions, while reducing the moving mass. The motorization integrates an 84 mm ferrite and a 25 millimeter coil. A double copper ring, designed to counter the alternating magnetic flux produced by the coil and disturbing the magnet, is embedded according to the exclusive TICR (Thermal & Inductive Control Rings) technology. Mounted symmetrically around the coil on the field plate and in the presence of a ventilated aluminum coil support, the two rings manage both electromagnetic control and heat dissipation (+25% compared to a conventional structure). Ultimately, the efficiency of the speaker is increased, in particular its dynamics and reliability.
Always with the aim of fully exploiting the C150 speaker, the latter benefits from the new exclusive M-Guard technology. Its purpose is to control the coil excursions when it is heavily stressed to avoid crossing the limits of linear excursion, which leads to distortions, bottoming out, and at worst, the breakage of the speaker. Acting as a "brake recoil" (progressive shock absorber), the M-Guard process allows the speaker to absorb up to 6 dB of additional tension without distorting (or almost) the listening experience. Given these constraints, for sufficient rigidity and precision, the C150 basket is also made of injected aluminum. Securely attached to the field plate, it dissipates the heat of the entire unit, ensures the ideal placement of the motor, the spider and the suspension between them. Finally, its openings are amply sized to eliminate rear waves.
Atohm Sirocco 1.24 and 2.24, strategic location of the vents££££
Model [abc]bass-reflex[/abc], the Atohm Sirocco 1.24 and 2.24 speakers contain a vent at their base, that is to say located far from the speakers to avoid any possibility of reflection/diffraction when it is close to a membrane. And the tuning frequencies as well as the total amount of damping have been precisely measured. The 2.24 column, subject to vertical standing waves linked to its suitable structure, integrates SWD (Standing Wave Dumper) technology based on a laminar absorption space placed in its base and composed of an acoustic filter and a damping volume.
Atohm Sirocco 1.24 and 2.24, filtering and adjustment of the tweeter attenuation££££
In the end, the drivers of the Atohm Sirocco speakers prove to be temporally aligned on the vertical plane. They also make the most of the gentle slope filters (here 6 dB/octave + impedance compensation circuits) for a gradual transition at the frequency level for perfect management of the directivity lobes and natural sound reproduction. Namely, the attenuation of the tweeter level is adjustable directly at the rear of the speakers through a three-position selector (2 dB steps for each position). It is therefore possible to customize the response of the speaker according to your tastes and, above all, the listening room and its placement in it.
As you can see, Atohm and its boss/developer Thierry Comte have not done things by halves for the development of the new Sirocco speaker series, with many new technologies implemented in addition to new speakers. On paper promising, the sound of these speakers discovered live during a demonstration at the Paris Audio Video Show does not disappoint. On the contrary, it is surprising considering the price of the speakers, with an energy that is still incredible, immediately positioning the Atohm Sirocco at the top of the quality-price podium. Test to come.
Available immediately, in light wood, walnut or white colors.
Indicative prices: €1,690 for a pair of Atohm Sirocco 1.24, €2,790 for a pair of Atohm Sirocco 2.24
Reminder of the key characteristics of the Atohm Sirocco 1.24:
• Type: 2-way speaker
• [abc]Midrange[/abc]-[abc]woofer[/abc]: C150 DCR 04 15 cm
• [abc]Tweeter[/abc]: 20WSD20 DND 04F 20 mm silk dome
• Load: [abc]bass-reflex[/abc]
• Sensitivity: 88 dB
• Impedance: 4.4 ohms minimum
• Frequency response: 47 Hz-25 KHz
• Cabinet dimensions (L x D x H, mm): 180 x 260 x 345
• Max/peak admissible power: 100 W
• Weight net unit weight: 7 kg (unit)
Reminder of the key characteristics of the Atohm Sirocco 2.24:
• Type: 2.5-way speaker
• Midrange-woofer: C150 DCR 04 15 cm x 2
• Tweeter: 20WSD20 DND 04F 20 mm silk dome
• Load: bass-reflex
• Sensitivity: 88 dB
• Impedance: 4.4 ohms minimum
• Frequency response: 40 Hz-25 KHz
• Cabinet dimensions (W x D x H, mm): 220 x 260 x 990
• Max/peak admissible power: 320 W
• Net unit weight: 14.9 kg (unit)
