Tweeter / Midrange

All three Philharmonic Speaker models make use of the same cutting edge tweeter design using Air-Motion-Transformer technology. This technological concept is based on an accordion-like folded membrane generating high sound pressure with relatively low amplitudes in the motion of the membrane.

The film membrane has low mass and is therefore especially suited for high frequencies. Although the Air-Motion-Transformer principle is not new, it finds its way increasingly into speaker design only recently due to new powerful magnets, new membrane materials, as well as new bonding techniques and optimized cabinets. The Air-Motion-Transformer unit that comes standard in Philharmonic Speakers is very costly but delivers an unmatched performance.

The midrange driver covers a wide frequency band and has proven itself with an extremely natural and nice sounding performance in the Celesta and Angelica.

Crossover networks

Philharmonic Speakers are passive loudspeaker systems and therefore need an external amplifier. Music sources cannot be plugged directly into the speaker. The signal coming from the amplifier is split within the speakers: The crossover network directs the appropriate frequency range to the best fitting driver. Another task of the crossover network is to eliminate irregularities coming, for instance, from the baffle step. This may sound simple, but is a challenging task. Aspects like the radiation pattern, flank slope and phase shift must be taken into account. The best solution out of a sheer endless number of possibilities has to be found. In short: The crossover network is the heart of the speaker and strongly depends on the know-how of the speaker designer. The Philharmonic Speakers are built with the following design principle regarding the crossover network: As few components as possible, but as many as needed. The main focus is on a linear frequency response and optimal phase position at the crossover frequencies. Wherever reasonable, film capacitors are employed instead of electrolytic capacitors.


Bass technology

The Celesta and Angelica use woofers with a three-layered sandwich-membrane that consists of aramid fibers with a hexagonal inner structure. This allows for a high degree of stiffness in the membrane while keeping the moving mass low at the same time. The high stiffness guarantees the form stability of the cone during operation, resulting in crystal clear and powerful bass reproduction. The theoretical concept of the hexacone membrane is convincing but listening to the practical results is a unique experience.

In the Konzertina a small woofer with a coated glass fiber membrane is engaged. This woofer performs perfectly in the test lab and fulfils the highest demands of sound quality as well.


The cabinet of a speaker should not add its own sound and is not meant to be a resonating body as is the case with musical instruments. The cabinet’s main task is to prevent the sound waves emitted forward from the woofer to overlay with those emitted towards the rear. Otherwise, the sound waves would cancel each other out due to the phase shift. In addition, the cabinet itself should resonate as little as possible. This behavior can be expected from high-mass materials. Therefore, parts of the Konzertina and Celesta cabinets are made out of a special concrete. This is not only advantageous in respect to sound, but together with the front and rear panels of beech plywood also gives the speakers a unique look and feel.

Find out more on the next page


As close to realty as possible

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Dr. Clemens Barthel
Hirtenweg 16
D-34212 Melsungen
+49 (0) 157 506 788 21

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