Twentyfive - a Line Array       as in Klang+Ton 2/2007

Twentyfive aus Klang+Ton 2/2007
Technical data:
- impedance: 8 Ohm
- rated SPL: 85 dB (at 2.83V, 1m)
- frequency range (-8dB): 80-18 000 Hz
- size (HxWxD): 233.6 x 18.4 x 21.1 cm
- speaker type: sealed cabinet
Ideal radiation all around – everywhere in the room, independent of height or angle; immediately the expert will come up with a line array. That's a radiation source in form of a line – ideally infinite. That's where the name line array originates from. The name Twentyfive denotes that 25 drivers are used per speaker.

Our rooms are usually bordered by floors and ceilings. Therefore, infinity in this case means limitation from floor to ceiling. The radiation area then behaves like an area in infinite space originating from an infinite line array. Due to the linear arrangement of drivers the reflections from ceiling and floor can, therefore, be neglected.

Such an array was designed by Christian Gather and Holger Barske. 25 Visaton FRS 8M full range drivers per loudspeaker were used. Each drivers represents roughly 31 cm2 radiation area, altogether 25 x 31 = 775 cm2, for bass, midrange and treble.

Efficiency with 85 dB seems to be rather low. But then we shouldn't forget that the output level doesn't drop 6 dB per doubled distance but only 3 dB. That's because the envelope area that the sound has to pierce through is not four times higher with doubled distance, but only twice as high (it's a linear not a quadrate relationship). Therefore, 4 metres away from the speaker the sound pressure level is the same as a standard speaker - 91 dB (2.83V/1m).

The Twentyfive is extremely slim - just 12.4 cm wide and 18.1 cm deep. The 25 drivers are connected as follows: 5 each in parallel, and the packs of five in series.

Excerpt of the review in Klang+Ton 2/2007:
... "Tonality is great, but that is the same with a single FRS8M. The moment of truth comes when the volume is cranked up. Don't get it wrong, this is no party animal. From a sound balance point of view this loudspeaker possesses all the virtues of a single Visaton, a concise reproduction of vocals and - above all - instruments over the entire frequency range. The big difference to a small single 8 cm driver is dynamics. Just imagine that 50 small diaphragms, each one equipped with its own extremely well controlled drive, are at work here. Like almost no other speaker, with the exception of lounge suitable horns, the Twentyfive is able to reproduce jumps in dynamics realistically. OK, the sound pressure is not big enough for large drums, but everything above just bangs, creaks and jumps into your face. And lets not forget that the distortion is extremely low, ensuring that the sound is tight and balanced without being sterile or lifeless. It is difficult to find a loudspeaker that is so at ease with different kind of music material, without being impressed or intimidated - and that's a lot of fun. Finally a hint: if you want to solve the centre problem of your home cinema, and you are not shy to dive into it, just build yourself five or more Twentfive's, add a potent subwoofer and open up a movie house. It's difficult to find a more lounge suitable and more practical loudspeaker with similar dynamic ability."

Our kit consists of:

  • 25 x Visaton FRS 8M
  • 1 bag wool
  • self-adhesive sealing tape
  • 100 x PAN screws 3.5x17 mm
  • 25 m cable 2 x 1.5 mm2
  • gold plated brass binding posts
  • description / building instruction
  • the crossover components to be mounted on wood:
  • 8.2 mH ferrite core coil, 2.6 Ohm
  • 100 uF ELCO non-etched
  • 1.8 uF MKP capacitor
  • 2 x 12 Ohm MOX10 resistors (brown-red-black)
  • 3 x 22 Ohm MOX10 resistors (red-red-black)

the kit: Order No. str-twentyfive,
Price per speaker (without cabinet)   EUR 406,00 excl. VAT: € 341.18 / $ 392.35

Please not: the Klang+Ton kit is designed for anything between 40 and 60 Watts (crossover components). Under normal circumstances this is certainly enough. But since the maximum power handling according to Klang+Ton is 25 x 30 Watts continuous we made sure that our high-end version doesn't have any power limitations.

Twentyfive with high-end crossover:

The kit with high-end crossover contains the same components like the standard version,
version with the following exceptions:

the high-end kit: Order No. str-twentyfive-he,
Price per speaker (without cabinet)   EUR 543,00 excl. VAT: € 456.30 / $ 524.75

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