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."
the kit: Order No. str-twentyfive, Price per speaker (without cabinet) EUR 395,76 excl. VAT: € 341.17 / $ 399.17
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.
the high-end kit: Order No. str-twentyfive-he, Price per speaker (without cabinet) EUR 529,31 excl. VAT: € 456.30 / $ 533.87
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