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Quad - Inside the
L-Series Each model within the Quad L-series
is hand-built from beginning to end. No 'off the shelf' components are used anywhere
in the design (except the magnet). Every part is not only designed in-house, but
tooled in-house, and then manufactured in our own factory.
The bass units diaphragms are formed from ultra-strong, but lightweight KEVLAR fibres.
These are then lattice woven to further improve strength and also improves resonance
control. The fibres are resin impregnated and baked to produce the appropriate cone
stiffness, strength and weight properties. Finally, the cone is mounted onto a specially
developed butyl rubber surround. The voice coils are painstakingly hand wound to the
aluminium former ensuring the drivers have excellent linearity and consistency. The
lightweight but strong aluminium former 'wicks' heat away from the central coil region to
maintain peak performance and the optimum excursion of the long-throw driver. The coils
are vented to reduce the effect of any pressure build-up in the central cone region.
An expensive, very fine grain powder magnet gives excellent 'traction' to the coil meaning
that the cone tracks the music signal very accurately giving a fast and accurate sound.
The drivers' chassis is die-cast aluminium which prevents flexing in the bass units during
high excursions. Finally, a profiled phase plug provides additional cone axial rigidity
and also improves off-axis performance.
The tweeter unit is derived from a thorough understanding
of high frequency acoustics. Although it is now fashionable to use metal dome tweeters,
the supposed extra bandwidth (within the inaudible area of the sonic spectrum) these
create, often comes at a heavy price - the often unpleasant 'tizz' of such drive units
significantly hardens the sound and can sound very fatiguing. It is better, we believe, to
make the audible frequency as accurate and precise as possible with a very relaxed, yet
precise performance. This gives the Quad 22L a laid-back air of authority - never trying
too hard, or sounding strained and unpleasant - but with no loss of detail. It is also a
misconception that silk domes have a limited frequency response. We test every tweeter
beyond 37Khz, way beyond the threshold of audibility. They have a useful response to
around 50kHz.
Many years of experience have manifested themselves in the high-frequency driver. A
compact yet powerful neodymium magnet keeps the tightest control on the diaphragm. Phase
coherency is particularly important to ensure the bass integrates perfectly with the
treble, and of course, to create a truly holographic stereo image - the hallmark of a
classic Quad sound. This tweeter is a very low distortion device; it measures typically
less than 1% distortion at 103dB (equivalent to normally loud playback) output at a
distance of 1 metre - quite extraordinary.
The Quad L-series crossover uses air-cored chokes with
large gauge, 'low loss' wire. The capacitors are audiophile grade polypropylene and low
loss metallised polyester. A simple crossover topology is used to preserve phase coherency
and integration. Instead, cabinet design is used to 'tune' the loudspeaker to a flat
frequency response. Four heavy-duty gold-plated terminals allow for connection using
substantial speaker cables. |