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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.

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L-Series Dynamic Loudspeakers 99-Series Components ESL Electrostatic loudspeakers II-forty Valve Amplifiers
 
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