QUAD Vacuum Tuber Amplifier Systems II-FORTY, Brochure & Specs

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The standard QC-twenty-four
is line level only. There is an
option of a solid-state phono
stage which can be added
when new, or at a later stage.
“Quad has succeeded where few of hi-fi’s
gamblers dare: They’ve followed the ESL-989
with not just a worthy amplifier, but with a silent
smooth and precise control unit as well.”
– Ken Kessler, hi-Fi News
Peter Walker always believed that an amplifier
should be as simple as possible - engineer with the
fewest possible components and with a performance
largely independent of those components.
The QC-twenty-four, a low-noise RIAA curve
phono stage has an understated elegant simplicity,
although we use high quality components wherever
these appear in the signal path.
Bifurcated contact relays (crossing each other at
right angles to make a better contact) are used on
each input to maintain the best possible signal
conduction. Gold-plated connectors and a carefully
screened enclosure are further examples of the
attention to detail throughout the construction.
The total line gain is 15dB, with a high quality
potentiometer controlling the output levels.
Reminiscent of the original QC-22 control
module, there is a simple balance control
allowing for variation from left to right of up
to 12dB.
Amplification is provided courtesy of a twin
triode 6111, new old-stock valve - originally
designed for use in the guidance systems of
missiles and manufactured to exceptionally high
tolerances. The remarkably long expected life-
span of this valve means we can comfortably
build it into the PCB without the compromises
usually experienced when using valve seats. Two
buffered tape loops are provided as standard.
A completely new design, the QC- twenty-four pre
amplifier is both neutral and detailed. Using a military
specification 6111 valve, which is so reliable, it’s
hard-wired to the circuit board.
Everything has on this pre amplifier has been
designed to maintain optimum signal purity. From
the relay switching to the gold-plated terminals, each
component has been selected specifically for its
audio performance.
The chassis is painted to match both the Quad II-
Classic and the Quad II- forty power amplifiers, making
it the perfect partner to both systems.
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