QUAD ESL-989 - Manual (Page 7)

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When experimenting, it is preferable to use good recordings or works with which you
are familiar in the concert hall or good quality speech.
The ESL loudspeaker, being a dipole source, has considerable advantages over
conventional loudspeakers in terms of room placement. No energy is radiated in the
plane of the diaphragm and as a consequence, the respective axial room modes are
discriminated against. Normally the loudspeaker is placed at an angle to both
horizontal room axes and will excite both sets of horizontal axial modes, 3 dB less
than with a conventional source and discriminate entirely against the vertical axial
modes.
The loudspeakers should be placed at least 60cm (2 ft) from the rear wall of the
listening room and angled towards the listener and never in corners or alcoves or
behind furniture. Because the ESL is a totally homogeneous sound source it will be
found that they can be placed considerably further apart than normal, broadening
the stereo sound stage. Close proximity to the side walls is not detrimental to
performance. Simple geometry will show that if the ESL loudspeaker is placed at an
angle to the side wall, there will be no audible reflection at the listening position.
The ESLs are provided with optional floor spikes which screw into the four threaded
holes in the baseplate. The heights of the individual spikes can be adjusted to
ensure that the loudspeaker sits securely level on the floor.
Take care to avoid the tips of the spikes which are quite sharp.
ESL BASE AND SPIKES
Programme Material
A small note of caution. We believe that a pair of Quad ESL loudspeakers give a
more realistic picture of an acoustic event than has been possible before, but only if
the best source material is used. They are very revealing of faults in recording
techniques and ownership of these loudspeakers will cause you to re-assess the
virtues of your collection of recordings.
Loudspeaker Phasing
If there is any doubt about the way the loudspeakers are connected, their phasing
can easily be checked by playing a mono source when the sound should appear to
emanate from a point midway between the two loudspeakers. If this is indefinite,
then the connections to one of the loudspeakers should be reversed. When correctly
connected, the loudspeakers will give a definite centre sound source with more full
bodied tenor and bass registers.
ESLmanual Feb02 11/02/04 9:14 AM Page 7