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Special acoustically transparent cloth is used in the grille assembly. However for the very best performance, you may wish to remove
the grilles.
To do this, unscrew the brass knob from the rear of the cabinet, and screw it into the threaded insert at the bottom of the grille assembly.
Pull gently outwards and lower the grille, so that it clears the lip at the top of the cabinet.
Grille Removal
Loudspeaker drive units contain large magnets. These are capable of generating a substantial magnetic field extending a considerable
distance beyond the sidewalls of the speaker enclosure. This field can cause picture distortion if the speakers are placed too close to a
CRT television or monitor. For this reason, Glenair should be placed no closer than 1.5m to a television or monitor.
Proximity to Televisions & Monitors
Like all loudspeakers, the drive unit in your Tannoy Glenair a while to reach optimum performance, as the stresses in the materials
relax - especially in the suspension system. For this reason, it is beneficial to run the system at fairly high levels at normal room
temperature, for approximately 20 hours to achieve best results.
Running In
One of the unique advantages of the Tannoy Dual Concentric™ principle is that the low and high frequency sound radiation is generated
on the same axis. The high frequency unit is mounted behind, and concentrically with, the low frequency unit. High frequency sound
radiates from the centre of the low frequency unit through a carefully designed high frequency exponential horn. Low and high
frequencies are therefore fully integrated at source. It is this feature that gives the Dual Concentric™ driver such unique sound
reproduction qualities.
There are other significant benefits. The high frequency unit does not obstruct the low frequency unit in any way (a unique feature
when compared with other so called coaxial systems). Polar dispersion of sound is symmetrical in both horizontal and vertical planes.
By careful crossover network design the virtual acoustic sources of the high and low frequency units can be made to occupy the same
point on the axis. Therefore the total sound appears to emanate from a single point source located slightly behind the drive unit. This
means that the loudspeakers, when fed from a high quality stereo source, can recreate a full and accurate stereo image.
Tannoy Dual Concentric
™
Drive Unit
The low frequency section of the Dual Concentric™ driver has exceptional power handling and dynamic range. The low frequency
cone piston is produced from selected multi-fibre paper pulp. This is specially treated to absorb internal resonance modes.
The treated fabric surround is designed to correctly terminate the moving cone and provide optimum compliance and linearity at large
excursions. The cone piston is driven by a high power motor system consisting of a single layer copper ribbon coil suspended in a
precision magnetic air gap. The coil is wound with a special high temperature adhesive system and individually cured to ensure reliable
operation at high peak power inputs. The shape of the low frequency cone is arranged to provide optimum dispersion of audio frequencies
at both the high and low ends of the spectrum. The cone flare continues the high frequency horn profile to ensure a smooth transition
at the crossover point.
The Low Frequency Section
The high frequency driver consists of a wide dynamic range compression unit giving superb transient performance with a smooth uncoloured
response. The compression unit feeds acoustic power through a phase compensating device, the Tannoy Tulip Waveguide tm, to the throat
of the acoustic horn. This horn provides an acoustic impedance transformation to match the compression unit radiation into the listening
environment.
A aluminium alloy diaphragm, formed by a specially developed process, produces a piston with a very high stiffness to mass ratio. Optimum
molecular grain structure gives long-term durability. A low mass precision single layer copper clad aluminium coil provides the driving force
for the diaphragm, energized by a powerful ferrite magnet system. A copper pole piece cap ensures Eddy Current losses are minimized, thus
reducing non linear distortion. A damped acoustic cavity controls the compression driver response and ensures further correct acoustic
impedance matching to the horn throat.
The High Frequency Section
During the design of the crossover network the acoustic, mechanical and electrical interactions of the high and low frequency sections have
been fully analysed. The crossover is therefore an integral part of the design of the system. The crossover network provides complex equalisation
in both amplitude and phase for each section and fully integrates the response at the crossover point.
All components are high precision, low-loss and thermally stable. Very high quality audio grade polypropylene capacitors are used for the
high frequency feed. Air-cored and large laminated iron core inductors avoid saturation effects. The components are laid out to minimise
inter component coupling and are placed well away from the driver magnetic field. Top quality silver-plated van den Hul wiring is used for
the low frequency section, while Acrolink 6N ultra high purity copper wire is used for the high frequency wiring.
The complementary design of crossover and drive units means that the loudspeaker system as a whole behaves as a minimum phase system
over the audio band and therefore the acoustic sources of the high and low frequency sections are aligned in time and space to ensure accurate
reproduction of stereo images.
The Crossover Network
Our hearing mechanism locates natural sound sources with great accuracy by using the naturally occurring phase differences (or arrival times)
at middle frequencies, and intensity differences at higher frequencies, between each of our ears. Naturally occurring sounds pass through the
air to the ears at constant speed (345 metres/second or 1132 feet/second). All frequencies travel at the same speed and therefore a frequency
independent time delay is associated with the distances involved. (The familiar time delay between a flash of lightning and the associated
clap of thunder is an example). Human hearing relies on the constant nature of the time delay with the intensity to locate natural sounds
accurately. A pair of Glenair loudspeakers can uniquely reconstruct stereo images and provide excellent localisation of recorded sounds. The
Tannoy Dual Concentric™ driver principle ensures that the source of sound at high frequencies is one the same axis as the source of sound
at low frequencies.
The careful design of crossover network complements the drive unit to provide a coincident sound source at frequencies where the human
ear derives phase information for localisation. The loudspeaker system exhibits a time delay response that is in essence independent of
reproduced frequencies. In addition, the amplitude (or intensity) response is linear, smooth and consistent. This provides the correct intensity
information to recreate the original sound stage.
A Note on Auditory Perception
