JAMO D 8ADD, Owner'S Manual

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The special 1½” midrange dome has been chosen to obtain a sufficiently low crossover frequency between the bass and midrange areas
in order to ensure wide horizontal dispersion.
This is important to enable the centre loudspeaker to cover a “broad” listening position, when several persons are listening.
With a low crossover frequency, out of phase problems between the two woofers are avoided, allowing the required dispersion to be
realised.
In order to ensure perfect transition to the woofer, the midrange unit is fitted in a specially designed horn, which has been tuned to just
below the resonant frequency of the unit.
The horn provides a better coupling between the diaphragm and the surrounding air, which results in a linear reproduction and higher
efficiency in the lower midrange area.
Woofer
The diaphragms of the two woofers are manufactured in fibre glass, which is a rigid and quite heavy material. The relatively heavy moving
mass and the resulting low resonance frequency have been chosen partly to achieve optimum harmony with the Aperiodic Chamber
and partly to obtain the desired powerful and precise reproduction of the bass area below 1000 Hz.
The woofer’s frame is made in die-cast plastic. This ensures that the magnetic force stays concentrated around the voice coil instead of
spreading out into the basket. Also the magnetic strayfield is perfectly controlled, so that the loudspeaker can be placed directly on top
of a TV set without causing discoloration of the picture.
Design D 8SUR
Cabinet
The most conspicuous feature about the Jamo D 8SUR loudspeaker set is the design. The unique design was developed not only to
please the eye, but equally to satisfy the ear. Jamo D 8SUR is manufactured in 16 mm MDF board and accurately dampened with acoustic
foam. The surface of the foam is shaped in a “honeycomb” pattern to obtain the largest possible surface area and thus maximum
dampening of the sound radiating from the rear of the units.
To achieve optimum sound reproduction, the designs of the two loudspeakers in a pair are laterally reversed and therefore they are
available only in sets of a left and right loudspeaker (see the marking on the back of the loudspeakers).
Drive units
The treble is a soft dome tweeter.
The unit is oil cooled and has a voice coil wound of thermosetting wire on an aluminium voice coil former, for high power handling.
The woofer units have a specially woven fibre glass diaphragm. Other than the exclusive design, the special weave ensures a uniform
material thickness over the entire diaphragm.
A loudspeaker diaphragm can be compared to a piston, and to comply with the heavy demands on the diaphragm material’s stretch and
compression properties, the composite fibre material is composed of four different types of glass and treated with a tough-hardening
resin. This results in a light and rigid cone with good internal damping. Combined with the natural rubber suspension, which ef-fectively
prevents vibrations from travelling back to the diaphragm, the result is a very well-controlled diaphragm that operates without break-ups
in its working range.
The unit’s basket is made from injection moulded carbon fibre reinforced ABS. Using a non-magnetic material such as ABS ensures that
the magnetic force stays concentrated around the voice coil instead of spreading out into the basket.
As a result, the efficiency of the unit is increased, and the loudspeaker may be placed closer to a TV set without risk of discolouring the
image. Compared to a conventional metal basket, the acoustic properties are significantly improved, as the ABS material has a much
higher internal damping.
The unit has a large magnet and a heavy voice coil with a diameter of 25mm.
All these properties lead to an open and precise sound reproduction with unsurpassed attack.
Jamo D 8SUR is designed to enable a diffuse sound reproduction giving the listener the feeling of being enveloped in sound. In
conventional loudspeakers, this type of design will usually lead to a lack of efficiency in the
deep bass area.
However, in order to meet the demands of digital 5.1 sound, Jamo D 8SUR is equipped with a filter to significantly improve the bass
reproduction: at low frequencies, the loudspeaker acts as a traditional box with two woofer units working in phase, giving a bipolar
characteristic.
At high frequencies, the phase of the reproduction will gradually shift to give the loudspeaker a dipole characteristic. In other words,
Jamo D 8SUR combines the best of these two principles.
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