4
GB
The units frame is manufactured in die-cast magnesium. Here the rigidity of the material is utilised to ensure that the heavy magnet
system and the voice coil remain in perfect position in relation to each other.
Furthermore, the magnesium frame ensures that the magnetic force stays concentrated in the magnet system instead of spreading out
into the basket.
Woofer, D 870
The keywords for choosing the woofer to be used in the D 870 were deep and transient. The woofers pressure die-cast magnesium
frame is therefore equipped with a powerful magnet system to control the travel of the long voice coil and the pressure die-cast PP
diaphragm, whose total mass is relatively large.
This careful combination of features results in an authoritative, pure and undistorted reproduction of even the deepest frequencies.
Crossover network
As described above, it has been of primary importance that the speaker units used should be of such
superior quality that they would have no shortcomings which would later have to be corrected for in
the crossover network.
Therefore, the crossover network in the D 8 Series is a relatively simple - in the most positive sense of
the word - low-order construction.
The advantage is that both the acoustic and the electrical phase angles are kept at very small values -
which of course is of great importance, both in terms of sound quality and amplifier load.
Another advantage is the high temperature stability achieved, meaning that the crossover frequencies
will always remain stable - even when the speakers heat up, which causes a change in their impedance.
The result is that the speaker units will always work within the intended frequency areas and that the
transition between the units remains perfectly stable in all circumstances.
Of course only components of the best quality have been employed in the crossover network: Foil
capacitors, wire-wound resistors and coils with a high Q factor. For the important midrange area, coils
with air cores are used to eliminate hysteresis errors.
The crossover network is mounted directly on the solid 24K gold-plated loudspeaker terminals to
ensure the shortest possible signal path and thereby prevent signal loss.
The internal wiring for connection to the woofer and midrange units is made with the newly developed
Jamo High Definition OFC (Oxygen Free Copper) Flat Cable with a sectional area of 2.5 mm
2
. This cable
features low resistance, no self-induction and low capacitive reactance, which means that it will not
affect the signal from the amplifier in any way, thus permitting full control over the units.
The advanced tweeter makes other demands on the cable. To ensure a natural reproduction of even the most delicate harmonics, it is
very important to have as low a capacitive reactance as possible. This has been achieved with another newly developed cable type, the
Jamo High Resolution Frequency Control OFC Flat Cable. This cable has a sectional area of 1.5 mm
2
and large separation between the two
conductors.
Cabinet
Even the best units will never be able to provide optimum performance if a similarly serious approach has not been applied in manufac-
turing the cabinet. Therefore the units are mounted in Jamos world-patented NCC (
N
on
C
oloration
C
ompound) material. The NCC front
is a sandwich construction consisting of two die-cast plastic shells which enclose a core consisting of a mix of quartz sand and a
resonance-dampening binding agent. One of the characteristics of the NCC material is that it is very heavy and extremely resonance-
dead. The efficient natural dampening means that when you listen to Jamo D 8, all you will hear is the sound of the units - there will be
no contribution or sound colouring from the front plate - not even when you play loud! Also, the sound cannot travel back and forth in
the baffle between the units.
The units are naturally countersunk in the front panel, just as all edges are rounded in order to reduce diffraction to a minimum - for the
same reason we have manufactured the front fabric panel in thin MDF board and made sure there is a very close contact between the
loudspeaker and the fabric panel.
All manuals and user guides at all-guides.com
