JAMO D 4 - Manual (Page 5)

5
D 450
D 450 is a 2½ way dual bass reflex system featuring a 6½”
woofer, a 6½” mid-woofer and a 1” DCD tweeter.
The 2½ way configuration has sort of become a hallmark of
Jamo. We are using this configuration in a number of products
starting with our highly acclaimed D 870 speaker.
The reason for choosing this configuration is that it grants you
the best of two worlds: The tweeter and mid-woofer reproduce
the full frequency range, so, this 2 way system is “securing” the
coherent, harmonious and smooth sound well-known from
traditional 2-way systems. Then the additional woofer blends in
below 150Hz to add the extra cone area and power handling
needed to give full fidelity in the low bass.
The dual bass reflex configuration means
that the cabinet of D 450 is divided into two
chambers – one for the tweeter/mid-woofer
and one for the designated woofer.
This gives several advantages: First of all the
sound pressure inside the cabinet from the
woofer does not influence the mid-woofer
and vice versa. This of course eliminates
colouration and thus results in cleaner
sound reproduction.
Furthermore, each chamber is optimized for drivers intended to work
in it. The internal partition is angled so that the mid-woofer is given all
possibilities of “breathing” freely whereas the fact that the woofer
couples acoustically to the cabinet adds “acoustic” weight to the
moving mass of the woofer and thus attenuates the woofer around
100Hz.
Finally, the partition wall also works as an internal bracing of the
cabinet and thus reduces cabinet vibrations – to ensure that what you
hear is the sound from the drivers – not from the cabinet vibrations!
D 450 features gold plated bi-wiring/amping terminals. With the upper terminals you
connect to the tweeter whereas the lower terminals connect to the mid-woofer and
woofer. This split was chosen in order to separate the heavy current flow in the midrange
and bass from the more delicate signal to the tweeter. The bi-wiring/amping facility gives
you all the possibilities of “tweaking” the sound balance.
The D 450 can be placed either by using the adjustable spikes securing a good mechanical
coupling to the floor independent of floor materials or, if you prefer to decouple it from
the floor, by using the enclosed rubber absorbers.