Technical Description Jamo D 4 Concept
Technical Description Jamo D 4 Concept Contents: Page 1. General system description 3 2. The products: 2.1. D 400 2.2. D 430 2.3. D 450 2.4. D 4CEN 2.5. D 4SUB 3 4 5 6 6 3. Driver explanation 3.1. Tweeter 3.2. Mid-woofer/woofer 3.3. (Sub) woofer 8 9 11 4. Electronics (D 4SUB) 11 5.
General description With the Jamo D 4 Concept the goal was to create “the link” between high-end hifi and surround sound and at the same time focussing on versatility – or flexibility – in system configuration and placement.
Wall mount: The rear wall “amplifies” low frequencies and the floor actually gives a dip in approximately the same range due to the first floor reflection reaching the ear in opposite phase with the direct sound from the speaker. The speaker can be used as full range. In this case the subwoofer should be adjusted to blend in seamlessly in order to suit the room and personal preferences. However, D 400 is intended for crossover at 80 or 100 Hz – again depending on the room.
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.
D 4CEN D 4CEN is a 2 way bass reflex system featuring two 4½” woofers and a 1” DCD tweeter. The design of D 4CEN is kept as compact as possible in order to make it easier to place the speaker close to the TV set. So, the height of just 16-cm/6.3 inch is just enough to house the two powerful 4½” drivers. Actually, you would probably expect that in order to obtain optimum timbre matching between centre and front speaker you need to use the same size of driver.
As mentioned the D 4SUB goes very low in order to reproduce the extreme bass contents of movie soundtracks with full authority. However, under certain circumstances this can create a problem, which is why some decoders feature a Boundary Gain Compensation filter. This filter compensates for the room influence at low frequencies, as any room amplifies the lowest frequencies.
Drivers Tweeter The tweeter in the D 4 range, has already been well acclaimed in Jamo products, as it is used in the Jamo D 7 THX Ultra2 system, winner of the EISA award as “High-end Home Theatre 2002/2003”. However, to suit the exact purpose in D 4, we developed a new, asymmetric front baffle. D 4 asymmetrical tweeter design The tweeter was chosen for 3 main reasons: 1. Extremely low distortion 2. Totally freedom of accentuation of “s” sounds. 3.
In fact, the choice of “motor” materials makes use of magnetic oil for cooling and resonance damping unnecessary! All these features in combination allow the diaphragm to move effortless and the result is a very natural, detailed, dynamic and open sound reproduction. Mid-woofer/woofer The woofer of the D 4 speakers features a brand new wood fibre cone. This unique cone is made from wood fibre material, characterized by very uneven fibres with different resonance properties.
However, the anodised aluminium centre plug is probably the most conspicuous feature of the D 4 woofers. It replaces the traditional dust cap in the centre of the loudspeaker cone at the place where the dust cap would normally be mounted thereby making the cone lighter and thus faster. Also this prevents potential break-up points where the dust cap would have been glued to the cone. In addition, it prevents over- and under pressure behind the dust cap when the cone moves back and forth.
(Sub)Woofer The 8” woofer features a vented magnet system and a Ø 38 mm / 1½” aluminium voice coil former. The 4-layer voice coil is 28 mm / 1.1” long allowing linear excursions up to +/- 10 mm / 0.4” – and still with >70% of the B*L product available! The magnet system features a vented pole piece in order to avoid over/under pressure behind the dust cap (mechanical damping) when the cone is moving. The cone is made from air-dried paper.
Cabinets All D 4 cabinets are made of heavy MDF board, a solid and resonance dead base for the drivers to work in. However, the most remarkable cabinet feature is probably the Double Curved front baffle. It is common knowledge that one of the most rigid constructions at all is a round shape; a ball, an egg etc. Therefore the front baffle of D 4 has been “cut out” from a giant ball and thus the name “Double Curved” front baffle.
