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 |
3 |
2.2. D 430 |
4 |
2.3. D 450 |
5 |
2.4. D 4CEN |
6 |
2.5. D 4SUB |
6 |
3. Driver explanation |
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3.1. Tweeter |
8 |
3.2. Mid-woofer/woofer |
9 |
3.3. (Sub) woofer |
11 |
4. Electronics (D 4SUB) |
11 |
5. Cabinets |
12 |
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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.
So, what are the “problem areas” in doing that?
Well, it could be extended treble response “demanded “ by the new multi-channel sound formats, it could be the extended bass response “demanded” more and more by the extreme movie soundtracks – and at the same time maintaining musical fidelity, absolute coherence, perfect imaging etc. And last but not least, products that you can actually live with in your home . . .
This of course was a huge challenge for the development team; acousticselectronicsand mechanical engineers as well as our design team from Carl Bro.
The code word in the whole process was: Form follows function
The result of this can e.g. be seen in the slim line cabinets without any edges to cause diffraction, the double curved front baffle which is not only a very rigid and resonance dead construction but also improves time alignment of the tweeter.
Of course the task also demanded choice of very high quality materials and development of completely new and very powerful driver units.
The sound reproduction of the D 4 is very detailed, clear and open in the
entire spectra, with a large listening window making it easy to locate instruments, vocals and subtle details when listening to music or experiencing a movie.
The Products
D 400
D 400 is a closed 2 way system featuring a 5¼” woofer and a 1” DCD tweeter (see more details about the driver units later in this document).
This is probably the most compact high-end hifi speaker ever made - just 11 cm/41/3” deep.
And not only is this a true high end performer it is also a very versatile speaker that can be used for 2 ch. hifi, as front, centre and surround speaker in a surround set-up with identical main speakers and as surround speaker in a set-up with the D 430 and D 450.
The D 400 is optimised for wall mounting –which gives several advantages.
When wall mounted more parameters are “controlled” than with a free standing position: As there is no distance from the speaker to the rear wall, we know that low frequencies are acoustically amplified and how much. We recommend placing the speaker 1 metre above the floor. The most common listening distance is 2 – 4 m / 6 – 12 ft., so we can quite accurately predict the contribution from floor reflections too.
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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.
The resonance frequency of the tweeter is as low as 600 Hz. The x-over to the mid-woofer is set at 1.7kHz but due to the excellent low frequency extension we use a low Q 2nd order filter to roll it off downwards. So, actually it plays down to 1 kHz. Thereby, we secured a seamless integration between the drivers, and avoided potential phase errors caused by high order filtering.
D 430
D 430 is a 2 way bass reflex system featuring a 6½” woofer and a 1” DCD tweeter.
This compact bookshelf speaker can be placed on a bookshelf – or on the designated D 4FS stand – providing a very stable placing at the correct listening height.
The D 4FS 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. The design and choice of material for the rubber absorbers (PUR 80 Shore A) was made to match exactly the D 4 speakers.
The D 430/D 450/D 4CEN all feature Jamos Convex Tapered Vent. This high
flow bass reflex port design ensures less turbulence and allows 5 dB higher SPL before port noise occurs – which means that in practical life, port noise is eliminated!
The D 430 features gold plated bi-wiring/amping terminals – giving you all possibilities of “fine-tuning” the sound by using cables that suit exactly your equipment, your room and personal preferences.
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