JAMO D 4 User's Manual
Contents
1. D 4CEN D 4CEN is a 2 way bass reflex system featuring two 414 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 4 2 drivers dB Resulting sound Actually you would probably expect that in order to Ovetioe reproduction obtain optimum timbre matching between centre and front soeaker you need to use the same size of driver What happens when placing too much cone area in a relatively compact cabinet is an overshoot before the He woofers starts to roll off This overshoot is often heard on centre channel speakers as if the sound was recorded with the microphone placed directly on the chest of the actor not exactly contributing to voice intelligibility The cone area of the two 4 woofers equals less than that of one 6 2 woofer but due to the fact that the two woofers are placed closely together and that they are working in the same frequency range they load each other at the lower midrange frequencies This means that in this range the cone area equals a 6 2 woofer So actually by reducing the cone area we achieved exactly what we wanted acoustically identical drivers and thus a seamless transition between the front speakers Woofer loading The D 4CEN is of course magnetically shielded for placing in the vicinity of a normal CRT t2. linear treble reproduction 7 The voice coil former is made of aluminium for optimum heat disposal The voice coil is made of cupper plated Hz aluminium wire because aluminium weighs less than cupper but the copper plating is needed because of its conducting qualities The wire from the driver s terminal to the voice coil is a thin litz wire Usually the voice coil wire continues to the terminals However litz wire features much higher compliance and therefore it has less influence of the movements of the voice coil Impedance With copper plating Jamno 8 Lets get personal 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 And thus when these fibres are pressed into shape to form a loudspeaker cone the different fibres will prevent each other from vibrating Furthermore the cone is coated twice in order to fine tune rigidity and internal damping First it is lacquered on both sides for increased stiffness and as a side benefit UV resistance is obtained and secondly it is coated on the b
3. Technical Description Jamo D 4 Concept Janno Lets get personal 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 ACANA 3 Driver explanation 3 1 Tweeter 3 2 Mid woofer woofer 9 3 3 Sub woofer 11 4 Electronics D 4SUB 11 5 Cabinets 12 Jamo Lets get personal 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 acoustics electronics and 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 re
4. ackside with a tough hardening resin to maximise internal damping eae The result is a cone with very well controlled break up modes resulting in extremely low distortion all over and a very open and detailed midrange for optimum voice reproduction The basket is made of magnesium giving several benefits First of all it makes it possible to create a very open basket even behind the spider thus ensuring high airflow at low frequencies avoiding reflections at high frequencies and preventing under overpressure causing mechanical losses Secondly as magnesium is a non magnetically material the magnetic force from the magnet does not spread out in the basket but stay concentrated where it is needed around the voice coil Finally the very rigid material ensures that the heavy magnets and the voice coil always are perfectly aligned with the voice coil in the exact center of the magnet gap To ensure that the units are firmly attached and airtight it is mounted using 6 screws and the backside of the basket features two thin silicon stripes Besides from ensuring air tightness the silicon stripes also prevent any potential vibrations that could arise between the cabinet and the unit Janno 9 Lets get personal 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 dus
5. equencies compared to the 2 layer type in the same cabinet The combination of magnet size force and length of the voice coil wire results in the so called B L Product In popular you could call this the size of the engine in a loudspeaker Janno 10 Lets get personal Sub Woofer The 8 woofer features a vented magnet system and a 38 mm 1 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 gt 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 Normally when making paper cones the water is pressed out of the cone simply because letting it air dry is way too time consuming However there is a quite significant advantage from spending the extra time When letting the paper air dry the cone is approximately double thickness compared to a pressed cone Still the low weight is maintained but due to the increased cone thickness it is simply more rigid an extremely important feature for a long throw woofer that is going to be fed by a400 W amplifier The foam surround allows fast movement at its low frequency working range Electronics D 4SUB Amplifier The D 4SUB features a 400 Watt Class D amplifier that operates at a highly efficient 85 Thi
6. etween All materials are characterized by excellent acoustic properties i e high internal damping This prevents vibrations from travelling from one driver to another Also the planar design gives optimum working conditions i e a minimum of diffractions for the asymmetrical placed tweeter By choosing the asymmetrical design no distances from cabinet top and sides to the tweeter are identical and thus edge reflections do not accumulate The result is a crystal clear treble reproduction which is essential in order to benefit from the extended treble contents of the new multi channel sound formats The finish of the D 4 is a light anthracite lacquered front baffle combined with black ash light or dark apple wood finished cabinet sides Janno 12 Lets get personal
7. mplifies the lowest frequencies The magnitude of the room s amplification depends on the NE eee eee eo are actual room and where you are positioned normally it A increases the closer you get to a wall This can result in too high bass level from approx 60 Hz and increasing downwards C a aai In the range between 20 30Hz it peaks up to 5 10dB in an Cornpensati n average room 20 55 Hz At first impression this could sound really impressive but especially when listening to music the sound can be boomy and rather annoying And certainly terms like coherent and harmonious become impossible to use Therefore the D 4SUB has a quite unique feature Boundary Gain Compensation is built into the D 4SUB on a separate input thus always granting you optimum benefit from the D 4SUB The level control is placed on top of the D 4SUB elegantly integrated in the design it grants easy access when you want to adjust the level depending on software type and format music movie DD DTS etc Janno 7 Lets get personal 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 asyM metric front baffle D 4 asymmetrical tweeter design The tweeter was chosen for 3 main reasons 1 Extremely low distorti
8. on 2 Totally freedom of accentuation of s sounds 3 The low range extension The 1 tweeter features a completely new design of the diaphragm dome called Dual Concentric Diaphragm The coated textile diaphragm looks like two rings one on the inner and one on the outer side of the voice coil hence the name Dual Concentric The quite eye catching centre plug has two purposes It is a wave guide and it clamps the diaphragm The purpose of clamping the middle of the dome is to eliminate out phasing of the treble at high frequencies At high frequencies only the cone area just around the voice coil is able to follow the voice coil whereas the middle of the dome typically breaks up and actually is in opposite phase resulting in zero or very limited output from the tweeter By clamping the middle of the dome and only using a ring of the cone area on each side of the voice coil the tweeter is able to reproduce frequencies up to 40kHz The magnet features a vented pole piece leading into a chamber at the backside The chamber and the ventilation hole in the pole piece are tuned in for achieving the very low resonance frequency at 600Hz normal resonance frequency for a tweeter is around 1 5k Hz Furthermore the pole piece is copper plated in the magnet gap in order to reduce eddy currents The Without copper plating purpose of this is to obtain linear impedance throughout the full frequency range and thus a
9. rial 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 Janno 4 Lets get personal D 450 D 450 is a 2 2 way dual bass reflex system featuring a 612 woofer a 6 2 mid woofer and a 1 DCD tweeter The 2 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 gi
10. s means that 85 of the power consumption is dedicated to the speaker and only 15 is dissipated as heat It is manufactured from SMD components The advantages are that signal paths are kept very short and that the electronics is much more resistant to the shocks and vibrations that arise inside a subwoofer The results are better sound and a prolonged lifetime for the subwoofer Auto On Off Forget all about the subwoofer once it is connected as this feature automatically sets the subwoofer in stand by after approximately 20 minutes without input signal The start up sensitivity is 3mV and it stays on as long as the signal is above 1mV Phase and Cut off controls Place the subwoofer where it is most convenient the controls ensure that the sound from the subwoofer can be adjusted to blend seamlessly with the sound from the rest of the speakers Jamo 11 Lets get personal 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 It consists of a shell moulded from foamed ABS plastic mounted on an MDF board with resonance damping foam in b
11. sonance 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 514 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 soeaker 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
12. t 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 4 dB when the cone moves back 2 3dBovershoot and forth The advantage is 4 more dynamic and precise sound reproduction Tweeter Woofer Without alu plug hot voice coil The aluminium centre plug also has a cooling With alu plug effect on the voice coil providing greater power cool voice coil handling capability and very important a stable sound reproduction when playing loud Freq x over point The mid woofers all feature lightweight 2 layer voice coils in order to achieve maximum attack the ability to start and stop precisely and minimum distortion these acoustic properties are of utmost importance for optimum voice reproduction In the designated woofer for the D 450 there is a small but significant difference It is supposed to work only at the lowest frequencies By using a heavy 4 layer voice coil we can reduce sensitivity at high and mid frequencies while gaining efficiency at low frequencies This works in 2 ways A high B L product will increase port output and reduce bandwidth around port resonance The increased weight will counteract the increased B L at higher frequencies The result is a gain of about 3 dB at low fr
13. too Janno 3 Lets get personal 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 Wall 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 Result with compensation D 400 is intended for crossover at 80 or 100 Hz again depending on the room Floor 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 2 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 6 2 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 mate
14. ves 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 Janno 5 Lets get personal
15. ype TV D 4SUB The D 4SUB is equipped with two very powerful 8 woofers in a closed cabinet The advantage of using two 8 woofers instead of one large is higher power handling capability as the heat is disposed of in two voice coils magnet systems and a more compact design making it a lot easier to find a suitable placing of the subwoofer The cone area of the two 8 woofers equals the size of an 11 woofer The class D amplifier delivers solid 400 watt continuous output more than enough to secure sufficient headroom even for a subwoofer reaching down to 22Hz 6 dB The stand by power consumption is lt 1 watt so unless you are not using the subwoofer for a longer period of time there is no need to disconnect it from the mains Just let the automatic on off circuitry do the daily job for you Thanks to the heavy MDF board cabinet the powerful amplifier and the specially developed woofers the D 4SUB delivers a deep precise and detailed reproduction of the low register perfectly matching the sound from the D 4 front speakers Jamo 6 Lets get personal 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 dB This filter compensates for the room influence at low frequencies as any room a
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