ongratulations on your fine judgement. In its class the DALI 15a is one of the very finest loudspeakers on the market. To get the maximum performance from DALI 15a we recommend that you read this manual before installing your new speakers. POSITIONING SIGNAL SOURCES CONNECTION PHASING DAILY USE DOCUMENTATION MEASUREMENTS SPECIFICATIONS IT | | O3 | SA | St | SIND Please note that DALI 15a is provided in mirror-imaged pairs. The right speaker has ALI 15a gives the best oblique bevelling on the left, and sound reproduction when the left speaker has oblique placed on a speaker stand at a bevelling on the right. height of 30 cm (12 in). They Dali 15a should be placed may be close to the back wall vertically. but should not be placed at a Corner location should be distance of less than 50 cm (20 avoided. in) from the side walls. Alternatively DALI 15a may be placed on the wall or on a bookcase. 50 cm / 20 in 30 - 60 ст / 12 - 24 т. >< he distance from ANGLING (TO А your normal listen- N ot normally neces- ing position to both sary except where speakers should be | the walls are highly equal. This distance sound absorbent. In this should also equal the case a slight angling distance between both may improve stereo speakers. В imaging. \ A Te recommend the use of Limited sound reproduction is the best speaker cables often caused by misadjustment and, especially, a very good and/or weak signal equipment. turntable or CD-player. E pu EEE CRECER E ONCE AR ARENA LA aa ja 3 AI he gold plated terminal on DALI 15a makes it possible to use banana plugs or heavy bared wires for amplifier connection. IMPORTANT! Turn off the amplifier when you are working at loudspeaker connection! o get true stereo-reproduc- tion it is necessary that the loudspeakers are phased correctly. Always connect the amplifier + to the loudspeaker +, and the amplifier — to the loudspeaker —. Ón most speaker cables one of the leads will have an indication making it easy to do this the right way. AMPLIFIER ‚+ — LOUDSPEAKERS = + he main point here is: enjoy the music! The only regular maintenance required is occas- sional cleaning of the surfaces. Dust with cloth. Brush with a clothes- brush or vacuum clean with a brush attachment. he Bass System The bass performance of DALI 15a is a result of much experimentation to determine the optimum balance between enclosure volume, lower cut-off frequency and ef- ficiency. As every speaker designer knows, these three pa- rameters are directly related and it is the correct balance of compromises that makes for a successful design. We wanted to keep the internal volume of DALI 15a at 29 lit- res, thus sacrificing something in terms of either efficien- cy or lower limit. A reference output of 115 dB at 1 metre stipulated a cut-off frequency of 38 Hz. This reference effi- ciency is directly comparable to DALI 7a. However, by virtue of its greater volume, DALI 7a plays 4 Hz lower in the bass. A short explanation of the physics concerning bass re- sponse is in order here. The bass capabilities of a speaker follow a quadratic function: That is for every octave of ext- ra bass performance, four times as much air must be mo- ved. To achieve good efficiency with a-3 dB point of 38 Hz requires a bass driver with special construction techniqu- es. It must have both a very large magnet sytem and a ve- ry long linear excursion limit. It is this design that we ha- ve implemented for DALI 15 a, along with a thick (1 mm) polypropylene cone and an enormous magnet assembly - equal to that used by DALI 7a. Due to its smaller size, however, efficiency is somewhat lower and to compensate for this we have changed the impedance to 6 Ohms. This has the effect of drawing more amplifier current, hence maintaining high efficiency (for the same volume control setting). The system is a pure 4th order Butterworth type, tuned in to provide flat response through the pass band. The Midrange and Treble System The midrange driver is the same 3” dome unit employed in DALI 7a. It is fabricated from a textile compound which is first impregnated then later surface-treated with a dam- ped compound. The driver is mounted in a large double chamber sub-enclosure, and the result is exceedingly neut- ral response from 600 Hz to 4000 Hz. With increasing frequency, dome drivers become prog- ressively smaller acoustically with the result that the centre stops oscillating entirely and eventually only the voice-coil assembly moves. Hence a transition must occur from piston action to breakup mode, and it is the quality of the surface treatment that dictates how smooth this will be. With correct application this can be accomplished extremely smoothly resulting in very flat frequency re- sponse. This critical process of coating the dome is ac- complished by hand, requiring great skill and precision. Since we make such stringent demands on this process, we are assured of receiving the best of the production. Ac- cordingly we must pay more, but the extra quality more than compensates for the additional outlay, 6 For frequencies 3000 Hz and upwards, a¥% metal dome unit is used. This driver has been designed with equal care and precision, The magnetic circult is built around a solid core and bottom plate, providing less magnetic loss and maximum flux density across the air gap. In addition it has the extra advantage of blending particulary well with the rest of the system. Linear Directivity Crossover Design Expressed simply, this concept involves smooth frequen- cy response measured both on axis and off axis at very wi- de angles. This very critical and largely overlooked perfor- mance parameter tells us much about the final »room in- terface«. The basic theory is that the frequency compositi- on of reflected sound should not be significantly different from what we can measure conventionally, that is at 1 metre on axis. We stipulate that the response measured at angles of up to -70 degrees should not be significantly different from that measured at 0 degree. Only if this area is optimised will real smothness and precise imaging be achieved. In practice, linear directivity is achieved by matching the crossover frequency directly to the driver's diameter and employing asymmetric 40 dB/Decade (12 dB/Octave) and 60 dB/Decade (18 dB/Octave) slopes. Only the finest com- ponents are used: heavy coils, metallised polypropylene capacitors and LC-OFC cable. The Enclosure No loudspeaker is better than its enclosure. This sounds simple, but cabinet design is as complex a science as any other area in loudspeaker construction. It has been proved empirically that control of enclosure resonances is crucial, especially those with a wide low Q nature. Therefore, we spare no effort to construct cabinets synthesising thick- ness of walls, bracing, materials and damping. The research into cabinet behaviour includes three di- mensional accelerometer measurements to closely moni- tor behaviour of resonances. In conjunction with many hours of listening tests, these techniques have given us the DALI 15a cabinet - one of the finest in production reg- ardless of price. The front baffle is fabricated from 50 mm high density fibre board, the back from 20 mm closely pressed hardboard and the sides of 22 mm premium grade chipboard. Veneer is used on both sides to control reso- nances further. The massive front baffle and the stagge- red thickness provide truly »boxless« quality to the sound. Dali 15a is a design based on research and understan- ding, not guesswork and chance. And each component has been chosen to »integrate« particulary well with the whole system, the result is truly outstanding, a speaker which must surely rank in the top of its class. Frequency response on axis and 70° off axis. Input impedance. Cabinet type. ................... .. .. B4 bassreflex Drivers Woofer .............. ..... 10”, super long stroke Midrange 1111111111 . ... 3”, dome Tweeter ........ ............... 3/4”, metal dome Crossover . . Linear Directivity. 1st. quality components Crossover frequency LL LL LL 1000 Hz, 3000 Hz Impedance. ......................... . .. 8 ohms Systemresonance ................... ...... 36 Hz Frequency response + 3dB ............ 38-25,000 Hz Listening window + 2dB hor. ......... .... | 140° Ver. .............. +9°,-7° Sensitivity (2.8V). ............ 89 dB/Im Recommended amplifier powerratings ................ .. 20 to 200 W/channel Dimensions Height ............ 54 cm (21 1/3”) Width. ........................_ 29.5 cm (11 2/3”) Depth ........... 31.5 em (12 1/2”) Net Weight ............. 15.5 kg Specifications are subject to change without notice in the course of product improvement.
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