JBL K2 M9500 - AllegroSound

1 M9500 MONITOR LOUDSPEAKERSOWNERS MANUALM9500 Version 9/14/95 7/27/98 2:58 PM Page 1 GENERAL SYSTEM DESCRIPTIONThe JBL M9500 monitor loudspeaker system represents arefinement of the principles that have guided JBL s high-levelmonitor system design over the last thirty keeping with contemporary monitoring practice, the systemis essentially of two-way design. A horn-compression driversection covers the frequency range from 650Hz above and below the high-frequency section are mirror-imaged low-frequency transducers in ported stereo pair of loudspeakers exhibits both vertical and horizontal symmetry for effective point source radiation andfor accurate stereophonic imaging.

2 All transducers make use ofshielded neodymium magnets, and the systems can be used inproximity to video monitors with no M9500 system uses stand-alone dividing networks thatfacilitate various electronic options, including bi-wiring, tri-wiring, and biamplification. The networks are designed aroundthe finest components available and make use of dc bias onthe capacitors for greater single M9500 system is capable of producing sine wave out-put levels of 110 dB Lp at one meter with extremely low distortion. In terms of wide band program, this translates intolevels of 120 dB Lp for the stereo pair at normal listening distances of 2 and 3 enclosures are made of thick sections of medium-density fiberboard, liberally braced, and have an attractive,scuff-resistant and InspectionThe complete M9500 system is shipped in eight containers, asdetailed below.

3 2 Lower low-frequency enclosures2 High-frequency/horn enclosures2 Upper low-frequency enclosures1 Dividing networks (2 networks in one package, including 6 hook-up cables and 4 9-volt batteries)1 Low-frequency grilles (4 in one package) Make sure that you have all containers. Unpack them carefullyand inform your JBL dealer of any sign of damage. It is recommended that you save the packaging for future use. Version 9/14/95 7/27/98 2:58 PM Page 2 System SetupThe M9500 systems are modular, each consisting of a stack ofthree separate enclosures. The larger of the bass enclosuresare placed at the bottom, and the high-frequency/horn modulesstack on top and are aligned by the screws that protrude onthe bass section.

4 The smaller bass modules are placed on topof the high-frequency modules and are similarly recommend that you do not assemble the M9500 systemsuntil you have determined their best location in your listeningroom or control room. In general, the listening angle for beststereo imaging should be in the range from 45 to 60 degreesand the loudspeakers should be placed no closer than about 25or 30 cm (10" or 12") from the wall behind them. Sidewallsshould be somewhat farther away, and the loudspeakersshould be toed inward toward the primary listening room itself should be quiet, well-damped, and free of obvious flutter echoes or standing the loudspeakers to the networks using the cablesprovided.

5 Note that there are different cables for high-frequency and low-frequency hookup; they cannot be intermixed. For positive contact, insert the Speakon connectors and turn them one-eighth turn clockwise. Electronic OptionsYour next concern is the amplifier/ loudspeaker operating various hookup options are shown in Figure 1. We willdescribe each of these options:Option A, single full-range mode of operationrequires a relatively large, high-quality amplifier capable ofdelivering up to 800 watts per channel into 4-ohms. Note thatall sections of the network are connected in parallel with thestraps B, this mode, identical power amplifiersections are fed full-range program; one amplifier is connectedto the high-frequency portion of the system, and the other isfed to the low frequency sections in parallel.

6 Many users willuse a large stereo amplifier to drive the low- frequency sections and a smaller one for the high-frequency sure that the stereo amplifier used for the paralleled low-frequency sections can deliver the necessary power into 4 C, mode of operation is similar to B,but with each low-frequency section driven by its own amplifier. In this case, each low-frequency amplifier section willlook into 8 + To M9500 IBHFHFLF1LF2R0 BRBRI nputBiampNormB+ To M9500 CHFHFLF1LF2R0 BRBRI nputBiampNormB+ To M9500 Figure hookupoptions; views of the rearpanel of the dividingnetwork.

7 A, single full-rangeamplification; B, bi-wiringwith two amplifiers; C, tri-wiring with three amplifiers;and D, biamplification withexternal electronic dividingnetwork and separate high-and 9/14/95 7/27/98 2:58 PM Page 3 Option D, mode of operation requires adedicated electronic dividing network crossing over at 650 recommend the JBL DX-1 with internal compensationmade for the M9500 system. If this mode is used, make surethat the screwdriver adjustment on the back of each networkis set in the biamp trim switches on theback of the networks provide three set-tings (zero, plus, and minus) so that the systems can betrimmed for the acoustical characteristics of the of the operating mode you choose, we recommendthat only the finest hookup wire be used between the ampli-fiers and dividing networks.

8 We recommend that the wire sizebe no smaller than square millimeter cross-section (#12 AWG). The inputs to the networks can accommodate spadelugs, pins, bare wire, or individual banana internal 9-volt battery that is used to bias the capacitorswill normally last at least 5 years. You may test it by pressingthe gold logo on the front of the network. If the LED on thefront of the network illuminates, the battery is functional andneed not be TransducersLF1LF2 RBRI nputBTo M950 DHFHFLF1LF2R0 BRBRI nputBiampNormB+ To M9500HF outLF outElectronic dividingnetwork(650 Hz crossover) Silver plated pole pieceFront coverDiecast aluminum housingSerpentine phone plugAquaplas-dustedtitanium diaphragmFoam acoustic padTop plateNeodymium magnetReturn circuitScreenThroatThreaded mounting holes Aluminum shorted turnCopper shorted turnCooling vent (1 of 3)

9 Neodymium magnetReturn circuitEdgewood aluminum ribbon voice coilCentering spiderDiecast frame/ magnet chassisFiberglas/Aquaplas composite coneFoam complianceFigure view ofJBL 475Nd high-frequencycompression driver. Notethe curved (equalized) pathsfrom the diaphragm to thedriver's view ofJBL 1400Nd low-frequencytransducer. Note bothaluminum and coppershorting 9/14/95 7/27/98 2:58 PM Page 4 The JBL model 475Nd compression driver used in the M9500has a smooth titanium dome 101 millimeters in diameter thathas been lightly coated with Aquaplas damping aluminum ribbon voice coil operates in a magnetic flux fieldof tesla (16,500 gauss).

10 Mid-band efficiency is 20%, whileat the peak value of driver impedance it is in excess of 50%.The driver uses JBL s Coherent Wave phasing plug, whichprovides equalized path lengths from all sections of thediaphragm to the driver's output. The driver is mounted on theH9500 horn, a design used only in this system that providessmooth loading down to 500 Hz and exhibits consistent horizontal dispersion over its operating are two JBL model 1400Nd low-frequency transducersin each loudspeaker system. A single 1400Nd is capable of handling instantaneous input signals of 600 watts, corresponding to a midband peak output of 118 dB Lp at a distance of one meter.