JBL 12MB3P Rev.00 06 Ing Spec Sheet
User Manual: JBL JBL - Manuals+
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MIDBASS 12MB3P 12" for midbass professional sound reinforcement. Offering high power capacity, outstanding mid range response and exceptional long-term performance, this transducer is ideal for compact enclosures (closed, vented or horns). This transducer exhibits excellent acoustics with work horse construction. Designed for smaller enclosures, the 12MB3P is a versatile high performance midbass. General construction includes a sturdy cast frame, impregnated cloth surround, stable spider and a large central vent channel for reducing long-term heat build-up. SPECIFICATIONS Nominal diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 305 (12) Nominal impedance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Minimum impedance @ 306 Hz. . . . . . . . . . . . . . . . . . . . . . . 6.4 Power handling Musical program¹ . . . . . . . . . . . . . . . . . . . . . . . . . . . 1000 AES² . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 00 Sensitivity (2.83V@1m) averaged from 200 to 2,000 Hz . . 101 Power compression @ 0 dB (nom. power) . . . . . . . . . . . . . . 2.6 Power compression @ -3 dB (nom. power)/2. . . . . . . . . . . . 1.6 Power compression @ -10 dB (nom. power)/10. . . . . . . . . . 0.8 Frequency response @ -10 dB . . . . . . . . . . . . . . . . 90 to 4,000 mm (in) Ω Ω W W dB SPL dB dB dB Hz 1 Power handling specifications refer to normal speech and/or music program material, reproduced by an amplifier producing no more than 5% distortion. Power is calculated as true RMS voltage squared divided by the nominal impedance of the loudspeaker. 2 AES Standard (200 - 2,000 Hz). % m² (in² ) cm³ cm3 (in³) (in3) mm (in) mm (in) Atmospheric conditions at TS parameter measurements: Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 (73) Atmospheric pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,016 Humidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 °C (°F) mb % Hz l (ft³) Thiele-Small parameters are measured after a 2-hour power test using half AES power . A variation of ± 15% is allowed. NON-LINEAR PARAMETERS Le @ Fs (voice coil inductance @ Fs) . . . . . . . . . . . . . . . . . 1.666 Le @ 1 kHz (voice coil inductance @ 1 kHz). . . . . . . . . . . . 0.475 Le @ 20 kHz (voice coil inductance @ 20 kHz). . . . . . . . . . 0.123 Red @ Fs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.36 Red @ 1 kHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.18 Red @ 20 kHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.85 Krm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Kxm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24.3 Erm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.64 Exm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.55 Tm T mm (in) m (ft) 1/°C °C (°F) °C/W(°F/W) mm (in) mm (in) Ω g (lb) µm/N kg/s Packing dimensions (W x D x H). . 35,5 x 34,5 x 16 (13.9 x 13,6 x 6,3) cm (in) MOUNTING INFORMATION Number of bolt-holes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Bolt-hole diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 .0 (0.28) mm (in) Bolt-circle diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 (11.57) mm (in) Baffle cutout diameter (front mount).. . . . . . . . . . . . . 281 (11.06) mm (in) Baffle cutout diameter (rear mount). . . . . . . . . . . . . . 275 (10.83) mm (in) Connectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Silver-plated push terminals Polarity . . . . . . . . . . . . . . . . . . . . . . . . . . Positive voltage applied to the positive terminal (red) gives forward cone motion Minimum clearance between the back of the magnetic assembly and the enclosure wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 (3) mm (in) ø 312 mH mH mH Ω Ω Ω mΩ mH 118 8x ø 7 ø 279 ADDITIONAL PARAMETERS βL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.7 Flux density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.02 Voice coil diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 (4) Voice coil winding length. . . . . . . . . . . . . . . . . . . . . . 18.0 (50.0) Wire temperature coefficient of resistance (α25). . . . . 0.00410 Maximum voice coil operation temperature. . . . . . . . 304 (582) θvc (max.voice coil operation temp./max.power) . . . 0.6 (1.14) Hvc (voice coil winding depth) . . . . . . . . . . . . . . . . . 13.5 (0.53) Hag (air gap height). . . . . . . . . . . . . . . . . . . . . . . . . . . 8,0 (0.31) Re . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 .3 Mms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52.0 (0.1146) Cms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 30 Rms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 ADDITIONAL INFORMATION Magnet material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Barium ferrite Magnet weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,640 (92) g (oz) Magnet diameter x depth. . . . . . . . . . . . . . 200 x 24 (7.87 x 0.95) mm (in) Magnetic assembly weight . . . . . . . . . . . . . . . . . . . 6,600 (14.55) g (lb) Frame material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aluminum Frame finish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Black epoxy Voice coil material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aluminum Voice coil former material. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kapton Cone material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Long fiber pulp Volume displaced by woofer . . . . . . . . . . . . . . . . . . . . 4.6 (0.162) l (ft3) Net weight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7,450 (16.42) g (lb) Gross weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8,200 (18.07) g (lb) ø 294 ø 208 THIELE-SMALL PARAMETERS Fs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Vas. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 (1.80) Qts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.48 Qes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.50 Qms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.55 ηo (half space) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.28 Sd. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.0530 (82.2) (8.90) Vd (Sd x Xmax) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .145.7 66.3 (4.05) Xmax (max. excursion (peak) with 10% distortion) . . . 2.75 (1.1) Xlim (max.excursion (peak) before physical damage). 10.0 (0.4) 46 61 11 Dimensions in mm. MIDBASS 12MB3P POLAR RESPONSE CURVES RESPONSE CURVES (0° AND 45°) IN A TEST ENCLOSURE INSIDE AN ANECHOIC CHAMBER, 1 W / 1m 50 Hz 110 30° 100 Hz 330° -10 60° 100 0 -6 300° -20 dB 90° 30° 0 -6 -10 60° 30° 0 -6 330° -10 60° 300° -20 dB 270° 90° 250 Hz 330° 300° -20 dB 270° 90° 270° 90 240° dB 120° 150° 180° 240° 120° 210° 150° 330° 30° 180° 240° 120° 210° 150° 330° 30° 180° 210° 80 500 Hz 30° 70 200 Response Curve at 0°. Response Curve at 45°. Hz 2k 300° -20 dB 90° 20 800 Hz -10 60° 60 0 -6 0 -6 1,25 kHz -10 60° -20 dB 270° 90° 330° -10 60° 300° 0 -6 300° -20 dB 270° 90° 270° 20k 240° 120° 150° IMPEDANCE AND PHASE CURVES MEASURED IN FREE-AIR 180° 210° 240° 120° 150° 180° 240° 120° 210° 150° 180° 210° 2 kHz 200 90 30° 0 100 300° -20 dB 90° degrees ohms 45 330° -10 60° 150 0 -6 270° 240° 120° 150° 180° 210° Polar Response Curve. 50 -45 0 -90 20 200 Hz 2k 20k Impedance Curve. Phase Curve. HARMONIC DISTORTION CURVES MEASURED AT 10% AES INPUT POWER, 1 m 140 HOW TO CHOOSE THE RIGHT AMPLIFIER The power amplifier must be able to supply twice the RMS driver power. This 3 dB headroom is necessary to handle the peaks that are common to musical programs. When the amplifier clips those peaks, high distortion arises and this may damage the transducer due to excessive heat. The use of compressors is a good practice to reduce music dynamics to safe levels. FINDING VOICE COIL TEMPERATURE It is very important to avoid maximum voice coil temperature. Since moving coil resistance (RE) varies with temperature according to a well known law, we can calculate the temperature inside the voice coil by measuring the voice coil DC resistance: R 1 TB = TA + B − 1 TA − 25 + α 25 RA 120 dB TA , TB= voice coil temperatures in °C. RA , RB= voice coil resistances at temperatures TA and TB, respectively. α25= voice coil wire temperature coefficient at 25 °C. 100 POWER COMPRESSION Voice coil resistance rises with temperature, which leads to efficiency reduction. Therefore, if after doubling the applied electric power to the driver we get a 2 dB rise in SPL instead of the expected 3 dB, we can say that power compression equals 1 dB. An efficient cooling system to dissipate voice coil heat is very important to reduce power compression. 80 60 20 200 Response Curve. Distortion Curve, 2nd harmonic. Distortion Curve, 3rd harmonic. Hz 20k NON-LINEAR VOICE COIL PARAMETERS Due to its close coupling with the magnetic assembly, the voice coil in electrodynamic loudspeakers is a very non-linear circuit. Using the nonlinear modeling parameters Krm, Kxm, Erm and Exm from an empirical model, we can calculate voice coil impedance with good accuracy. SUGGESTED PROJECTS HB1206A1 HB1205A3 HB1205D1 PAS1MA1 PAS2MA1 PAS3MA1 PAS3MA2 PAS4MA1 PAS5MA1 For additional project suggestions, please access our website. TEST ENCLOSURE 24-liter volume, sealed box. Specifications subject to change without prior notice. Code: NA Rev.: 00 - 06 / 06 www.seleniumloudspeakers.com
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