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JBL 4345 Speakers - $1000



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Location: chicago, il
Date Posted: 12/09/2009
These units will produce continuous sound pressure levels exceeding 120 db. Use them with caution, as hearing damage could result from sustained listening at very high levels. The model 4345 speakers are rated at 200 watts continuous program power (400 watts below 290 Hz). The charted frequency response is 32 Hz to 20 kHz within 5 db of mean value, at full rated power. Distortion is rated at less than 1% below 800 Hz and less than 2% above 800 Hz, at 105 db SPL (sound pressure level)

These are large units, weighing almost 230 lbs. (104 kg) each, and measuring approximately 44 (112 cm) H by 30 (76.2 cm) W by 18.5 (47 cm) W. The actual cabinet internal volume is approximately 9 cubic feet (250 liters).

The units employ a JBL 2245H 18 (460 mm) low frequency driver, which uses a 4 (100 mm) edge-wound copper ribbon voice coil. The magnetic assembly consists of a 20 lb (9.1 kg) magnet rated at 12,200 gauss. This unit also employs a special ultra-compliant surround which permits large cone excursions while at the same time damping instabilities. The cone material is designed to significantly reduce distortion effects caused by standing waves in the cone surface. The 2245H operates only at frequencies below 290 Hz, and the built-in dividing network (cross-over) is capable of being split so the low frequencies can be supplied by a separate amplifier (bi-amped), or everything can be run from one source.

The mid range driver is a model 2212H unit, featuring a 10 (250 mm) diameter cone unit, which uses a 3 (75 mm) diameter edge-wound voice coil operating in a 12,200 gauss field generated by a 10.25 lb (4.7 kg) magnetic assembly. This driver is mounted in an acoustically isolated sub-chamber of 0.5 cu ft (14 liters) volume. The sub-chamber effectively prevents interaction between this driver and the low frequency unit. The mid-range driver operates from 290 Hz to 1300 Hz.

The high frequency driver is a model 2421B compression driver with a 1 3 4 (44 mm) diameter voice coil and 15,000 gauss magnetic assembly weighing 3 1 4 lbs (1.5 kg) . This unit has an edge wound aluminum voice coil assembly coupled to a pneumatically formed aluminum alloy diaphragm only .002 (0.05 mm) thick. The small moving mass in a very intense magnetic field generates very high acoustic levels with superb transient definition. The high frequency driver operates between 1300 Hz and 10 kHz, and uses a combination of a model 2307 2308 horn-lens assembly for proper acoustic loading and wide angular dispersion.

The ultra-high frequency driver is a model 2405 slot-radiator with a 1 3 4 voice coil suspended in a 16,500 gauss field, which is generated by a 3 1 4 lb (1.5 kg) magnetic assembly. The drivers ring-shaped diaphragm is coupled to a slot-radiator giving almost 90 degrees of horizontal dispersion. The ultra-high frequency driver operates at frequencies above 10 KHz, and ranges up to approximately 22 Khz.

The cabinet is constructed of a combination of 3 4 (19mm) and 1 (25mm) panels plus a 15-ply front panel. The outer surfaces of the sides and top are finished in oiled walnut veneer. (Note - the walnut finish is in need of a light buffing and a re-oiling, a relatively simple task. Refinishing is standard procedure, and should be done every 3 to 5 years, as necessary). You could do this yourself, or a local cabinet shop will be able to help you.

These units will produce distortion free sound from a minimum of 25 Hz to an upper limit of at least 22 KHz, and do it with ease, clarity, and definition that very few, if any, speaker systems can ever hope to even approach. The ability to reproduce incredible amounts of acoustic power at all frequencies while at the same time keeping distortion below 2% (less than 1% for the low frequency notes) must be heard to be believed. The low frequency sound can actually be too low to hear properly, but is instead manifested as an earth-quake like rumbling that shakes your walls and furniture (and you), and is perceived as a sort of whole-body experience. Seeing the low-frequency driver moving almost an inch (25 mm) back and forth at 25 Hz while your whole body experiences a sort of sonic meltdown is a truly unforgettable experience.

Additional Information:
keywords: JBL 4345 Speakers

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