Audio Database

4345

JBL 4345
850,000yen(one-set, around the 1981 time)

Description
 
The large-sized speaker system of the professional series which adopted the newly developed 46cm Woofer.

46cm cone type Woofer 2245H developed by uniting examples of traditional craftsmanship and a state-of-the-art technology is carried in low-pass.
It improves property sides, such as efficiency, a linearity, a low distortion, and it not only says that cone paper only expanded this Woofer compared with the conventional 38cm cone type Woofer, but enables the outstanding low-pass play.
The material selected carefully is used for a cone part, and in order to make a mass and rigidity the optimal, the dumping agent (Langsa positive) original with JBL is applied to a back side.
Moreover, the SFG structure of JBL original is adopted as a magnetic circuit, the magnetic field in a voice coil gap is made symmetrical, and the second higher-harmonic distortion is conjointly reduced with the flux stabilizing ring wound around pole piece.
Furthermore, the large diameter of 100mm of a piston action area and a thing 25mm in length are adopted, the amount of linear peek displacement amounts to 20mm, and the voice coil lessens the comression of the output at the time of high power with the enhancement of heat sink capacity.

2122H of a 25cm cone type Woofer is carried in inside low-pass.
The new cone paper which decreased the distortion besides a cross over frequency is adopted, and the copper ribbon voice coil of the diameter of 75mm, the SFG magnetic circuit, etc. are carried.
The closed mold back cavity was prepared in these 2122H, and the interference from other units is prevented.

The driver 2420 and the horn lens 2307+2308 are carried in the mid-high range.
Moreover, 2405 was carried in the high region which reproduces 10kHz or more, new technology was carried in the ring diaphragm of the ultra-thin manipulation, and top endless bitter orange juice is improved.

The network part is developed based on the new high separation network design of JBL, makes relation of sound smooth by adding a small capacity capacitor to the mass capacitor selected carefully, and is raising the transparent feeling.
Moreover, a two-channel multi-amplifier drive (channel dividers 5234 using) is carried out at 290Hz, and also the drive by a built-in network is possible.

The enclosure is carrying out the design which uses the hard particle board of 21mm thickness, and also prevents an unnecessary oscillation of a stationary wave etc. by considering internal reinforcing materials as an asymmetrical placement.

Using

Rating of a mode
Scheme 4 ways, 4 loudspeaker bass-reflex scheme, and a floor type
Unit For low-pass: 46cm cone type (2245H)
For inside low-pass: 25cm cone type (2122H)
For mid-high ranges: Horn type (2420+2307+2308)
For high regions: Ring type (2405)
Frequency characteristic 32Hz-20kHz±3dB
Directivity (horizontal x vertical) 60 degrees x 30 degrees (-3dB, 16kHz)
Output sound pressure level 95dB/W/m
Impedance 8ohms
Allowable input 120W (at the time of a network)
200W (multi-amplifier Lo)
100W (multi-amplifier Hi)
Cross over frequency 320Hz, 1.3kHz, 10kHz (at the time of a network)
290Hz, 18dB / oct (at the time of multi-amplifier)
Enclosure dimension 253L (Woofer)
14L (mid Woofer)
Dimensions Width 765x height 1096x depth of 470mm
Weight 112kg (at the time of an original packaging)