The Ultimate Studio Loudspeaker Original JBL Model 4350 Studio Monitor.
The JBL 4350 is a four-way system designed for bi-amplification. It achieves smooth reproduction within 3 db from 30Hz to 20 kHz with controlled high frequency dispersion and exceptional transient performance. These Studio monitors are capable of wide dynamic range with low distortion and of the high acoustic output required for precise reproduction of the original sounds.
The two low frequency loudspeakers are driven independently of the other components in the system. This allows the utilization of two moderately powered amplifiers rather than a single large model lessen the possibility of distortion, even at high volume levels.
Low Frequency Loudspeakers
Two 15 inch (380 mm) low frequency loudspeakers are mounted in in a ported enclosure that provide accurate reproduction and high power handling capacity at very low frequencies. Each loudspeaker is driven by a 4 inch (100 mm) diameter voice coil, fabricated of edge-wound copper ribbon wire and an 18 5/8 lb (8.5 kg) magnetic assembly with a flux density of 12,000 gauss (1.2 T).
Music fundamentals lying in the region between 250 Hz and 1.1 kHz are reproduced by a 12 inch (300mm) loudspeaker housed in a sealed sub-chamber and driven by a 4 inch (100 mm) edge-wound copper ribbon voice coil. The driver achieves high acoustic efficiency and effortless reproduction even at extreme volume levels.
High Frequency Compression Driver
Reproduction from 1.1 to 9 kHz is accomplished by a massive compression driver energized by a magnetic assembly weighing 23.75 lb (11 kg). Its 4 inch (100 mm) edge-wound aluminum ribbon voice coil suspended in a magnetic field of 18.000 Gauss (1.8 T) drives a diaphragm pneumatically drawn to shape 0.003 inch (0.08 mm) aluminum alloy.
High frequency output is distributed by an exponential horn combined with a slant plate acoustic lens. The 11 plates of the lens is set an angle of 38 degrees and operates in a manner analogous to a divergent optical lens. The lens provides controlled propagation of high frequency acoustic energy.
Ultra-High Frequency Transducer
The highest octave of the audio spectrum is reproduced by a compression driver specifically designed for ultra-high frequency reproduction and dispersion. Its 3.25 lb (1.5 kg) magnetic assembly develops a flux density of 16,500 Gauss (1.65 T) and drives a 1.75 inch (45 mm) edge-wound aluminum ribbon voice coil. The driver utilizes a ring diaphragm pneumatically formed of 0.0022 inches (0.06 mm) in anodized aluminum foil stock. Output is directed through a diffraction horn providing 90 degree dispersion in the plane perpendicular to the diffraction slot while restricting dispersion in the vertical plane to approximately 40 degree. The maintains smooth response within 3db to 20 kHz.
Frequency Dividing Network
The low frequency loudspeaker operates to 250 Hz and require an attenuation rate of 12 db per octave below and above the crossover frequency. Transition may be accomplished with Electronic Frequency Dividing Network or with several electronic crossovers or filtering devices commercially available.
Components of the 4350 are housed in a rigid enclosure incorporating two acoustic chambers. The two low frequency loudspeaker are housed in a bass reflex chamber which has an internal volume of 9.5 ft (265 liters). Proper loading to 25 Hz is accomplished by a distributed port consisting of 6 openings. The mid-range loudspeaker is mounted in a second sealed sub chamber.
Maximum power Input
Below 250 Hz 200 watts continuous sine wave at 4 ohm
Above 250 Hz 100 watts continuous sine wave at 8 ohm
Below 250 Hz 4 ohm
Above 250 Hz 8 ohm
Power output 110 db SPL pink noise measured
at 10 ft (3 m) in a room volume of
2000 ft (57 m) with ½ rated power
input (-3 db)
126 db SPL approximate program
peak output measured a 10 ft (3 m)
with ½ rated power input (average)
Sine wave, on-axis 30 Hz – 20 kHz, -3 db
1/3 – octave band -3 db at 31.5 Hz, +2 db at 1 kHz
(500Hz reference) +2 db at 16.5 kHz
Polar Response No less than -3 db at 60 degree horizontal
and 30 degree vertical to 12 kHz
½ power, 108 db SPL 1% or less third harmonic from
10 ft (3 m) 35 Hz to 1.2 kHz
single frequency 3% or less third harmonic from
1.2 to 5 kHz
1/10 power, 101 db SPL 0.6% or less third harmonic
10 ft (3 m) generation from 1.2 to 5 kHz
Low 250 Hz electronic, 12db/octave
Mid 1.1 kHz
High 9 kHz
Finish Re-veneered oiled walnut
Grille 4 black fabric 2 damaged but will fit see pictures
Low Frequency 9.5 x 9.5 ft (265 litres)
High frequency 1.6 x 1.6 x 1.6 ft (45 litres)
Net Weight 260 lb (118 kg)
Shipping Weight 303 lb (138 kg)
Power output measured with B&K Impulse Precision Sound Level Meter.
Unlike many theater type loudspeaker systems that exhibit sensitivity peaks
in the mid-range the 4350 provides substantially the same sensitivity from the
full range of frequencies. Measured sensitivity below 500 Hz or above 2 kHz
may be considered greater than that of other systems claim higher sensitivity
Caution Sound pressure levels produced by the 4350 may cause permanent
hearing loss. The suggested maximum exposure is 115 dBa for no more than