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FIG. 1: A wealth of DIP switches on the LSR28P’s rear panel allows you to adjust a number of parameters, ranging from tailoring the speaker’s frequency response to trimming and attenuating input (click image for larger view). |
The monitor draws its juice from a standard IEC Type II power cable, and a generous 9 1/2-foot cable comes standard. Power is switchable between 115 and 230 VAC from a switch on the back of the unit. The power amp operates at either 50 or 60 Hz. A 5-amp line fuse is employed on units shipped Stateside, whereas units shipped out of the country get a 2.5-amp fuse. If you plan on taking these speakers with you outside the United States (as if hauling them to your studio isn’t enough of a workout), make sure you have the right fuses packed.
The LSR28P features Neutrik dual 1/4-inch and XLR input jacks (see Fig. 1 for a view of the back panel). The 1/4-inch jack is balanced but accepts unbalanced plugs. Input can be attenuated with the DIP switches by 4, 8, or 12 dB (–12 dB is achieved by turning on the –4 and –8 dB switches simultaneously). An input trim control, adjustable from 0 to –12 dB, is also provided. The trim is activated by its own discrete DIP switch and can be used in conjunction with the preset attenuation switches for fine level control.
Three low-frequency and two high-frequency DIP switches allow you to tune the speakers; these are great for adjusting the monitors’ output to match the acoustics of the room. Bass can be cut or boosted by 2 dB below 150 Hz. The default low-frequency roll-off is set to a 36 dB octave slope, but it is switchable to a 24 dB octave slope for extended low end. This is excellent for monitoring subharmonic bass—you may not hear these frequencies, but you can see the woofers working. Highs can be cut or boosted by 2 dB above 1.8 kHz.
Cool Speakers
A 1-inch titanium-composite diaphragm tweeter handles the high frequencies. This design is said to improve transient response and reduce distortion, especially at low volumes. The waveguide surrounding the tweeter is an elliptical oblate spheroidal type with a reported 100 5 60–degree dispersion rating, a targeted listening area of ±30 degrees horizontally and ±15 degrees vertically—a very respectable sweet spot.
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JBL |
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Audio
Quality
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PROS:
Incredibly flat. Handy frequency and volume sensitivity controls.
Excellent optional extended bass response. Very cool looking. |
Though neither the woofer nor the tweeter is shielded, the monitors emit incredibly low magnetic radiation. When I first got the LSR28Ps, I assumed they were shielded and I planted them on either side of my computer monitor, about two feet away from the screen. Amazingly, there were no ill effects. According to JBL, the speaker directs its focused magnetic energy inward toward the drivers, resulting in very little magnetic leakage. Well-built computer monitors with internal self-shielding can likely sit close to the LSR28Ps; inexpensive screens with no internal self-shielding probably won’t fare so well.
A dual-flared bass port that JBL calls a Linear Dynamics Aperture (imagine a tube with outward sloping edges on both sides) is located on the cabinet’s rear. The oval-shaped port is quite large, measuring about 5 1/2 inches wide by 3 1/2 inches tall—big enough to put your whole forearm into and grab the tweeter’s magnet, if you feel so inclined. The port’s architecture is supposed to eliminate air turbulence at high volumes, an affliction suffered by smaller, more traditional bass ports.
Reprinted with permission from
Magazine, December, 2000© 2000, Intertec Publishing, A Primedia Company All Rights Reserved
