Linear Spatial Reference Bi-Amplified Monitor
by Alex Artaud
The number of compact powered monitors on the market continues to swell. JBLs LSR25P Linear Spatial Reference Bi-amplified Monitor joins a crowded field, vying for the ears of engineers working in post-production, surround sound and multimedia facilities. With their futuristic, silver-coated appearance, the LSR25Ps ($958/ pair) proved to be a surprising bantam terror sporting plenty of
Unveiled in 1998, the LSR Series is a much-lauded development from JBL. In particular, the clarity of imaging and transparency from its TEC Award-winning LSR28P monitors have drawn praise from mixing engineers. While the LSR25P is substantially smaller, its design remains consistent with the series, and it upholds the enviable LSR reputation.
The LSR25P is a front-ported design featuring a 5.25-inch woofer and a 1-inch tweeter, powered by onboard 100-watt and 50-watt amps for a max peak of 110 dB. Covered by a black grille, the woofer incorporates JBLs Symmetrical Field Geometry (SFG) technology, designed to offer excellent distortion performance at high SPLs. The tweeter is a titanium/ composite diaphragm encircled by an indented Elliptical Oblate Spheroidal (EOS) Waveguide, offering 100°x60° dispersion. The Waveguide includes a thin, protective vertical bar over the tweeter. Both components are shielded for use near video monitors. A power switch and volume control are located on either side of the woofer. An LED shines green when powered up and flashes red if either amp clips.
The LSR25P cabinet is tapered front to back, with the amps heat sink forming the back panel. Dimensions are 6.8x10.6x9.5 inches, and each cabinet weighs in at a substantial 17 pounds. Rear inputs include RCA (-10 dB) and XLR (+4 dB) connectors and an IEC AC socket. All connectors mount vertically; an odd choice given that the XLR jack is a nonlocking type. Rear-mount DIP switches provide tweaking options: an 80Hz highpass filter, boundary compensation for bass and low-mid frequencies and a gentle ±1.5dB cut/boost above 2.2 kHz. The DIP switches are recessed about 2 inches into the back of the monitor, so system adjustments require a flashlight and a thin screwdriver or probe. Two rear points are provided for attaching an Omnimount 75-Series wall bracket.
For my listening tests, I took down my Meyer HD-1s and put up the LSR25Ps, spaced about four feet apart, roughly four feet from the listening position, with the drivers at ear level. First, I listened to mixes I liked and knew wellprimarily very dynamic musique concrète selections with piercing highs and pit-of-the-stomach lows. The sources typically combine heavily processed orchestral instruments with various electronic sounds. The LSR25Ps were impressive, with a clear, balanced image across the frequency range, even at high SPLs.
For acoustic instrumentation, I listened to cuts from Gonzalo Rubalcabas amazing Inner Voyage. The LSR25Ps presented a good balance between piano, upright bass and drums. While I missed some of the hiss of the brush and the loping quality of the bass, the articulation was clear.
I did extensive A/B tests with both Meyer HD-1s and the LSR25Ps larger cousins, the LSR28Psperhaps not an entirely fair comparison, but quite revealing. I was struck by how well mixes I had done on the LSR25Ps translated to the HD-1s. With the exception of a slight dip around the crossover, the LSR25Ps sounded smooth with an impressive depth, considering the monitors size and bulletproof, cast-aluminum housing. After trying various DIP switch settings (including the boundary compensation, which I didnt like), I felt the speakers sounded best in the default positions.
Readers used to Genelec 1029s might feel that the LSR25Ps share their balanced characteristics and transient response, if not the crispness and high-end detail. But I found the LSR25Ps to be a bit warmer and never experienced fatigue from extended use.
In summary, the LSR25Ps are very impressive. While probably best suited for work not requiring clear, low-end definition, they can be easily augmented with the optional LSR12P subwoofer ($1,223). The LSR25Ps are well-suited for post-production facilities, and the consistent, pleasing image of a single speaker configuration recommends them for use in small surround mixing environments. The LSR25Ps small size and shielding makes it an ideal choice as a multimedia/Internet audio monitor.
Alex Artaud is a musician and independent engineer living in Oakland, Calif. He can be contacted at firstname.lastname@example.org.
Reprinted with permission from Magazine, October, 2000
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