Hands-On Review:JBL's LSR Monitors


Review: JBL's LSR Monitors


Part 1: The Holy Grail of Speaker Design, JBL's LSR Philosophy, The LSR Line


JBL's LSR-Linear Spatial Reference Studio Monitor System LSR28P and LSR25P near-field monitors
Designers and manufacturers of monitor loudspeakers pursue a Holy Grail all their own: the accurate acoustical representation of the electrical audio signals sent to their speakers. An ideally designed speaker gives voice to an audio signal with no added coloration whatsoever - no EQ bump, no added warmth or brightness. Any coloration or "character" that belongs in a recording should be in the mix long before signal gets to the speakers. The current trend in powered near-field monitor speakers furthers this quest.


By careful design and match of the speaker's internal power amplifier to the driver units, the designer of a powered monitor can effectively "divorce" or remove an external power amp's influence over the drivers' performance and, therefore, the monitor's final sound. This "systems" approach to accurate monitoring and listening started with studio control-room design in the late 1970's, where designers controlled the room's shape, construction materials and placement of the soffit-mounted monitors. In these studio designs, the entire room and speakers are designed to work together as a total system to achieve an accurate sound at a certain focus point. For the most part, engineers were looking for good on-axis frequency response in these rooms...the mixing "sweet spot." With the loudspeakers available in those days, they were lucky to get that! Now, with the wider use of near-field monitors turning any existing room into an instant monitoring work space, the loudspeaker designer must go beyond on-axis performance and insure that the monitor performs well over a wide listening area in most acoustic spaces.


The LSR Philosophy
Linear Spatial Reference, or LSR, is JBL's tag for their measurement and design philosophy. LSR considers many other factors besides on-axis performance. Quoting the JBL LSR manual: "...this includes the direct sound field, the reflected sound field and the reverberant sound field." These are important factors to producers and engineers who make all major mixing decisions - sound image placement, EQ, balance and timbre - within a 30-degree vertical and 60-degree horizontal virtual aperture in front of the monitor speakers. The LSR philosophy was accomplished by a complete top-to-bottom design and rethinking of every component in the powered loudspeaker. From cabinet materials to individual drivers to the final assembly of the die cast parts, the entire line of LSR units reflects JBL' s intent to make a line of monitors in sizes to fit every room and purpose. Their end goal is that sound quality and balance from smaller production rooms, main music mix rooms and larger dubbing theaters will translate well.


The LSR Line

JBL makes several speaker systems in the LSR line. They are:

LSR32 - a three-way system with a 12" woofer that's available in horizontal and vertical orientations
LSR28P - two-way system with an 8" woofer
LSR25P - two-way with a 5.25" inch woofer
LSR12P - 250-watt active subwoofer


The 32, 28 and 25 speakers all have controls to revoice them to co-exist with an external subwoofer unit. On the front of all of these systems (except the LSR32) are green LED operating indicators that change to red when the system is in clip.

For purposes of this review, JBL kindly sent me two pairs: the LSR28P and LSR25P. Both the 28's and 25's are designed for vertical orientation and I advise not setting them up differently.