Rogers LS5/9 Classic SE Loudspeaker Lab Report

Lab Report

If the 'naked' LS5/9 looks rather utilitarian then it's as well to know it was designed to be seen and heard with the tight-fitting Tygan grille left in place. So be careful how you read Graph 1 – the blue trace here is the forward response without the grille (where responses errors increase to ±3.3dB above 6kHz), rather than with as is usually the case! But let's first recap – the larger cabinet and reflex-loaded 210mm polypropylene bass/mid driver offers fundamental advantages over the smaller, closed-box LS3/5A. Sensitivity is higher despite the 27-element/3rd-order crossover, meeting Rogers' 87dB specification, at 86.6dB/1kHz and 87.2dB/500Hz-8kHz. Measured on Rogers' preferred mid-baffle axis, the forward response retains a suggestion of the 'BBC dip' through mid and presence, partially masked by undulations between 2-6kHz. These contribute to the overall ±3.0dB and ±2.4dB response errors [see Graph 1] and are reflected in the cone/surround mode seen on the CSD waterfall [see Graph 2].

The bass unit has a –6dB bandpass of 72Hz-288Hz [green shaded area, Graph 1], free of obvious spuriae until breakup, and supported by the front port, tuned to 38Hz but with a useful 29Hz-113Hz (–6dB) output. The diffraction-corrected nearfield response indicates a LF extension of 59Hz (–6dB re. 200Hz). So is this encouraging sensitivity and good bass achieved with recourse to a punishingly low impedance? Fortunately not... With relatively high minima of 5.69ohm/172Hz/–8o and 5.89ohm/2.9kHz/+2o combined with maximum phase swings of –47o/103Hz and +30o/74Hz (all >12ohm) the LS5/9 Classic SE will not prove burdensome for the 'average' integrated. PM

621rogers.lab1

Response inc. nearfield summed driver/port [green], freefield corrected to 1m at 2.83V [yellow], ultrasonic [pink]. Left, black; right, red; w/o grille, blue

621rogers.lab2

Treble and cabinet modes are well damped, leaving breakup in the PP bass/mid cone at 2-6kHz

Sensitivity (SPL/1m/2.83V – 1kHz/Mean/IEC) 86.6dB / 87.2dB / 85.2dB
Impedance modulus: minimum & maximum (20Hz–20kHz) 5.69ohm @ 172Hz, 24.1ohm @ 89Hz
Impedance phase: minimum & maximum (20Hz–20kHz) –47° @ 103Hz, +30° @ 74Hz
Pair matching/Resp. error (200Hz–20kHz) 2.1dB/ ±3.0dB/±2.4dB
LF/HF extension (–6dB ref 200Hz/10kHz) 59Hz / 22.1kHz/22.7kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 0.6% / 0.07% / 0.2%
Dimensions (HWD) / Weight (each) 460x275x285mm / 12kg
Prices £4899-£5599 (£1599 stands)

COMPANY INFO
Rogers International UK Ltd
Virginia Water, UK
Supplied by: Rogers International UK Ltd
0333 533 0135
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