Cambridge Audio SX-80 Loudspeaker Lab Report

Lab Report

This tickled-up version of Cambridge Audio's longstanding SX-80 shows relatively modest ±2.6dB and ±2.4dB response errors (200Hz-20kHz) combined with pair matching of ±1.4dB (a tighter ±0.9dB below 4kHz). So while the forward response is a little 'untidy' [see Graph 1, below] the trend is reasonably flat, yielding a sensitivity in excess of its 87dB specification at 87.8dB (500Hz-8kHz). The dips in response [black/red traces] are linked to resonances at 1.2kHz and 6.5kHz [see CSD waterfall, Graph 2] and at 2.6kHz with a bold discontinuity visible on both phase and impedance spectra [not shown here]. Incidentally, the frame grille has a big impact above 2.5kHz [blue trace] and should not be used for 'serious' listening.

Cambridge Audio offers an 8ohm rating for the SX-80, but a nominal 6ohm is more appropriate given the impedance minima of 5.5ohm/37Hz and 5.6ohm/149-212Hz – coinciding with the 18Hz-200Hz/–6dB bandwidth of the port – but with phase angles no greater than a few degrees. The biggest swings reach +40°/865Hz and –28°/24Hz where the modulus remains above 12ohm and the 'toughest' region still quite mild at 535Hz/8.0ohm/+35°. There's a reactive upswing at ultrasonic frequencies (+85°/80kHz) but the SX-80 still looks easy enough to drive with budget amps like the AXA35 [HFN Sep '19]. At the bass end of the spectrum [green shaded area, Graph 1] distortion is low at typically 0.25% (re. 90dB SPL). Meanwhile, the native –6dB roll-off of the two mid/woofers reaches 61Hz, augmented by the 27Hz output of the generously-proportioned port to yield a total diffraction-corrected bass extension of 45Hz (–6dB re. 200Hz). PM


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


HF resonances are well damped leaving two modes at 1.2kHz and 6.5kHz linked to the bass cones

Sensitivity (SPL/1m/2.83V – 1kHz/Mean/IEC) 88.6dB / 87.8dB / 85.8dB
Impedance modulus: minimum & maximum (20Hz–20kHz) 5.5ohm @ 37Hz, 22ohm @ 1.5kHz
Impedance phase: minimum & maximum (20Hz–20kHz) –28° @ 24Hz, +40° @ 865Hz
Pair matching/Resp. error (200Hz–20kHz) 1.4dB/ ±2.6dB/±2.4dB
LF/HF extension (–6dB ref 200Hz/10kHz) 45Hz / 23.4kHz/24.1kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 0.25% / 0.3% / 0.65%
Dimensions (HWD) / Weight (each) 950x200x276mm / 13kg
Price £399

Cambridge Audio Ltd
Supplied by: Audio Partnership PLC, London
0203 514 1521