PMC fact fenestria Loudspeaker Lab Report

Lab Report

For the size of cabinet, the fenestria's 86dB rated sensitivity is not especially high and, in practice, turns out to be substantially lower on test at 82dB/1kHz, increasing to 82.7dB when averaged across 500Hz-8kHz. Thankfully the speaker is a complex but not especially tough 6ohm nominal load to drive. There's a 4.7ohm/81Hz minimum and despite the load remaining sub-8ohm from 8Hz-170Hz, 370Hz-2.7kHz and above 4.6kHz, the largest phase angles are a very modest +25°/–32°. High SPLs will still demand a high power amplifier but, despite the diminished sensitivity, THD is low at ~0.25% through the bass and very low through the passband of the dome mid at ~0.1% (re. 90dB SPL). Driver modes are very well controlled too [see CSD Graph 2].

The ideal listening axis, on the mid dome, is not far off the 'average' seated height but if you sit higher (towards the treble dome) then the response dips between 2kHz-5kHz (–3.7dB/4.6kHz). This effect was more obvious with one speaker, hence the 1.3dB pair matching (tightening to 0.5dB, 200Hz-3kHz and 5kHz-20kHz). Otherwise the forward trend has a mild 'BBC dip' with a lift above 8kHz responsible for the ±3.1dB and ±3.3dB response errors, followed by some lobing above 20kHz [pink shaded area, Graph 1]. PMC's useful HF control operates above 2kHz [blue traces, Graph 1] tilting up/down to reach a sensibly modest, but certainly audible, ±1.1dB above 6kHz. Meanwhile, the quartet of bass drivers peak at 79Hz (40Hz-425Hz, –6dB), augmented by the folded transmission lines at 22Hz-136Hz to deliver a low, corrected LF extension of 33Hz [–6dB re. 200Hz; green shaded area, Graph 1]. PM


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


Cabinet is fairly 'silent' leaving a bass driver mode at ~1kHz and minor dome modes at 5kHz–8kHz

Sensitivity (SPL/1m/2.83V – 1kHz/Mean/IEC) 82.0dB / 82.7dB / 81.3dB
Impedance modulus: minimum & maximum (20Hz–20kHz) 4.7ohm @ 81Hz, 11.6ohm @ 255Hz
Impedance phase: minimum & maximum (20Hz–20kHz) –32° @ 29Hz, +25° @ 160Hz
Pair matching/Resp. error (200Hz–20kHz) 1.3dB/ ±3.1dB/±3.3dB
LF/HF extension (–6dB ref 200Hz/10kHz) 33Hz / 26.8kHz/25.9kHz
THD 100Hz/1kHz/10kHz (for 90dB SPL/1m) 0.25% / 0.09% / 0.9%
Dimensions (HWD) / Weight (each) 1700x370x623mm / 80kg
Price £54,995

The Professional Monitor Company Ltd
Supplied by: PMC Ltd
01767 686300