LABORATORY TEST RESULTS
The frequency response of the Boenicke W5 SEs was not particularly flat, as you can see from Graph 1, where Newport Test Labs has spliced two traces together: the pink noise trace from Graph 5 and the high-frequency trace from Graph 2. You can see that the trace is admirably uniform from about 58Hz up to 5.5kHz, where it’s only ±3dB but above 5.5kHz it rises to +7.5dB at 7.5kHz, then to +11dB at 13kHz. Although this rise starts at a frequency that’s above that of the highest note on a piano keyboard (which is 4.1kHz), I would expect that this speaker would sound bright, due to this rise’s effect on harmonics. I would also expect some audible effects from the wideband lift in the frequency response between 80Hz and 250Hz.
The low-frequency response is shown in greater detail in Graph 3, using a nearfield acquisition technique that simulates the response that would be obtained in an anechoic chamber. You can see that the low-frequency response starts rolling off fairly steeply at 100Hz.
The impedance modulus (Graph 4) shows the cabinet has been tuned to 55Hz, so response will roll off very steeply below this frequency and the glitches in the trace at around 160Hz, 400Hz and 2.8kHz would suggest tiny resonances of some kind, but they’re so small I can’t imagine there would be any audible effect. (You should ignore the glitches at 100Hz, 1kHz and 10kHz: these were caused by the test equipment’s range-switching circuitry.) The impedance is mostly below 8Ω and drops all the way down to 2.3Ω at 6kHz. This should not cause any issues, as the phase angle is 0° at this frequency. Also, at the frequency at which the phase angle is most severe (62°) the impedance is a comfortable 6.5Ω. Boenicke puts the ‘nominal’ impedance at 4Ω, but it should really be stated as 2.8Ω, or at least 3Ω. The differences in the impedance traces measured of the left and right speakers show that the driver matching is not of the highest standard.
Graph 5 shows the frequency response of the Boenicke W5 SE measured using wideband pink noise, where the trace shown is the averaged result of nine sweeps measured on a grid three metres on-axis from the front-firing driver. The trace above 1kHz shows more how the human ear would perceive the high frequency response, eliminating the sharp peaks and dips shown in Graph 1 and Graph 2, which were obtained using a gated measurement to ensure measurement accuracy beyond that which the human ear is capable of discriminating. This graph shows the overall frequency response as extending from 58Hz to 20kHz ±5dB.
Graph 6 is a composite that shows individual measurements of the various drivers. You can see the response of the full-range front-firing driver (light blue) rolls off very steeply below about 180Hz. The response of the rear-firing ambience tweeter (pink trace) is very smooth, extending from 6kHz to 28kHz ±2.5dB. Note that the level at which the trace is shown on the graph is not referenced to the other traces: it’s just been positioned there for clarity. This graph also extends the measurement of the rear-firing bass reflex port, and you can see there’s some unwanted output between 450–800Hz and also at around 1.5kHz.
Newport Test Labs measured the sensitivity of the Boenicke W5 SE using its standard wideband averaging methodology, which is always tough on small speakers because of their limited low-frequency response, and using this technique, the lab measured sensitivity at 79dBSPL at one metre, for a 2.83Veq input. This is the lowest sensitivity ever measured by the laboratory, and also 8dB lower than Boenicke’s specification of 87dBSPL/w/m.
Although there will always be minor differences due to different measurement techniques, and I have learned that manufacturers always publish the most ‘optimistic’ sensitivity figures, I had to wonder how Boenicke arrived at its result, given that Tang Band specs the bass driver with a sensitivity of 82dBSPL and Fountek specs the sensitivity of its full-range driver at 84.3dBSPL. The low sensitivity also means that whereas you’d only need 32-watts of power to drive a speaker of industry-average sensitivity to over 100dBSPL, you’ll need 130-watts of amplifier power to drive the Boenicke W5 SE to the same sound pressure level.
The Boenicke W5 SE demonstrated an impressively-extended bass response for such a small loudspeaker. Its midrange response, although not smooth, is acceptably flat. Despite having a minor rise in the high-frequency response the laboratory was still able to measure an overall frequency response of 58Hz to 20kHz ±5dB.
The very low efficiency combined with low impedance will, however, make amplifier matching crucial in extracting the best performance from this design.
Results mentioned, tabulated in performance charts and/or displayed using graphs and/or photographs should be construed as applying only to the specific sample tested.