Measurements, continued
The speaker’s horizontal radiation pattern, normalized to the response on the tweeter axis, which therefore appears as a straight line, is shown in fig.5. The dispersion is very well controlled, with the contour lines in this graph evenly spaced throughout the midrange and mid-treble region, implying accurate, stable stereo imaging. The radiation pattern narrows in the region of the on-axis peak in the high treble, suggesting that experimenting with toe-in will be advantageous. Fig.6 shows the 805 D4 Signature’s dispersion in the vertical plane, again normalized to the response on the tweeter axis. A suckout develops in the crossover region 5° above the tweeter axis, with the mid-treble region becoming suppressed 5° and more below that axis.
Fig.7 shows the spatially averaged response4 of the 805 D4 Signatures in my room. The low-frequency register is slightly shelved down—as I wrote in the main review text, it wasn’t possible to reinforce the bass by moving the speakers closer to the wall behind them—but the in-room response is respectably even in the midrange. As expected from fig.4, there is an excess of energy between 3kHz and 12kHz.
The red trace in fig.8 repeats the spatially averaged response of the 805 D4 Signature; the blue trace is that of the B&W Diamond Series 804 D4 tower that I reviewed in January 20225; the green trace is that of the GoldenEar BRX that I reviewed in September 2020.6 The three speakers behave similarly from the lower midrange through the low treble. The in-room responses of the three speakers differ most at high frequencies. The BRX’s treble slopes gently down in a linear manner, primarily due to the increased absorption of the 4 I average 20 1/6-octave–smoothed spectra, taken for the left and right speakers individually using a 96kHz sample rate, in a vertical rectangular grid 36” wide × 18” high and centered on the positions of my ears. This tends to smooth out the peaks and dips below 400Hz that are due to the room’s resonant modes.
5 See stereophile.com/content/bowers-wilkinsdiamond-series-804-d4-loudspeaker.
6 See stereophile.com/content/goldenear-brx-bookshelf-reference-x-loudspeaker.