PSB Alpha A/V loudspeaker Measurements part 2

But when you look at the curves more closely, there are other differences. The 1999 sample's upper-midrange peak is a little lower in frequency, which ties in with both the slight nasality and the forward upper mids I noted in my auditioning. The 1992 sample has a slight peak at 2.1kHz; in the newer version, this has moved up in frequency to 3.2kHz.

Fig.5 shows how the Alpha's response varies to the sides of the tweeter axis. (Just the differences are shown in this graph, which means that the on-axis response appears to be a straight line.) As very often is the case, the speaker's dispersion is wider in the bottom octaves of the tweeter region than it is at the top of the woofer's passband. This will tend to accentuate the effect of the peaks in the upper-midrange and presence regions. However, a similar plot in the vertical plane (fig.6) reveals that suckouts in the crossover region develop quite swiftly above and below the tweeter axis. This might work against the audibility of the high-frequency peak, though I suspect it contributed to the occasional HF edge I noted.

Fig.5 PSB Alpha A/V, lateral response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90 degrees-5 degrees off-axis, reference response, differences in response 5 degrees-90 degrees off-axis.

Fig.6 PSB Alpha A/V, vertical response family at 50", from back to front: differences in response 45 degrees-5 degrees above axis, reference response, differences in response 5 degrees-45 degrees below axis.

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