I never had a chance, when it was made possible for me, to audition the B&W 805 Diamond in a controlled manner. I really would have liked to. Fortunately, I got the opportunity to listen and evaluate, although just within certain time limits, the latest compact (H 331mm x W 191mm x D 250mm) B&W loudspeaker: PM1, a cool looking 2-way vented loudspeaker with certain recognizable B&W landmarks such as the drop shaped tweeter enclosurer.
However, according to B&W, the PM1's Nautilus tube-loaded tweeter is a new design. The 1" aluminium dome used goes up to 30kHz but its response has been extended up to 40kHz by reinforcing it with a carbon fiber ring. The surround is the same as in the Diamon series tweeter. The result, according to B&W, is the sweetest sounding non-Diamond tweeter there is. The 5" bass/midrange driver sports Kevlar fibre cone and a new anti-resonance plug. The mushroom-shaped device is said to be constructed from polymer foam, and in addition to killing resonances also reduces cone break-up modes, contributing to midrange clarity and detail.
The drivers are crossed at 4kHz. Of the crossover itself B&W says it's the simplest possible featuring similar high-quality components incorporated in the company's flagship 800 Series Diamond speakers.
Flowport and Matrix are proprietary B&W technologies applied to PM1 too. The Flowport breathing apparatus quarantees, by regulating airflow in and out in a certain way, that a big sound can generated from a small speaker. The technigues minimises turbulence and extraneous noise.
Not unlike the 800 Series Diamond speakers, the PM1 uses B&W's Matrix bracing system, a grid of strong interlocking panels. The purpose of these is to silence the cabinet, and let only the drivers be heard.
The frequency range is claimed to be 6dB down at 42Hz and 60kHz; the ±3dB values on reference axis being 48Hz - 22kHz. Dispersion figures are rarely published in the context of such 2-way dynamic monitors but here they area for the PM1: horizontal: over 60º arc, vertical: over 10º arc (within 2dB of reference response). Harmonic distortion (2nd and 3rd harmonics, 90dB, 1m) is said to be below 1% between 110Hz - 22kHz.
As for other specs, nominal impedance is 8Ω (minimum 5.1Ω); the sensitivity moderate 84dB SPL, and recommended amplifier power 30W - 100W into 8Ω on unclipped programme. I drove the PM1 with Rotel's RCX-1500 multi function device with 100W output power (?? ohms). The amp seemed to partner the PM1 quite well.
The cabinet with a curved baffle is finished with a luxurous looking real wood Mocha Gloss veneer (other finishes optional). The black grill is surrounded with an aluminum frame. This is one of the few loudspeakers on the market that looks better with the grill on than without. Despite the separate tweeter on the top, the overall appearance is smaller than in the images.
During the audition the PM1 (9.3kg) sat on its own 62 cm high (excluding spikes) good-looking stand.
The quality of the sound was obvious in many respects right from the very beginning. The sound had maturity. It was secure. Very clean and distortionless, with no obvious discrete points in the frequency response. The sound had a nice, appealing picky character that I liked a lot. A guitar's metal strings sounded metal with great natural attacks and natural harmonics; it was not harsh or sharp and hasty. Violin instruments sounded equally nuanced and with a good tone and multiple details, even the lowest level ones. It tells something about the tonal balance that despite the audible details, solo violins didn't steel the main role in the whole, as compared to the accompanying orchestra. And what a refinement! The treble was well integrated with the rest of the frequency band, and was particularly smooth and silky, so much so that sometimes I felt that the highest registres of the string instruments came out somewhat thin.
When I said that the sound was clean, I referred to the area from the midrange to the treble especially. Some such standmount loudspeakers try to impress with an immediate and present mid-range supported by the elevated lower mids and upper bass. As to the former, I'm quite positive that the PM1 is not one of them. But as to the latter, I cannot be sure.
The bottom octaves were slightly overlapping the lower mids making the presentation from 50Hz up not quite as clean and cut and academic as it should have been ideally. However, my feeling was that that quality wasn't attributable to the speaker. Instead the culprit appeared to be the rather small and ill-shaped listening room. When I dragged the speakers closer to the listening seat, almost mimicking near field listening, the bass/low mids of the PM1 was much less prominent. Although I cannot, based on this listening session, be sure what the PM1's bass performance really is like, I got a feeling that this little beauty is capable of the sort bass reproduction that unless one sees to it that the placement of the speakers and and other relevant acoustic considerations are properly taken into account, at least in such small rooms, bass may partly dominate the sound and lessen the effect of the original musical performance.
Having said that I must also confess how much I enjoyed listening to music through the PM1's airy and loose sound (no box colouration whatsoever). The focus point of the sound was on the speaker level between the speakers. The soundstage wasn't too narrow, nor too tall. The sound was three-dimensional but didn't escape too far back from the speaker line.
Music progressed nicely in time, never taking a moment's rest between two consecutive musical events. Hits and attacks came precisely when the ear so expected. Even tougher music samples (big orchestras) sounded rhytmical, coherent, and whole.
As with all B&W loudspeakers, the coherence of the PM1 makes it slightly a self-contained and conservative reproducer. This is the price it pays for its otherwise super smooth and fluent performance. As a consequence, the listener learns to realize that the PM1 sounds emotionally involving but not in a direct or obvious way but indirectly and in a less sensual way. This does not make the PM1 a lesser seducer, just different.
The B&W PM1 is a compact high-quality highend loudspeaker, superbly built, looking good and distinguished, and armed with major sonic resources. The price 2500 euro per pair.