Wharfedale Diamond 5 Bookshelf speakers
Almost a decade ago, Wharfedale (one of the earliest British loudspeaker manufacturers) introduced a diminutive two-way speaker system that delivered 1 remarkable sound quality. The Diamond, as it was called, was widely recognized for its wide-range, smooth, uncolored sound and very small size, at a price (in 1984) of $190 a pair.
Although the Diamond's size has increased slightly over the years, it is still one of the smallest speakers that can legitimately claim hi-fi quality. Its new curved, molded-plastic speaker panel is said to enhance the system's high-frequency dispersion as well as its appearance (it is one of the few speakers that actually looks better with its grille removed). The wooden cabinet feels like solid concrete or steel when rapped, with not a hint of audible resonance.
The basic speaker complement remains virtually unchanged, although both drivers are new. A new 5-inch woofer, with a polypropylene cone and multilayer voice coil, is used with a newly designed 1-inch aluminum-dome tweeter, cooled and damped with magnetic fluid. The enclosure, ported on its rear panel, is made of 15-millimeter (approximately 5/8-inch) particleboard except for the front panel, which is 1 inch thick in addition to having a rigid plastic front molding.
Wharfedale claims a frequency range of 47 Hz to 25 kHz for the Diamond V. Its sensitivity is given as 86 dB sound-pressure level (SPL) at 1 meter with a 2.83-volt input. The nominal impedance of the system is 6 ohms, and it is rated to stand up to 100 watts input. Wharfedale says the Diamond V was designed to give its best bass performance when placed 2 to 12 inches from the wall behind it.
It was impractical for us to locate the Diamond V speakers that close to the wall; instead, we placed them on 26-inch stands a couple of feet from the wall behind them. In that position, their averaged room response was very flat above 1 kHz, varying only +/- 1.5 dB from 800 Hz to 12 kHz. There was a tweeter resonance of about 5 dB at 14 kHz. In the woofer range (with a close microphone spacing), the maximum output was at 120 Hz, falling gently at higher frequencies and at 12 dB per octave below about 90 Hz. The woofer response spliced to the room curve in a somewhat ambiguous manner at about 1 kHz. The actual transition might have been somewhat lower, but our choice seemed to correlate best with what we heard.
The Diamond V's quasi-anechoic MLS frequency response was among the flattest we have measured through the middle- and high-frequency range, with a variation of just +/-1.5 dB from 500 Hz to 10 kHz and +/- 3 dB from 300 Hz to 20 kHz. High-frequency dispersion was also good, with the output 45 degrees off-axis down only 5 dB at 10 kHz and 8 dB at 20 kHz.
One of the Diamond V's most impressive qualities was its bass extension. Although the bass level dropped off appreciably with decreasing frequency, the fact remains that this little speaker, which can be held on the palm of one hand, put out a healthy 50 Hz when required, as well as a perceptible 40-Hz fundamental. Unless the speaker was pushed to its limits, its bass remained true, instead of degenerating into distortion as would happen with most other small speakers.
The impedance curve exhibited two bass resonance peaks, 22 and 26 ohms at 100 and 30 Hz, respectively, and a maximum of 18 ohms in the range above 100 Hz. The minimum impedance was 6 ohms at 60 and 250 Hz.
The Diamond V's measured sensitivity was 88 dB, somewhat better than rated. At a constant drive level of 3.5 volts, corresponding to a 90-dB-SPL reference level, woofer distortion was between 0.5 and 1 percent from 2 kHz down to 100 Hz, rising to 2 percent at 65 Hz and 5 percent at 40 Hz.
Although the information supplied with the speakers did not mention their crossover frequency, group-delay measurements suggest that it is about 4 kHz. The system withstood single-cycle burst inputs of 600 to 800 watts at 1 and 10 kHz without damage or untoward sounds, but at 100 Hz the sound became hard at about 22 watts and progressively harder as the power increased to 145 watts, where the woofer cone clearly reached the limits of its suspension. The speaker suffered no damage from this rather abusive treatment, however.
In listening tests, the Wharfedale Diamond V sounded every bit as good as its measurements would suggest. It had a full-bodied sound, not at all thin, although with music that contained strong, deep bass it could not match larger speakers having more driver area or enclosure volume. Still, its sound was invariably remarkable for such a small speaker and remained musical and balanced at all times. Also (and very unusual for a speaker of this size), the Diamond V's bass output extended low enough to make it usable with a real subwoofer (one that operates only below 50 Hz or so), unlikely as such a configuration might seem.
We are impressed that Wharfedale has managed to hold the line on the Diamond's price despite inflation and design improvements. At $300 a pair, the Diamond III was a terrific value five years ago, and the Diamond V is an even greater one now.
