King of the Minispeakers?
Infinity InfiniTesimal full-range loudspeaker system in molded case with oak end panels plus removable swivel mounting brackets for automobile or wall use. Dimensions: 6 1/2 by 11 1/2 inches, 5 1/2 inches deep. Price: $175. Warranty: "limited," five years parts and labor. Manufacturer: Infinity Systems, Inc., 7930 Deering Ave., Canoga Park, Calif. 91304.
If the InfiniTesimal had appeared even five years ago, we would hardly have believed that so fine a sound could issue from so small an enclosure. As it is, we are mighty impressed despite the parade of good sounding minis that have preceded it. This is not (by a small margin) the tiniest nor (by a larger one) the least expensive, but we certainly don't know any we like better.
Infinity has used its Emit tweeter, rated (and checked out at CBS) to beyond 35 kHz, in combination with a hardworking little woofer. It is axiomatic that something must be given up when enclosure size is reduced: deep bass, efficiency, dynamic range, clean reproduction, or a combination thereof.
The InfiniTesimal essentially takes the last approach via a balance of tradeoffs so canny that at first listening the laws of physics appear to have been broken.
They have not been, of course. The anechoic measurements show bass resonance to be relatively high-a little above 100 Hz-with the usual rolloff below. The sensitivity is low (at just under 80 dB of sound pressure level for a 1-dBW input), but not so low that extraordinary power is required.
Nor should such power be applied; signs of distress appear before input power reaches 19 dBW (80 watts) at 300 Hz or, on pulsed signals, peak levels 10 dB higher. In other words, the little speaker will play loud with a medium-power amplifier (by today's standards), but it should be expected neither to fill big rooms at more-than-moderate levels nor to withstand the drive of really big amps.
But as long as it is not pushed too hard it will stand comparison, even in fairly large rooms, with other speakers in its price class, size no object. Short of the organ pedal-tone range (which no speaker in this class should be expected to do an exemplary job with), its sound is astonishingly clean and well defined in the bass and free of coloration above. Measured harmonic distortion is not particularly low at the 0-dBW (1-watt) level, averaging roughly 0.5% second and 0.25% third above the resonance frequency. But even at the higher-level distortion test (the lab limited the level to 87 dB SPL at 300 Hz to stay clear of outright overload), the figures do not increase markedly.
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Infinity InfiniTesimal Loudspeaker System
Average omnidirectional output, 250 Hz to 6 kHz 79 3/4 dB SPL for 0 dBW (1 watt) input
Continuous on-axis output at 300 Hz 101 dB SPL for 19 dBW (79.5 watts) input
Pulsed output at 300 Hz 111 dB SPL for 29 dBW (817.6 watts) input "Nominal" impedance 3.7 ohms at 210 Hz
ANECHOIC RESPONSE CHARACTERISTICS (1 watt input)
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The omnidirectional anechoic curve shows a very gradual rolloff as frequency increases above resonance, while the on-axis curve is just about horizontal. In either case the various peaks and dips do not exceed about ±2.5 dB with respect to the general "lie" of each curve, but the divergence of the two does suggest a gradually progressing tendency to beam as frequency increases. Yet, perhaps because the onset is so gradual, the dispersion seems very even in practice.
So why even consider larger speakers if the InfiniTesimal is so good? There is the question of deep bass, which can easily be obtained in greater abundance-though by no means with necessarily greater clarity-from a larger enclosure. More important, to our way of thinking, is the dynamic range. When the speaker is pushed hard, both the clarity of the sound itself and the erstwhile excellence of the stereo image begin to evaporate. Both spatial and instrumental textures thicken and become fuzzy; hard-driven highs take on qualities that might variously be described as grainy or buzzy or blurred, while the midrange becomes very opaque. Even so, the wonder is not that these effects occur, but that they are not more pronounced and at even lower output levels; so small an enclosure simply can't be expected to do everything superbly.
And it does a great deal very well indeed. Despite the extended highs and flatness of response-which, in this price range, often is accompanied by a brightness that lends some edginess or nasality to voices and strings-the InfiniTesimal reproduces violins and sopranos convincingly. Male voices have excellent balance, with neither the throatiness of an over-bright speaker nor the chestiness of one having an exaggerated midbass (a common way of "compensating" for lack of really deep bass). Infinity does offer, on the back panel, a two-position slider intended to trade away a little of the mid-bass (around resonance) for a little more response below around 60 Hz, but the effect is so subtle (about 1 dB either way), both in the lab and in the listening room, that its value is marginal. High transients-from xylophone to the tinklier instruments-are very well reproduced; the woofer seems less quick than the tweeter, and bass drums and similar sounds are not quite as sharply defined.
You could find another speaker that will do better in one respect or another at the price, but not, in our experience, one at this size and in all respects at the same time. For its obvious intended purposes-relatively small spaces from car interiors to moderate-sized rooms, where a speaker's bulk is a major consideration-the InfiniTesimal makes a significant contribution to fine sound. We rate it a winner.
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