Technics SB-R100 Speaker System Review

Technics describes the SB-R100 as a “flat speaker system” primarily in reference to its shape, and in that respect the phrase is both apt and accurate. In addition, however, our experience with this unusual speaker suggests that, while a truly flat frequency response has yet to be achieved in a loudspeaker, the SB-R100 comes closer to that goal than many far more massive and expensive speakers we have tested.

The two-way SB-R100 measures only about 12-3/8 inches square and a mere 2-9/16 inches deep, so its physical flatness is indisputable. It is part of a line of super-slim audio components recently introduced by Technics that includes a combination stereo receiver/cassette deck that is the same depth as the SB-R100 and the similar but slightly larger SB-R200. The components in this line are designed to be hung on a wall (!), but the receiver/cassette player can also be placed flat on a table, and the speakers come with stands that support them at a slight backward angle when they are placed on a bookshelf or other flat surface.

Our tests were limited to the SB-R100 speaker. Both models feature a novel concentric planar-driver array using the honeycomb construction introduced a few years ago in several larger Technics speakers. From the outside, the SB-R100 appears to have a single 9-inch flat-diaphragm driver with several concentric bands on its surface. Closer examination reveals that the woofer is a 7-inch-diameter ring with a 1-1/8-inch tweeter at its center. Surrounding the woofer diaphragm is an annular ring, about 9 inches in diameter, that serves as a passive radiator for the woofer. Each of the three sections of the speaker is decoupled from its neighbors, enabling them to move independently within their respective frequency ranges. The crossover frequency is 1,000 Hz.

The SB-R100, including its metal-mesh grille, is finished in black and weighs 10 pounds. It has no level controls. The tweeter is protected against damage from excessive input by an automatic thermal circuit breaker, which can be reset by pressing a button on the rear of the speaker. Also on the rear are spring-loaded connectors that accept the stripped ends of the speaker wires. In addition to the table stand, a bracket is supplied to hang the speaker on a wall like a picture. Technics recommends wall mounting for best bass response.

The honeycomb radiating surfaces of the drivers are formed plastic and have a very high ratio of stiffness to mass, thus greatly reducing the amplitudes of many of the resonant modes of vibration that occur on a conventional paper or plastic cone. The radiating surfaces are in the same plane, which improves the phase coherence of the acoustic output. Despite its small size, the SB-R100 is rated to handle up to 100 watts of music program input (its companion receiver is rated at 30 watts output).

The Technics SB-R100 is sold in pairs. Suggested retail price per pair is $260.

Lab Tests

Initially we listened to the SB-R100 speakers mounted on shelves (with their stands) as well as hung on the wall. The wall position produced better sound, we felt, so we used that placement for our measurements and later listening tests. The averaged room-response curve was impressively flat through the midrange and high frequencies, within ±3 dB from about 200 to 20.000 Hz. The bass response, with the microphone close to the speaker, was at its minimum at 700 Hz and had a small peak at 140 Hz; it fell off rapidly at lower frequencies, to about —20 dB at 50 Hz. When the bass response was spliced to the room curve, the overall composite frequency-response variation was ±4 dB from 90 to 20,000 Hz.

The quasi-anechoic axial frequency-response measurements made with our IQS FFT analyzer were generally similar to the room-response curves. A 6-dB overall variation from 180 to 20,000 Hz is certainly good performance for any speaker, and especially for one in this price range. The polar response showed moderate directivity above 7.000 Hz, and the overall group-delay variation was 0.4 millisecond from 4,000 to 20,000 Hz, reaching 2 milliseconds or more in the woofer’s range (below 2,000 Hz).

The speaker’s sound-pressure level (SPL) at 1,000 Hz, measured at a 1-meter distance, was 86 dB with the standard input of 2.83 volts. The input level needed to produce the 90-dB SPL at which we measure bass distortion was 4.47 volts. The distortion was about 5 percent in the range from 90 to 100 Hz, increasing rapidly at lower frequencies to 10.7 per cent at 70 Hz. Clearly, low-bass response is not the forte of the SB-R100, although one could hardly expect stronger bass in view of the speaker’s extremely small volume and radiating surface area combined with its relatively high efficiency. By sacrificing efficiency, the SB-R 100’s bass range could have been extended, but since it was designed to be used with a 30-watt receiver, we feel that the Technics engineers chose the optimum compromise.

Measured impedance reached a minimum of 6.5 ohms at 1,750 Hz, but over most of the audio range it was 7 to 9 ohms (the two bass resonances of this ported speaker were at 50 and 115 Hz). We drove the speaker with short tone bursts to determine its peak power-handling ability. At 100 Hz there was an audible rasping sound with an input of 42 watts (based on the measured 15-ohm impedance at that frequency). At 1,000 Hz the acoustic waveform clipped at 51 watts (into 8 ohms), and at 10,000 Hz we observed a soft rounding of the speaker’s waveform at 90 watts (into 10 ohms).

Comments

The Technics SB-R 100 is a very unusual speaker, and not only because of its size and mounting options. When we first heard the speaker in Japan last year, we were very favorably impressed by its smoothness and generally easy sound. We have had similar initial reactions in the past, however, only to be disappointed when the speakers finally reached us for extended listening and lab measurements. But that was not the case this time. Frankly, we were not entirely prepared for the sound we heard from the diminutive and rather unassuming SB-R 100.

During much of the listening period, we also had on hand some large, expensive, highly regarded speakers from another manufacturer, and comparisons, if not entirely reasonable, were unavoidable. The most obvious difference between the SB-R100 and the others was, not surprisingly, in bass response. But when the program did not have a substantial bass content (below 100 Hz), it was often necessary to walk up to the speakers to determine which pair was playing!

Another surprise was finding that, despite their objectively thin bass, these speakers did not sound at all bass-shy. Perhaps their smooth, uniform midrange and high-frequency response allows them to deliver the essence of the music with sufficient fidelity to compensate for the absence of gut-thumping bass. Our reaction to these speakers was shared by more than one visitor who was amazed to hear what they could do, especially when reproducing a high-quality LP or a Compact Disc.

It is difficult to describe the sound character of the SB-R100 speakers, beyond their lack of deep bass. The sound is just plain good—good enough that we never felt the urge to switch to larger speakers during our extended listening sessions. If you are short on floor or shelf space and can spare a couple of square feet of wall space, and if you won’t mind a pair of solid black squares on your wall, the Technics SB-R100 may well be the answer to your audio prayers. And if you like deep bass, a pair of these would make nearly ideal satellites for a three-piece system with a subwoofer. In any case, the price is right, and so is the sound.

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