Manufacturer's Specifications
Frequency Response: 3.5 kHz to 30 kHz: 3.5 kHz to 18 kHz it 2 dB.
Dispersion: 180 degrees.
THD: Less than 0.45% below 15 kHz, 20 watts input.
Nominal Impedance: 16 ohms.
Maximum Power Handling: 60 watts rms.
Drivers: 4.
Dimensions: 9 in. W. x 5 1/4 in. D. x 3 in. H.
Finish: Solid Walnut.
Price: $117.00 per pair.
There is no doubt that many otherwise good speakers fall off in frequency response above 10 kHz or so. Many others radiate a narrow beam at high frequencies, thus restricting the stereo image, and so the idea of marketing a simple add-on unit was born. The Microstatic units have been available for some time now and we have received many letters from people who have been very satisfied with them. E. T. Canby tested them some time ago, and he said, "I can think of more than one pair of speakers I would like to update with a set of Microstatics." However, this is the first opportunity we have had to test them ourselves. The system uses four small cone speakers, two 1 1/4 in. and two 1 1/4 in., mounted in an arc so that the dispersion is 180 degrees-not omnidirectional as described in one leaflet. There is a choice of crossover points, 3.5 kHz and 7 kHz, and a variably level control is provided. Our pair was supplied with a switch, possibly so we could demonstrate to ourselves the difference which occurs when the unit is connected.
Measurements
Figure 1 shows the response measured with one-third octave pink noise with the switch in the 3.5 kHz crossover position. A was taken on-axis with three positions of the level control. B was measured at 30 degrees off-axis, and C at 60 degrees.
Fig. 1--Response with the switch in the 3.5 kHz position, taken with one-third
octave pink noise. A shows the effect of the level control, while B was measured
at 30 degrees off-axis, and C at 60 degrees.
Fig. 2--Response with the switch in the 7 kHz position. Taken on-axis with
level control in three positions.
Fig. 3--Toneburst response. A is at 5 kHz, B at 10 kHz, and C at 15 kHz.
Fig. 4--Impedance characteristics at various frequencies.
Figure 2 shows the response on-axis with the switch in the 7 kHz position. It will be seen that suitable adjustment of the level control will give a response within 2 dB from 2 kHz to 16 kHz with little variation in radiation pattern. Figure 3 shows toneburst characteristics at 5, 10, and 15 kHz and Fig. 4 gives the impedance curve. White noise tests showed very low coloration. So much, then, for the measurements, except to mention that the impedance is high enough not to affect amplifier loading.
Listening Tests
For our listening tests, we assembled a variety of speakers: a large Advent, AR 3a, ADC 303ax, Martin Crescendo, and a Dyna A-25. The greatest improvement was noticed with the A-25. To quote the owner, "It sounds like a $200 speaker!" Overenthusiastic? Perhaps, but the overall sound was much more airy and spacious. With the A-25, the 3.5 kHz crossover was used. The Advent sounded best with the switch in this position too, but the ADC 303ax and the AR 3a were better with the higher crossover. The AR speaker still did not sound like an LST, but the difference in dispersion was noticeable.
Dispersion with the ADC 303ax and the Martin Crescendo is already quite wide, but here again the contribution from the Microstatics made a difference. Summing up, the Microstatics can be recommended with confidence. They are not particularly cheap but they do what they are supposed to do: what else can we say?
--T.A., G.W.T.
(adapted from Audio magazine, Jul. 1973)
Also see:
Microstatic Full-Range Loudspeaker (Equip. Profile, Jun. 1973)
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