MANUFACTURER'S SPECIFICATIONS:
Impedance: 8 ohms.
Frequency Response: 33-20,000 Hz ±3 dB in average room.
Tweeter: Mylar dome.
Woofer: 10" high compliance.
Dimensions: 22 3/4" H x 13" W x 11 3/4" D.
Price: $99.95.
The 303AX, the latest version of ADC's popular 303A loudspeaker system, is a real winner. The main change is in the newly designed acoustic suspension woofer, which provides a better low end and improved power handling capability. The result is a very fine speaker system which is better by a substantial margin over its predecessor, and stands in the forefront of $100-category speakers.
The smartly styled bookshelf-sized 303AX is finished on all sides in oiled walnut, with aluminum trim around the black-and-chrome grille cloth panel. The 10-in. high-compliance woofer crosses over to a 1 1/2-in. Mylar dome tweeter at 1500 Hz. The midrange and tweeter switches, recessed into the rear of the cabinet, together with speaker terminals, can be set to one of two positions. Incidentally, "midrange" refers to frequency response, and not to a separate speaker. We found the attenuated position sounded best, with a 2- or 3-dB boost of the amplifier's treble control.
In search of a more meaningful speaker response test, we departed here from our previous multi-microphone averaging technique and used a 1/3-octave-band pink noise as the source, plotting the speaker's output as sensed by a condenser microphone three feet away, on axis, in a listening room. We feel that this type of random noise simulates music more closely than sine waves, representing more of what we hear. Furthermore, our results so far point to improved correlation between measurements and listening experience.
When measured in this way, the ADC303AX has a wide, smooth frequency response of ±3 dB between 40 and 10,000 Hz (excepting a 5-db peak at 64 Hz), which are the limits of our microphone calibration at this time. But it was obvious that the 303AX did not stop there. Dispersion is good and no prominent aberrations were detected anywhere in the audible spectrum. Short of going to a three-way system, it would be difficult to improve on this design.
In listening, we noted a particularly good low end and a smooth quality throughout--especially on strings. The speaker sounds pleasant and clear, with no apparent frequency favoring. It sounds bright when it's supposed to. And it can handle lots of power. In matters of efficiency, it is on the reasonable side of inefficient acoustic suspension speakers. We recommend a power amplifier of at least 20 watts rms per channel, though 25-30 would take advantage of the speaker's qualities even better.
The ADC 303AX represents particularly excellent value because it is an especially fine-sounding bookshelf system at the price range where you get the most quality for your money.
(Audio magazine, Jan. 1970)
Also see:
ADC Stereo Cartridge 10E MK IV (Equip. Profile, Dec. 1972)
ADC (Audio Dynamics) XLM Stereo Cartridge (Jul. 1972)
ADC Model LMF-2 Tonearm & ZLM Phono Cartridge (Equip. Profile, Jan. 1979)
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