AT-32 Dual Moving MicroCoil Stereo Phono Cartridge
Manufacturer's Specifications:
Frequency Response: 10 Hz to 24 kHz.
Recommended Tracking Force: 1 to 2 grams.
Channel Balance: 0.75 dB.
Channel Separation: 30 dB at 1 kHz, 20 dB at 10 kHz.
Output at 5 cm/S: 0.4 mV.
Stylus Tip: 0.2 x 0.7 mil nude-mounted elliptical on 0.12-mm square shank, whole diamond.
Stylus Cantilever: Beryllium.
Recommended Load Impedance: 17 ohms.
Generating System: Dual moving microcoils (inverted "V") and samarium cobalt magnet.
Dynamic Compliance: 9 x 10^-6 cm per dyne.
Weight: 6.8 grams.
Price: $300.00.
AT-650 Universal Stereo Moving-Coil Matching Transformer
Manufacturer's Specifications:
Input Impedance: 3, 20, 40 ohms and Pass.
Load Impedance: 47 kilohms.
Frequency Response: 10 Hz of 100 kHz.
Voltage Gain: 20 at 3 ohms, 8 at 20 ohms, 5.6 at 40 ohms.
THD: Less than 0.05 percent at 1 mV.
Output Cable Length: 30 1/2 in. (77 cm).
Output Cable Resistance: 0.025 ohm.
Dimensions: 4.5 in. (114 mm) W x 2.6 in. (66 mm) H x 5.8 in. (148 mm) D.
Weight: 31 oz. (888 grams).
Price: $250.00.
A cult seems to have formed that ascribes phenomenal music reproduction to the moving-coil phono cartridge, relegating all other types to a rather lowly status. Therefore, it comes as no surprise that the highly respected Audio Technica company has joined the ranks of manufacturers of moving-coil phono cartridges with their superb AT-32. And, in turn, the moving-coil aficionados will probably be highly elated to read the re view of yet another superb moving-coil phono cartridge--the Audio-Technica AT-32.
To overcome poor tracking, a problem common to many moving-coil cartridges, Audio-Technica has developed a new stylus assembly/coil design which minimizes moving mass at every critical point, thus permitting higher compliance without unwanted resonances.
The moving "MicroCoils" are them selves extremely small, and mounted in an inverted "V" as close as possible to the cantilever fulcrum, to further reduce their effective moving mass. Because of this positioning, the mass actually presented to each record groove wall is substantially less than the mass of both coils.
Behind the coils is a vital key to the improvement of tracking ability--a unique radial damping ring that has been individually tensioned to a specific and critical compliance value. The ability to "hand tune" each individual cartridge insures optimum tracking ability at all frequencies, allowing the individual cartridge to take full advantage of the entire mass-reduction program.
The stylus cantilever is made of beryllium, one of the most rigid and least massive materials known. Its stiffness eliminates flexing which could contribute to increased distortion. Mounted on the beryllium cantilever is a factory replace able 0.2 x 0.7 mil, nude-mounted elliptical diamond stylus with a 0.12-mm square shank. The square shank reduces mass and ensures a more accurate tip alignment with the record groove.
The body of the AT-32 consists of a bright gold-finished housing with a translucent brown plastic bottom. The stylus guard is totally removed rather than being hinged to the body. Besides the possibility of misplacing or losing the stylus guard, it became loose and had a tendency to fall from the cartridge body after many removals. Further, it would be helpful if the front of the cartridge had a vertical indexing line to assist in cueing as well as in adjusting the azimuth for correct vertical alignment. The AT-32 is packaged in a gold-finished, hinged, plastic case which contains the usual mounting hardware, a screwdriver, and a stylus brush. The owner's manual is thorough and one of the best I have seen.
Because of the low output voltage, the Audio-Technica AT-32 must be used with either a preamplifier's or receiver's moving-coil (MC) phono input or an out board step-up matching transformer or pre-preamplifier. The phono cartridge is connected to the input of the pre-preamplifier or to the 20-ohm input of a matching transformer; the output of the device is then connected to the preamplifier's or receiver's magnetic phono input. If need be, the step-up can be accomplished with Audio-Technica's AT-630 or AT-650 matching transformer.
Measurements
The AT-32 phono cartridge was mounted in an Audio-Technica AT-S headshell and used with the Audio-Technica AT-1010 DTS tonearm mounted on a Luxman PD-555 vacuum turntable.
The cartridge was oriented in the headshell and tonearm with the Dennesen Geometric Soundtracktor. Voltage step up was accomplished with the Audio Technica AT-650 Matching Transformer. Because the AT-650 was designed for the AT-32 phono cartridge, all measurements were made using this transformer. The transformer's frequency response was tested from 20 Hz to 200 kHz to make certain its output was flat to at least 50 kHz. The measured response was superb, ±0.25 dB from 20 Hz to 40 kHz, -0.75 dB at 50 kHz, -2.5 dB at 100 kHz, -6 dB at 150 kHz, and-8 dB at 200 kHz. The measured gain was 27.3 dB at the 20-ohm tap, and the square-wave rise-time was 3µS at 1 kHz.
Fig. 1--Frequency response of Audio Technica's AT-650 transformer.
Fig. 2--Frequency response and separation of the Audio-Technica AT-32 cartridge
using the CBS STR-170 test record.
Fig. 3--Frequency response and separation of the AT-32 using the JVC TRS-1005
test record.
Fig. 4--Response to 1-kHz square wave, AT-32 phono cartridge.
Laboratory tests were conducted at an ambient temperature of 74° F ±-1° (23.33° C) and a relative humidity of 56 percent, ±3 percent. The tracking force for all reported tests was 1.9 grams (measured with a Technics Stylus Pres sure Gauge, SH-50P1), with an anti-skating force of 2.0 grams. The Sound Concepts DMR-100 digital dB meter was used wherever applicable. As is our practice, measurements were made on both channels, but only the left channel is reported unless there is a significant difference between the two channels, in which case both channels are reported for a given measurement.
Frequency response, using the Columbia STR-170 test record, was-0, +1 dB from 40 Hz to 8 kHz, +1.75 dB at 10 kHz, +2.5 dB at 15 kHz, and +3 dB at 20 kHz. Separation was 24.5 dB at 1 kHz, 19.5 dB at 10 kHz, 14.75 dB at 15 kHz, and 11.5 dB at 20 kHz. Using the JVC TRS-1005 test record, the frequency response was-0, +0.5 dB from 1 to 10 kHz, +1 dB at 15 kHz, +1 dB at 20 kHz, +0.75 dB at 25 kHz, +1.25 dB at 30 kHz, +1.5 dB at 40 kHz, and +0.75 dB at 50 kHz, all equal to-0, +1.5 dB from 1 to 50 kHz. Separation was 31 dB at 1 kHz, 20.5 dB at 10 kHz, 16.5 dB at 15 kHz, 14.75 dB at 20 kHz, 11.5 dB at 30 kHz, 10.5 dB at 40 kHz, and 6.75 dB at 50 kHz. From these data it is evident that the AT-32 has a superb frequency response and an excellent high-frequency separation.
The 1-kHz square-wave response shows little overshoot followed by mini mal ringing that decayed rapidly. This type of square-wave response is common with moving-coil cartridges having an extended frequency response. The cartridge-arm low-frequency lateral resonance was at 8.5 Hz at an amplitude of +3 dB; vertical resonance was 7 Hz.
The high-frequency resonance was at 44 kHz, and the effective tonearm plus headshell mass was 37.23 grams.
The following test records were used in making the reported measurements:
Columbia STR-170, STR-100, STR 112; Shure TTR-103, TTR-109, TTR 110, TTR-115; Deutsches Hi-Fi No. 2; JVC TRS-1005; Nippon Columbia Audio Technical Record (PCM) XL-7004; the B & K QR-201 0, and the Ortofon Direct-Cut Pickup Test Record 0001. Wt., 6.77 g; d.c. res., 15.6 ohms; tracking force, 1.9 g; anti-skating, 2.0 g; output (using AT-650 transformer), 1.55 mV/cm/S; IM distortion: (4:1) +9 dB lateral, 200/4000 Hz, 1.15 percent; +6 dB vertical, 200/4000 Hz, 2.5 per cent; crosstalk (using Shure TTR-109), 28 dB; channel balance, 1 dB; trackability: high freq. (10.8 kHz, pulsed), 30 cm/S, mid-freq. (1000 and 1500 Hz, lat. cut), 25 cm/S, low freq. (400 and 4000 Hz, lat. cut), 24 cm/S; Deutsches Hi-Fi No. 2 300-Hz test band was tracked cleanly to 77 microns (0.0077 cm), lateral at 14.5 cm/S at +8.70 dB and 43 microns (0.0043 cm), vertical at 8.12 cm/S at +3.64 dB.
The AT-32 phono cartridge played all test bands cleanly on the Shure Obstacle Course--Era III. On the Shure Obstacle Course--Era IV, the cartridge began to have some difficulty with level 4 of both the harp and flute and the flute and bells test bands, where an intermodulation type of distortion was becoming evident. In general, the AT-32 performed exceedingly well since only on rare occasions is a commercially available phonograph record cut at a velocity greater than 20 cm/S. The level 4 test bands of the harp and flute and flute and bells are recorded at velocities greater than 40 cm/S.
Use and Listening Tests
Listening tests were performed both before and after measurement. Without a doubt, the AT-32 is a superior phono cartridge with a well-defined and tight bass, excellent applause definition, first rate sonic clarity, excellent transient response, and lack of detectable coloration, particularly when reproducing high recorded levels. I was especially impressed with its ability to cleanly repro duce the cannon fire on the Tchaikovsky 1812 recording (Telarc DG-10041).
The excellence of the AT-32 was never more evident than when it was playing dbx-encoded records, where the record surface noise was not present to compete with the recorded music, thus making our aural evaluation of the phono cartridge that much easier. All in all, the AT-32 will have no difficulty in maintaining a position among the very top moving-coil phono cartridges.
-B.V. Pisha
( Audio magazine, Dec. 1981)
Also see:
Audio-Technica AT160ML Cartridge (Equip. Profile, Sept. 1984)
audio-talk from audio-technica -- Number 7 in a Series (ad, Sept. 1984)
ADC Model LMF-2 Tonearm & ZLM Phono Cartridge (Jan. 1979)
Audio-Technica AT666EX Disc Stabilizer (Jan. 1983)
= = = =