MANUFACTURER'S SPECIFICATIONS:
Stylus: Naked diamond (no mounting bushing), 0.2 x 0.7 mils. Frequency Response: 15-25,000 ± 3 dB, 50 to 10,000 ± 1.5 dB. Channel Separation: Better than 25 dB at 1000 Hz; better than 20 dB between 500 and 10,000 Hz. Stylus Force: 1-2 grams. Output Voltage: 1 mV/cm/sec.
Load Resistance: 47,000 ohms. Vertical Tracking Angle: 15 deg.
Weight: 8.5 grams.
Price: $69.95.
The B & O cartridge employs a radically different design for a moving-iron model in that it has a “X” mounted on the end of the stylus bar. The tips of the x are disposed adjacent to four pole pieces around which are the two pairs of coils.
As the stylus follows the groove, the movements of the cross in the magnetic fields generate signals in the coils, which are in a balanced push-pull circuit that minimizes external hum fields and ensures low distortion. A similar model fitted with a conical stylus is known as SP 10, with a tip radius of 0.6 mils.
The cartridge is of molded plastic construction, with the coils and magnets enclosed. The stylus assembly with its "micro cross" is carried in a metal shell which slips over the plastic body, and the stylus arm is protected by a clear plastic cone.
The mounting lugs are part of the plastic molding, and a separable 3-degree plastic wedge is provided for mounting in the arm of an automatic turntable to ensure an average vertical tracking angle of 15 deg. throughout a stack of records--the variations being from 18 deg. on the first record, 15 on the fifth, and 12 on the tenth. The wedge is not used when mounting in a transcription arm. Five terminal pins are provided so that a separate ground can be connected when a fifth wire is available in the arm. Otherwise, a shorting spring may be fixed to the ground pin and one of the output ground pins.
Performance
Frequency response was measured using a CBS-100 record, with the result shown in Fig. 2, which also shows crosstalk between the two channels. Figure 1 shows square-wave response from CBS STR-110, which also provides IM measurement grooves at five increasing levels using 400 and 4000 Hz in the lateral mode, five levels using 200 and 4000 Hz, lateral, and three levels each in the vertical mode at each pair of frequencies.
Since we have very little experience with these measurements, we will only give a distortion figure for the lateral +9 level at 200 and 4000 Hz-2.0 per cent-and for the vertical +3 level at the same pair of frequencies-10.0 percent. Future measurements on other cartridges may be compared with these as they are published.
Fig. 1--Square-wave response.
Regardless of the apparently high IM figures, we have little to compare them with, so we can only say that the cartridge in use gave an excellent account of itself, comparing favorably with other well-known models with a possible edginess on very high frequencies. We played the Deutsche Grammophon 139010, "Pictures at an Exhibition," with the Berlin Philharmonic Orchestra-one of our favorite test records--and could find no fault whatever with the reproduction. We also played RCA's "Alexander Nevsky" a heavily modulated selection--and found it reproduced excellently. We noticed the edginess in some solo violin numbers in other recordings, and in a few passages cymbals were not as crisp as we would expect. On the whole, however, reproduction would satisfy most any music lover.
Frequency response is seen to be better than specifications, with response being within 1 dB from 40 to 15,000 Hz. There were two different peaks in the two channels, one of 1.5 dB at 17 kHz, and the other of 2 dB at 19 kHz. Using the wide range pickup response record with its band from 500 to 50,000 Hz, we found response was clown 5 dB at 25 kHz. Separation varies from 15 dB at 40 Hz to a range from 23 to 25 dB from 150 to 9000 Hz, then reducing to 10 dB at 20 kHz.
Outputs and frequency responses from the two channels were within ±1 dB except as noted heretofore.
Fig. 2--Frequency response.
The thorough and complete measurement of cartridges involves hundreds of separate observations, many of which are beyond the facilities of this observer's laboratory. However, for the needs of the average user, our figures should be sufficient.
-C.G.McP.
(Audio magazine, Oct. 1970)
Also see:
B&O MMC 20CL Phono Cartridge (Equip. Profile, Mar. 1980)
Bang & Olufsen SP-12 phono cartridge (ad, Oct. 1970)
Azden GM-P5L Cartridge (Jan. 1987)
ADC Model LMF-2 Tonearm & ZLM Phono Cartridge (Jan. 1979)
Audio-Technica AT160ML Cartridge (Sept. 1984)
Bang & Olufsen Beogram CD X Compact Disc Player (Mar. 1986)
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