|Home | Audio Magazine | Stereo Review magazine | Good Sound | Troubleshooting
Departments | Features | ADs | Equipment | Music/Recordings | History
Frequency Response: 20 to 25,000 Hz.
Output Voltage: 3.5 mV per channel at 1000 Hz. Channel Balance: Within 2 dB. Tracking Force: 3/4 to 1 1/2 grams. Input Impedance: 47,000 ohms (nominal); can be used up to 70,000 ohms without audible change in response. Inductance: 720 mH. D.C. Resistance: 630 ohms. Typical Trackability at 1 gram: 400 Hz-28 cm/ sec; 1000 Hz-35 cm/sec; 5000 Hz-30 cm/sec; 10,000 Hz-22 cm/sec. Stylus: Elliptical diamond, .0002 x .0007 in. radii. (.0007 spherical stylus available on V-15 Type II-7).
Weight: 6.8 grams.
The Shure line of cartridges has improved and improved over the years since its introduction of the monophonic "Dynetic" which was introduced in 1957. The "V-15" of a year or so ago was a big step forward, to be followed by the Type II, which has been a standard for some time. Now they have introduced the "Improved" V-15 Type II, and it does exhibit a number of improvements, primarily to the ear rather than to measuring instruments. To the eye, the only apparent difference is the possibly shinier housing and the red lettering of "Shure" and "Super-Track" instead of the black on the earlier model. But then, the principal use to which we put phono cartridges is to listen to them rather than to measure them-a procedure which is complicated, even if you already have the equipment.
Before doing any listening, however, we first went through the usual measuring procedures, comparing an original "unimproved" V-15 Type II with the "improved" model. Let it be said here and now that both channels of each cartridge came within less than 0.5 dB throughout the entire range from 20 to 20,000 Hz when playing a CBS Labs STR-100 test record. And from 20 to 8000 Hz, both cartridges measured alike within 1 dB. The "improved" cartridge followed the same general curve shape above 8000 Hz as did the original Type II, but reached some 4 dB higher in response at 20,000 Hz. Both models showed a dip starting from 1000 Hz and reaching a maximum of 4 dB at 8000 Hz, which is not at all unusual with cartridges. To obtain the curves shown in Fig. 2, the cartridge outputs were fed singly through an equalized pre amp consisting of an N5709T Signetics integrated circuit with suitable equalization so as to follow the RIAA curve throughout the spectrum, except that there is no "rolloff" above 1000 Hz as would be required for a phono pre amp. This test amplifier deviates a maximum of 0.8 dB from the RIAA curve at frequencies below 50 Hz.
Thus it should provide a curve which is essentially a straight line from 20 to 20,000 Hz when playing the STR100 test record with one exception.
The record is cut with a curve represented by two straight lines which intersect at 500 Hz-below that frequency the record drops off at 6 dB per octave, while above it is flat. Thus the output cannot be flat when played through an amplifier which is compensated--as is the usual case--with RC networks, since they invariably cause a curvature at the intersection, resulting in a "bump" in the output of about 3 dB at 500 Hz. A shunt resonant circuit across the output of the test preamp was used to eliminate this bump. This circuit consisted of an inductance of 100 mH, a capacitance of 1.1 µF, and a resistor of 68 ohms. This was placed across the output of the equalized preamp after its output resistor of 100 ohms, and before feeding into the a.f. voltmeter level-setting network of 10,000 ohms. All of this circuitry is shown in Fig. 3.
The net result is to provide a flat response across the range of the "bump" caused by the recording curve in the STR-100 record.
Channel separation is also shown on Fig. 2, and ranges from 13 dB at 20 Hz to 25 dB at 50 Hz, and then remains around 25 to 2000 Hz, at which point it decreases gradually to 15.5 at 18,000 Hz, then increases slightly to 19 dB at 20,000 Hz. Since a level change of 6 dB is completely adequate to move the apparent source of the sound from one speaker to the other, this separation (which is the result of measurement rather than specification) is excellent. Output measured 0.93 mV for a stylus velocity of 1 cm/sec at 1000 Hz.
After several hours of comparative listening between the "improved" and normal V-15 Type II cartridges, we are convinced that the new one is easily capable of handling higher stylus velocities than were possible heretofore. This is noticeable most readily in the type of music of which this observer is not likely to be in the habit of playing. Most classical music is recorded with a reasonable level, and in fact, we have rarely measured any classical recordings which exceeded a maximum stylus velocity of 20 cm/sec. On the other hand, we have measured velocities as high as 44 cm/sec on some of the louder "rock" records, and on these, the improved V-15 sounded much cleaner than did the older cartridge, and this was with a stylus force of 1 gram, which is sort of a median between the manufacturer's recommended "3/4 to 1 1/2 grams" of stylus force. Thus the V-15 Type II Improved cartridge is strongly recommended to all who are likely to play those recordings which are likely to be cut at the maximum stylus velocities.
(Audio magazine; Mar. 1970)
= = = =
Prev. | Next