Transcriptors "Vestigal" Tone Arm
TRANSCRIPTORS (Ireland) Limited is importing the "Vestigal" Tone Arm, a new design employing a vertical pivot assembly located very close to the phono cartridge to reduce effective tone arm mass in the vertical direction as much as possible. Balancing the arm and applying stylus force is accomplished through a string-and-weight system, with the string running the length of the arm from the hinged cartridge shell to the tone-arm upright. There it is attached to a pivoted drum that keeps a constant tension on the string. The amount of tension is determined by an adjustable counterweight that moves along a threaded shaft attached to the drum's circumference.
Other adjustments provided for include means to bring the horizontal rotation of the arm parallel to the disc surface, height adjustment, stylus overhang, anti-skating compensation, and a stop to keep the arm from swinging into the la bel area of the disc. The low effective mass of the arm is claimed to result in negligible susceptibility to acoustic feed back or record-warp effects, and it is further claimed that tracking forces as low as 1/10 of a gram may be attained. The arm is of all-metal construction, and uses jewel-bearing pivots throughout.
Price: approximately $100.
ADC Model WDDS-12 Speaker System
AUDIO DYNAMICS CORP. has a new speaker system, the Pritchard WDDS 12 (the initials stand for "wide dispersion/discrete source"). The system is a multidirectional radiator, with the woofer (a 12-inch air-suspension type) facing directly forward and the tweeters, of which there are four, angled slightly to either side on subsections of the enclosure's three-part front panel. Two types of tweeters are used, both having Mylar dome diaphragms, but with diameters of 11/2 and 3/4 inches. One of each type is mounted on either side of the enclosure.
Frequency response is 30 to 25,000 Hz ±2 dB, and varies no more than 3 dB from on-axis response over a lateral angle of 120 degrees. Crossover between the woofer and tweeters takes place gradually over the range of 600 to 5,000 Hz. The nominal impedance of the sys tem is 6 ohms. A four-position contour switch offers a choice of flat response, high or mid frequencies reduced by approximately 2 1/2 dB, or both reduced by that amount. The Pritchard system has a sealed enclosure of oiled walnut with a foam grille. Dimensions: 26 x 14 1/2 x 12 inches. Price: $350. An optional pedestal base (shown) finished in matte-black aluminum is $25.
Dokorder MK-50 Dolby Cassette Deck
A NEW stereo cassette deck has been introduced by Dokorder. The Model M K-50 has Dolby B-Type noise reduction, a tape selector with positions for "normal" and chromium dioxide, and a "Cue & Review" function that permits direct switching from play to fast for ward and rewind (to assist in locating specific points on the tape). Slider-type adjustments are used for setting recording and playback levels; these are separate for each channel. Push-key trans port controls are provided, including pause and eject functions. The micro phone inputs and a stereo headphone jack are recessed into the trim strip on the deck's front edge. Frequency response is given as 30 to 15,000 Hz with standard tape and 30 to 18,000 Hz with chromium dioxide. Signal-to-noise ratio is better than 60 dB with Dolby, 50 dB without; wow and flutter are under 0.1 per cent. A C-60 cassette can be fast wound in less than 100 seconds. Dimensions of the deck are 16 x 11 3/4 x 4 inches. Price: $249.95. A wood base is included.
Heathkit AD-1013 Four-Channel Audio Scope
HEATH'S new four-channel audio scope consists of a 3-inch cathode-ray oscilloscope with inputs for up to four audio channels and for an FM multipath display, plus a self-contained audio-frequency generator to provide test and calibration signals. The multifunction instrument is housed in a cabinet that matches the size and general styling of the Heath AR-1500 receiver. The scope's display modes, which are chosen by an eight-position selector switch, include signal-strength vectors for each of the four channels (which can be selected separately) and the familiar "scrambled-egg" pattern for stereo. For displaying all four channels simultaneously, an internal circuit assigns each of the inputs its own quadrant on the scope screen.
The FM multipath display, which is also useful for determining signal strength and channel center, receives its input from tuners and receivers that have the appropriate oscilloscope outputs. (An adaptor kit that adds these jacks to the Heath AR-15 receiver or AJ-15 tuner is available from Heath for $24.95.) The AD-1013 will also function as a normal a.c. scope (with triggered sweep) for inputs connected to the five-way binding posts on the front panel. Sweep range is selected by a four-position decade switch and an associated continuously variable control. The audio-generator section is continuously variable and roughly calibrated at eight important frequencies from 20 to 20,000 Hz. Out put is held constant within 0.25 dB over the range covered, and the level control affects the signal available from the front- and rear-panel output jacks. The AD-1013 also has trace-position and gain controls (vertical and horizontal) and focus and intensity adjustments. The sensitivity of the oscilloscope is 25 milli volts (peak to peak) per centimeter (1 volt per centimeter in the four-channel display mode). Input impedance is 100,000 ohms, and the frequency response is 5 Hz to 200 kHz ±3 dB. Overall dimensions of the AD-1013 are 18 1 1/2 x 5 1/8 x 13 1/2 inches. It is available only in kit form for $199.95, with a walnut cabinet costing $24.95 additional.
BSR Model FEW-2 Frequency Equalizer
THE Metrotec division of BSR is offering a new addition to its line of multi band tone controls. The Model FEW-2 acts in five two-octave bands with center frequencies of 60, 240, 1,000, 3,500, and 10,000 Hz, with a continuously vari able amplitude adjustment range of ±12 dB at each setting. It is a stereo device, with separate slider-type controls for each channel. Tape-monitor jacks and switching are provided to retain these facilities for any system in which the unit is installed in the tape-monitor loop.
The equalizer has less than 0.007 per cent distortion and a signal-to-noise ratio of 80 dB. Input impedance is 75,000 ohms, with a 10-ohm output impedance.
The built-in amplification stages provide approximately unity gain. The maximum output is 9 volts. The unit is supplied with a wood cabinet and a translucent flip-down front cover that protects the control settings from being accidentally disturbed. Dimensions are 8 3/8 x 4 5/8 x 5 1/2 inches. Price: $99.95. Other BSR equalizers scheduled for introduction soon are a stereo unit with twelve bands per channel (Model FEW-3) and a four-channel version of the FEW-2.
Pioneer SX-1010 AM/Stereo FM Receiver
PIONEER'S most powerful stereo receiver, the new SX-1010, is capable of 100 watts continuous output per channel (8-ohm loads, both channels driven simultaneously) at any frequency from 20 to 20,000 Hz. Its special operating features include two sets of step-type bass and treble controls acting at 50 and 100 Hz (bass) and 10,000 and 20,000 Hz (treble), two magnetic-phono inputs, and connectors and switching for two stereo tape decks (with dubbing possible from one to the other). There is also switching to accommodate an external Dolby noise-reduction unit, and a four-channel adapter. A tone-control DEFEAT switch is also provided. The front panel has phone jacks for two stereo headsets and inputs for two microphones. Up to three pairs of speakers can be handled. The receiver has switchable FM interstation noise muting, 6-dB-per-octave high- and low-cut filters, and audio-muting.
Additional amplifier specifications for the SX-1010 include harmonic and intermodulation distortion of less than 0.1 per cent at any power level up to rated out put and signal-to-noise ratios of better than 95 (high-level inputs) and 70 (phono inputs) dB. The FM section has an IHF sensitivity of 1.7 microvolts, a 1-dB cap ture ratio, 55-dB AM suppression, and stereo separation exceeding 30 dB from 50 to 10,000 Hz. Image, i.f., and spurious-response rejection are all 110 dB.
Harmonic distortion for stereo reception is under 0.3 per cent. The SX-1010 has approximate dimensions of 20 1/2 x 7 x 17 1/2 inches. It is supplied with a walnut cabinet. Price: $699.95.
Ampex Pre-recorded Tape Catalog
A COMPLETE listing of the Ampex line of prerecorded tapes for 1974 is now available in the form of a sixty-four-page mail-order catalog. All tape formats are represented, on such labels as Deutsche Grammophon, London, Philips, Van guard, RCA, Blue Thumb, Buddah, Kama Sutra, Mercury, Motown, Project 3, and over one hundred others, for a total of more than 1,500 selections, some of which are available in four channel or with Dolby B-Type noise-reduction encoding. A special section is devoted to open-reel tapes, which are becoming difficult to find in retail outlets.
The catalog is offered as part of the Ampex Shopper's Service, which makes the company's complete line of consumer tape products available on a mail order basis, with no membership fee or minimum purchase required. Supplementary mailings keep customers up to date on new Ampex releases, and discounts on tapes are offered periodically.
The mail-order service honors major credit cards. The catalog is free from:
Ampex Catalog Offer, Dept. A200 SR, Box 178, Elk Grove Village, Ill. 60007.
CTS Loudspeaker Catalog
CTS, one of the largest suppliers of "raw" loudspeakers to the audio and musical-instrument industries, has pre pared a seven-page catalog describing the fifty-five models available directly to consumers from CTS retail dealers.
Among the "high-fidelity" models are tweeters, mid- and full-range drivers, and woofers ranging in diameter from 8 to 12 inches. All of these are cone-type units, with nominal impedances of 8 ohms. Also listed are speakers for such special applications as public address, car and aircraft installation, and musical-instrument reproduction. CTS also offers 12- and 15-inch "heavy-duty" drivers in full-range and woofer models, with exceptionally high sensitivity and power-handling capabilities of 100 watts continuous.
For those interested in complete speaker systems, the catalog lists ten recommended designs (in one-, two-, and three-way configurations) based on CTS components. These can be purchased as system "packages" containing drivers, crossover-network components, wiring diagrams, and recommended enclosure dimensions. (The purchaser can build the enclosures or adapt existing ones.)
The catalog is available free of charge at CTS dealers or by writing: CTS of Paducah, Inc., Dept. SR, 1565 North 8th Street, Paducah, Ky. 42001.
Also see:
TECHNICAL TALK--What Is Noise?
AUDIO QUESTIONS and ANSWERS--Advice on readers' technical problems LARRY KLEIN