NEW PRODUCTS: Roundup of latest audio equipment
and accessories.
Robins' Eight -track Tape Cleaner
The Robins "Soundtrack Scrubber" contains a mildly abrasive polyester belt designed to clean the tape within an eight -track cartridge. In operation, the device's specially shaped end is inserted into the loading slot of an eight -track record/player, and the tape cartridge to be cleaned is in turn inserted into the Scrubber's other end. A linkage within the Scrubber drives the cartridge from the ma chine's capstan, and the tape is pressed against the polyester belt and cleaned as it cycles through the cartridge. The Soundtrack Scrubber's cleaning belt is sufficiently long to clean about two hundred cartridges. After each cartridge, the belt is advanced a little to bring an unsoiled spot into contact with the tape. A refill spool of cleaning belt is supplied with the device. The Soundtrack Scrubber, Robins catalog No. 30-001, costs $11.99.
McKay Dymek Broadband Antenna
The DA 100 is a preamplified antenna covering the radio spectrum from 50 kHz to 30 MHz, including the AM band. It consists of a collapsible 4-foot whip antenna mounted on a small weatherproof box and a separate a.c. powered electronics module. The antenna it self is to be installed in some (preferably) high place outside. The electronics unit is located indoors. The performance of the DA 100 is said to equal or exceed that of the usual long-wire antenna typical in such applications. It is an omnidirectional device having an output impedance of 50 ohms. The electronics module measures 9 x 5 x 9. Price: $125 by direct order from the factory only.
Jensen Speaker For Budget Systems
At about $60, Jensen's Model 20 is intend ed for audio installations of modest cost or as remote speakers. The 8 -ohm system has an 8 -inch air -suspension woofer and a 2 -inch cone tweeter to provide a stated frequency range of 35 to 20,000 Hz. The manufacturer advises that at least 10 watts of amplifier power per channel is required to drive the system. The maximum power rating is 40 watts. The Mod el 20 has dimensions of 1814 x 11 x 81/2 inches and weighs 18 pounds. Finish is walnut -grain vinyl with a sculpted grille.
Technics Turntable Has Professional Features
The Technics "Professional" series of products has been augmented by the SP 10MkII, successor to the SP -10 direct-drive turntable. The new turntable, intended for the broadcast industry as well as the audiophile market, has a start-up time of one -quarter second at 33 1/3 rpm, permitting reliable cueing from standstill. A combination of mechanical and electronic braking systems stops the platter in 0.3 second and prevents it from rotating while stopped.
The three -speed (33 1/3, 45, and 78 rpm) SP 10MkII has a direct-drive motor with speed referenced to a quartz -crystal oscillator and servo -controlled by a phase -locked loop. Speed drift is a maximum of ±0.002 percent under any likely load or drag conditions.
Weighted rms wow and flutter are 0.025 per cent, and rumble is -50 dB by the DIN A standard, -70 dB by DIN B. The full-size platter weighs about 6 1/2 pounds. The electronics for the turntable are contained in a separate power unit, and the main controls (solenoid assisted) are duplicated in a remote-control box supplied. The turntable's dimensions are about 141/2 x 14 1/2 x 4 inches. Approximate price: $700.
Mid-price Receiver From Pioneer
The Model SX-750 occupies approximately the middle ground in Pioneer's new line of AM/FM stereo receivers. Maximum rated output into 8 ohms is 50 watts per channel, 20 to 20,000 Hz, with no more than 0.1 percent harmonic or intermodulation distortion.
Noise is -70 dB for the phono inputs and -90 dB for high-level inputs. The FM section's us able sensitivity is 10.7 dBf (1.9 microvolts); 50 -dB quieting sensitivity is 17.2 dBf (4 microvolts). Other FM specifications include: capture ratio, 1 dB; AM suppression, 55 dB; alternate -channel selectivity, 80 dB; spurious -response rejection, 90 dB. FM frequency response is 30 to 15,000 Hz +0.2, -2 dB, and stereo separation is 30 dB throughout that range.
The SX-750 is distinguished by the silver and white styling of the latest Pioneer receivers. The basic controls-volume, balance,, bass, and treble-are augmented by lever switches for tone -control defeat, high -cut filter, loudness compensation, mode, and tape monitoring and dubbing. There is a stereo-headphone jack and a front-panel microphone input. Most of the input and output connectors are mounted on a horizontal shelf in the rear of the receiver. A walnut-grain vinyl top and walnut -veneer side panels decorate the SX-750, which has approximate dimensions of 19 x 6 x 14 2/3 inches. Approximate price: $400.
Sound Guard
Ball Corporation's "Sound Guard" is a dry lubricant, in liquid spray form, intended to be applied to records and then spread around with a buffing pad to leave a film about five millionths of an inch thick. The film is said to reduce stylus friction-and hence record wear-and to lessen the anti -skating requirements of record players. It is also said to subdue certain types of surface noise. The trade name for the lubricant is "Vac Kote," a substance developed by the Ball Corporation for use on space vehicles. Reportedly, it adheres to the vinylite material of records but not to itself, so that build-up of the substance in record grooves is avoided. One application will last for a number of playings, according to the manufacturer. Sound Guard fluid sufficient for treating about twenty records comes packaged with a pump-spray applicator and a buffing pad. Price: $7.
Threshold Class-A Power Amplifier
A dynamic biasing circuit enables the new Threshold 800A stereo power amplifier to per form as a Class -A device without entailing the high heat and power dissipation usual with Class -A designs. The circuit is a high-speed configuration that is able to follow rapid variations in the input signal and alter the bias accordingly to keep the output transistors in the most linear portion of their transfer characteristic. Under low -signal conditions the bias is reduced enough to limit quiescent current (and hence idling power consumption) to comparatively reasonable amounts. Though thermal requirements are therefore less than they would be for a comparable amplifier without dynamic bias, they are still substantial. The 800A has twenty-four output transistors per channel, and it is cooled by a two-speed fan. The amplifier incorporates a number of protective devices, including comparator circuits that switch the amplifier off when the output waveform deviates too much from that of the input.
Rated power output is 200 watts per channel (8 ohms) from 20 to 20,000 Hz with a maximum of 0.1 percent harmonic and inter-modulation distortion, decreasing at lower power levels. Power consumption at idle is approximately 300 watts. Front -panel facilities include large meters that read average output levels, gain controls, an indicator light to show the status of the thermal circuit breakers, and a "Saturation Control" that sets the threshold of a passive limiter. The limiter is designed to prevent "hard" clipping by rounding the waveform peaks and thus inhibiting the production of high -order distortion products. The amplifier measures approximately 19 x 8 3/4 x 18 1/4 inches overall and weighs about 90 pounds. Price $2,165.
Moving-coil Cartridge with Replaceable Stylus
Superex will be U.S. distributor for the Satin moving -coil cartridges, a line consisting of three models, all of which have user-replaceable styli. The stylus assembly itself consists of the diamond tip, the cantilever, and the pivot/suspension. It is attached to the main body of the cartridge by a magnetic clasp, and the cantilever engages a small met al yoke to which the coils are joined.
The Satin M-117 has a 0.5 -mil conical (spherical) stylus; the M -177E is fitted with a 0.2 x 0.8 -mil elliptical stylus, and the M -177X has a 0.1 x 2.5 -mil Shibata stylus. Frequency response extends from 10 to 25,000 Hz for the M-177, to 40,000 Hz for the M -177E, and to 45,000 Hz for the M -177X. Said to be able to drive most magnetic-phono inputs directly (without the transformer or pre -preamplifier usually required for moving -coil cartridges), the three pickups have outputs between 3 and 3.5 millivolts for a recorded velocity of 5 centimeters per second. For the E and X models, tracking -force range is 0.5 to 1.5 grams; the spherical model's range is 0.75 to 2 grams. All three cartridges weigh 9 grams. Prices: M-177, $140; M -177E, $170; M -117X, $190. Replacement styli are, respectively, $60, $90, and $120. Superex also offers a resistive net work ($30) made by Satin that goes between cartridge and preamplifier, and which is said to provide optimum cartridge damping.
Marjen Speaker System
A relatively new company, Marjen, has brought out a line of three speaker systems, all employing 8-inch woofers and 2-inch cone tweeters in various configurations. A representative system, the Model I, has a single woofer and two such tweeters for a rated frequency response of 44 to 20,000 Hz ±3 dB. The crossover frequency is 2,000 Hz. Recommended amplifier power into the system's nominal 8 -ohm impedance is 10 watts mini mum and 75 watts maximum.
High -frequency output is adjustable on the Model I by means of pushbuttons that provide a ±3 -dB alteration around a designated "flat" setting. The enclosure, measuring 22 x 10 1/2 x 10 1/2 inches, is constructed of solid and veneered pine; grille cloths are available in black or natural. Price: $139. The Marjen Models II and III ($169 and $249, respectively), have generally similar specifications and features flew Products latest audio equipment and accessories with additional tweeters and (Model III) woofers.
Heath catalog
The latest catalog of Heathkit products runs to 96 pages and describes several hundred electronic and electronics -related kits, many of which are designed to be assembled by to tally inexperienced constructors. The Heath product line includes audio equipment (receivers, amplifiers, tuners, tape machines, equalizers, mixers, and speaker systems) spanning a broad range of prices, as well as al ready -assembled turntables, phono cartridges, and headphones. There are also tele vision sets, console radios, musical -instrument amplifiers, and electric organs, all in kit form, together with test equipment, marine and amateur -radio electronics, and automotive and hobby accessories. Catalogs are free from: Heath Company, Dept. 350-04 SR, Benton Harbor, Mich. 49022.
New Four-channel Tape Deck by Akai
A moderately priced four-channel tape deck with track-synchronization facilities (Akai's term is "Quadra-Sync") is being introduced by Akai America as the GX-270DSS. The Quadra-Sync feature permits synchronized recording on all four channels in sequence, enabling the user to "build up" a final recording from separate parts re corded at different times and to replace some parts with others without affecting the rest of the material.
The three-motor, two-speed (7 1/2 and 3 3/4 ips) transport takes 7-inch reels and is sole noid switched. Automatic reverse is provided for playing back stereo tapes, and a pitch control (which operates in both record and play back modes) varies tape speed over a range of ±5 percent. Microphone/line mixing works by two-section knobs for each input channel, with the front sections controlling microphone levels and the rear the line levels.
The machine's record-playback frequency response is 30 to 21,000 Hz ±3 dB at 7 1/2 ips and 30 to 15,000 Hz ±3 dB at 3.75 ips, both with low -noise tape. For a 0 -dB recording level, harmonic distortion is under 1 per cent; signal-to-noise ratio exceeds 54 dB for a 0 -dB recording level. Wow and flutter are less than 0.07 percent at 7 1/2 ips. The GX-270DSS, which comes in a wood case, has dimensions of 17 1/2 x 18 1/2 x 7 1/2 inches. Price: approximately $900.
Kenwood Turntable With Anti-resonance Resin-concrete Base
The semi-automatic KD-2055 has a base molded of Kenwood's new "ARC" (anti-resonance resin concrete) material, a mixture of limestone, glass powder, and polyester res in. The high -density base has substantial mass and a high degree of internal damping, both of which are said to reduce audio-frequency vibration and acoustic feedback. The ARC material resembles polished marble.
The principal automatic feature of the two-speed (33 1/3 and 45 rpm) KD-2055 is an end-of-record tonearm return that also functions (when a pushbutton is pressed) to interrupt play at any point on a record. There is also a damped tonearm cueing mechanism. The KD-2055's arm is a tubular S-shaped design with adjustable anti-skating. The full-size platter is belt -driven, with wow and flutter of less than 0.06 percent and a rumble level lower than -65 dB. Dimensions (with the hinged dust cover supplied) are about 19 x 14 1/4 x 5 3/4 inches. Approximate price: $140.
Allison Model 4
The line of "Stabilized Radiation Loading" speaker systems from Allison Acoustics continues with the Model Four, which is de signed for shelf installation. The Allison practice of positioning the woofer as close as possible to the nearest room boundary is achieved in the Model Four with a top-firing woofer of 8 -inch diameter. Two of the manufacturer's "Convex Diaphragm" tweeters are used, one on each of two angled side panels. The system is meant to be installed with its back abutting a wall. Crossover frequency of the Allison: Four is 2,000 Hz, and the system has a minimum impedance of 6.5 ohms (8 ohms nominal). Minimum recommended amplifier power is 30 watts per channel; a 70 -watt peak input is said to produce an acoustic output of at least 0.5 acoustic watt over most of the frequency range. A three -position switch adjusts the frequency balance of the system from nominally flat to gradual high -frequency rolloff, simulating the overall balance of a typical concert hall. Overall dimensions are approximately 19 1/2 x 11 x 10 inches; finish is oiled walnut. Price: about $175.
NOTICE: All product descriptions and specifications quoted in these columns are based on materials sup pled by the manufacturer.
Recent fluctuations in the value of the dollar will have an effect on the price of merchandise imported into this country. Please be aware that the prices quoted in this issue may be subject to change.
Also see:
TAPE HORIZONS: Sync and Swim, by CRAIG STARK
LETTERS TO THE EDITOR (Feb 1977)
Source: Stereo Review (USA magazine)