Piezoelectric Element In New Stat-Brush -- The Stat-Brush is a new antistatic
record-cleaning device available from Le-Bo Products. It consists of a velvet
cleaning head with an attached brush mounted on a handle. A piezoelectric element,
activated by a switch on the handle, puts an electric charge on the velvet
head, neutralizing the static charge on the record surface. The brush traps
the dust loosened by the charged head. The Stat-Brush is first applied to a
spinning record near the la bel and then slowly drawn toward the rim while
the user presses and releases the switch several times. Price: about $25.
Disc-only Preamp from Accuphase -- The Accuphase C-220 Stereo Disc Equalizer is essentially a precision RIAA preamplifier for disc program sources. It includes a "head" pre-preamplifier for use with moving-coil cartridges, but it can also be used with other types of magnetic phono cartridges. The input impedance of the C-220 can be selected at 100, 30,000, 47,000, or 100,000 ohms when not using the head amp; with the head amp on, input impedance is fixed at 100 ohms. Two sets of phono inputs are provided; in addition, there are jacks that accept the output of the regular system preamplifier and feed it to the power amplifier. "Class-A" push-pull circuitry is used throughout the C-220. Controls include a row of pushbutton switches for power, disc 1 or disc 2, head amp on/off, and input impedance for discs 1 and 2 as well as rotary step-type balance and volume controls.
With the head amp on, the input sensitivity of the C-220 is 0.1 millivolt (mV); with it off, sensitivity is 2 mV. The head-amp input is de signed for a maximum signal of 20 mV, and the maximum phono input without the head amp is 400 mV. The main output of the C-220 is rated to deliver 2 volts rms at maximum volume setting (output impedance is 200 ohms).
Maximum output is 10 volts. The frequency response of the C-220 is 20 to 20,000 Hz ±0.2 dB; total harmonic distortion is 0.01 percent at rated output over this range of frequency.
The signal-to-noise ratios (IHF A weighting) are 72 dB with the head amp and 85 dB with out (at rated output). Approximate dimensions of the rack-mounting model of the C-220 (Type A) are 3 1/4 x 19 x 13 1/2 inches; the Type B (non-rack-mounting) measures 3 1/4 x 17 1/2 x 13 3/4 inches. Price: under $900.
Sound Concepts' Time-delay Unit Has Reverb Function -- The SD-550 from Sound Concepts is a time-delay system for ambience synthesis in audio systems. Utilizing analog shift-register integrated circuits (bucket brigades) for its de lay action, the SD-550 can produce between 5 and 100 milliseconds of delay between front and rear speakers. A front-panel control permits the delayed rear-speaker signal to be mixed with the front-speaker signal if desired. In addition, between 0 and 90 percent reverberation can be applied to the input signal.
A high-frequency roll-off control is provided, and the rear-speaker level is adjustable. The delay circuitry incorporates a two-to-one compander to insure adequate signal-to-noise levels in the rear channels. Slide controls are provided for delay time, reverberation, high-frequency roll-off, front mix level, and rear-speaker level. The front-panel control complement is rounded out by four rocker switches which select delay range, rear-speaker output, front-speaker output, and in put source. The SD-550 can be used with mono, stereo, or quadraphonic signal sources; rear-channel quad signals can be passed unadulterated or processed with delay and/or reverb. A rack-panel version of the SD-550 is available. Dimensions are 3 1/2 x 15 1/4 (19 for rack unit) x 9 inches. Price: $675 (standard or rack mount).
Audio Buff for Dirty Dustcovers -- For those of you with well-worn and soiled turntable dustcovers, Elpa Marketing Industries is introducing Audio Buff, a plastic cleaning and polishing kit. Audio Buff Cleaner is a nontoxic and antistatic formulation for cleaning and dusting clear plastic materials; the complementary Audio Buff Polish is in tended to protect and restore maximum transparency to the surfaces. The cleaner and polish are sold together in 4-ounce bottles. Price for both: about $5.
Sansui Turntable Has Fluid-damped Tone Arm -- A new direct-drive turntable, the SR-838, is available from Sansui. The SR-838 has a twenty-pole brushless d.c. motor, the speed of which is servo-controlled by a phase-locked-loop circuit incorporating a quartz-crystal oscillator. The headshell of the "S"-shaped tone arm has gold-plated contacts for headshell connections, and the arm shaft is filled with a damping resin. The arm features a "mass-concentrated fulcrum" pivot assembly in which substantial mass is concentrated at the tone-arm fulcrum for improved stability. Tracking force is adjusted with a rotating counterweight calibrated in tenths of a gram. All controls for the SR-838 are located on a panel at the front of the turn table base; these include pushbutton switches for power, speed (33 1/3 and 45 rpm), and engagement of the quartz-servo circuit, as well as a pitch control and a cueing lever. Pitch is adjustable within ±2.5 percent. The SR-838 has less than 0.025 percent wow and flutter, and the speed deviation is under 0.002 percent. Rumble is more than 72 dB below the signal level. The SR-838 has a 2-inch-thick solid board base finished with black lacquer, and rubber feet are provided for feedback insulation. The hinged dustcover is removable. Approximate dimensions of the SR-838 are 6 3/4 x 19 1/2 x 15 1/2 inches, and weight is about 28 pounds. Price: $390.
PSE Equipment Has Individual Test Data--Professional Systems Engineering has introduced a new preamplifier and power amplifier, the Studio One and Studio Two. The Studio One preamp, a class-A design utilizing discrete components exclusively, features bass and treble tone controls, each with four selectable turnover frequencies spaced at octave intervals: 100, 200, 400, and 800 Hz for the bass and 1,500, 3,000, 6,000, and 12,000 Hz for the treble. Up to 15 dB of boost or attenuation is available from each control, and a pushbutton "tone" switch is provided for bypassing the controls entirely. Regular low- and high-frequency filters are also pro vided. The Studio One has built-in r.f.-rejection circuitry, and all a.c. wiring is isolated from the amplifier stages. Total harmonic distortion is under 0.01 percent from 20 to 20,000 Hz for a 2-volt output. Slew rate is over 50 volts per microsecond, and signal out put at the onset of clipping is 17 volts rms.
The signal-to-noise ratio for the phono preamp is over 88 dB for a 10-millivolt, 1,000-Hz input (IHF A weighting); for the high-level section it is 98 dB for a 2-volt out put. Dimensions of the Studio One are 3 1/2 x 18 x 10 inches.
Also new from PSE is the Studio Two power amplifier, a class-AB all-discrete device. Rated to deliver 80 watts per channel continuous power into 8 ohms from 20 to 20,000 Hz, the Studio Two has less than 0.02 percent total harmonic distortion over this band. The 4-ohm power rating is 140 watts with 0.04 percent total harmonic distortion. The clipping point is 100 watts per channel into 8 ohms (both channels driven). Sensitivity is 1.2 volts for an output of 100 watts (8-ohm load). The slew rate of the Studio Two is over 100 volts per microsecond, and the signal-to-noise ratio at rated output is over 100 dB. The unit is the same size as the Studio One except for an added 1/2 inch of depth.
Each Studio One and Studio Two released for sale is individually tested, and the test results are packed in the unit's carton. Price of the Studio One and Studio Two: $495 each.
New Low-cost Speaker Systems from AR -- The new AR-15 from Acoustic Research (shown) is a two-way acoustic-suspension speaker system of bookshelf size utilizing an 8-inch woofer and 1-inch dome tweeter. The two drivers are crossed over at 1,700 Hz, and there is a three-position "contour" control for the tweeter (nominal attenuation is 6 dB in 3-dB increments). The AR-15 is said to have 180-degree dispersion up to 15,000 Hz; the speaker's power response is nearly flat up to 15,000 Hz (down 2 dB at 18,000 Hz). On-axis frequency response is 48 to 24,000 Hz ±3 dB.
The AR-15, which has a nominal 8-ohm impedance, will produce a sound-pressure level of 86 dB at 1 meter on axis when driven with 1 watt. The manufacturer recommends that it be used with amplifiers delivering be tween 15 and 100 watts per channel continuous power. Dimensions of the AR-IS are 21 1/2 x 11 3-4 x 7 3/4 inches and weight is 24 pounds. The cabinet is of oiled-walnut veneer, and a black foam grille is provided. Price: $130.
AR is also offering the AR-18, a smaller bookshelf system employing an 8-inch woofer and 11/4-inch radiator in an acoustic-suspension enclosure. A two position tweeter-level control is provided. On-axis response is 58 to 21,000 Hz ±2 dB, and the impedance is a nominal 8 ohms. The recommended amplifier power range is 15 to 100 watts per channel continuous. The cabinet, finished in walnut-grain vinyl veneer, measures 16 1/2 x 9 1/4 x 6 1/4 inches, and the system weighs 13 1/2 pounds. The AR-18 is sold only in pairs. Price: $130 per pair.
Kenwood's Top-of-line Integrated Amp
Kenwood's new top-of-the-line integrated amplifier is the KA-9100, which features a three-position supplementary gain control that raises or lowers gain by 10 dB. This feature is primarily intended to compensate for variations in signal level from different accessory devices. The KA-9100 also has a two-position loudness-compensation switch plus separate power meters for each channel with adjustable ranges of 0 to 3 or 0 to 100 watts.
Independent power supplies are provided for each channel of the power amplifier, and the preamplifier also has its own power supply. A tape-through circuit permits tape-to-tape dubbing while the amplifier is in use playing a third program source. The tone controls have turnover points of 400 and 3,000 Hz and can be bypassed with a switch on the front panel.
The unit has rear-panel jacks for preamplifier output and power-amplifier input so that either may be used independently.
The KA-9100 is rated at 90 watts per channel continuous power into 8 ohms from 20 to 20,000 Hz. Total harmonic and intermodulation distortion are 0.03 percent each or less.
Phono sensitivity is 2.5 millivolts with a signal-to-noise ratio of 83 dB for the phono in puts. The high-level inputs have a 150-millivolt sensitivity and a 100-dB signal-to-noise ratio (IHF A weighting used on noise figures).
The low- and high-frequency filters, cutting off at 18 and 8,000 Hz, respectively, have slopes of 12 dB per octave. Approximate dimensions of the KA-9100 are 6 x 17 x 15 inches; weight is about 37 pounds. Price: $500.
Impedance Adjustable On AEI Speaker -- The Evolution 1 is a new two-way acoustic-suspension loudspeaker system from Audio Engineering, Inc. The system's 10-inch woofer and 1-inch dome tweeter are crossed over at 1,500 Hz with a novel circuit said to be capable of handling large amounts of power.
The impedance can be adjusted to nominal values of 4 or 8 ohms (which affects the low-bass amplitudes) and a two-position level control is provided for controlling the high-frequency response of the system.
The frequency response of the Evolution 1 in a non-reverberant field is 35 to 17,000 Hz +1.5,-2 dB. It will produce a sound-pressure level of 88 dB at 1 meter with a 1-watt input at 4 ohms. Minimum continuous power input is 15 watts per channel into 4 ohms, and the sys tem can handle up to 150 watts of short-term music power. An amplifier delivering 50 watts per channel continuous power is recommended. The Evolution 1 is available in walnut-veneer and vinyl finishes and has dimensions of 25 x 15 1/2 x 9 1/2 inches. Weight is about 43 pounds. Price: $137 in vinyl, $156 in walnut.
Sansui Tuner Has Recording-level Reference Switch -- Sansui's TU 717 AM/FM stereo tuner, styled in black with a contrasting white dial face, has four lever switches for power, inter-station-noise muting, i.f. bandwidth, and multiplex noise cancelation. A fifth switch connects an internal 400-Hz oscillator to the out put to provide a fixed reference for the adjustment of recording levels on tape machines. Pushbuttons control AM, FM mono, and FM auto (in the "auto" mode, the tuner automatically switches from mono to stereo when tuned to a stereo broadcast). A flywheel tuning knob and an output-level control round out the control complement. The FM dial scale is linearly calibrated, and LED's indicate AM, FM, and FM stereo. Signal-strength and channel-center meters are located above the scale.
The TU-717 has a usable sensitivity of 10.1 dBf; 50-dB quieting sensitivity is 13 dBf in mono and 37.2 dBf in stereo. The tuner frequency response is 30 to 15,000 Hz +1,-2 dB, and distortion is 0.07 percent in both mono and stereo when the wide i.f. band width is used. Alternate-channel selectivity is 80 dB (narrow i.f. bandwidth), and the cap ture ratio is 1.2 dB. The stereo separation is 45 dB. The ultimate signal-to-noise ratio of the TU-717 is 80 dB in mono and 77 dB in stereo. A rack-mounting adapter with grab handles is provided with the tuner (shown); this hardware is user-installed. Dimensions are 6.25 x 17 x 15 3/8 inches. With the rack-mounting adapter, dimensions are about 6.4 x 19 x 16 1/2 inches. Price: $320.
Wide-dispersion Tweeter in New Infinity Speaker
The Qa is a two-way air-suspension speaker system from Infinity utilizing their electro magnetic induction tweeter (EMIT). The tweeter, with effective radiating dimensions of 1 x 1/2 inch, is said to provide exceptionally wide lateral dispersion. The 10-inch woofer has a lightweight cone coupled to an unusually heavy surround. The crossover frequency is 2,500 Hz.
The frequency response of the Qa is 42 to 32,000 Hz ±3 dB, and the nominal impedance is 4 ohms. Amplifiers delivering between 15 and 150 watts per channel continuous power are recommended for driving the Qa. Infinity suggests that the Qa be raised 12 inches above the floor for optimum performance, and optional pedestals are offered for this purpose. The cabinet measures 25 x 14 1/2 x 12 inches. Price of the Qa: about $140. A pair of pedestals costs $40.
Library of Congress Offers Brief History Of Phonograph -- To commemorate the centennial of the Edison phonograph, the Library of Congress is offering a forty-page booklet titled A Wonderful Invention: A Brief History of the Phonograph from Tinfoil to the LP. Written by James T. Smart and Jon W. Newsom of the Library, it includes a descriptive history and a listing of items shown at the Library of Congress exhibition on sound recording, which closed September 30. Brief discussions are devoted to such topics as the early inventions of Edison, Bell, and Berliner, the development of the recording industry (with all its accompanying legal battles), and the launching of the long-playing record. The booklet has twenty black-and-white illustrations. It is available from the Information Office, Library of Congress, Washington, D.C. 20540. Price: $2.50.
NOTICE: All product descriptions and specifications quoted in these columns are based on materials sup plied 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.
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Also see: Pioneer SX1250 receiver
AUDIO QUESTIONS and ANSWERS: Advice on readers' technical problems