Crown Output Control Center and Electronic Crossover/Filter
Crown International offers two accessories of potential interest to owners of elaborate stereo installations. One is the Model 0C-150 stereo output control center, with switching facilities for three stereo amplifiers, three pairs of speakers, and three stereo headsets, including electrostatic headphones. A switch-selected choice of two attenuators is provided for the two front-panel headphone jacks so that headphones can be listened to safely and comfortably at the same volume-control set tings used with speakers. Terminals for electrostatic headphones are on the rear panel; they are always "live" and employ no attenuation. Prominent on the OC- 150's front panel is a pair of 3 1/2-inch meters that indicate power levels passing through the unit. The meters are calibrated in both volts and deci bels and have five pushbutton-selected sensitivity ranges descending in 10-dB steps from 0 to-40 dB, corresponding to full-scale readings from 140 to 1.4 volts on the appropriate voltage scales. Pushbuttons also-choose VU or peak-reading response for the meters. In the peak-reading mode, continuously variable controls set the hold-time characteristics for the meters from zero to infinity (at infinity, for example, the meters will register and "hold" indefinitely the highest level achieved by the incoming program). Except for the meter-amplifiers, the 0C-150 is purely a passive switching device, having no effect on the noise, distortion, and other characteristics of the signals passing through it. The unit's dimensions are 17 x 5 1/4 x 8 1/4 inches.
Price: $299. A walnut cabinet is $45 additional.
Another accessory, the Model VFX-2, is usable as a two-channel electronic crossover or a filter set. For "bi-amp" electronic-cross over operation, the high- and low-frequency controls for both channels are simply set to the desired dividing frequencies. The VFX-2 can also be used for "tri-amp" mono applications if both of its internal filter channels are employed. Rear-panel switches convert the VFX-2 to band-pass-filter duty; the frequency controls are then used to define the lower and upper limits of the pass band. The controls, eight in all, are divided into groups of two for each frequency band of each channel.
One of the two is calibrated in decades and selects the range, while the other is continuously variable from 2.5 to 20. In the rear the VFX-2 has "normal" or phase-inverted out puts for all bands and inputs for balanced or unbalanced sources, with or without level adjustment at the inputs. Rated output of the de vice is at least 6.4 volts into 600 ohms or more, with less than 0.01 percent intermodulation distortion. When set for unity gain, the signal to-noise ratio is 113 dB referred to maximum rated output. The filters have 18-dB-per-octave slopes; an internal modification permits the two channels to be cascaded for correspondingly sharper attenuation characteristics. All inputs and outputs are designed to accept standard 'hi-inch two-conductor phone plugs. Dimensions of the VFX-2 are 19 x 3 1/2 x 5 3/4 inches; adapters permit rack mounting.
Price: $299.
Tandberg 3500X Stereo Tape Deck
The Tandberg 3000 series of medium-price, 7-inch open-reel tape decks now includes the Model 3500X, which employs the company's well-established "crossfield" biasing and "joystick" transport control. The basic ma chine is a quarter-track stereo unit with tape speeds of 7 1/2, 3 3/4, and 1 7/8 ips. In addition to the crossfield bias head, separate erase, re cord, and playback heads permit off-the-tape monitoring, and a front-panel switch expands this capability to provide sound-on-sound and echo. The recording-level meters are peak reading devices, equalized to show the effects of treble boost on the recording signal. The microphone jacks, intended for dynamic microphones, feed inputs whose sensitivity is automatically adjusted to suit the microphone impedance. Input and output level controls are separate, consisting of a total of four sliders. In addition to the joystick transport selector, the 3500X has a pause control. Automatic end-of-tape shutoff is photo-electrically activated. There is a front-panel headphone jack.
Within a tolerance of ±-2 dB, frequency response for the 3500X is 30 to 22,000 Hz at 7 1/2 ips, 40 to 18,000 Hz at 3 3/4 ips, and 40 to 9,000 Hz at 1 7/8 ips. For a playback distortion of 3 percent (corresponding to a 0-VU re cording level), the A-weighted signal-to-noise ratio is 64 dB at 7 1/2 ips.
Wow and flutter for the three speeds are, in descending order, 0.07, 0.12, and 0.25 percent (weighted rms).
The machine is adjusted for low-noise, high output tape. Walnut side panels enclose the transport, giving overall dimensions of 16 1/4 x 15 3/4 x 7 1/4 inches. Price: $549.90. Optional accessories include carrying case and dust cover, rack-mounting hardware, and micro phones. A version incorporating Dolby noise reduction, the Model 3600XD, costs $699.
Motorola Eight-track Tape Players
Six models make up a new line of automobile eight-track tape players from Motorola Auto motive Sound Products. All are stereo units, and all but one are designed for under-dash bracket mounting with quick-release brackets (facilitating easy removal of the player when the car is parked) optionally available. The first model (TM124S), designed for installation spaces as small as 6 x 2 x 6 1/4 inches, has separate volume controls for each channel, a treble-cut tone-control switch, and a track selector button and track indicator. Addition al features available on more elaborate units include slider-type volume, balance, and tone controls, track-repeat switches, fast-forward, and automatic ejection of the tape cartridge when the ignition switch is turned off.
The most fully equipped of the under-dash models is the TF756S, which has a built-in stereo FM radio, and at the top of the line is the Model TF875AX, designed for in-dash mounting with adjustable-position control shafts, and incorporating both stereo FM and AM facilities. Suggested prices range from approximately $30 to $170, excluding speakers, which are available at extra cost.
Pioneer TX-9500 AM/Stereo FM Tuner The most advanced tuner from U.S. Pioneer is the new Model TX-9500, whose construction details include a five-gang tuning capacitor, MOSFET front end, ceramic i.f. filters, and a phase-locked-loop multiplex section.
IHF sensitivity is 1.5 microvolts, with 2.5 microvolts (3.5 in stereo) providing a 50-dB signal-to-noise ratio. The tuner's ultimate signal-to-noise ratio is 80 dB in mono, 75 dB in stereo. Frequency response is 20 to 15,000 Hz +0.2,-1.5 dB, and stereo separation is 35 dB or better from 50 to 15,000 Hz. Image, if , and spurious-response rejection are all 110 dB: AM suppression is 55 dB, and the capture ratio is 1 dB. Alternate-channel selectivity is 85 dB, while total harmonic distortion is 0.15 percent in mono, 0.2 percent in stereo.
The TX-9500's unusually wide dial scale is calibrated linearly, with signal-strength and channel-center tuning meters located just above and to the center. The interstation noise muting, effected through a reed-relay switch, has two sensitivity modes; one of these functions normally, while the other also mutes those stations judged to be of inadequate strength for good stereo reception. The tuner's mode selector has positions for AM, FM AUTO, and FM MONO: a fourth position routes a pulsed 440-Hz tone to the tuner's outputs at a level equivalent to 50 percent FM modulation. This makes it possible to set tape-recording levels in advance when dubbing off the air.
On its rear panel, the TX-9500 has balanced and unbalanced antenna inputs (300 and 75 ohms, respectively), jacks for the connection of an oscilloscope, and output jacks at fixed and variable levels (a front-pan el control sets the levels for the variable jacks). FM de-emphasis is switchable be tween the standard 75 microseconds and the 25 microseconds used with a Dolby decoder on Dolbyized broadcasts. Finally, an output is provided for feeding any four-channel FM decoder that may become available in the fu ture.
The dimensions of the TX-9500 are approximately 16 1/2 x 6 x 14 3/8 inches. Price: $399.95.
TDK Super Avilyn Cassettes
Avilyn, a magnetic material developed by TDK for video-tape applications, has now been adapted for use in a new line of TDK SA (Super Avilyn) cassettes. It is described as a patented mix of iron oxide, cobalt, and other proprietary elements, with the iron and cobalt particles brought directly together by means of an absorption process that produces a combination particle. For cassettes, the material is applied to 1-mil Mylar base film in a homogeneous coating.
Avilyn is said to match the excellent high-frequency characteristics of chromium dioxide while providing higher output and less distortion at mid and low frequencies. The tape is designed to be used with the chromium dioxide bias and equalization settings provided on most high-quality cassette machines.
The head-wear characteristics of Avilyn are said to be identical to those of iron oxide.
TDK SA cassettes are available as C-60's, priced at $3.59, and C-90's, at $4.79.
Syn-Aud-Com Sound-system Seminars For several years, Synergetic Audio Concepts has been holding intensive three-day seminars on the design and implementation of high-performance professional sound systems in major metropolitan locations around the country. Conducted by president and founder Don Davis, an eminent name in the field of electroacoustics, the seminars are intended to be of special service to practicing and prospective concert sound men, designers of high-quality sound-reinforcement systems for meeting places, and specialists in the installation of monitor systems for recording studios and similar applications. Topics include speaker-system design, acoustic gain and feedback in various environments, and sound-system equalization. The training also involves hands-on experience with the latest instrumentation for acoustic measurements.
Although the seminars are suitable for those with limited math backgrounds, emphasis is placed on mastery of equations useful in predicting sound-system performance. To this end, each enrollee receives three slide-rule-type calculators for the important formulas as well as a text (in loose-leaf binder) to serve as a study aid and reference. In addition, enrollees are eligible to receive quarterly installments of the Syn-Aud-Con newsletter and technical notes for the year following, as well as periodic personal technical assistance and computer time. Those who complete the seminar are awarded a "Sound System Designer" certificate. Registration fees range from $325 to $275, depending on the number of persons attending from a given organization.
A free brochure describing the seminars and listing the dates and locations (as well as pre-arranged hotel accommodations) is avail able. Write: Syn-Aud-Com, P.O. Box 1134, Tustin, Calif. 92680.
PUBLISHER'S NOTICE: Recent fluctuations in the value of the dollar will have an effect on the price of merchandise imported into this country. So, please be aware that the prices quoted in this issue may be subject to change.
-------------------
Also see: