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290
AN AUDIO CONTROL CENTER
IRVING KALIKOW, ACL, and OSCAR H. HOROVITZ, FACL
You can play, mix and monitor all
of your audio signals with this simple yet ingenious sound system
FIG. 1: Low-cost control center (above) uses crystal pickups and mounts all its operating controls on its own panel board (see 3).
fIG. 2: Hi-fi control center uses magnetic pickups and shifts volume, mixing functions to own panel. Note two arms on single table.
30" APPROX.
MOST of you sound and movie enthusiasts will agree that, in order to make the most effective use of the new soundwith-film techniques (whether you employ magnetic tape or film), it is best to have voice, music and, sometimes, sound effects available at the will of the recorder. Therefore, this article will describe a simple, self-contained and portable unit which can serve as your audio control center in these recording operations. Essentially this device will consist of two turntables, a monitoring headset for these turntables, a microphone and input for same, an output to the recorder, and provisions for controlling the volume and mixing the sound from either of the turntables and the microphone. These essentials may, in turn, be interpreted in two models: one is a reasonably low-cost unit (see Fig. 1) for the budget minded, the other a high fidelity setup (see Fig 2) for those to whom superior audio results are more important than price. We shall discuss and diagram both of these units forthwith. Since the low-cost unit actually embodies all of the essentials, let us consider it first.
LAYING OUT THE DESIGN
The layout of the parts on the turntable panel is pictured in Fig. 1 and diagramed in Fig. 3. The turntable spindles should be set 12!/2 to 13 inches apart, and their pickup arms should be 8 inches apart, midway between the vertical spindles. This will allow either arm (or both) to play on either record table. The connections for switching the turntable motors on and off are obvious; just observe due caution in handling and insulating for 110 volts. The connections for the microphone mixing circuit, earphone monitoring and playing arm switching are a bit more complex; they are diagramed in Fig. 4. Be sure
PARTS NEEDED FOR LOW-COST CONTROL CENTER
Approx. cost each
Two 3-speed turntables $10.00 $20
2 on-off switches .50
1 panel light
2 crystal turnover pickups 10.00
2 selector switches
3 potentiometers
2 resistors
1 tone control condenser.
3 phone jacks
1 set of earphones
Wire and shielding .
1.30
1.00
.20
.50
FIG. 3: The layout of low-cost operating parts and controls are diagramed, dimensioned here.
1 1
2. 2.0
Total for parts $54.*
PARTS NEEDED FOR HIGH-FIDELITY CONTROL CENTER
Approx. cost each 2 spring mounted turntables, 3 speed . . . $25.00 2 on-off switches 50
1 panel light
2 magnetic reluctance pickups 14.00
2 preamplifiers 1 1 .00
2 selector switches (silent type) 1.30
2 condensers 25 micro 1.00
2 potentiometers 1-00
2 resistors 20
3 phone jacks .50
1 set of earphones
Wire and shielding
Total for parts V'4'41
$50.0
1.0
.61
28.01
22.0*
16
2.0
2.0
.4
1.5
2.3
2.0i