Movie Makers (Jan-Dec 1953)

72 Victor Animatograph adds magnetic Magnesound, a three-piece adapter, converts any Victor sound projector to magnetic functions MAGNESOUND, an attachment kit whereby any existing Victor Animatograph optical sound projector may be converted for magnetic sound recording and reproduction, is now available. The Magnesound kit is comprised of three units: an amplifier, which provides correct equalization factors essential to high-fidelity magnetic recording; a magnetic sound drum, which carries separate playback and recorderase heads, and a high-impedance microphone. Suitable cables, for connecting the Magnesound component with the sound projector, round out the assembly. Victor Magnesound, complete with carrying case, lists at $199.45. Installation of the Magnesound unit with one's Victor sound projector can be performed by the purchaser. The steps are as follows: (1) Remove from the projector the optical sound drum and the exciter lamp. (2) Insert in place of the optical sound drum the Magnesound drum. (3) Plug the cable attached to the Magnesound drum into a four-pin socket at the left end of the Magnesound amplifier. (4) Connect the inter-amplifier cable from a two-pin socket at the right end of the Magnesound amplifier to the phono input of the Victor projector. (5) Connect the Magnesound amplifier power cord with that unit and a suitable AC power outlet (115 volt, 60 cycle). (6) Position the motor shield (which comes with the kit) on the projector motor housing. In operation, a Victor sound projector converted in this way to magnetic functions performs (within its existing capacities) much as does any primary magnetic sound projector. Recordings may be made at either 16 or 24 frames per second and on either a 100 mil full stripe or on a 50 mil half stripe (in combination with a 50 mil optical sound track) . Both of these operations call for the use of single-perforation film stock, either in the original or in duplicate form. There is no provision for recording or playback on a 25 mil quarter stripe coated on double-perf silent films. MAGNESOUND, comprised of a magnetic sound drum, auxiliary amplifier, microphone and cables, installed on the Victor Sovereign. Also, although any Victor sound projector to which the Magnesound attachment has been added can still function as an optical sound projector, it cannot do so interchangeably at the snap of a switch or the throw of a lever. Reconversion to optical sound operation is carried out by removing the Magnesound drum, replacing it with the optical sound drum, reinstating the exciter lamp and disconnecting the inter-amplifier cable from the projector's phono input. The Magnesound amplifier unit offers a simplified control panel on which there are positioned, from left to right, a single microphone and phono input, a volume control, a magic-eye type of recording level indicator, a combined record-playback switch and, of course, an onoff power switch. Accidental throw of the record-playback switch to the record — and therefore erase — position is guarded against by an ingenious coin-slot design of the control knob. In operation, the slot in this knob must be aligned with a similar slot in the control shaft and the two of them are then turned to the record position by the insertion, as a lever, of a dime or other thin object. Functioning of this safety device may be eliminated by tightening a setscrew in the knob. But Victor recommends that this by-passing action be taken only after long experience and familiarity with the Magnesound amplifier controls. On certain models of Victor optical sound projectors one or more special parts may be needed to complete their conversion to magnetic sound functions. On the Victor Escort (Model 60-10) and on the New Lite-Weight (Model 60-4), for example, interference may continue even after the Magnesound drum is properly positioned. To eliminate this, a special hum shield is available which can be mounted by the purchaser on his own projector. Also on the Model 60-4, the projection lamp will not burn when the exciter lamp has been removed. A special plug, designed for insertion in the exciter lamp socket, is provided to complete this circuit. Technical specifications of the Magnesound adapter, released by Victor exclusively to Movie Makers, include the following: At 24 fps operation, the Magnesound amplifier has a frequency response of from 70 through 8000 cycles per second, plus or minus 3 db at the audio output jack. The signal-to-noise ratio (signal to hiss) is 60 db, signal to hum 50 db. The impedance of both input and output is high impedance, with a maximum of % of a volt input. The total power requirement of the equipment is 75 watts. The magnetic head component within the sound drum has an output of 3 milli-volts at 2000 cycles. The recorderase head is positioned at 11 o'clock on the sound drum curve, the playback head at 1 o'clock. The head characteristics are: 2500 ohms at 1000 cycles, self resonant at 50 KC. It utilizes a 50 KC AC erase; current 12 milliamps. The recording current-frequency curve: constant current to 3000 cycles; up 6 db per octave above 3000 cycles; }4 milli-amp maximum audio signal. Playback equalization: 6 db per octave above 3000 cycles; 6 db per octave from 2000 cycles down to 70 cycles.