PRESERVE TONAL PURITY
November 4, 1940
The operation of RCA Victor's remarkable new "Tone Guard" developed to preserve tonal purity in the 1941 RCA Victrola, is shown in this drawing.
The "Tone Guard" is a system of grooved wells around the inside edge of the phonograph compartment.
(For the purposes of the drawing, the portion of the Guard across the rear of the cabinet is not shown).
Mechanical noise, present in all phonographs, is trapped and destroyed to such an extent that the amount of interference escaping through the "Tone Guard" is actually less than that which passes through the solid wood of the cabinet.
Another essential part of the "Tone Guard" system is the
sound proof covering, shown beneath the motor board, which completely
seals all objectionable noise in the record playing compartment.