Apparatus for combining phonograph signal with auxiliary audio signal

#This invention relates to apparatus for combining audio signals, and more particularly to apparatus for combining an auxiliary audio signal with the output signal of a phonograph, or the like. Even more particularly, this invention relates to a novel device for selectively amplifying the combining the signals from a microphone, electric guitar, or the like, with the signals produced by the needle of a conventional phonograph.

#As is known by those skilled in the art, the electrical signal that is generated by a conventional phonograph needle or tape player head is fed to an associated amplifier, which amplifies the signal and feeds it to one or more speakers, which in turn produce an audible sound. While it is desirable to be able to superimpose a second audio signal on the signal which is emanating from the phonograph needle, this heretofore has not been possible, except by multiple taping or recording processes.

#For example, it is common for artists to make several recordings of the same song or musical piece, superimposing the second and successive recordings on the immediately preceding recording. In this way it is possible for the same vocalist, for example, to record a song in three-part harmony, each part having been recorded by the same artist.

#In the drawing the sole FIGURE is a wiring diagram illustrating schematically audio signal apparatus and a signal superimposing device therefor made according to one embodiment of this invention.

#Referring now to the drawing by numerals of reference, 10 denotes a metal or plastic housing containing a potentiometer, which is denoted generally at 12. The potentiometer comprises a pair of resistors R1 and R2, 13' and a pair of sliding contacts 13, which are ganged or otherwise coupled together to slide in unison on the resistors R1 and R2 in response to the operation of a conventional knob or the like (not illusrated), which is mounted on the exterior of housing 10. This potentiometer 12 may be of the 100K, linear taper, dual gange type.

#At one end thereof the resistors R1 and R2 are adapted to be connected releasably by conventional jacks (not illustrated) and lines 14 and 15 with the output of a conventional phonograph denoted at 16. The slidable potentiometer contacts 13, 13' are adapted to be connected also by conventional jacks (not illustrated) and lines 18 and 19 with the input of a conventional phonograph amplifier 20. In other words, the output or phonograph signal from the phonograph 16 could be fed directly to the input (18, 19) of the amplifier 20, if desired. In the present case, however, the phonograph signal passes through the potentiometer 12 before reaching the amplifier 20. The output of amplifier 20 is fed in a conventional manner to a speaker and/or speakers 22 associated with the phonograph 16.

#At their ends remote from the lines 14 and 15 the resistors R1 and R2 are connected by a line 23 through a resistor R3 to ground, and through a line 24 and a capacitor C1 to an input terminal 25, which is adapted releasably to be connected to the signal output of an auxiliary signal device 26. This auxiliary signal device may comprise a conventional microphone, an electric guitar, or a similar device capable of generating an audio signal of the type which is capable of being amplified and fed to the speaker system 22.