Realistic QV-3 Four Channel Stereo Synthesizer
I have a couple of these Realistic Quatravox units from the 1970s from Radio Shack around the house. They convert two-channel stereo into four-channel for a surround sound effect. When these units were out quadraphonic sound was the latest fad, Radio Shack marketed these as a low cost alternative to get into four-channel sound.
Granted, it does not produce true quadraphonic sound but the effect has a good sound for such a simple unit. They require no external power, just a circuit with switches and resistors, and does not require four-channel recorded material.
Realistic QV-3 Four Channel Stereo Synthesizer
I have a couple of these Realistic Quatravox units from the 1970s from Radio Shack around the house. They convert two-channel stereo into four-channel for a surround sound effect. When these units were out quadraphonic sound was the latest fad, Radio Shack marketed these as a low cost alternative to get into four-channel sound.
Granted, it does not produce true quadraphonic sound but the effect has a good sound for such a simple unit. They require no external power, just a circuit with switches and resistors, and does not require four-channel recorded material.