Quadraphonic audio systems failed to replace stereo in the 1970s, despite backing from all the major manufacturers and recording houses. Network externalities played a significant role in this episode, and I use the installed-base model of Farrell and Saloner [1986] to explain quad's failure. I find that the introduction of competing incompatible quadraphonic systems hindered the development of a viable user base, and I argue that the systems' sponsors introduced their products in a technologically premature state in order to prevent one another from preemptively establishing the quad standard. As a result, self-fulfilling consumer and retailer expectations doomed quadraphonic sound.