Sam Phillips’ Slap Back Echo; Luckily in Mono


‘Slap back echo’ was created by Sam Phillips for Elvis Presley’s Sun recordings and later simulated by RCA. Using cepstrum and autocorrelation, we find that the tape delay used in Sun Studios was 134 – 137 ms, which is so long that the echo is perceived mainly as a distinct echo in the time domain, more than a coloration of timbre in the frequency domain. Even though the delay time is long, the echo is still perceived as rather “intimate”, because the echo is in mono. Panned in stereo, the feeling of being inside a quite small room would disappear. The simulations by RCA, using a hallway instead of tape echo, shows somewhat shorter and less pronounced delays.

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