Dynagroove

Dynagroove is a recording process introduced in 1963 by RCA Victor that, for the first time, used analog computers to modify the audio signal used to produce master disks for LPs. The intent was to boost bass on quiet passages, and reduce the high-frequency tracing burdens (distortion) for the less-compliant, "ball" or spherical-tipped playback cartridges then in use. With boosted bass, tracing demands could be reduced in part by reduced recording levels, sometimes supplemented by peak compression. This added top-end margin permitted selective pre-emphasis of some passages for greater perceived (psychological) brilliance of the recording as a whole. As with any compander, the program material itself changed the response of the Dynagroove electronics that processed it. But, because the changes were multiple (bass, treble, dynamic range) and algorithmic (thresholds, gain curves), RCA justifiably referred to the analog device as a computer.

RCA claimed that Dynagroove had the effect of adding brilliance and clarity, realistic presence, full-bodied tone and virtually eliminated surface noise and inner groove distortion. In addition, Dynagroove recordings were mastered on RCA magnetic tape. Hans H. Fantel (who wrote liner notes on the first Dynagroove releases) summed it up with, "[Dynagroove] adds up to what is, in my opinion, a remarkable degree of musical realism. The technique is ingenious and sophisticated, but its validation is simple: the ear confirms it!"

The process was not received well by some industry commentators, with many audio engineers of the time referring to Dynagroove as "Grindagroove". Dynagroove was also sharply criticized by Goddard Lieberson of the competing label Columbia Records, who called it "a step away from the faithful reproduction of the artist's performance;" and by Harry Pearson, founder of The Absolute Sound, who termed it "Dynagroove, for that wooden sound." Another noted detractor of Dynagroove was J. Gordon Holt, the founder of Stereophile magazine, who in December 1964 wrote a highly unfavourable article entitled "Down with Dynagroove!" Holt, a noted audio engineer and writer of the 1960s and 1970s, slammed Dynagroove as introducing "pre-distortion" into the mastering process, making the records sound worse if they were played on high-quality phono systems.

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