They compressed it, rolled off the bass and purposely introduced distortion 
in the inner grooves.  It was a variable EQ process too, boosting lows in 
quiet passages and rolling off treble near the inner grooves.  I don't know 
why, they just did.

From Chesky records:
This reissue choice by Chesky is an especially interesting one. The original 
shaded dog release of this recording (catalog no. LSC-2614) was the first 
classical recording by RCA issued with the Dynagroove process. For those 
unfamiliar with Dynagroove, this was an attempt by RCA to make their 
recordings playable on inexpensive phonographs by compressing and limiting 
dynamics, as well as boosting the bass during quiet passages. As history has 
tragically shown, this was the first step taken by RCA's corporate 
management along the path to destruction and ruin of a once great company.

This recording was originally engineered by Lewis Layton and produced by 
Richard Mohr, the very same team that produced some of the greatest RCA's 
made at Orchestra Hall Chicago. Unfortunately, the original shaded dog that 
I own of this recording is anything but great, with the dynagroove process 
turning a very good performance into a wheezing mess. On this dynagroove 
doggie you can hear the equalization of the low bass and the truncation of 
the dynamic contrasts take place quite clearly.

The Chesky Records reissue is thankfully cut from the original 30 ips 
session tape, thus avoiding the dynagroove equalized production tape. This 
Chesky reissue was engineered by Jeremy Kipnis and Rick Essig at the 
Frankford Wayne Mastering Labs in New York. This re-mastering, like all the 
other Chesky re-mastering, was apparently done directly from the original 
three track session tape with no equalization or other processing done.

a quote from another site:  "About the time the Ravel was recorded, RCA had 
developed its ill-advised Dynagroove process for mastering LPs, which 
leveled dynamic range and boosted high frequencies in an attempt to make 
recordings sound better on less-expensive equipment (of course they sounded 
dreadful on quality hi-fi sets)."

----- Original Message ----- 
From: "Lou Judson" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Sunday, February 12, 2006 7:13 PM
Subject: [ARSCLIST] Dynagroove, was Record tracking

> Pardon this if it is OT - I am curious about this. I have only heard a few 
> Dynagroove records, and rather than do laborius research, can someone 
> describe what is going on with them?