anbody ever hear of an outfit called dynagroove records?

Yogiboy and geoffkait are correct.  I've sometimes referred to these records as "Dynaflaps" because they were so thin.  But some were very good sounding - like ARL 2-0731 - Schubert Piano Trios with Rubenstein, Szeryng and Fournier.  Still play that one once or twice a year.

Dynagroove was not a recording process RCA Records used, but rather an LP pressing technology, and a real, real bad one. Some RCA titles were pressed in a few different versions of RCA L:P's: Shaded Dog, Black Label, Red Label, and finally in the late-60's as Dynagroove LP's. 

That  Dynagroove read was very interesting.   Never investigated why but those records never impressed me.   

And then came DynaFlex.

+1 bdp24! RCA's failed attempt to improve the sound by altering the EQ during the process of cutting the master. None of the resulting LPs made from this method sound good! Worthless junk, IMO! The record jackets stated on the fronts "Dynagroove".