Recording and mastering studio in Toronto, Ontario. Operated under this name from 1954 until 1979, it housed two recording studios, Studio A and Studio B.
Records cut at this studio are identified by "TG", "GT", "TXG", "TXD" "TD", "XT", "ZDT", "TX", "DT" etc. etched in the deadwax/runout.

The "T" stood for Toronto and the other letter(s) indicated the quality of the source material used, sometimes used in combinations:
G = good source
X = poor source (distortion, sibilance, pops, etc.)
D = source had distortion
Z = source had sibilance

Originally founded in 1948 by Toronto media company CHUM Ltd.. Around the same time, RCA Records started a recording operation in the Royal York Hotel.
In 1954 CHUM Ltd. sold the studio to RCA Records.
In 1979 RCA Limited sold the studio to McClear Place Studios Ltd. and renamed to McClear Place.

Engineers known to have worked there (and McClear Place):
1948-1979 Bill Dowding (1979 to 1983 at McClear)
196x-1973 Fred Burchill
1962-1967 Peter Houston
1964-1966 Graham Newton
1965-1975 George Semkiw
1969-1976 Hayward Parrott
1969-1971 Phil Sheridan
1970-1976 Alan Moy (etch as "GAM")
1974-1979 David Balan (1979 to 1987 at McClear)
196x-197x Alex Downie
196X-197x Jim Morgan (left early 1970s to join Captain Audio, returned as Chief Engineer 1976-1979)
197x-197x John Curl
197x-197x Cub Richardson
197x-1979 Kevin Fuller (etch as "KF" and "K.E.F.", also at McClear in 1980s)
197x-1979 Colin Murphy (also in 1980s at McClear)
197x-198x Mark Smith (9)