(!!) (#1 EL37 Pair) EL37 Mullard black plate 1955-1957 (81ma and 83ma) tested on Amplitrex AT1000)
(!!) (#1B EL37 Mullard Pair) EL37 Mullard black plates double "O" getter halos 1957-1960 same build (79ma and 78ma) matched Amplitrex
(!!) (#2 EL37 Pair) CV586=EL37 Mullard brown base black plate NOS 1955-1958 (85ma and 93ma) (Very close Gm) tested on Amplitrex
(!!) (#2 EL37 PAIR) EL37 Mullard black plates NOS around 1960 (72.5ma and 74ma matched on Amplitrex)
(!!) (#3 EL37 BEST PAIR) EL37 Mullard black plates used/good 1956-1957 (73ma and 76ma) matched on Amplitrex
(!!) (#3 EL37 pair) EL37 Mullard NOS brown base gray plate NOS 1962-1966 (77ma and 85ma)
(!!) (#4 EL37 Pair) EL37 Mullard used/strong ma, gray plate, same build 1963-1969 (75ma and 79ma) matched on Amplitrex
(!) (#1 EL37 - BEST SINGLE) EL37 Mullard black plate NOS 1955 (106ma) tested on Amplitrex
(!) (#2 EL37 - BEST SINGLE) EL37 Mullard NOS black base gray plate NOS 1966 (93ma on Amplitrex AT1000)
(*) EL37 Mullard like new gray plate, 1 upside-down "cup shape" getter halo, made on or before 1955 (91ma on Amplitrex AT1000)
CV586=EL37 Mullard black plate NOS 1950-1955 (76ma on Amplitrex)
CV586=EL37 Mullard gray plate NOS 1962 (96ma on Amplitrex AT1000)
EL37 gray plate NOS/60% 1960's (59ma on Amplitrex)
EL37 Mullard black plate used/65% output 1957 (63ma on Amplitrex AT1000)
EL37 Mullard branded Philips Miniwatt gray plate like new, small rattle inside base, made before 1955 (81ma on Amplitrex AT1000)
EL37 Mullard gray plates used/60-65% double "O" getter halos 1960's (60ma on Amplitrex AT1000)
EL37 Mullard used/50-55% output 1956 (52.8ma on Amplitrex AT1000)
