Matched Pair General Electric GE 12B4 12B4A Vacuum Tubes Valves 9ED4 T39 A seven out of ten

A seven out of ten

It is dead quiet when the preamp is muted and has excellent frequency response and dynamics even though it tests poorly

new in box Sylvania 9JW8 tubes tested to spec on our Paul Hart-calibrated TV7/U

Transconductance measured 2850 micromhos for Tube One with a current draw of 21

Enhanced Cooling: no

Matched Pair General Electric GE 12B4 12B4A Vacuum Tubes Valves 9ED4 T39 A seven out of tenThis matched pair of GE 12B4A tubes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Tube One measured 33 while Tube Two measured 34 where minimum (65%) is 32 and 100% is 49. Wish I could tell you how they sound, but I don't have any equipment that uses these. WE HAVE SCORES OF THOUSANDS OF VACUUM TUBES. IF IT'S NOT LISTED, WE MAY HAVE IT. PLEASE ALSO SEE OUT ETSY SISTER SITE "LOWTECHTWOO"