Matched Pair Philco Type / Number 27 #27 Vacuum Tubes Valves Black Plates 2nd Quarter BW27 They have 56-26 188-4 and

They have 56-26 188-4 and 61-26 188-4 date/provenance codes

new in box Sylvania 6SH7 tubes tested to spec on our Paul Hart-calibrated TV7/U

sound-staging

new in box GE 22JR6 tubes tested to spec on our on our Jackson 648

30/31 and 34/34 where minimum (65%) is 25/25 is 39/39

Matched Pair Philco Type / Number 27 #27 Vacuum Tubes Valves Black Plates 2nd Quarter BW27 They have 56-26 188-4 andThis matched pair of Philco Type 27 triodes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 35 for Tube One and 36 for Tube Two where minimum (65%) is 25 and 100% is 38. The tubes have rounded black plates; wire snubbers for increased rigidity and lowered microphonics; dimpled sheet getters; excellent flashing and well secured bases and bottles that are nice and