Matched Pair Sylvania 6BL7 6BL7GTA Vacuum Tubes Triple 3 Mica NOS NIB Music Of The They have 3-13 188-5 and

They have 3-13 188-5 and 3-26 188-5 date/provenance codes

I am playing it in my Pro-Ject Tube Box S phono preamplifier with an Ortofon X5-MC high output moving coil cartridge as I write and it absolutely silent

Tube One (Philco-LABELED

gray ladder plates

Matched Pair Sylvania 6BL7 6BL7GTA Vacuum Tubes Triple 3 Mica NOS NIB Music Of The They have 3-13 188-5 andThis new old stock, new in box, almost perfectly matched pair of Sylvania MANUFACTURED 6BL7GTA dual triodes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 46 48 for Tube One and 48 47 for Tube Two (Sylvania MANUFACTURED, RCA LABELED). (Minimum (65%) is 25.) They have top D getters; anode radiators for cooler operation and longer tube life; copper support rods; a