Matched pair new old stock, new in box Sylvania GB-5670 396A 2C51 Dual Triode Tubes. Identical date codes (JF), charcoal plates, top halo getter, nickel pins. The Sylvania Gold Brand line was made for critical industrial and laboratory applications and with very tight quality control. A very rare and excellent version of the 396A. Tested for shorts, gas and mutual conductance on calibrated TV-7D/U tube testers. tests @ 44/48 and 44/48 where the minimum good value on the TV-7 is 26/26. Boxes show wear. See photos.
All tubes tested on TV-7D/U tube testers calibrated by Dan Nelson.
These tubes are a step up from the GE 5 Stars and many claim to be on par with the W.E. 396a What you can expect from these tubes are a smooth detailed treble with a hint of sparkle, a well struck mid range and full bass response. The sound stage is open with a slight bit of air to them but not enough to smear the detail. Instruments are well placed and articulate. This is a well balanced tube.
