6 Sylvania Type / Number 58 #58 Vacuum Tubes Engraved Stamped Base Lot Of Six

6 Sylvania Type / Number 58 #58 Vacuum Tubes Engraved Stamped Base Lot Of SixThis lot of six Sylvania number type 58 stamped engraved base tubes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas and they measured as follows: 27, 35, 37, 44, 52 and 59 respectively, where minimum (65%) is 36 and 100% is 55. 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" AND OR CALL OR TEXT US AT 202

new in box RCA 6BS8 tubes tested to spec on our Paul Hart-calibrated TV7/U and comes in a wholesaler's sleeve

Plates: black ladder plate

It is the tube on the left and is shown running with the RCA single that is also for sale separately

new in box GE 50L6GT rectifier tube tested to spec on our Paul Hart-calibrated TV7/U

Transconductance measures the efficiency of a tube and also serves as a tube life measurement proxy as tube efficiency diminishes with age

well-defined bass and sparkling

These tubes have nifty shoulder / Coke bottle glass envelopes

I am playing it in Bottlehead Crack headphone amplifier as a 12AU7 substitute and it sounds excellent

Transconductance measured 50 for Tube One and 54 for Tube Two where minimum (65%) is 40

Noise: -85

new in box US-made 1S5 tubes tested to spec on our TV7

new in box Sylvania 12BZ7 tube tested to spec on our TV7/U