Sylvania ONE (1) Type 56 Triode tNOS TESTED Vacuum Tube Audio 1932-1942

This listing is for one (1) Type 56 Triode vacuum tube in the ST (Coke bottle) tube shape. It has a black bakelite octal base, black round plate, and foil getter.

Your tube has been fully tested on our calibrated Knight 600A tube tester with like new, NOS results (tNOS). Here's what that means: to qualify for this listing, several stringent conditions must be met: the emissions for each section must test within between 80% and 120% of bogey values, consistent with original 1932 RCA, Western Electric, Sylvania, GE, and/or Tung-Sol datasheet specifications for new tubes of this type. The tube must also show no shorts, no open elements, and no measurable heater-cathode leakage. The tube might have mechanical wear or have the label rubbed off - these are very old! Unbalanced and used-testing tubes are available in a separate listing at a significant discount. Every tube you receive from Sound By Doc is guaranteed against failure for 60 days after purchase, an industry extreme!

OPTIONS (use offer feature in Reverb):

Want a regular white box? $1 extra per tube

Most of our tubes are tested with one of our Amplitrex AT1000 tube testers, but these fantastic testers do not have built-in support for this tube type. Therefore, this type is tested on our Knight 600A tube tester from 1969. Most vintage testers use a proportional emissions test at 30VAC and extrapolate to real, working voltages, but not this one! The Knight tester is revered for its 250VAC, real-world emissions test and for its robust gas test. Since we have not calibrated your tester, we cannot guarantee that the test results on your tester will be the same.