1- NOS Marconi 12BH7A NOS Long Black Plates Horseshoe D Getter Audio Tube

Description: 80/80 Marconi made for cbs extra thick micas / solid Black plates Horseshoe d getter Tv7 tested TUBES Test Results are available upon request if not photographed in the listing or already stated. 90 % of our tubes are Tv7 tested The tv7 tester has been around a long time and is a trusted tester . Military standards were tubes needed to meet 60% (minimum value) There isn't a specific percentage or data set anywhere that universally designates a vacuum tube as "new old stock" when using a tester nor for what test result is given. The best way is to calculate the GM - and check the data sheet for each tube - a nos tube should typically measure between the average and maximum micromhos(GM) Tubes do not give the same reading across testsrs - even the same model tester will give a different reading sometimes. When testing vacuum tubes, testers typically measure various parameters like emission, transconductance, and leakage. Tubes that test within certain specifications may be considered good or usable, but whether they are specifically labeled as "new old stock" depends more on their history and how they were acquired than on the test results alone. NOS is subject to interpretation and there is no specific definition for it either. There are suggestions and opinions. All our tubes have been tested for GAS SHORTS TRANSCONDUCTANCE & EMISSIONS If they are listed they have none of the aforementioned. Please see my notes on noise tests below ***We have a few different testers available to ensure the quality of the tube***** (as some tubes can not be tested on the tv7) Tv7 testing is tedious and I spend 12-13 hours a day testing tubes and double testing tubes - if you notice a mistake(like a picture doesn’t match the title) please be gracious and let me know. UNLESS PHOTOGRAPHED WITH THE ORIGINAL BOX- tube will come in repackaged white boxes- 50-90 year old cardboard packaging doesn’t hold together well. ***we have over the last 20 years amassed a huge collection of vintage amps/ parts / tubes and have decided to downsize that collection Every tube has been marked for tracking and security purposes - these marks wipe off easily and without the mark no return will be accepted - Sound quality is tremendously SUBJECTIVE. Please let us know what your intended application is prior to purchase if you have a specific sound in mind and/or just don’t know what you want. NOISE TEST. This is a very marginal test, only for special checking. This test needs sound amplification; hearing listening to noise with headphones would indicate a real disaster inside a tube (THE shorts test WOULD already BE evidence OF THIS) some testers do have noise test jacks that connect to either headphones or to the antenna/ground terminals of an AM radio. There is nothing wrong with performing that noise test. *****this test is not going to tell you whether the tube will be silent in your SET (single ended triode) amp or in anything else. *****Ultimately, the best way of testing a tube for microphonics is in an actual chassis or amplifier similar to one in which it is intended to be used.” Since amps have a wide variety of circuit designs and tube placement, this test is most effective in YOUR AMP or one that is almost identical. Hence, most people advertising tubes as tested for Noise or Microphonics are probably NOT testing them in any meaningful way for you. “Noise” and “Microphonics” are often buzzwords for other issues. (Shorts/ leaks) -there is a small percentage of tubes that have a problem with noise but far less than most people think. *****In properly designed circuits objectionable “tube noise” is seldom found. ******* In other words, it is a rare tube that will be noisy when used in most circuits. Always check the data sheet of the tube you plan to use. Tube testers and noise testing- Tube testers do not test for these problems in the manner in which you think, except to the extent that a tube tester with sensitive leakage detection will find far more “noisy” tubes than a tube tester with only “fair” leakage sensitivity, to the extent that the noise is due to this problem. Listening through headphones to tube on a tester is half as good as putting in amp and listening for noise. 1. RETURNS: I want you completely satisfied with your purchase from me. I will bend over backwards to make sure that you are a happy customer, prior to and after purchase. PLEASE message me BEFORE you open a return. Additionally please not that you can not return a tube for reasons against eBay policy- saying defective or not as described because your different tester reads the tube different is unacceptable. 2. PLEASE NOTE: Tube silkscreen (lettering on the tubes) is VERY fragile. It can be wiped off and destroyed VERY easily. RETURNS ARE NOT ACCEPTED BECAUSE YOUR TESTER SAYS SOMETHING DIFFERENT THAN MINE. If you don?t like the sound of a tube, so long as it is still in the same condition as arrived message me and I?ll work with you

Price: 72 USD

Location: Columbia, Tennessee

End Time: 2024-12-04T02:37:10.000Z

Shipping Cost: 4.63 USD