Description

Tv7 tested NOS TUBES Test RESULTS AVAILABLE ON REQUEST Tubes tested on tv7u the Military standards were tubes needed to meet 60% (minimum value) Tv7 testing is tedious and I have spent 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 - thousands of tubes to be listed within the coming weeks! ***we have over the last 20 years amassed a huge collection of vintage amps/ parts / tubes and are downsizing businesses*** my husband is owner of VintageBlissAmplification and his work is highly sought after in the music industry. While that has nothing to do with a tube we are selling, it has everything to do with the knowledge of testing our tubes to ensure quality. ***** Every tube has been marked for tracking and security purposes - these marks wipe off easily and without the mark no return will be accepted - 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. Loose elements or other defects will not be found. What about the “noise test” in a tube tester? It is true that 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. However, 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 “most satisfactory way of testing a valve which is suspected of being microphonic is in an actual chassis or amplifier similar to one in which it is intended to be used.” (RCA Radiotron Designer’s Handbook, Third Edition, p.245). 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 is probably NOT testing them in any meaningful way for you, and may be outright puffery that the “noise test” was ever performed at all. True “noise testing” (other than using the tube in the exact equipment you plan to use it…) requires a highly sensitive mechanical-based or vibration-based test apparatus, and such devices were ONLY created and used by professional engineering and testing labs run by very large entities back in the old days– such as the US military, Westinghouse labs, etc. Furthermore, “Noise” and “Microphonics” are often buzzwords for other issues. Certainly there is a small percentage of tubes that have a problem, but far less than most people think. In properly designed circuits, (which has NOTHING to do with how much you paid for your amp…), objectionable “tube noise” is seldom found. In other words, it is a rare tube that will be noisy when used in most circuits. Thus, if you find yourself rejecting more than one or two tubes because of “noise”, then you probably have equipment with aggressive circuit design or other design issues (such as transformer placement, shielding, etc). For example, some amps push a tube to its maximum design ratings. That is asinine. No electronic component is truly expected to operate successful at its maximum design rating. In fact, the opposite is true. “De-rating” is a standard practice in electronics. For example, if a circuit calls for a half-watt resistor, you install a one-watt (or bigger) resistor. So, it is true that aggressively designed amps will certainly cause many normal tubes to exhibit “noise.” Blaming this on the tube is incorrect. The blame should be placed on questionable circuit design, and just because you paid “top dollar” for your expensive amp or preamp does not mean that you bought quality. It only means that you paid a lot. Accordingly, if you own equipment that is susceptible to “noisy tubes”, then place the blame where it belongs — on your equipment, NOT on the tubes. Expect that your cost-of-ownership will be much higher because you will buy many tubes that you find noisy but that most everyone else would not have any problems with them in their equipment. You have to pay to play. 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