Nos Mullard U. K. Made 6au6 Ef94 Low-noise Macintosh Mr-67 71 Pair

90 % of our tubes are Tv7 tested some can't be tested using the tv7. We have a variety of testers available. All our tubes have been tested for. GAS SHORTS TRANSCONDUCTANCE & EMISSIONS. Please see my notes on noise tests below.

Test Results are available upon request. We have a few different testers available to ensure the quality of the tube (as some tubes can not be tested on the tv7). Tubes tested on tv7u the Military standards were tubes needed to meet 60% (minimum value).

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. 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 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.

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. 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). 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 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 is probably NOT testing them in any meaningful way for you. 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. ^there is a small percentage of tubes that have a problem, 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. So if you find yourself rejecting more than one or two tubes because of "noise", then you probably have an aggressive circuit design or other design issues (such as transformer placement, shielding, etc).