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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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Tubes Asylum Questions about tubes and gear that glows. FAQ |
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In Reply to: Minimum value of each tube tester posted by b9ronaldo on March 17, 2006 at 15:36:10:
Ronaldo
The first tubes you mention which are preamp tubes will not get much data from even the best testers for all paramaters of the tube.
How many times have we put 12ax7s in a tube tester and have them read 25% of new and yet perform perfect in a preamp..By the same token I have seen high testing mullards or RCA 12ax7s only to be microphonic as hell when put in a circuit.
If your buying high priced preamp tubes used,always go to a reputible seller..I get a higher price when I sell my 12ax7 telefunkens becuase my testing not includes emissions and leakage and shorts and mutual conductance,but I also have a signal generator hooked up to both sides of the tube with a set of high impedance headphones and while Im injecting a 5khz signal into the tube for about 40 minutes straight while periodically tapping the tube and listening for microphonics..if I hear any then the tube gets rejected.This is the only way to test real functionality.. I have it set up so I can do this on my heath tt-1 and my sencore mu 140.
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Follow Ups
- The sad about testers are they dont tell much of a story. - MIchael Samra 20:52:09 03/17/06 (3)
- 25% & perform well........... - Jimmy 03:04:08 03/18/06 (1)
- Re: The sad about testers are they dont tell much of a story. - b9ronaldo 02:14:56 03/18/06 (1)
- Re: The sad about testers are they dont tell much of a story. - Mark Bos 15:17:54 03/18/06 (0)
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