One of the dirty little secrets of tube use in audio gear is that one of the primary, make that the primary, consideration is audible noise.NOS manufacturer grading of tubes generally has nothing to do with noise. Likewise, the conventional testers that we use - I have both a Hickock 752 and a TV-7DU - check for filament, transconductance and/or emission. I don't really think that any of these parameters is going to say anything about noise. All we can really do is tell if a tube is outside of its operating specs or match tubes. Without listening, we can say that a tube is bad, but probably not how quiet it is in an audio circuit.
Tube myths Joint Army Navy vs Non Joint Army Navy
Joint Army Navy tubes, commonly referred to as JAN tubes, were tubes produced for the military. Tubes meant for the military, had to meet certain specs, as outlined, in the contracts, each manufacturer, had with the military. Though some contracts, called for a specially produced tube(RCA 5692, for instance), the vast majority of them, called for the same specs, as the industries, who tubes were mainly produced for, had. Consumer use, of tubes for audio, was small in comparison. The reason most think JAN tubes, are "better" tubes, is based on the myth, that they are different tubes. If the specs on a tube, say 6922 for example, were the same, for the Navy, as they were for , say, Hewlett Packard, then both tubes, were ran off the same lines(at different times, as orders dictated), with the same tooling, and same personnel. They are essentially, the same tubes. Most factories, ran a certain number of tubes, and then labelled them, as the orders, dictated. So a tube labelled H/P, was the same as a tube labelled Beckman. So you tell me, "which tube is better?"
- ...
- 13 posts total
- 13 posts total