Tube Characterization: 6DJ8, 6922, 7308, CCa, etc


Does anyone agree with me that there should be detailed descriptions of the sonic characteristics of each of the popular versions of each of the above tubes. I've read Joe's Tube Lore and a number of manufacturers web-sites which are great general direction guides but they really don't tell us what we need to know in specific and defined terms. Perhaps starting with an overall sonic characteristic like liquid, or warm, or dry or transparent then their response at the frequency extremes (since this is always an issue with tubes), then perhaps individual characteristis with say female voice, piano etc. and then imaging. We would all purchase a set of cheap base line tubes that are known for consistancy and have clearly defined caharacteristics so that comparisons could be made to this benchmark. Then use benchmark recordings. Even better if we had the same equipment best yet if we benchmarked every component in the chain but not necessary because we would be dealing in relatve values.

Of course there is the question of synergy with existing equipment and the fact that we all don't hear exactly the same and so on and so forth, but again, it would all be relative. "Tube "A" has has better defined bass than the benchmark by a factor of 3 on a scale of 1-10 IMO" for instance. Of course this wouldn't be an exact science but it would give us real direction and be more useful than "this is a really great tube or this is a really, really great tube" or slavishly depending on the opinion of the tube specialty store who may be as honest as the day is long but does have to move what he has in stock. If we can bring this evaluation process closer to science we could spend less time playing this silly expensive guessing games and spend more time exploring the kind of sound we like and buying the kind of sound we want (not to mention, listening to more music) Thoughts?
anacrusis
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Yes, worthwhile indeed. I would personally be interested in hearing from anyone with a Conrad Johnson Premier 17 about tube experiences. I'm currently using Mullard E88CCs with a back-up quad of Amperex/Holland 6DJ8s and would be quite happy with either. Dave
this question can only be answered in the context of a particular tube circuit.

it is difficult to generalize because circuits differ, even discounting the variable of differences in perception of sound.
I've found TFK 6DJ8s to be accurate, linear and true across the frequency range. Mullards are nice but a little warm to my ears in my system. It's not really what this tube sounds like versus that, it all depends, But if I were going to make generalizations, it would be just the opposite of your observations, just my 2ยข.

Happy listening,
Joe
You guys might want to check out issue 7 of Vaccum tube Valley (VTV). An analysis of about 26 different versions plus a history of the development with pictures of versions from different eras.

In VTV has done such test on a number of tube types. I don't necessarily agree with any of them but it is basically what this thread proposed.

BTW-I think this endeavor is fruitless. You can change the sound of tube by just changing the operating point (plate voltage, load ressistors, heater voltage,...). Also, the sound in different topologies(anode follower, cathode follower, cascade, mu follower, etc..) vary with the same tube.