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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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mrtennis
3,295 posts
 
gentlemen:

how can a statement regarding the sonic characteristic of atube be independent of a tube circuit ?

not all 6sn7 tubes sound the same and not all 6 volt tubes sound the same, provided a tube circuit is tube sensitive.

there is sufficient variation within tube class to render a generalization stating a "generic" tube sound not a good basis for selecting a component.
atmasphere's avatar
atmasphere
11,793 posts
 
Mrtennis, you might reread the caveats I included earlier. However I might also point out that this experience is from working with literally thousands of tubes. I do agree that the tube type ought not be the criteria for selecting a component, although I would hesitate at buying any new component that uses tubes that are out of production or doesn't sound right with current production. That is one reason we switched to 6SN7s- the current production sound much better than the current production 6DJ8s.

Of course, we have our own reasons for thinking that we have a handle on transparency that allows us these judgements :)

FWIW we tried several types in circuits that were identical in topology, but optimized for each tube. The differences became very clear.
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anacrusis OP
69 posts
 
Your responses to this thread, even those in opposition to my ideas are very much appreciated. There is some great information and some true audiophile wisdom here. I've even decided to purchase an integrated for a second system with 6SN7 tubes at the preamp stage.

Though I would concede that there may be no absolute basis for tube selection because of differences in circuitry, there are certainly preamps out there that expose similar qualities in particular tubes. (if my mullard and telefunken tubes sound the same in my preamp as yours, it's probably likely that every other tube will expose similar qualities in my preamp as in yours)

I have come upon a tube that I would like to share with you (with fellow DK owners for sure) that I feel is absolutely amazing and it's a Valvo E188CC. The person who sold it to me claimed it to be a Mullard, but it doesn't look like any other Mullard I have ever seen. The midrange and highs are neutral and transparant and the bass is close to if not the best I've heard. I highly recommend auditioning this tube if you can.

I've continued this discussion on audio asylum on recommendation and have received some quite interesting information there as well. Thanks again for your input.
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