2. amps-preamps
  3. 1154378997

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
atmasphere's avatar
atmasphere
11,931 posts
 
Ah- OK. The 6SN7 will *generally* offer you smoother sound with less 'hash', especially at higher volume levels where airbourne vibration can affect the tubes. Detail will be the same and 6SN7s will generally allow you more drive ability as they will handle higher currents better than 6DJ8s. Lifespan seems better too. The 6SN7 will make less gain, but often that is not an issue in driver circuits, line sections or DAC outputs.

Another way to describe the difference is that circuits with 6SN7s sound more refined, while those with 6DJ8s sound more brash.
Post removed 
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
11,931 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.
Post removed 
More to discover