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

Showing 2 responses by jafox

My tube rolling experiences with many tubed-based components is polar opposite to the comments made by Bartokfan. What exactly are people trying to wiggle out of? Quantifying how each and every brand/model tube will sound in each and every component? Sorry, but as Albert already alluded to, it's just not that easy.

In some cases, the differences can be subtle. And in others not at all. There have been times where a single pair of tubes changed in a component resulted in greater refinements than I had achieved in past component upgrades that costed far more. If all you hear time and time again is a subtle change, that indicates the limitations of the component or system under evaluation and not the process of comparing tubes.

From what I have learned with trying various Mullards, Telefunkens, Brimars, etc., EL34, 12ax7 and 6922/6DJ8 tubes, I would never make final judgement on any component that contained Sovtek tubes. These things are mediocre at best. No master audio engineer can resolve this with fancy capacitors, point-to-point wiring, teflon boards, chassis dampening, 18 stages of regulation, etc.

As for what tubes the designer puts in a new product, obviously new off-the-shelf tubes are the only option due to availability and guarantee issues. But with very little effort, many of us hear components perform at levels even their designers never heard.

Bartokfan, you are free to keep the stock tubes in your preamp all you want. And this is good news to the rest of us as there is one less person to compete with when a good deal on older tubes becomes available. But do not condemn the efforts and experiences of others who have significantly different results than yours. And to claim it is nonsense clearly indicates you have a lot less experience with this process than a number of Audiogon members whose reports in these forums echo mine to a T. Afterall, you are into component rolling while the rest of us do it at the tube level.

What I find silly is to go through preamp after preamp, amp after amp, etc., the cost of shipping and potential for damage, until I find a stock unit that meets my goal. Sorry Bartokfan, but it is not that simple...it is naive. I'd rather purchase a few pairs of tubes that cost me $10 or $20 to ship, try them in my system, keep the ones I like and put the rest back on the used market. Now that's simple. It sure beats packing and shipping 50-100 lb components around the globe.

Through the sharing of tube-rolling knowledge by others with the same components as mine, I have taken my system to a performance level that I never knew possible with these components. Rather than put a negative spin on this and call it a silly game, I think of this as a continued quest for refined magic.
Mrtennis - When I owned the BAT P10 a few years ago, I never got around to playing with the many different tubes like I did after I got the Aesthetix Io. So I have no experience that may or may not match your findings with the P5. It may very well be insensitive to tube changes ..... BUT .... have you tried the Tele 6922/6DJ8's here? And what about the Mullard 6922?

After reading Albert's numerous details on tube trials with the Aesthetix models, I wasted no time to play with this for the Io. And as much as the stock Io was far beyond the stock P10 in how in rendered 3-dimensionality and decays, the Mullard and Tele tubes took this to yet another level. And when I got the Aesthetix Callisto, I went back to read Albert's tube experiences and found nearly identical results in my system with this. The only thing that I have learned recently is that a strategically placed pair or two of Brimar 12ax7's in my system can add just a little more foundation on the bottom end, and a little more sparkle on top with just a tiny bit of midrange magic loss from displacing the Teles. It's all about fine tuning to a personal "balance".

With knowledge on how incredible the Tele 6DJ8 was in both Aesthetix models, I discovered how far it took the Wolcott amps as well as an older Counterpoint NPS400 amp. A pair of these alone has improved each component significantly.

As much as Ken Stevens likes to run with Sovteks in his preamp and amps, I found the Mullard 6922 and 12ax7 to take the JL-3 amps far beyond the Sovteks in terms of tonal coherency which results in a more natural (not edgy) top end. I did however try several different 12au7's here and could not hear a difference. And I had similar findings when I had the CAT Ultimate II on loan for a few months to compare to the Io/Callisto. Some people have reported they did not like the Mullards into the CAT preamp at all but it was a major improvement over the Sovtek in my system.

My system's resolution took on a huge boost when I put in a power line conditioner. This followed with power cable upgrades throughout makes tube differences even greater. But even nearly 20 years ago when I owned the ARC SP-10, I remember the RAM tubes that I put in this made quite a sonic improvement to the tubes from ARC. And when I sold the SP-10, I kept those tubes and used them in the LS5 and got the same benefit over the stock ARC tubes. No doubt improved system performance makes these differences even greater. But 20 years ago, my system was not known for detail and resolution and yet tube changes in the SP-10 were not subtle.

So unlike your lack of success with tubes bringing on significant changes, my hodge-podge collection of components over the years, from many different manufacturers, has given me quite different results. I'm kind of a midrange textures, harmonics, ambience, bloom, decays, etc., fanatic, so this is what I listen for with tube trials. Many systems out there lack much of this magic and in such cases, these differences might get lost in the wash.

And thanks Ecclectique.