2. amps-preamps
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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
unsound
7,329 posts
 
I suspect that some manufactures choose some particular tubes due to cost, reliabilty, market perception, ease of use, and especially avialability, as well as "inherent sonic qualities".
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anacrusis OP
69 posts
 
Okay, curiosity got the better of me and I had to see what was going on in this thread. Albert, as you know, I do value your opinion and will no doubt be calling you at some point.

Many of us, certainly tube users, choose sound produced by circuits employing tubes because to us they are different if not preferable to the sound produced by all solid state circuits (with a few notable exceptions). We could call this particular class of sound “the tube phenomena.” We have come to this choice through observation and analysis. My hypothesis is that design engineers employ tubes because of their inherent sonic qualities and not because of electrical parameters that can otherwise be achieved by solid state devices which are cheaper and generally accepted to be more reliable. It would logically follow that these design engineers would want the full measure of benefits that can be derived from the device around which they are basing their design. Wouldn’t you? I know I would. Now you may choose to agree or disagree with my hypothesis but without some conjecture there would be no basis for experimentation. Without experimentation opposing opinions are themselves mere conjecture. Every opposing opinion I have seen in this thread is logical and valid. Does anyone have evidence to support these views? If you do, I would like to investigate whether or not there are certain classes of circuit design (as i suspect there to be) that can be identified by a certain design approach and if “common” designs yield similar sonic results based on a control tube. If we can then name these circuits and identify them within our own equipment, perhaps through consultation with the engineer we would then have a testbed. The idea is to agree upon what we can prove and bring this noble quest closer to fruition for the greatest number of people. If it finally comes to having to share my findings only with other DK Design owners then so be it. Though opinions would seem to lead in that direction, hard indicators do not.
atmasphere's avatar
atmasphere
11,793 posts
 
Tvad and Neebee, there is no doubt that I support my design decisions !! :)

-And the reason that I made those decisions is based on the experience that I had with the tube types I mentioned. The 6DJ8 was a popular intrumentation tube (look in an old Tektronix scope sometime) and is very good in that application. Unfortunatly, the tube was not originally intended for audio and while it is very linear, it has a micorphonic tendancy that is profound relative to other tubes.

Despite that it has been popular in audio for a long time. However if one pays attention to what it and other tubes do, it will be seen that any equipment that uses it will have a coloration particular to that tube- you all know what I am talking about. The fact of the matter is that audio (high end anyway) equipment ought to have *no coloration at all* so if you want that you will have to start with a less troublesome tube. It really is that simple.

I was influenced to try the 6SN7 after seeing the the MFA Luminescence preamp (which was extraordinary in its day) as well as the Vacuum Tube Research Labs stuff. It was easy to discern why the tube had/has a serious following.

So I was just letting you in on what I have found to be true over the years (I think most of the more respected people posting here do exactly the same). I hope this is not troublesome.
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