This is a continuation of the thread:
Tube Characterization: 6DJ8, 6922, 7308, CCa, etc
This above thread was dense with information regarding tube selection, classification and characterization but like many threads, branched off into more specific areas of focus. Though I would definitely refer to this original thread as a point of reference, what I would like to do here is condense much of the information specific to it's original intention. The objective evaluation of 6Dj8 family of tubes.
One of the most thoughtful responses and one for which I am most grateful is:
My advice if you are tube rolling is to be careful about documenting what you are doing, and make sure you can return tubes that you buy from NOS/antique dealers! *Above all* remember that you are supposed to be having fun and don't go off the deep end. Its not pretty
To this end I have decided to cool my jets a little and take a more moderate approach.
The questions are:
1) Can a tube within an audio component be evaluated for its sonic qualities or will the associated circuitry be so influential on the sound that such an evaluation would be pointless unless put into a specific context (ie the same preamp)
2) Will a tube retain enough of its sonic signature with specific components or specific circuits to make such an evaluation fruitful?
3) Is there an objective language or terminology that we can use which will make such an evalutaion comprehensible?
Many of the most experienced audiophiles in this forum feel that it can not be done, at least meaningfully. A number of others feel reservedly that it can and a few are of the opinion "let's give it a go". Some just find pleasure in trying out different brands on a casual basis(a very sane point of view imo).
Some contributers feel and for good reason that the manufacturer used certain tubes for good reason and that tube rolling would just be making trade-offs. If you want a different sound, buy a different preamp, cd player, what have you.
Before anyone undertakes such a study they should refer to the existing information contained in "Joe's Tube Lore", and evaluations done by Vintage Tube Sevices, VAC, and Vacuum Tube Valley, especailly issue #7 (thanks to Jab and Rchau). Consider that some components are just more sensitive to tube changes than others. Lastly, be sure that you can return, at least exchange tubes for
One comment by Atmasphere I found particulary interesting was his assertion that:
If you are dealing with the best of the best in all tube types you will find them all very close.
and also adds that the 6SN7 series of tube is iherently better than the 6DJ8 series and to me supports the idea of just changing preamps. By the way Raymond Chowkwanyun of enjoythemusic does a capsule review of this tube type:
http://www.enjoythemusic.com/magazine/equipment/0304/6sn7.htmThere is also a strong contingent of contributers that feel nos tubes are inherently better sounding than nns tubes. At the prices some old stock tubes are going for I find it difficult to believe that a modern tube manufacturer can't duplicate or even improve construction methods producing superior tubes and still make a nice profit but that so far does not seem to be the case.
Imin2u, if you are still interested, may I suggest starting with some of those tubes you have that haven't otherwise been reviewed and we can start putting them through their paces. We can move from there to confirming existing findings.
I invite anyone who would like to be a part of this experiment to tell us a little about the sound your favorite 6DJ8, what you use it in and if you'd be willing to run other tubes through your system.
