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In Reply to: RE: 6SN7 tube posted by Mendel on January 07, 2015 at 06:53:44
Thank you all for your advice, I really appreciate it. When I first started rolling 9 pin tubes, I got carried away, bought alot more than I will ever use, finally decided 12at7 Amperex bugle boys. Now I want to try these tubes and see where it takes me. This time I asked for advice from folks that I knew would have information to make this a more logical decision. Not that music is logical, when I look at what I have spent on this over the last 55 years, it is amazing. Thought I was done until had to start using headphones and the journey started all over again. Many thanks, Don
Follow Ups:
I am curious sometimes about tube rolling, and the extent to which one could ever really say that "brand X" has an intrinsically different tonal quality from "brand Y."
Any tube two tubes of the same type will inevitably have different values for the mutual conductance, the plate resistance, and so on. If one pulls out one tube and pops in another and it sounds "better," could it simply be that by chance the biasing set up in the amplifier happens to be more appropriate for hitting the ideal operating point of the second tube than it was for the first tube?
In other words, might one simply be roaming around in the parameter space of possible values for the characteristic properties of the tubes until one happens to hit one that is ideally suited to the way the biasing, etc., is set up in one's amplifier? If one, for example, changed the value of the cathode resistor in the amplifier somewhat, and then repeated the exercise, maybe now it would be a different tube amongst the set of candidate tubes that happened to be the one that hit the sweet spot for the newly-configured amplifier?
Even statements such as that "brand X systematically sounds better than brand Y" might be subject to the same kind of influences. For example, it might be that brand X systematically happens to have a lower mutual conductance than brand Y, and that given the choice of cathode resistor value in one's amplifier, this meant that brand X tubes ended up closer to the ideal operating point than brand Y tubes. But this would not mean there was a general statement that "brand X is better than brand Y," but merely that the person making the report happened to have selected a value for the cathode resistor that was better suited to brand X than brand Y.
I'm not saying there couldn't be any more to it than this, but I am just curious how one could make statistically significant general assertions about the superiority of one brand over another when there must be so many confounding factors involved.
Chris
"I am curious sometimes about tube rolling, and the extent to which one could ever really say that "brand X" has an intrinsically different tonal quality from "brand Y."
Any tube two tubes of the same type will inevitably have different values for the mutual conductance, the plate resistance, and so on. If one pulls out one tube and pops in another and it sounds "better," could it simply be that by chance the biasing set up in the amplifier happens to be more appropriate for hitting the ideal operating point of the second tube than it was for the first tube?"
-I think so.
You could also flip this thought around, perhaps certain manufacturing processes and materials yield a product more consistent with the datasheet ideal, which was necessary in most cases for designing devices that will be made before replacement tubes.
"Even statements such as that "brand X systematically sounds better than brand Y" might be subject to the same kind of influences. For example, it might be that brand X systematically happens to have a lower mutual conductance than brand Y, and that given the choice of cathode resistor value in one's amplifier, this meant that brand X tubes ended up closer to the ideal operating point than brand Y tubes. But this would not mean there was a general statement that "brand X is better than brand Y," but merely that the person making the report happened to have selected a value for the cathode resistor that was better suited to brand X than brand Y."
-Similar to my thoughts above. If brand X was generally closer to datasheet ideals, then generally speaking it would be the desired tube to use in most cases compared to Y, generally speaking.
-Anything that strays too far from the datasheet ideals becomes a specific case which cannot have general qualities applied to it. I'm not saying tube Y is worse then X, it's just that, as you say, maybe brand Y needs some design changes to accommodate Y's actual parameters.
I also reserve room for thoughts that chemical composition of certain materials used plays a significant part as well.
I can't help but wonder if you tried to make the old style parts the same way today, that the costs and/or environmental hazards may make it somewhat prohibitive compared to the materials and techniques employed now by modern makers.
The circuit itself can be enhanced or not with a certain tube. For the most part a great tube sounds good in many circuits and a mediocre tube usually does not sound great anywhere.
"..could it simply be that by chance the biasing set up in the amplifier happens to be more appropriate for hitting the ideal operating point of the second tube than it was for the first tube? "
Yes and a good argument for getting a curve tracer and building our circuits around the exact tube we are going to use.
I'm too cheap and lazy for that but I would never argue against it.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
of high end tube gear may be doing exactly that, what with 'only' currently manufactured tubes available for use in their gear.
I've heard some REALLY good sounding tube gear with some REALLY crappy Russian and Chinese tubes in it!
They must be doing SOMETHING right. =:-0
.
Have Fun and Enjoy the Music
"Still Working the Problem"
I think personal experience has something to do with it. I tend to rely on my experience of personal use of a product, combined with others that have seen the same results. Tube rolling for me, has been hit and miss. I have followed the forum leads, some panned out, some did not. However, it is my experience that, on average, most congrugate info is accurate. Reusing the tubes I have purchased, I can generally tell soon after warmup why the tube was placed in the little used box as opposed to my rotate stock box. I was in a flight electronics tech waaaaayyy back in the early 1960's, was trained on tubes just as solid state was coming into it's own. Now you want to be confused that was the time to do it. Still in school, got tube theory locked down tight, then go to the next school and instead of electron flow thru the tube, we now have hole flow in the reverse direction, bla bla bla, I learned to drink right after that. But I think you have to trust to some extent, sincere people that want to help, as I have seen here on this forum, to use their experiences to help guide the way. I appreciate people that will take the time to give advice, you can usually see or tell the ones that just want to talk that don't have the knowledge. Sorry for the long wind, got a good nights sleep for a change! One more question if I may, I have purchase many tubes from this reseller on Ebay, and wondered if anyone had any experience with this tube.
"But I think you have to trust to some extent, sincere people that want to help, as I have seen here on this forum, to use their experiences to help guide the way...."
Yes, I'm not in any way doubting their sincerity. I'm just wondering to what extent they may be finding which tubes are better matched to their specific amplifier, with its specific choices for resistor values, etc., rather than finding intrinsic and universal superiorities of one manufacturer's tubes over another's.
Chris
There is no doubt that the circuit effects the performance of any given tube. There is a right tube for every circuit, and every given listening preference. Agree that it is impossible to recommend "the best" tube of any type.
That said, the general sound of certain tubes of a given type seems to be common over a large variety of gear and well documented by a wide variety of listeners. Everyone (pretty much) describes the grey glass RCA VT-231 as rich sounding, or the Ken Rads as having great bass, or the Tung Sol roundplates and metal based Sylvania 6sn7Ws as being all around great sounding. These descriptions are made by many different listeners with many different types of gear.
Experimentation with different tubes in a given piece of equipment is the only way to determine what is best for you. But it is nice to have a place to start, and other's experiences can be helpful in that regard. Nice to have a stash of different types to play with. One of the joys of owning tube equipment for me.
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