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NOS Tubes--Are they worth it? or accurate?

After doing considerable investigation, I question whether it is worth it to undertake the quest of finding NOS tubes. Just looking at the volumes of discussion on audioasylum about Amperex 6922's and how many of them don't sound that good, the fakes out there, the difficulty in confirming how much use the tubes have seen. It just seems like way too much to deal with.

I know many will say, buy from the reputable tube dealers, but at what cost? Is their inflated pricing worth investing into something that has a limited life and can quite probably never be replaced? I think that looking into current production tubes that sound good would make a lot more sense.

The other issue is that many of the amps and preamps we are using them in are were not designed around the sound of these NOS tubes. If you substitute another tube, I think you are drastically altering the sound from the designer's attempt towards his version of reality and accuracy to something that is totally unrelated to this man's intentions and work.

It seems that we then end up with a mish-mash of sonics that are tailored to an individual's preference and may be far, far removed from any accuracy at all.
saxo
thorman
1,262 posts
 
Yah they are worth it if you are willing to accept dissapointment now and then. You may not hit it on the mark the first time,so be patient and use dealers with good feedback or people you trust to deal with.
When designing these peices,manufacturers use tubes that are currently available,due to cost reasons,and sound consistencies.Manufacturers must have to have on hand many replacement sets available to customers,so thats probably why the must use generic tubes.
It is fun to try to squeeze out more performence,but its at a price. Time and Money!
pls1
432 posts
 
I've been playing around with tube amps since I was in high school 35 years ago. I've owned dozens and have designed and built around 8 or so (I have degress in electrical engineering and physics). Garfish's points are all accurate.

Speaking of accuracy, what makes you think that the original manufacturer had any special direct line to accuracy. Most high end equipment is "voiced" which means the engineering ends and the subjectivity takes over.
saxo OP
98 posts
 
On asylum, this very topic came up, and someone posted that the old NOS tubes had somewhat different electrical characteristics than, say Sovtek 6922s. So, yes, you are distorting the original design parameters by putting NOS tubes in. Contrary to your claim, many manufacturers state that they do strive to design for accuracy as well as sonics.
pls1
432 posts
 
To Saxo:
Individual tubes from the same manufacturer have slightly different electrical characteristics. Hence matching on various parameters. If "many" manufacturers strive for accuracy in their tube designs, which I doubr but I'll take your word for it, I would have to say that since every piece of tube equipment I have ever heard has a noticable sonic signature, that those manufacturers have not succeeded.
saxo OP
98 posts
 
Pls 1, since you have engineeering background, do you believe that it is not possible to design an accurate tube amp or preamp? If, for example, you look at bench measurement frequency response on a Sonic Frontiers Power 2 or 3, you will find almost a dead flat response. You don't see that very often in tube amp reviews, I know. However, again, into an actual load, who knows? But doesn't that apply to transistor designs as well?

Regarding the SF amps, from my experience and everything I have read, listeners still find there are deviations from flat in these amps. Maybe I'm answering my own question here. That we don't know how to design a truly accurate piece of equipment.

Be that as it may, it still seems that pieces that show gross frequency response deviations show these dips and peaks in their sonics as well. So, what do measurements tell us? Something and nothing both.
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