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RE: Any Current Production 12xx7 Tubes Worth Buying Yet?

Posted by TubeAcolyte on March 27, 2017 at 11:27:17:
Ahoy!

Well, without more information about your equipment, it's a little tough to tell.

On the one hand, I agree. In a lot of applications, there's nothing like NOS to restore your equipment's performance. The tubes follow the specs to which they were made, and the gear reacts accordingly.

On the other hand, my research indicates that many NP (new production) tubes often fall outside spec right out of the factory, which is passed onto the distributors. While the tubes may work in a given circuit, further measurements and testing reveal some interesting (if not jarring) results. A lot of newer tubes simply don't adhere to the datasheet's indicated plate resistance, gain, transconductance, etc. And we're not talking a +/- 3% margin of error. No, we're talking 10-20%, if not more.

I'm having a little trouble at the moment to find the data I'm talking about. I've buried the link in more than one AA post, though.

My theory is that some tubes sound off as a result of operating points, rather than the often-highlighted "magic sound" NOS tubes have. I've had some NOS tubes that sound "meh" and I have had NP tubes that put into question the crazy prices some pay for tubes. Examples include the TJ Full Music 12AX7, the Sovtek 12AX7LPS (a tested and well-selected one), the Penta KT88SC (also known as the Preferred Series KT88), and the Gold Lion KT77. The TJ Full Music 12AX7's clock in at $60 to the pair - they ain't cheap, but they are serious contenders. They have a warmth and character I would have associated with old British valves, but with a delicate "modern" flavour to them. They're really something.