Exactly the same question I was thinking. Chinese, maybe? I assume that were they to build these themselves, they would use the bragging rights and claim "proudly made in Illinois" or something like that. Somehow their silence points to the usual suspects.
I had an EH that put on a fireworks show once (without breaking the glass), and I don't like the look of the brown bases when over time they turn burnt black. A Ruby version had a crooked bottle... I've had great luck with J.J.'s more recently. There's a place called Eurotubes near where I live (Portland Oregon) that burns in and measures and matches all JJ tubes. Google Eurotubes to see how thorough they are. All dealers should do this. I believe they work directly for JJ. Any weak tubes get weeded out up front. I suspect that all tube makers have had the occasional bad tube or bad batch. I'm very skeptical about there being an audible difference between any of them, since it's so easy to compare them without fully normalizing all of the variables. Each tube should be re-biased for the exact same degree of class AB, and the level should be within 0.25dB. Every tube will bias up slightly differently than any other random tube of same number, and the slightest difference in volume level can sway an opinion. I would expect the biggest difference to be how they saturate (clipping), but again there are many variables with that. My top priority is reliability, and get the circuit around the tube right.
JJ2A3-40 installed....they rock....
An externally hosted image should be here but it was not working when we last tested it.
the amp used the 26 tube as preamp, when one of the opt's died, the owner decided to try another tube for the first hole...
I read that the highway system implemented by Prima Luna is nothing new under the sun, the new is having built with solid state components in a small PCB, because I do it with vávlulas involved a tremendous expense and size, almost a new amp control added to the original .......
I certify that the circuit works wonders, no pun intended apology for this brand, but had a very good idea to apply the correct polarization point automatically even with valves as diverse as the EL-34 and KT-120. PL initially did not recommend it, but the user responses ensuring that output transformers bear the greatest current plate, the reason to thoroughly test the autobias and ended up accepting and recommending a good sales pitch, no doubt . I'm not sure with the KT-150 valve , however ......
Integrated Amplifier - $1799
Adaptive AutoBias
Apology for coming onto this late and somewhat side-tracking; I have a question:
Kevin,
How can this be? As far as I know the EL34s never had 'aligned' (to G1) screen grids as in KT... beam tubes - the pitch is different to that of the control grid. Is 'he' talking about beam tubes - which the classic EL34 is not. (This apart from some 6CA7s which came out with beam forming electrodes, but in which G1 and G2 were still of different pitch, at least to my knowledge.)
Kevin,
How can this be? As far as I know the EL34s never had 'aligned' (to G1) screen grids as in KT... beam tubes - the pitch is different to that of the control grid. Is 'he' talking about beam tubes - which the classic EL34 is not. (This apart from some 6CA7s which came out with beam forming electrodes, but in which G1 and G2 were still of different pitch, at least to my knowledge.)
Six year old post so I remember absolutely nothing about it at this point. You'd have to go read the original article in French; the comments are essentially paraphrased from the original French article.
My understanding is that the screen grid and control grid were aligned in the early Philips EL34, it is not something I can recall checking within the time frame I can still remember. I do remember seeing Philips metal base and some other EL34 (probably Philips subsidiaries) that appeared to have screen and control grids closely aligned. (note appeared, not verified by disassembly)
I don't believe any American manufacturer bothered, but could be wrong about that.
Wish I remembered more...
Here is some interesting commentary on screen grids oddly enough: http://www.oestex.com/tubes/screens.htm
My understanding is that the screen grid and control grid were aligned in the early Philips EL34, it is not something I can recall checking within the time frame I can still remember. I do remember seeing Philips metal base and some other EL34 (probably Philips subsidiaries) that appeared to have screen and control grids closely aligned. (note appeared, not verified by disassembly)
I don't believe any American manufacturer bothered, but could be wrong about that.
Wish I remembered more...
Here is some interesting commentary on screen grids oddly enough: http://www.oestex.com/tubes/screens.htm
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