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In the Forum: Melquiades Amplifier
In the Thread: Single-stage Melquiades vs. DHT amps
Post Subject: NOS vs new 2A3 tubesPosted by drdna on: 2/13/2009
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First of all, this not an attack on NOS tubes and it is all meant to be just sort of fun and educational. I happened to have all these 2A3 tubes side by side for comparison, so why not? I also have done the same thing with other tube types like 6SN7 but since nobody on this website uses 6SN7 in a circuit, I do not think it will be interesting to post it.
 floobydust wrote:
I can't fully respond to this as I don't have the new tube brands you have. I posted earlier regarding my personal findings with the EML 45 solid-plate versus NOS however. As a result I found the (known good) NOS 45 to provide a more neutral and accurate sound.
Anyway, no response necessary. I am just doing this for fun. Keep in mind also that the NOS Sylvania tubes are very good and to my ears better than many of the new manufactured tubes from Russia, China, etc.

 floobydust wrote:
I also have to question if many of the new manufactured tubes with old tube types even qualify as being a "true replacement." Not to mean it's not a good tube, but to point out that is not a true version of the original.

Well, yes, does it really matter, so long as it achieves the goal in the circuit if it is a "true 2A3." I don't see it as a Formula 1 race. However, I get the point, which goes along with my feeling that the Kron tubes and the two mesh plate tubes are sort of revolutionary with distinctly different sound, not characteristic of the limitations of the standard 2A3 tubes. An example: the side mirror was created in racing when a rear view mirror view was obscured by the engine/frame. The car was disqualified that year anyway, but side mirrors are now standard. We should not reject or exclude improvements to design.

 floobydust wrote:
Some of your comments do cause me to wonder about some things... mainly the conditions of your tests. It's unclear (at least to me) what amplifier you are using as a test subject and what are the specifics regarding it.

It is the Moondog 2A3 circuit, basically which can be seen at http://home.earthlink.net/~ivol/audio/moondog.htm.

 floobydust wrote:
Perhaps the NOS 2A3 was no longer running in an optimal setup. In my humble view, if you don't verify proper operation of each set of tubes, then the overall test is somewhat suspect.
Sure, but on the other hand I would say it is a fair test in that all tubes were run under identical conditions.

 floobydust wrote:
Based on my experience with the EML 45, I would not be inclined to purchase a pair of their 2A3 tubes... but the Kron tube seems intriguing and I may look into their 2A3.
The mesh plate tubes are quite different; do not discount them.

 Romy the Cat wrote:
So, I wonder, if it would be possible that in some cases Adrian’s old tube run out of power as Adrian did mention bass deficiency. Also, the new tubes might have less grid current and as soon the 2A3 runs out of negative grid voltage and grid current begin to rise then the old tube might need more powerful driver.

So, without a demeaning the results of Adrian’s finding I would propose that his observations are good as they are but if we would demand a definitive comparing then more methodologically kosher environment shell be used. I would say that to be on a save site it need to be sure that both old and new tubes are used in the equal way. I think two measurements are necessary. First one, is to show how a given tube battles A2 class or how linear it is with positive voltage on grid. Let agree the for 3W tube it matters. Second, I would like to make sure that each tube individually set it the right operation point. I would like to drive a full power over the tube and to see that currant and voltage would clip at the same time. Ok, now it the interesting moment – what to do it they are not the same. To change operation point? To change loading? All of it affects Sound it and the question would be: what is the sound of tube vs. what the sound of the given operation?
Again, it is just a my own test in my own circuit with a few listeners. I would say that my impressions of other types of tubes generally coincide with the many stated on various forums, so I do not think my set-up is abnormal in any way; it is a real-life application for 2A3 tubes and I expect any 2A3 I buy to function in it.

I again just mention that the Sylvania 2A3 has a "kind of neutral sound" - not audio neutrality for the Sound as has been discussed here before, but more regular audiophile neutrality, with middle of the road balance and omission of errors. It is not a bad tube, actually a very nice traditional 2A3.

Adrian

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