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Ray, thats the fabulous JJ 2A3-40

Posted by drlowmu (M) on September 3, 2008 at 19:56:12

In Reply to: RE: But, uh, that's the answer to a different question. posted by Ray Moth on September 3, 2008 at 18:30:04:

Ray,

That is the JJ 2A3-40, with the same plate as the JJ 300B, and a 2A3 grid structure, and a BENEFICIAL 2.5 VAC filament, so it can run on (better sounding than D.C.)2.5 V.A.C. That is one heck of a triode output tube Ray. Trumps their 300B due to the 2.5 VAC filament.

They made it with EIGHT vertically running, evenly spaced cathode wires, across the plate structure, so the cathode is symmetrical and substantial as far as emissions are concerned.

All the vintage 2A3s, 45s, 300Bs, 10s, 50s, etc. have either a V or W or M shaped filament structure, (except the very first monoplate 2A3 with a 12 string Harp filament structure), and these typical cathode shapes are NON linear, or, should I say NON SYMMETRICAL in the way they emit electrons. The Vaich tubes originally, and the current EMLs use an even better execution of these eight filament wires, evenly spaced, but the JJ 2A3-40 gets the job done.

Our mutual friend Dennis experiments with all the 2A3s, old and new, in his Serious Stereo 2A3 DC amp, and I learn from him.

Probably the best sounding 2A3 ever made is the current production EML 2A3 mesh plate. Isn't that nice to know!! Its costly, but if properly operated, can last 40,000 hours. The old Vaich AVVT mesh plate 2A3s are "up there" too, in terms of quality and cost, but having been long discontinued, they are unobtanium.

Enter the JJ 2A3-40 a few years ago. It is the "audio give away of the century" according to Dennis. Its about one fifth the cost of the ultimate 2A3, an EML mesh plate, but its performance is no wheres near its cost level, it plays wonderfully, if you adjust your circuit to get the most from the tube. It is robust, top to bottom, and has lots of nice qualities. A good solid plate tube, like this JJ, when optimized, sounds different than an EML mesh plate. The mesh will have lots and lots of nuances and air, and micro detail, but the solid plate, ran properly, will bring additional positive aspects to the music presentation, that the EML mesh will not.

Now Ray, for the part that is likely going to "disconnect" you:

Dennis finds these tubes run great, and sound wonderful at about 245 P-K and about 43 mA of current. I don't think he'd ever run them higher than 285 VDC. 245 VDC at 43 mills is 10.53 watts dissipation. And its glorious there with the amp adjustments he has made!!

So, the question becomes, do we want quality, or quantity? An extra watt or so at the expense of degrading the sound, and cutting the tube life in half or in quarter? How much louder would our friend uW's amp be if it were 5 watts, rather than two, or three? That would be a fraction of a dB. Not enough to make a real difference. Quality or quantity. Beauty, or numbers??

What I would like to convey to uW and others is to do what Dennis has done, ie: build an amp with a 200 watt power supply, and operate it at, say, two watts, The first two watts will be glorious, and the amp will sound far more powerful than amps rated ten times its wattage, because the design was done as a entity, everything, and I mean everything, was considered in its execution. A perfect balance.

So that is the story, as I know it, about the JJ 2A3-40. If I was building a 2A3 amp, that is the tube I would not hesitate to buy.

Jeff Medwin

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Edits: 09/03/08

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