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Single Ended Triodes (SETs), the ultimate tube lovers dream.

RE: Maximum Output

Nope! I'm not saying that at all.

The JJ simply doesn't go into minute convulsions at 43 ma. if it's "overloaded"-- (distortion!)--- anywhere nearly as much as old-design tubes-- just because the load changed a little bit.

It's FAR more load-tolerant. It's like a CAT D-9 up against a Bobcat.

I think we both can predict the outcome of that.

Sure-- JJ had to "meet" the old specs-- otherwise, people won't buy the tube and plunk it into their creaky old amps, and yes, the advertised plate resistance is 800 ohms. I said ADVERTISED-- and yes, it will measure-out-- it's not wrong. If one uses the old calcs. for a 2A3, and plunks this tube in, it will operate just like the old NOS tube. But, there, the similarities END. .

This is a new, better, and far more versatile tool, so learn to use it-- which is just what I did. When I get a new tool, I find out what IT does--- I already know what the old tool does-- but I'm going to use the new tool, so I study IT as well as the old tool.

These tubes (JJ and EML, etc.) are designed to operate at far greater dissipation levels than old 2A3's. The JJ-2A3-40 will dissipate up to 40 watts, not crap-out at 15.

At 250 volts across it, and at 43 ma. plate current, one might expect that it would be rugged alright, (it is), but it might not cater well to the low plate current. NOT SO! It sounds clean, clear, fast, ultra-dynamic, super-powerful and has a super-wide bandwidth.

Into 2.5K? That's coasting on a Banana Peel for it. This thing could drive 1K! No, I'm not going to design for 1K, but I'll bet that this tube could drive it.

Since you're a measurements man, I suggest you set up to do what I used to do.

RUN YOUR OWN PLATE RESISTANCE CURVES. Then, you know what is happening for YOUR chosen specs & OP. points, etc.

To do this, I used a variable 0-650 VDC supply for the plate. I tapped a battery set at the voltages I thought would be within the ranges where I might want to operate the tube-- for the applied grid-bias.

At each grid bias point, the variable Plate supply had previously been set at ZERO. At each point, I measured the grid bias. Then, I upped the D.C. voltage on the plate in steps-- At each step, I measured both voltages.

Of course, plate current was being measured all the time.

I drew up a graph, and plotted all the op. points. (use commercial graph paper).

I did this on many tubes. NONE of them were ever perfect, some fell-in close to specs, (At SOME op. points), others did not.

EIMACS, in particular, were off quite a bit. I made about 25 plotted points for each tube.

This was more important when analyzing small-signal tubes, but I did it for all of them.

It's just another item for your basket of calcs. If you're going to do all this calculated stuff, then this will help you do it right.

---Dennis---







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