New Nelson Build dubbed the Arch Nemesis

[Pano]

Yeah, OK. I took a lot of time looking at OPT yesterday and it's not easy to find what is needed. Not even close. Would be nice to know more about the Electroprint option.

Running the voltage up and making this a "SS Triode" amp is an interesting idea, if the transistor will handle it. SDJP120R085 should be OK in that regard. But then you'd need a voltage gain stage at the input. It becomes another amp.

 

[buzzforb]

Please don't let the 1000 word article delay the publishing of an informative chart or graph. (Deeply embedded is the implication of a yet-to-be-designed/fabricated SIT device that would best triodes when connected to a 5-40/1 transformer ---- the single device amp of all single device amps.)

He already has the SIT's.

 

[buzzforb]

I talked to Bud about it at length. From what I remember, he suggested running the voltage up. Way up. Driving the current down so that the Output Tx requirements became more realistic as Pano noted above.

I suppose at high voltage...one could actually run a tube PS.

Easily done, But what would become of the loadline. More bias current always seems to be a major part of the sound of these devices. What effect would dropping this into the mA region have on final sound?

 

[Pano]

That's a very good question. Wish I had an answer.

 

[Nelson Pass]

Easily done, But what would become of the loadline. More bias current always seems to be a major part of the sound of these devices. What effect would dropping this into the mA region have on final sound?

With SITs the load-line is the thing, otherwise you would pick a nice Mosfet
or Jfet and operate as if it were a pentode.

With SITs we see that the "mu" is relatively constant within a reasonable
range so that the voltage and current parameters (load-line) can be
optimized for a range of load values at a fixed wattage and not wander far
from the sweet spot. This character is dependent on the specific device.

I have tested my parts to 64 ohms (the Nemesis primary) and down to 2
ohms without the relationships falling apart. As the parts are not voltage
rated to replace a 300B, I am not expecting that they will practically drive
more than a 500 ohm load at 10 watts (for example).

 

[buzzforb]

Do you have a typical output graph for your new toys that you could share for education purposes?

 

[Nelson Pass]

Here's the Yamaha 2SK77

 

[Nelson Pass]

Here's the Sony 2SK82

 

[buzzforb]

Tha really does look different, doesn't it.

 

[Nelson Pass]

And the SIT-1

 

[buzzforb]

It seems I need to start writing Santa again I bet you are making some wonderful amps with these things.

 

[Nelson Pass]

I left the Vgs figures off the 2SK77.

Here they are.

 

[buzzforb]

Oh yeah. Thanks, once again.

 

[Michael Rothacher]

Nelson, could I trouble you for the pinout on the 2SK82?

I have some lightbulbs that really want to meet them.

Thank you,

Mike

 

[Nelson Pass]

 

[Tea-Bag]

acroman on ebay sayz the 2sk82 is a p-channel device?

 

[aparatusonitus]

Hi Nelson,

If you have a few extra 2SK77, I'm willing to exchange these for genuine, brand new Yamaha 2SJ27. I can even send all I have so you can match few complementary pairs for you and myself.

Regards, Ivo

 

[Michael Rothacher]

Thank you, sir.

 

[Nelson Pass]

Alas, I don't have any 2SJ27's.

 

[aparatusonitus]

Alas, I don't have any 2SJ27's.

I do...so I want to exchange a few of mine 2SJ27's for yours 2SK77's