E130L PP Power Amplifier - Page 2

frentec · 13th November 2020, 03:36 PM

The transformers are being made with UL winding, it was offered at no extra cost, but I may not use it, 6V in is a lot, any suggestions are welcome, it is a loosely based design. I do have a couple of ccs boards built from kk audio somewhere.

artosalo · 13th November 2020, 03:38 PM

If semiconductors are OK, then this is well working 6N6P LTP.

artosalo · 13th November 2020, 03:42 PM

Quote:

UL winding, it was offered at no extra cost, but I may not use it...

Then you are limited to pentode mode (with 150 Vdc to screen grids).
In this case you will need even more GNFB.

Quote:

6V in is a lot, any suggestions are welcome..

Add one 6N6P as a voltage amplifier, ahead of the LTP.
Then you can add negative feedback easily.

frentec · 13th November 2020, 03:49 PM

I also have some 2c22 7193 tubes, would these be better?

frentec · 13th November 2020, 03:57 PM

If that's the case then I probably will use the UL Tap

frentec · 13th November 2020, 04:55 PM

Quote:

Originally Posted by artosalo

Then you are limited to pentode mode (with 150 Vdc to screen grids).
In this case you will need even more GNFB.

Add one 6N6P as a voltage amplifier, ahead of the LTP.
Then you can add negative feedback easily.

I ordered 8 more 6n6p's

Depanatoru · 05:06 PM

With only 250V max on G2 ( and typical 150V ) this is not a tube for ultralinear or triode mode in push-pull , even if you want . Maybe for single-ended .
So the best option is a stabilized G2 voltage , 150V or so .
Very similar with horizontal sweep tubes , wich have low voltage G2

artosalo · 13th November 2020, 05:05 PM

This is what I would build...

v4lve lover · 13th November 2020, 05:07 PM

Agreed, very good schematic, i would substitute another BJT like MPSA42 for the TL431 instead because the CCS will have slightly better AC impedance at the expense of DC stability. The latter being of no real concern given that its a AC coupled design.

artosalo · 13th November 2020, 05:29 PM

The point where CCS is, i.e. at the cathodes of 6N6Ps has quite low impedance.
Then the demand for high dynamic impedance of the CCS does not exist.
Actually a LTP works fine even with a few kilo ohms resistor as a tail.

The idea of the CCS I suggested is that it has low noise and does not need negative supply voltage.

13th November 2020, 03:36 PM	#11
frentec diyAudio Member Join Date: Feb 2013 Location: France	UL Winding input voltage The transformers are being made with UL winding, it was offered at no extra cost, but I may not use it, 6V in is a lot, any suggestions are welcome, it is a loosely based design. I do have a couple of ccs boards built from kk audio somewhere.

13th November 2020, 03:49 PM	#14
frentec diyAudio Member Join Date: Feb 2013 Location: France	2C22 I also have some 2c22 7193 tubes, would these be better?

13th November 2020, 03:57 PM	#15
frentec diyAudio Member Join Date: Feb 2013 Location: France	UL Tap If that's the case then I probably will use the UL Tap

13th November 2020, 05:01 PM	#17
Depanatoru diyAudio Member Join Date: Jul 2006	With only 250V max on G2 ( and typical 150V ) this is not a tube for ultralinear or triode mode in push-pull , even if you want . Maybe for single-ended . So the best option is a stabilized G2 voltage , 150V or so . Very similar with horizontal sweep tubes , wich have low voltage G2 Last edited by Depanatoru; 13th November 2020 at 05:06 PM.

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13th November 2020, 05:07 PM	#19
v4lve lover diyAudio Member Join Date: Aug 2010 Location: Surrounded by glass, no really my room is full of tubes	Agreed, very good schematic, i would substitute another BJT like MPSA42 for the TL431 instead because the CCS will have slightly better AC impedance at the expense of DC stability. The latter being of no real concern given that its a AC coupled design.

13th November 2020, 05:29 PM	#20
artosalo diyAudio Member Join Date: Feb 2010	The point where CCS is, i.e. at the cathodes of 6N6Ps has quite low impedance. Then the demand for high dynamic impedance of the CCS does not exist. Actually a LTP works fine even with a few kilo ohms resistor as a tail. The idea of the CCS I suggested is that it has low noise and does not need negative supply voltage.

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