27 driving 2A3/45/ or 300B

jmillerdoc · 22nd December 2009, 05:26 PM

Looking for a good schematic for a single ended 2 tube circuit with a #27 tube driving a 45, 2A3, or 300B.

Anybody know of anything?

Jeff

kmtang · 22nd December 2009, 05:34 PM

Hello Jeff,

The gain factor of 27 is only 9 with plate impedance of 9K. You would need to use two of them cascaded to drive the 45 or 2A3. I don't have a schematic handy for you but it should not be too difficult to work on one.

Johnny

serph1nia · 22nd December 2009, 07:23 PM

1. You will need a medium mu preamp/input tube
2. You will need to bring the impedance down.
You can use some sort of mu-stage. Or 2:1 transfomer, this will devide the impedance by 4.

Probably a better choice would be to use the 27 as a preamp and something else as the driver.

22nd December 2009, 05:26 PM	#1
jmillerdoc diyAudio Member Join Date: Mar 2009 Location: Lawton, OK, USA	27 driving 2A3/45/ or 300B Looking for a good schematic for a single ended 2 tube circuit with a #27 tube driving a 45, 2A3, or 300B. Anybody know of anything? Jeff

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22nd December 2009, 05:34 PM	#2
kmtang diyAudio Member Join Date: Nov 2004 Location: Vancouver	Hello Jeff, The gain factor of 27 is only 9 with plate impedance of 9K. You would need to use two of them cascaded to drive the 45 or 2A3. I don't have a schematic handy for you but it should not be too difficult to work on one. Johnny

22nd December 2009, 07:23 PM	#3
serph1nia diyAudio Member Join Date: Feb 2008	1. You will need a medium mu preamp/input tube 2. You will need to bring the impedance down. You can use some sort of mu-stage. Or 2:1 transfomer, this will devide the impedance by 4. Probably a better choice would be to use the 27 as a preamp and something else as the driver.

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