12AU7 SRPP buffer suggestions

Salas · 5th April 2007, 02:25 PM

Hello all

Is there any SRPP 12AU7 tried and good sounding circuit for line level buffer (no gain required just isolation and current) that you may suggest?

mod_evil · 5th April 2007, 04:05 PM

Why you like to use a SRPP? Why you don't use a WHITE CATHODE FOLLOWER? If you use a CF, you will have a small output impedance.

If you use a SRPP you will have a amplification of the half of the Mu of down tube...

The Cathode Follower, is a buffer unit, but SRPP isn't it.

Best Regards,
Felipe

mod_evil · 5th April 2007, 04:12 PM

This is a buffer, with the 12au7, in the CATHODE FALLOWER method.

The CCS of 5mA can be a resistor, or a CCS with LM317 or a transistor CCS...

=D

Salas · 5th April 2007, 04:31 PM

Thanks for your answer. Problem is that such I already have.
I am looking for something along the lines of the circuit attached and described as a buffer. Wanna do something creative with that second triode in the lil bottle you see...
Although when I simulated it in CircuitMaker it showed gain. If Frank is wrong about it being a buffer I am wrong asking for a buffer.

mod_evil · 5th April 2007, 06:05 PM

It isn't seem to me a SRPP stage...

Why, you isn't use the 12BH7 to make the CF? Or the 12au7... It is more simple than this circuit who you show here!

Best Regards,
Felipe

Salas · 5th April 2007, 07:49 PM

It was described as an SRPP buffer when they discussed it if I remember correctly. Or a grid lick bias something. Interestingly, it gives gain in CircuitMaker. But I remember that Frank said its a buffer. Frank is a regular here, I hope he spots the thread and will enlighten us. 12BH7 I have 2 types. One pair EH, one pair GE NOS. 12AU7 I have 10s of yummy NOS treasures so I wanna use 12AU7 so to change colors. Optimized White cathode follower with Ra=Rp/mu another good suggestion maybe? Does it sound really good vs single ended ccsed cathode follower?

Tweeker · 5th April 2007, 08:48 PM

It looks like a White Cathode Follower with an extra resistor and unbypassed cathode resistor at the bottom. These increase ZO and perhaps linearity.

Tweeker · 5th April 2007, 09:32 PM

Tubecad article on this/similar topology.

Salas · 5th April 2007, 10:18 PM

Quote:

Originally posted by Tweeker
It looks like a White Cathode Follower with an extra resistor and unbypassed cathode resistor at the bottom. These increase ZO and perhaps linearity.

...That uses grid lick bias too. Why I remember something about SRPP being stated its odd. I need holidays.

Nice link Tweeker! Thanks! Aha! the Aikido uses White cathode follower 2nd stage with newer formula suggestions. This is a well reviewed pre. I need second stage only.

sorenj07 · 17th April 2007, 01:29 PM

I recently modeled a White CF for use as a headphone amp using 12AU7's, I can scan it when I get home if you want. Zout = 38 ohms.

5th April 2007, 02:25 PM	#1
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	12AU7 SRPP buffer suggestions Hello all Is there any SRPP 12AU7 tried and good sounding circuit for line level buffer (no gain required just isolation and current) that you may suggest?

5th April 2007, 04:05 PM	#2
mod_evil diyAudio Member Join Date: Dec 2004 Location: Rio	Why you like to use a SRPP? Why you don't use a WHITE CATHODE FOLLOWER? If you use a CF, you will have a small output impedance. If you use a SRPP you will have a amplification of the half of the Mu of down tube... The Cathode Follower, is a buffer unit, but SRPP isn't it. Best Regards, Felipe __________________ Brazilian Tube Amp Builder.

5th April 2007, 06:05 PM	#5
mod_evil diyAudio Member Join Date: Dec 2004 Location: Rio	It isn't seem to me a SRPP stage... Why, you isn't use the 12BH7 to make the CF? Or the 12au7... It is more simple than this circuit who you show here! Best Regards, Felipe __________________ Brazilian Tube Amp Builder.

5th April 2007, 08:48 PM	#7
Tweeker diyAudio Member Join Date: Dec 2004 Location: Cincinnati, Ohio	It looks like a White Cathode Follower with an extra resistor and unbypassed cathode resistor at the bottom. These increase ZO and perhaps linearity. __________________ Be sure your foil hat has a good low impedance ground.

5th April 2007, 09:32 PM	#8
Tweeker diyAudio Member Join Date: Dec 2004 Location: Cincinnati, Ohio	Tubecad article on this/similar topology. __________________ Be sure your foil hat has a good low impedance ground.

5th April 2007, 07:49 PM	#6
Salas diyAudio Chief Moderator Join Date: Oct 2002 Location: Athens-Greece	It was described as an SRPP buffer when they discussed it if I remember correctly. Or a grid lick bias something. Interestingly, it gives gain in CircuitMaker. But I remember that Frank said its a buffer. Frank is a regular here, I hope he spots the thread and will enlighten us. 12BH7 I have 2 types. One pair EH, one pair GE NOS. 12AU7 I have 10s of yummy NOS treasures so I wanna use 12AU7 so to change colors. Optimized White cathode follower with Ra=Rp/mu another good suggestion maybe? Does it sound really good vs single ended ccsed cathode follower?

17th April 2007, 01:29 PM	#10
sorenj07 diyAudio Member Join Date: May 2006	I recently modeled a White CF for use as a headphone amp using 12AU7's, I can scan it when I get home if you want. Zout = 38 ohms.

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