12AU7 SRPP buffer suggestions - diyAudio
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Old 5th April 2007, 03:25 PM   #1
Salas is offline Salas  Greece
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Default 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?
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Old 5th April 2007, 05:05 PM   #2
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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
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Old 5th April 2007, 05:12 PM   #3
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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
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Old 5th April 2007, 05:31 PM   #4
Salas is offline Salas  Greece
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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.
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Old 5th April 2007, 07:05 PM   #5
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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
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Old 5th April 2007, 08:49 PM   #6
Salas is offline Salas  Greece
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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?
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Old 5th April 2007, 09:48 PM   #7
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It looks like a White Cathode Follower with an extra resistor and unbypassed cathode resistor at the bottom. These increase ZO and perhaps linearity.
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Old 5th April 2007, 10:32 PM   #8
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Tubecad article on this/similar topology.
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Old 5th April 2007, 11:18 PM   #9
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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.
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Old 17th April 2007, 02:29 PM   #10
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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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