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6SN7 6N8S preamp suggestions

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ruffrecords

ruffrecords

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Joined 2007
customtubeconsoles.com
vconsumer said:
Not complicated. A handful of inexpensive parts and very little real estate would get the job done. Besides, the OP said he was looking for high gain.
Click to expand...

I think 26dB is more than enough gain for a preamp. If you are going to start adding in semiconductor CCS then you might just as well make the whole thing out of semiconductors. Hardly a tube design in my view.

Have you tried it both ways? I have, and the difference was more than negligible.
Click to expand...

I very much doubt that. A 6SN7 at 5mA with a 10K resistor between has a plate load equivalent to at least 10*ra at which point the only distortion the circuit produces is due to the intrinsic distortion of the tube itself. Raising it to 100*ra or 100*ra with a CCS will make no noticeable difference. A 6SN7 mu follower will produce typically 0.04% or less distortion at 2V rms output and 99% of that will be intrinsic to the tube. Your CCS might reduce that to 0.039% if you are lucky. If you are telling me you can hear a 0.001% difference in distortion then the only person you are fooling is yourself. If there genuinely is a difference between the two it can only be because you built the mu follower badly.

Cheers

Ian
 
merlin el mago

merlin el mago

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Joined 2009
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merlin el mago said:
What about this schematic with R4, R6 400-500 ohms?
B+ 360V?
I have 240VAC tx, Salas shunt regulator spends 20V in-out so I have maximum 315-320Vdc regulated wich value for R8 have I to use to have 250VAC?
Schematic can be improved?




I will use Salas high voltage shunt regulator.
Click to expand...

vconsumer said:
Just replace the 47k resistors in the schematic above with CCSs. While you're at it, try the loctal 7N7 in place of the 6SN7.
Click to expand...

merlin el mago said:
Wich schematic?
Click to expand...

vconsumer said:
The last schematic in your first post.
Click to expand...

I didn't see any 47K resistor?
 
merlin el mago

merlin el mago

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Joined 2009
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Attached schematic with all changes, please check, thanks Ian.
 

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  • 6SN7 mu-follower.GIF
    6SN7 mu-follower.GIF
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