12v supply into buffer

[howdood]

Hi all, total newbie question here: I'm putting together a buffer for my bypass strip (either the Cornish transistor or the Klon TL071/72 layouts), but the only out I've got spare on my pedal board supply is the 12V one. Do I need to change any resistor values to maintain unity gain (I don't want to build a boost circuit by accident)? Any advice about where to start looking at the schematics for how to accommodate a 12v supply would be gratefully received!
Thanks!

[tempus]

We'd need to see a more detailed description of the circuit you're trying to build, but the short answer is probably not. The supply voltage for buffers do not affect resistor values.

Like I said, post a schematic so we can be sure though.

[R.G.]

As a partial answer, the opamp version almost certainly needs no tinkering with resistor values to maintain unity gain, as most opamp circuits are biased at about half the power supply by a resistor divider. This works as well with 12V in as it does with 9V. The opamp's output simply follows the change in bias voltage, so the output changes from about half of 9V to half of 12V. If there is a capacitor at the outputof the buffer to break the DC output of the buffer from being passed on, no worries. One reason opamps were invented was to get some isolation between things like biasing from things like gain. The gain setting resistors on an opamp don't change with power supply in normal circuits.

I'd have to look at the Cornish buffer schematic to give a coherent answer on it. Many transistor circuits do not have the isolation of gain setting from DC bias conditions that opamps do, so there is a significant possibility that it would need changes to the biasing to maintain unity gain. But I would have to look at its schematic to be sure. I don't have that handy.

[howdood]

Hi - thanks all! The (allegedly) "Klon buffer" is dead simple - I'm looking at the layouts at http://tagboardeffects.blogspot.co.uk/2011/04/klon-buffer.html.
The "Cornish buffer" is more complex, and there are some suggestions on the forums that some component values may not actually be ideal - http://guitarpedalbuilders.blogspot.co.uk/2012/07/pete-cornish-input-buffer.html

Those are the two I've narrowed it down to so far...
h

[JC103]

tagboard: http://tagboardeffects.blogspot.ca/2012/02/cornish-buffer.html

and this one: http://effectslayouts.blogspot.ca/2016/03/cornish-buffer.html