Input resistors with bi-polar PS.

[Artie]

I've noticed that many stompbox projects use a virtual ground, made up of a voltage divider. That means that the input and output resistors are "grounded" to the virtual negative supply rail. If one uses a true bi-polar power supply, should these resistors continue to be tied to the negative supply, or should they now attach to true ground?

[Auke Haarsma]

if using a true bipolar ps, you could get rid of the virtual ground and thus from the voltage divider resistors.

[Artie]

Yes, I understand that. What I mean is, do I "ground" the input and output resistors to "true" ground, or to the negative supply rail?   

[petemoore]

That means that the input and output resistors are "grounded" to the virtual negative supply rail
  A schematic might help me understand what 'input and output 'resistors are.

[Auke Haarsma]

If you mean the pulldown resistors, those are (still) connected to ground. But yeah, a schematic may help.

[caress]

i asked this same question a few days ago...

http://www.diystompboxes.com/smfforum/index.php?topic=70787.msg570052#msg570052

this is probably and HUGE oversimplification and might not be totally accurate, but virtual ground is halfway between your +9v and ground (0v) so if you change to a bipolar supply, ground (0v) is halfway between whatever +/- voltage you're using.

[Artie]

This is probably and HUGE oversimplification and might not be totally accurate, but virtual ground is halfway between your +9v and ground (0v) so if you change to a bipolar supply, ground (0v) is halfway between whatever +/- voltage you're using.

Perfectly stated! I really need to stop doubting my own intuition.

Thanks caress. Sometimes . . . we just need one more vote.