adapting single supply circuit for use with dual rail supply

[thetragichero]

Google results mainly give me the opposite question than I'm asking....

so I've been working on building preamp modules to replace the stock circuits in a Marshall mg100 head. one of the circuits originally was intended for 9v battery/supply operation so it uses a voltage divider into a voltage follower to split the supply. since a circuit doesn't care about what I call V+, 0V, and V-, is it just as simple as wiring V+ to V+, 0V to everything connected to the half supply voltage, and circuit 'ground' to V-? (let's assume all caps and op amps are properly rated for the voltage)
I think this is the answer but i'd much rather ask and confirm than say a bunch of eff words when it doesn't work lol

[GGBB]

a circuit doesn't care about what I call V+, 0V, and V-

In my limited understanding, that's an oversimplification, but for op-amp based pedal stuff is usually fine assuming the op-amps - and any other active devices - are split supply capable.

Consider DC power rails and AC signal separately.

Power rails are simple and as you stated - there is only Vpos, (Vpos - Vneg)/2, and Vneg, and they are the same for both designs e.g. +9, +4.5, 0 and +9, 0, -9 - so V+ stays the same, Vbias becomes 0V, and 0V becomes V-.

Usually signal ground needs to stay at ground/0V potential - so pure AC (unbiased) signals go to 0V in both configurations.

Where AC signal and DC bias are combined sometimes gets tricky and requires redesign, but for simple stuff generally treat it as DC so that the related device functions properly.

Watch our for devices that are only intended for single-supply use (e.g. NE570 - came up in a recent thread). Read device datasheets.

[amptramp]

Electrolytic coupling caps may need to be made bipolar or double value caps back to back since the output will fluctuate internally above and below ground.