So I'm working on a project with a cmoy and I used the same resistive voltage divider to split the rails. However I'm also using a microcontroller that when powered from these rails causes them to become very unbalanced (+3/-13) from the usual +/- 8V.
I fixed this problem by incorporating the schematic used in tangents guide labeled "VFB op-amp based virtual ground driver". I used an L2722 op-amp as per another recommendation. All works perfectly fine if I omit the 1K resistor in the output. The rails stay perfectly balanced this way. Adding the 1K resistor causes the rails to behave before I put in the op-amp.
The worrysome thing is that the op-amp gets quite warm. I can keep my finger on it but it gets uncomfortable after like 30-45s. Everything sounds great with absolutely no noise. I can draw up a schematic or take pictures if needed.
Basically the project goes like this. I have an AC-AC wallwart that is rectified then regulated using a similar circuit to tangents' ( I ommited some of the caps, but the needed ones are all there). Then the rails are split like mentioned above. Input signals first go through a mux then into a DS1802 digital pot. The rest is just like a standard cmoy. The digital pot and mux are controlled via a microcontroller (right now I'm prototyping using an Arduino Uno). Op-amp has a low gain (3-4 I dont remember) since I'm just using IEMs. Even at max volume theres not a hint of noise when using my computer as a source (no fancy sound cards or anything).
