I'm designing a +/-12V split rail supply for a eurorack (modular) sythesizer. I was adviced to put a pre-regulator block at a higher voltage a connecting to it several point-of-load regulators. Because of the transformer I have, I was required to use LDOs, and to save cost I tried to use only positive one's (the negative one's are three times as expensive, at least in through-hole version).
Here is the simplified schematic of what I've come up with:
The pre-regulator provides two 13.5V floating pairs of nets, which are then reduce to 12V at the load, and both GND nets are put together at that point. I think it works fine when only one POL regulator is connected, but it starts to break down when several of them are connected in parallel. The problem I think is that each U4 will not necessarily provide exactly 12V at their output.
Is there a solution that would allow me to keep the same regulators (which I already have)?