Question: For my diy synth, I have a Meanwell RT-65B PSU that delivers +11.5V, +5V and -12V. The +11.5 should be 12, but the difference is within the tolerance, according to the [datasheet](https://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/Rt-65/RT-65-spec.pdf).

I also have a [CV-12 module from midimuso](https://midimuso.co.uk/index.php/cv-12/) that requires 12V to operate. On that module, a LM317 regulator is used to produce +10.6V, which has to be exact because the module is used for tuning other oscillators. However, the +11.5 V don't seem enough for this, and the regulator won't go beyond +9.9V, making the module out-of-tune.

I'm not an electrical engineer and hardly know which part does what, and I'm curious which options I have left, other than buying a different PSU. Are there any regulators that are more suitable for this purpose? I have looked at the [data sheet for the LM317 regulator](https://docs.rs-online.com/0054/0900766b813862fa.pdf), but I'm not sure which part of it refers to the situation that I am in right now.

Answer: 
You have 3 solid options

1. Follow Marcus Müller recommendation from anouther answer - replace LM317 with proper LDO on CV-12 module
2. Replace Meanwell RT-65B PSU for anouther one which has at least 12,2V on 12V output (why 12,2V you may ask - your particular LM317 chip at your particular load provides 9,9V instead of 10,6V - 0,7V deficit when fed with 11,5V so it needs at least 0,7V higher input for desired output)
3. Add a boost converter beetween Meanwell PSU and CV-12. MT3608 adjustable booster boards are readily avaible and one of those can output 12,5V at 1A when fed with 11,5V (lets give LM317 a 0,3V extra headroom)
For completeness' sake, I'll add another important piece of information:

The RT-65B PSU has a trimmer to adjust the +5V output. However, it seems that the other voltages are referenced relative to the +5V rail, so adjusting it also adjusts the other rails. This is not stated on the data sheet, but a [kind Redditor informed me](https://www.reddit.com/r/AskElectronics/comments/y8vtg4/psu_does_not_deliver_enough_voltage_for_a_lm317/it3g9qc/?context=3) that this is the case. This way, I managed to get +12.0V and +5.3V, which makes the board behave as it should.

Nevertheless, this whole endeavor has taught me a lot, and I now understand some flaws in the design of the board.