I'm making a PCB for an audio amplifier + power supply (circuit [here](http://www.redcircuits.com/Page2.htm)). 

The power supply voltage rails with my transformer end up being about +/- 37V, and I want to generate a 5V rail from this for powering some cooling fans on the same PCB. This is pushing the limits of a typical voltage regulator (e.g. the max. input of a L7805 is 35V). 

I tried a DC/DC converter (a R-78C5.0-1.0) but this produces audible noise on a speaker at the amplifier output (I put 10 uF decoupling caps at the input and output). One thing I didn't try yet is the EMC filter suggested in the datasheet [here](https://recom-power.com/pdf/Innoline/R-78C-1.0.pdf).  

I found "high-voltage regulators" (e.g. an [LR8](https://www.mouser.com/datasheet/2/268/20005399A-909415.pdf)), but the max. output current is 30 mA, and my fans need about 100 mA. 

Is there a better way for generating 5V from 37V without producing EMC that I can hear as noise on the amplifier? 

UPDATE: I'm an idiot. It turns out the noise was coming from having some signal wires too close to the transformer. I rearranged everything and now I can use the DC/DC converter without producing any audible noise at the speakers.