Adding a small 5V fan for cooling any components to add for elecrtical noise isolation ?

[IWC Doppel]

I have been modifying the power supply on the analogue board on a naim AV2 and this will result in a lift of pre reg DC supply to the board LM317 and LM337 regulators. So I will move from a pre reg DC supply from +-20V to +-24V when the post reg supply is +- 15V. I have ordered some copper pads to add the the back of the existing heat sinks, which I will nylon bolt to the heat sinks. But want to keep the unit cool, so want to add a small fan to help the temperature rising too high internally and can

I can pick up a 4.3V DC supply near where I will mount the 5V fan. Other than say a 0.1uf cap to GND on the +ve side of the fan any better ways to isolate any electrical noise ?

 

[JMFahey]

Just curious, why will you increase the pre regulator power supply?
In any case, what is being fed from the +/-15V rails?
Apparently "a preamp"
Can't imagine you need a fan even if voltage drop goes from ~5V to ~10V per rail.
What is the actual current consumption?

 

[IWC Doppel]

The existing AV2 is fed by two 15.6V taps and a centre tap with the stock power supply. This feeds quite a bit on the board, so I looked at feeding a seperate regulated 15V in but I need +-15V for the 32 op amps with the analogue pre amp (only 5 milli amps each feed), so quite a bit of extra work and a one way trip with cutting board tracks etc.

So I tried just wiring in the transformer AC from the XPS-2 transformer using the 13.4V AC feeds and disconnect the existing AV2 15.6V feeds. Wow ! a big upgrade, even though the DC supply dropped from +- 20V to the LM317/337 to +-17V. The better taps would be to use the 17.9V taps but this did seem to get quite hot, I didn't measure how hot it got but given it's in a tight rack with units above and below thought about cooling as its hot already