SV: Re: [sdiy] Linear PSU options .. 7815/7915 vs LM317/LM337 vs 723 etc

[Steve Lenham]

> All I can say is that I have designed systems with less that 0.4nV/root 
> Hz, which is a lot better than almost any audio systems, and have used 
> 78xx/79xx regulators without any problems at all.  A properly designed 
> amplifier, or any circuit for that matter, will not care what the noise 
> level on the power supply is.  Generally, all I care about is that the 
> power supply have a good low impedance.

I can back up what James says - I've worked on high-gain mic preamps 
with -130dB noise levels which still used 78xx regulators and nothing more 
than a 100 ohm/47uF RC filter for the supply to the front end. Far more of a 
headache was a) hum pickup from the mains transformer and b) getting the 
ground layout right on the circuit board.

Steve L.