Originally Posted by WhiteDragon
LM338 is pretty straight forward to work with.
just follow the data sheet.
10,000 uf seems excessive
just keep things simple. likewise use a large heatsink
worse comes to worse
you can run 2 in regulators in parallel which allows 10 amp current.
but the idea is to stay with your original design and allow better heat dissipation with 2 devices 2 heatsinks. fan is good idea. might not be needed. otherwise every fan i know of can be turned off and on with a switch.
large heatsink is the easiest
pretty straight forward
headphone amp definitely doesnt need all this voltage and current. but the intention of building a bench supply makes sense.
22 to 25 volt transformer seems feasible. as mentioned smaller transformers tend to have poor regulation. meaning they have higher voltage when not fully loaded
Adding a fan connected to a sensor to manage heat dissipation is really more about learning how to program and implement sensor based features, and feeling fancy about doing so.
As for the comment about a headphone amp not needing all this voltage and current - "need" is highly subjective. You can power planar magnetic headphones directly from a smartphone. Will they sound good? Not really. Planars like power, and I like options. And who knows, maybe at the end of this I'll come to the same conclusion you reached - headphones don't need quite that much power, after all. There's really only one way to find out!
With regards to transformer regulation, after someone brought that to my attention in the above replies, I've narrowed down my options to transformers rated at 9% regulation, and between 30-36volts to avoid the problems you mention. Thanks for the pointers!