Battery power supplies are, in my opinion, a good thing. You avoid a mains transformer, ground loops and possible hum. If you take care of your batteries, and charge them with regular intervals, Lead Acid batteries will serve you for many years. I use 12 V sealed types, these are 1.2 Ah, and will keep Head amps and preamps running for 24 hours or a week, depending on current demands. They are not noise-free though, but can provide ample current to charge large capacitors, the Mallory types used here are 22.000 uF. Add some smaller capacitor values too. And there is always an option to use a 9 V high quality, low noise regulator after the batteries. Most preamps can live with a +/- 9 V supply.
Output is of course +/- 12 V, and I added a single 24 V output as well, since one of my MC Head amps need a single supply. You can use a switch or a relay to change between on
and charge
state, I ended up with a relay. Use fuses!!!!! If shorted, batteries can become extremely warm and even explode, throwing acid all around. No good. Put fuses directly on battery connections!!! Due to the size of your capacitors, they tend to get large, since the initial charging of the caps are current-demanding, I ended up with 9 amperes, use slow-blow types. Go as low as you can. Lead Acid batteries can deliver really serious currents, just think of a car battery - they can deliver more than 100 amperes... A simple, soft charge circuit is a possibility, if you want to reduce fuse rating. Could be a power resistor, another relay and a 555 timer circuit. Lots of options on the internet. Use a good charging unit, made for the battery size of your choice. Old DIN Loudspeaker connectors for the charging ensures correct polarity, can't be turned the wrong way!
