sweetbeats
Reel deep thoughts...
...somebody, sometime sort of promised some PSU schematics?
Check your PMs.
I would also like to mention (again?) Douglas Self's book, Small Signal Amplifier Design. He goes into good detail about mixer PSUs (up to some 5A delivery) especially wrt noise and protection.
I do need to get that book sometime.
One way to get RIPPLE down is a 2 stage filter after the rectifier so..Cap-R-cap where R is about 2.2 Ohms or whatever does not drop the regulator differential too low.
This concept is already incorporated in the PS-3500 +/-15V supply...22,000uF main filter, 100R series resistor, 100uF secondary filter and then additionally a small value bypass cap. There are also 470uF output filters with small value bypass caps.
...Also some noise reducing tricks around the regulators.
The +/-15V supply doesn’t utilize typical 7815/7915 regulators. Not sure if the noise reducing tricks are based around those kind of parts, but Teac did incorporate noise and ripple reducing tips found in the application examples on the datasheet for the Mitsubishi M5230L dual regulator. Datasheet here:
https://aliot.com.ua/pdf/m5230.pdf
Refer to cap C037 on the PS-3500 schematic.
Protection: 80,000 mfd of downstream capacitance could certainly put the regulation series devices in danger! Solution is a hefty diode rev' biased across the device. 'Mutual shutdown: Many ICs, the NE series for sure do not like having just ONE supply rail and will die. Self gives a simple diode circuit for protection but it probably could not be incorporated in those PSUs (can't tell. No map!) One bolt on solution is a relay that will only pull in for all the rail voltage. (can be bypassed with bleed Rs to cut the inrush current.)
These are *exactly* the kinds of solutions I’m looking at...or a 555 based delay circuit...anyway...*some* sort of soft-start circuit.
Do not (grannies and eggs here!) be tempted to up the res' caps. That would bugger the 'power factor' and give the mains traff a harder time. (The R then cap avoids this problem)
No temptation here...based on my calculations after conducting the load testing on the main transformer, 22,000uF main filters are probably overkill as it is, and justify the use of the small value bypass ahead of the regulator.