tracking regulator to solve everyone's problems?

[mazurek]

I have been trying to solve the active crossover/preamp power supply problem for a while. The issue everyone has is that on turn on and off opamps make noise because of unbalanced psu rails.

Anyways, I was making steps towards a prototype psu with relay switching based off of rod elliots design (I will surely fail my stats final because of this diversion). I don't yet have relays built into the crossover, but I was testing the psu with a relay shunt in my active crossover.

Casually, I observed that a relay shunt caused different turn off noise than before, presumably because of an uneven drain on the rails. So naively, I made a note that I should put an equal resistance on the other rail.

But I went back to the datasheet to see if national already solved this problem, and there it is on the LM79xx datasheet, a schematic for a tracking regulator. If this is indeed any good, I believe it would solve everyone's problems, and no one will need muting relays because the opamps will behave themselves if the regulators track together nicely down to 0V on turn off.

The published noise for their tracking circuit is slightly more than the datasheet values, I'm not sure if they are tested the same though. And I'm not sure if the regs will continue to track down to ~3 volts where things start getting hairy for the opamps.

Also, is this turn off transient bad for opamps, I read its bad for IC's, but I would think most audio opamps are pretty rugged?

Please forum gurus, any guidance.