Good post Harry
Nice collection to play with.
For Nicke,
I'm currently awaiting some professionally produced PCB's for the updated Jung reg's (with the tracking pre-reg).
I've built about 10 units as prototypes and they are fantastic, transforming everything they've been used with, from preamp supplies to portable MD units.
The differences between the circuits are interesting. The op-amp based units all offer lower output impedance, owing to the large small-signal gains available. The downside is that op-amp compensation being what it is open-loop BW drops with frequency, hence impedance at the reg o/p rises.
The discrete circuits have the potential to offer much wider OL BW, the POOGE one, for example offers flat o/p impedance to >100kHz.
This can, subjectively, be preferable in certain applications (primarily where noise is not the major concern) as it gives a neutral sound. Impedance is nearly always higher in these designs though, without some exceptional amplifier design.
Newer op-amps offer some hope here (Ad817 / AD825) offering much wider OL BW (to approx 10kHz). It's again at the expense of impedance and noise.
The other thing to bear in mind, as Walt mentions in his 2k update, the low-noise non-degenerated front ends of units like the AD797 can easily be driven into non-linearity in certain applications (notably digital designs with high levels of HF noise). As always careful selection for application is beneficial.
For my 0.02, the op-amp suppplies are marvellous for limited supply voltages, offering the lowest noise, low o/p impedance and stunning line rejections, discrete is the only option at higher V for power amps etc.
I recommend everyone to try the POOGE (with my updates) as it's easy to trial using prototype board (or even HH's beloved p2p!) and is such an order of magnitude better sounding than a 3-terminal reg. They're stable, cheap and fun!
Andy.