A couple of variants of this ideal regulator for audio applications.

Ideal because:

1. Stable and small output impedance in the 20-20k area and above (for 2x trans. version ~ 0.05ohm and ~0.005ohm for 3x trans. version).

2. Load current flows locally through the regulator`s output transistor only.

3. Excellent step response.

4. Little capacity electrolytic cap on regulator output or no electrolytic capacitor at all.

Also

5. High PSRR (for 2x trans. version 100db and 120db for 3x trans. version).

6. Noise < 1u (20-20000hz).

7. Simple and reliable.

In addition to the classical 2x transistor "nazar`s regulator" also described 3x transistor version characterized by much better output impedance and PSRR.

Also described a filter/voltage follower that makes better use of supply voltage (Uout...

“Dynamic Element Matching for High-Accuracy Monolithic D/A Converters” RUDY J. VAN DE PLASSCHE. IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. SC-11, NO. 6, DECEMBER 1976

Article from IEEE journal and datasheet about PCM58

AN 18-BIT DAC FOR CONSUMER APPLICATIONS” By F.J. Highton and K. Ito, 1988

Articles and patents about SONY (NTT develop.) MASH DACs.

“A 17-bit Oversampling D-to-A Conversion Technology Using Multistage Noise Shaping” YASUYUKI MATSUYA, KUNIHARU UCHIMURA, ATSUSHI IWATA AND TAKAO KANEKO. IEEE JOURNAL OF SOLID-STATE CIRCUITS, VOL. 24, NO. 4, AUGUST 1989

US Patent 5,021,788
US Patent 5,073,778
US Patent 5,148,168

From article https://s-audio.systems/diy/psu-without-electrolytic-eng
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Electrolytic capacitors are constant part of power supply of audio devices, but in terms of sound he does not bring anything good, dispersion of sound quality-type of electrolytic capacitor is very large. Sonically the best types of electrolytic caps are Nichicon KZ, FG, Panasonic Pureism, Black Gate FK, NX, Elna Cerafine, Silmic II, Silmic,but the attempt to eliminate from PSU electrolytic capacitors was very successful, instead is used "electronic capacitor" (right side of the circuit).
It is global negative feedback free electronic substitutes, that has a low and stable impedance 0,1...0,2Ohm (equivalent to cap 40000u) in the band to megahertz shunting NP0 0,1 microfarads Murata GRM31 in close to chips, it completely detach regulator (317\337) from load, therefore we have the ideal transient response when load "changes",...