3 Pin regulated supply VS zener based supply

[KevinLee]

Hello,

I have a little integrated amplifier with a zener based power supply for the op-amp based pre-amp section.

Would there be sonic benefits to replacing this with a regulated supply built with good quality 3-leg regulators?

I have searched and only found one thread that relates to this and nothing was definitive.

I would possibly build something like the Welborne Labs PS1 module.

Thanks

Kevin

[anatech]

Hi Kevin,
Many times performance will come down to how well the circuit is executed. A small modification to the existing circuit would really improve performance.

Replace the resistors feeding the zener diodes with constant current sources delivering around the same amount of current. You can bypass the regulated voltages with some low value capacitors, around 0.22 uF. You can play with the values. The bypass is intended to be in parallel with the existing electrolytic caps. May as well replace those electrolytic capacitors with new ones of the same capacitance value. A higher voltage is okay. Just make sure it fits the spot.

There is a fair amount of material available both here and on the web on constant current sources. Use your common sense when reading "white papers" and circuit descriptions. Some are nothing more than advertising hype.

-Chris

[lineup]

hi KevinLee

anatech gives some basic and good info

if you want to learn more
there is some good pages at www.tnt-audio.com
Diy & Tweaking > Solid State

General articles
http://www.tnt-audio.com/clinica/solidstate.html

* Crash course on solid state power supplies
o First chapter
o Second chapter
o Third chapter

* Crash course on voltage regulators
http://www.tnt-audio.com/clinica/reg..._noise1_e.html
o Part 1.1 - Introduction and methodology (Noise)
o Part 1.2 - Tests & plots
o Part 1.3 - Tests & plots
o Part 1.4 - Tests & plots (+ batteries!)

o Part 2.1 - Introduction and methodology (output impedance - LM 317)
o Part 2.2 - Methodology (output impedance - TL 431)
o Part 2.3 - Methodology (output impedance - Emitter follower)
o Part 2.4 - Methodology (output impedance - 2-transistor shunt)

o Part 3 - Ripple rejection

[lineup]

there are also very good articles
if you search with www.google.com
that can explain the basic different of
series regulation
vs.
shunt regulation

A good and easy way to do The Shunt Voltage regulation
for audio circuits,
is using the Adjustable Zener Shunt Diode called TL431

It will make 2.5 - 36 Volt, set by only 2 resistors.
http://focus.ti.com/lit/ds/symlink/tl431.pdf
TL431 comes in several different packages.
IC DIP type or TO92 type.