Local series regulators vs. global shunt regulator

[dBudBu]

This is my first post on DIYAudio and I’d like to thank everyone here for their contributions to this wonderful community. I’ve enjoyed reading many of the threads here.
The subject title says it all. I’ve been reading about the sonic virtues of shunt regulators and am convinced that they are the way to go. However it’s not practical to have a shunt regulator for each rail on every individual stage when there are multiple stages on a PCB. My question is in reference to analog preamp stages. In the case of multiple stages located distant from each other on a large PCB, would it be better to have one global series regulator followed by local series regulators dedicated to each PSU pin of each stage? Such as one LT317/337 to-220 main regulator followed by individual LT317/337 regulators in a to-92 package with their output pins located a few mm away from the device PSU pins.
Would it be better to have one shunt reg with remote sense wires going to a centrally located point on the PCB power traces with up to 12” of PCB trace between the sense point and the farthest device to be powered?
Would there be any benefit to using one global shunt reg feeding local series regs at the device pins? Or would that defeat the whole point of shunt regulation?
Has anyone compared the sonics of these different approaches? Can anyone comment in theory which should be better?

Thanks in advance for any replies,
Mark

[AndrewT]

When cost and space are taken into account, I think that multiple & local Shunt Regulators are not good value. They need too high a dissipation capability.
A discrete or IC Series Regulator offers better space and cost value for multiple & local regulation.

With local regulation the master PSU can be either unregulated but well smoothed, i.e. rCRC or rCLC to minimise ripple and mains borne interference.
Or one can use a master Series regulator, again IC or discrete, to meet the total demand of the connected circuits.

Or one can combine rCRC + Series regulator for the master PSU.

I'm tempted to reserve Shunt Regulation for low current, very high quality regulation for circuits that particularly benefit this necessarily bigger resource.

[Chris Daly]

Hi dBudbu
Welcome to DIY Audio forums. Andrew is quite right IC types like 317 and 337 regulators
offer good performance and its all about resources.

Single rail designs are a bit easier but,If you have both positive and negative voltages to cater for - try to use two smaller transformers, and a discrete positive supply and a discrete negative supply rather than a centre tap dual rail affair.

Observe star grounding,


Ic type regulators offer pretty good performance, but there are some great simple transistor designs like the common collector NPN, that is the collector is the input resistance feeds the base which can have a reference like a zener diode, and the emitter is the output. If you arrange 2 resistors instead of the usual one leading to the base from the collector and at that junction of the two resistors supply a capacitor of say 22uf and then further capacitance of 22uf from the base to ground, you can get some fairly amazing ripple rejection.

In a preamp design define how much current you need +20% and regulate the voltage centrally, then use diodes to define short pathway branches and decouple using capacitors. If you have specific components that can only tolerate so much current
a 317 or 337 can be very easily used as a current regulator in this case the calculation
is Vref/R. ie 1.25/ for say 75 ohms between Vout and Adjustment is 16.6ma

Ask questions of any of the DIY Audio members we are all here to help, Study the datasheets for components, and in every design define the right use of voltage and current. Some general rule of thumbs are For every amp of current use 1000uf
of capacitance. If its getting too hot redesign for less heat. Heat changes resistance
values. If it sounds good leave it.
,

Cheers / Chris