Newbie attempt at a full-fledged Regulated PSU

[karmik]

• Hi, i've been reading about regulators and best practices for building audio-oriented power supplies for a couple years now, i used voltage regulators ICs in the past (reference LM317 circuits and so on) but i never built a full fledged PSU from scratch.
  
  I ended up with this design, literally bumping together different bits of information i found here and on other sources. I'm very eager to hear your, even harsh, feedback and i'm willing to go back to the books if my lack of theoretical knowledge is so deep that i can't possibly tackle such a construction.
  
  Sources
  
  I based most of the design on Tangentsoft : Op-Amp Based Linear Regulators while double-checking some of the values of the components from WaltJung.org - Regulator & Reference Stuff and specifically Improved Positive/Negative Regulators.
  
  I can't say i understand the totality of it all, or even a better part of it but i was mostly able to follow the reasoning behind every choice explained in these articles (while taking a pass at checking the math behind it .
  
  
  I thank you right now for the patience you'll lend me.
  
  Schematics
  
  These are the schematics, with a few notes and questions i haven't been able to answer by myself. I also attached them to the post so pick whatever you prefer. The target regulated output voltage is 15V. If i actually master this way of building PSUs, i'm interested in learning how to scale up the design for 35V for another project (if possible, but i believe you'd need a different pre-regulator).
  
  
  • Warning: Large Image: Regulated PSU for Headphone Amp
  • EagleCAD Schematics
  
  
  Doubts and Notes
  
  
  • C2, C4, C5, C7 are noted as "Low ESR" in the original schematics, but why is it important? Can the circuit work with normal electrolytic caps?
    
    
  • In the document i mostly based my Jung regulator on, it says that Output voltage is VREF × (R2/R1 + 1).
    At the top of that document, it's mentioned that VREF can be obtained by a number of technologies. In the final design, i assume VREF is delivered by the zener diode D5 (LM329DZ) and it's therefore 6.9volts? this would yield an R2 value of roughly 120 Ohm (117 to be precise) and R1 of 100 Ohm, does it make any sense to you fine people?
    
    
  • Tangentsoft argues to use two different star grounds and in their schematics, they do use two different symbols for the respective grounds. I seemed to understand this is needed in a dual rail configuration, while at the moment i'm only interested in a straight normal PSU. I skipped on the multiple ground points.
    
    
    • Is this dangerous or bad in any _big_ way?
      
      
    • Can the circuit work with only one ground point?
    
    
  
  I deeply appreciate any feedback i might get from the community. I had tremendous response a few years back when i was trying to build a 3-way speaker (Here) and i've been lurking the forum very gladly ever since. Thanks in advance!
  
  
  Giulio