tweaking old psu


i wonder if someone could help me on this regulated psu. I purchased a while ago a Vincent SA-93 Preamp. My plan is to replace the OP Amp linestages with a descreet class-A linestage, but i need plus-minus 20-24ish Volts. Originaly symetrical 15 Volts are the output.

I asume that D109/D110 and also R140-R138 / R149-R151 "clamp" the LM317 and LM337 into plus/minus15Volts. Changing these values coult also change the railvoltages up to 20-24 Volts?

(Described for the +ve side): The LM317 is acting as constant current source of 1.25/11 = 114mA. T102/103 compare the 6v zener voltage with the potentially divided output to drive the shunt load. Increasing R140 to 8k2 will give you an output voltage trim range of approx 21.3 to 22.4v. You will need to up the input AC voltage to 24v to maintain the same headroom across the LM317. The power dissipation of T109 (and potentially its heatsinking requirement) will increase according to the output voltage increase. You will need to check the current requirement of the linestage falls within the 114mA capability.
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