ltspice - new and confused - what might I be doing wrong?

[LiftedTrace]

I'm new to ltspice.
I tried to draw up a schematic of a power supply I dont understand how it works, so I can try and learn.
Its for an audio amplifier and its supposed to take two negative voltages and output -12v.
Problem is, ltspice doesnt seem to know how it works either because its not displaying the correct values for its output.

Im clearly doing something wrong. Anyone out there know what I might be doning wrong?
Attached is the ltspice file.
The -12v should be close to -12, but im getting -110 ish.

[rfclown]

It doesn't need the -120 volt supply. Remove the connection to the -120 supply, and make that node ground instead. The output will be about -11.4 volts, a diode drop above the zener -12 volts (the base emitter voltage of Q1)

[Ian.M]

What do you expect with no load on -12V, and two resistors pulling the input and output of your regulator towards your -120V rail?  Add a load resistor between -12V and GND, and get rid of R1 and R2 and it behaves reasonably, though with only about 11mA of available base drive, you wont get much output current, nowhere near the approx 2.5A the MJE2955's SOA chart says it can handle.

[LiftedTrace]

Thank you. The load part didnt occur to me. Ill put a load on the -12 and see how it behaves.
As for removing resistors, i am trying to understand this design.
This is from an actual schematic and makes no sense to me, so i was hoping i could duplicate in software and try to play around and get a better understanding.
Ill try and find more -12v areas on the schematic and put those in too.

Thanks.

[Ian.M]

With a 470 ohm load resistor, it regulates even with R1, R2 present.  Any higher lets R1 drag the -50V supply towards -120V, dropping out of regulation if the load resistance exceeds approx. 720 ohms.

However I am suspicious of your AC sine voltage sources.  LTspice (and other SPICE3 compatible software) specifies the amplitude of a sine source as the peak voltage, but most schematics and your multimeter will give a transformer secondary voltage as its RMS value.  If you want to get a 50V RMS sinewave in LTspice you need to specify the peak voltage as 70.71 V or:

Code: [Select]

{50*sqrt(2)}