That's a very strange looking PSU. If the first diode had the cathode facing downwards, it would be a standard half wave doubler (are you sure it's facing that way?). The 2 ICs are regulators? I assume you drew them viewed as if the metal tab were towards the back? The first regulator is variable (LM317?) and the other is a 7824? Is the input of the second actually going to ground or is that a mistake? Out of curiosity, what are the resistors around the first reg? (sorry for the questions, just for clarification).
Does the phantom tap off the 73VDC also? Just trying to understand why they did that...
Someone please correct me if I'm wrong, but, if my calculations are correct, that 5W resistor was perilously close to dying the first time the preamp was powered on:
Original Neve circuits are spec'ed to run on +24V @ about 120-130mA. On paper, the doubler rectifier takes your 24VAC up to close to 68VDC, if your mains voltage is high or the trafo is not exactly 24VAC you could easily get the 73VDC you measured. That 5W resistor is there to drop voltage (as heat) before the regulator, and since we know what the circuit uses, we can figure out how much: V=IR = .130A x 270R = 35.1V (That's assuming the LEDs are running off another rail? I don't know.) So, if the circuit is plugged in, you should have about 35V less on the other side of the resistor.
OK, now for the power dissipated by the resistor under above circumstances:
P=IV = 35.1V x .13A = 4.563W !!! (If LEDs are running off this rail then I don't know how it didn't fry earlier).
Keep in mind that this is also not accounting for the couple seconds when you turn it on that Neve preamps suck double or more current (until the capacitors in the circuit fully charge). It's pretty quick, but still, way more than that resistor is made to handle. I wonder how many others might have the same nasty surprise coming....
They should have put a 10W in there. Better yet, they should have used a JLM
As far as the resistors go, do as geoff says, but get the 10W for sure, especially if you use 3 in series. It'll drop about 39 volts, and put out 5.07W of heat. Conversely, you could use 2 in series, drop 26V and dissipate 3.38W of heat, which should be OK for 5W resistors, but may or may not be OK for the first regulator, depending on what they have it regulating to.
As always, double check everything I wrote, I tendency to make mistakes is above average! ;D
Once you get it working check the ACMP thread for some mods to these chinese circuits. I would assume yours has some of the same issues, like lytics instead of tant caps, wrong zobels on the trafos, RC filters on the input connectors... it's a long read but some things may make your preamp a bit better.