Need +18,+9 and -9 volts supply

[j.frad]

Hi, I'm gonna need  a power supply that provides +18 volts as well as +9/-9V, I think I can use the GGG regulated PS with 24 volts ac to provide the +18, and then I can take that +18 DC to power my bipolar GGG +9/-9 supply.
My questions:

-What parts of the bipolar supply do I need to remove? my guess: the two rectifying diodes, but I'm not sure, what about caps?

-The schematic for the -9 and +9 regulators says that the can take an input voltage up to 30 volts, the GGG file says tha transformer should be 12 volts. That 12 volts, is it just the recommended output voltage for the transformer so that the regulator doesn't heat up dispersing too much voltage? Can I run them with 18 volts?

Any help would be appreciated!

My plan is building the www.musicfromouterspace.com WP20 analog synth (section DIY synth>>Miscelaneous) which runs on +9/+18 (off 2x9 volts batteries or in my case, a power supply) and to add to it the guitare trigger from the same site which runs off +9/-9volts. My concern is about grounds, I don't think I can turn the +9/+18 into +9/-9 because I'll be using the PCB from the site and I think there will be problems between audio ground and supply ground...

[R.G.]

You are correct to worry about grounds. There is and can only be one ground in a system.

I would recommend this:
1. Make a raw supply that provides +/- 22 to 24Vdc by using a 30 to 34Vct transformer, a diode bridge and two filter caps.
2. Make your +18 from the + side with a 7818.
3. Make your +9V from the + side with a 7809.
4. Make your -9V from the - side with a 7909.

You can make -9V from your +9V with a charge pump, but not the way you seem to be headed.

[j.frad]

ok, that's another problem I thought I might have, but I wasn't sure... thanks for your help!
So if I do that, I don't need the diodes, they're just for rectifying AC right?

And the caps, I'll have one cap after the 24V regulator, do I need to put one before the others as if I were chaining power supplies? this would put the caps in parallel, is it ok?

edit: ok forget it, I just understood...