Ultra-Clean 9VDC Power Supply not so clean at all

[sushyoshi]

Hi
I´ve just built my first power supply and it was thw ultra-clean 9 vdc power supply that is on the GGG site. The problem is that it aint so clean. 
Maybe i did something wrong. Heres what i did.
I got a spare wall wart that and took the tronsformer out of it. This would give me an output of 16VAC (on the schematic was 25VAC). I connected everything according to the schemating, the diode rectifier bridge, the 1000uF filter caps before and after the voltage regulator. i thing the voltage regulator gave an output of 22VDC and with the resistors i could get the 9VDC (according to the schematic). I solder everything and put it in a plastic box. Then i test it with my ruby amp and it really humms, then i test the amp with a battery almost no humm.
What can i be doing wrong? Do i really need a transformer with an output of 25VAC instead of 16VAC? At the output of the whole power supply instead of putting a 470uF caps i put a 1000uF caps, do you thins this is bad? Is it the plastic box that making the power supply not so clean at all?
Any suggestions?

[ranchak]

I have the same problem with mine. I added a 2200uF cap to the 1000uF cap coming off of the transformer. I have another power supply that I am in the process of building that looks to be much quieter than this design.

[the_random_hero]

*Don't use huge filtering caps after the regulator - stick with 10uf and a smaller one for radio-frequencies.
*16VAC should be fine. Regulators only need about 2V above the output voltage to function properly.
*1000uf caps shouldn't matter a lot. If anything, it's overkill.
*I don't think the plastic box will be causing a lot of problems, but is everything else star grounded?

[mac]

Rotate the transformer in the 3 axis. Sometimes the magnetic flux finds a perpendicular closed loop in the circuit inducing currents, ie hum.

Put some thick metal beetwen the transformer and the circuit. A lot of the magnetic flux will be dissipated in the metal.

Use a shielded cable for the 9v.

Just some ideas

mac