Power supply issue: Neovibe + Skyripper in one box

[Ry]

So I finally decided to box up my beloved Skyripper (unboxed since 2001) and thought that it would be great to put it in the same enclosure as my much more recently built Neovibe.  I decided that I wanted to run both pedals from the same 16VAC wall wart.  The Neovibe has it's own regulator to generate 15VDC and I had an 'ultra clean power supply' (the schematic has been floating around on the web for a long time, but now seems to be at home at GGG) sitting around that supplies -9v.  I wired both the Neovibe and Skyripper to the 16VAC supply and each works perfectly individually, but when I run them serially (Skyripper into Neovibe), the hum is tremendously loud.  It pulsates along with the lamp in the Neovibe.

What I'm guessing happened is that I have a ground reference issue between the two pedals, created by the negative power supply of the Skyripper.

Does anyone have any suggestions on how to fix this problem or where to start debugging it?

Ry

[R.G.]

You have already debugged the problem. The same 16Vac source supplying bridge rectifiers will cause the rectifier and grounds to interfere.

You will need to either use the 16Vac source only for the Neovibe or use the same DC output from a single bridge rectifier for both Neovibe and the 9V regulator.

[Ry]

Understood.  I will get rid of the rectifier on the -9v power supply.

Thanks!