"When I use an external S/PDIF effects unit with my Digi 001, I get a feedback loop. What am I doing wrong?"

The problem is you are sending your whole mix out of the S/PDIF port (to your effects processor) and then returning it to your mixer again. A certain recipe for problems. You need to set the 001 so its S/PDIF port sends only the signal intended for your effects unit. The procedure is as follows (courtesy of the Sweetwater Technical Support Staff):

1.Go under "Setups" and choose "Playback Engine"

2.Click "YES" to confirm.

3.Make sure your "OPTICAL" format is " ADAT"

4.Disable (take away the check) "Enable S/PDIF Mirroring". (This was causing the Feedback Loop!)

5.Click "Done"

6.Make sure the "Sync Mode" is set to "Internal"

7.Click "OK"

8.If you get a message stating your I/O setup has changed, click "OK"

9.Now go to "Setups" and choose "I/O Setup".

10.Click on the "Input" tab in the top left corner, and then hit the " Default" button in the bottom left corner. Do this for the "Output," "Insert," and "Bus" tabs as well. This will correctly rename all of your I/O's in the Pro Tools software.

11.When done press the "OK" button.

12.Now go under "File," choose "New Track" and create 1 "Stereo Aux Input"

13.Look at the Mix Window and find the new Aux Track. Assign its INPUT to "S/PDIF". Its output should remain at "Analog 1+2"

14.Now you can use the sends on any Audio or Aux tracks and set them to "Interface--S/PDIF"

15.The Send Fader will determine how much signal is sent to the effects unit. Your effects unit should be set to 100% Wet.

16.Make sure your effects unit's Clock is set to "External". This way you won't get any Clicks and pops when using the FX device.

17.If you can't set your effects unit's clock to External, you can change ProTools "Sync Mode" (Found under Setups/Hardware to "S/PDIF". Now the Digi001 will clock to the effects Units clock.

18.Enjoy!