Morley ABY Issue

[GuitarPilot65]

Mornin' guys & gals.
I attempted to use my Morley ABY pedal to switch between my DRRI and VVRI (guitar "in"; DRRI "out A," VVRI "out B").  With everything "on" both amps emitted a feedback-like pulsating buzz (Rev/ Vib off on both amps).  Is this a shielding issue with the pedal itself?  Perhaps the pedal's not a "true bypass" circuit between A & B?
Any insight would be greatly appreciated.

[sluckey]

I've never had any problems with my Morley A/B/Y. I've only used it with an AB763 DR, 5E3, and Marshall 18W. Some amps may just not like their inputs tied together. Here's an easy way to tell if it's the Morley or your amps...

Plug your guitar into the HI input of the DRRI. Connect another cable into the DRRI LO input and patch to the other amp. This does almost the same as the Morley except there will be a 68K resistor between the amp inputs, whereas the Morley just parallels the inputs.

And you can try the Morely on some different amps. You mentioned a VVRI. What's that? I assume it's some amp with VVR mod. Are you VVR'ing the entire amp? If so, I've heard this may put some dc voltage on the input at low settings. This may be an issue with the ABY.

[GuitarPilot65]

Thanks, Steve.
DDRI is AB763; Vibroverb RI (VVRI) is 6G16.  I was trying to alternate between them, NEVER send the guitar signal to both simultaneously.  Maybe I'll give it another try.
Regards.

[GuitarPilot65]

After some reading it seems I had created a ground loop with the Morley ABY.  Problem solved via one of those gray three-prong female to two-prong male A/C plug adapters.  Buzz eliminated when used with either amp.  Perhaps one day I'll trade the Morley for a Radial equipped with a "ground lift" switch:  http://www.musiciansfriend.com/compare?base_pid=153931&base_pid=620003