Noise / Interreference with Meris pedals with Ring powered

I have a Mercury 7 and I’ve noticed that with either the Omniport out of my MC8 or one of the non-configurable ports (7 or 8) from the MIDI Box the M7 is very noisy. I can hear what must be data pops and clicks through the rest of my pedal chain.

This doesn’t happen if I use a configurable MIDI port and remove power from the Ring completely.

I’m not sure if this is just the nature of Meris pedals? Maybe so in this case as the M7 isn’t designed to send data, only receive. Or is this the nature of some of the Morningstar hardware?

It’s a bit disapointing as I was hoping to use port 7 or 8 for the M7 to free up the configurable ports for devices that can’t work on 7 or 8. But in the end the MIDI Box might just be a 6-port connection for me instead of 8. :\

I’ve seen some threads about people modifying TRS cables to disconnect the ring or tip… my cables are not easy to disassemble and try this. But I’ll try some other non-TRS cables to see if it changes anything.

Meris devices receive MIDI on the tip and send MIDI on the ring, so there isn’t an opto-isolator built in (as per MIDI specs) to prevent ground loops. I’m not 100% clear why having the ring powered would cause a ground loop in this case but I guess one solution would be to use a modified cable. You can try using a mono cable as well and see if that helps.