2 headunits

DYohn wrote: I like the relay idea, but you couldn't simply trigger them from the remote on lead as that might still allow both to be on at the same time - or both to be forced off.  You need a mechanical selector switch.

Can you elaborate on this a bit?  How could it allow both to be on?  The NC (87A) and NO (87) contacts of a relay can NEVER be connected, so how could the two seperate outputs ever be connected?

If you add an external amp you would need to isolate the relay control circuit from the common remote line that both head units would share, but other then that there shouldn't be a problem using the remote turn on lead and a relay for each wire (or a couple 4PDT relays).

Kevin Pierson

If you used one 4PST on the output of each amp then they could still both be on or both be forced off.   Use a single 4PDT relay and then only one could be connected at a time, but if you turned both on whichever activated the relay would be the only one on.  You would not be able to select the alternate HU and leave both on.  I still think a manual selector switch is far more flexible and secure.Support the12volt.com

DYohn wrote: If you used one 4PST on the output of each amp then they could still both be on or both be forced off.   Use a single 4PDT relay and then only one could be connected at a time, but if you turned both on whichever activated the relay would be the only one on.  You would not be able to select the alternate HU and leave both on.  I still think a manual selector switch is far more flexible and secure.

You could install an inline toggle switch to the remote wire that triggers it.  Then you would have a "priority" set up with a manual over ride.    :)

You could eliminate the remote wire from the picture all together and just use a toggle switch by itself.  There are many options, all up to the installer.

Kevin Pierson

Absolutely, and using a toggle to control a relay is what I would do.  Like I said, a manual selector of some sort. Support the12volt.com