Using 4 & 8 ohm terminals simultaneously on PA a

Wayne Carver · Post by **Wayne Carver** » 25 Apr 2004 5:34 pm

Can I hook a 8ohm speaker to the 8ohm terminals and a 4ohm speaker to the 4ohm terminals of a pa amp simultaneously?

Blake Hawkins · Post by **Blake Hawkins** » 26 Apr 2004 5:27 am

Wayne, In general, no. Of course it depends on the amp.
Could you "get away with it" and not blow anything? Maybe. Again, depends on the amp.

Blake

Larry Clark · Post by **Larry Clark** » 26 Apr 2004 9:03 am

Wayne, I would not attempt to combine the outputs unless I got a definative "Go Ahead" from the manufacturer or a qualified amp tech. My educated guess would be no,since output configurations like that are usually and either/or and not meant to be combined. Experimentation could become costly.

Len Amaral · Post by **Len Amaral** » 27 Apr 2004 5:04 am

What if you are using a stereo amp? Using one side for an 8ohm load and the other for a 4ohm load should be OK.

Ken Fox · Post by **Ken Fox** » 27 Apr 2004 6:24 am

For a stereo amp OK. But if you do that with a single output transformer too much current will flow through the secondary windings of one of the taps. As the taps are in series to the secondary common, all the current for tap one and two will flow thru the first tap to get to the second tap. The windings to the first tap could be damaged.

David L. Donald · Post by **David L. Donald** » 27 Apr 2004 6:36 am

Both the last two posts.
If you not pushing the system too hard, you could run with different load charcteristis on differen channels.
But if you are pushing the amp to it's limits the last post could apply.
It is also a case of different impeadences also give different out put volumes in the room from the different types of speakers.

Typically for a large PA one stereo amp will do the same type of load both sides.
And definitely DON'T use a 4 ohm tap and an 8 ohm tap on one amp channel; at the same time.
T
hat would, depending on the amp, create some very weird much lower or higher impedance which could quickly dry it,
and also the speaker levels will be way off relative to each other.

C Dixon · Post by **C Dixon** » 27 Apr 2004 6:43 am

David is correct.

For moderate levels, probably never a problem with missmatching output impedances. But when you go full bore now that is a different story.

The problem with full bore even with "matched" impedances is you are destroying something far more important than the equipment.

carl