How to hook up multiple speakers on same amplifier?

Question

How to hook up multiple speakers on same amplifier?

Answer 1

Most amps expect to see 4 ohms of resistance minimum coming from the speakers.

Doubling up on speakers halves the ohms, approximately.

So, If you hooked two 8 ohm speakers to the same amplifier terminal (2 wires to + and 2 wires to -) your amp would work fine.

So, if your amplifier is stereo, you can connect four 8 ohm speakers safely in almost every case.

Trying to add more speakers could seriously damage your amp! Most amps are unstable below 4 ohms.

There are of course exceptions to what I've given you so far, but it's generally correct. Not all speakers are 8 ohms. If you can't tell, get a volt/ohm meter (10 bucks at radio shack) and check them.

If you do want to run more speakers, there are companies such as Speaker Craft that make impedance protection boxes (boxes that manipulate the ohm load that the amplifier sees) so that you could put as many as 8 pairs of speakers on a single stereo amplifier. They also have on/off switches for each pair of speakers.

Answer 2

It depends what you mean by "multiple" and what options are available on the amplifier.

If you have a speaker a/b switch on the front of your amplifier you can connect two sets of speakers to the "A" and "B" speaker terminals and simply select which ones to play (either or both).

If you have no A/B switch and just the one set of speaker terminals, you can add a speaker selector box (See link for options) or -- if you know what you are doing and are careful -- wiring extra speakers in parallel or series (or both).

HOWEVER, the speaker selector is a better/safer option since the lower impedence from speakers wired in parallel can be hazardous to your amplifier (many are not stable into low impedence loads (and if you try the protection circuit may trip, or you could fry the amplifier)), or if you wire in series the higher impedence will result in reduced speaker volume. Also, in either case you won't be able to adjust relative volume among the speakers.

If you have to ask what the latter paragraph means you should avoid these options and consider the speaker selector (which will do much the same, but is properly designed to avoid risk to your amp)