Why does my monoblock amp have 4 speaker terminals?

Have you ever went to hook up your subs and noticed your MONOBLOCK amp had 2 sets of speaker terminals?

But a monoblock amp only has one channel, right?

Isn’t’ that what mono means?

– Well – yes.

Then why does my mono amp have 4 speaker terminals? Is it a 2 channel amp or mono?!?

I get this question quite a bit. And for good reason…

It can be confusing when you go to hook up your subs to your mono amp and notice there are 4 speaker terminals. It looks something like this:

Zapco monoblock amp
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Don’t worry. It is in fact just one channel.

When you see an amp like this, both of the positive speaker terminals are wired together internally. And both of the negative speaker terminals are wired together internally (wired in parallel).

Amp manufacturers just do this to make it easier to connect multiple subs to one amp.

How do you connect subs to an amp like this?

Say you have two single voice coil 4 ohm subs and connect one to each pair of speaker terminals on the amp.

The final load the amp sees is 2 ohms because two 4 ohm SVC subs wired in parallel is 2 ohms.

What if you have just one sub?

Just use either of the two positive terminals for positive. And any of the negative terminals for negative. The remaining two will just have nothing hooked up.

This diagram does a great job showing a few different ways to wire subs to an amp like this:


monoblock amp wiring diagram

But don’t take my word for it. MTX has a great description on their website:

” A monoblock amplifier is a 1 channel amp (mono literally means 1).

Since bass is omnidirectional, meaning you can tell where it’s coming from, it isn’t necessary to run subwoofers in stereo.

You may see 2 sets of speaker terminals on monoblock amps and they will be labeled as either speaker 1 and speaker 2 terminals, or simply + + and – -. That is because the two + terminals are connected to each other inside the amp, as are the two – terminals.

The second set is there simply to make it easier to connect multiple speakers to the amplifier.

Do not confuse the two sets of terminals as separate channels.

If you’re not sure whether an amp is a mono or two channel amp, you can look at the labels above the speaker terminals. A multichannel amplifier will have the separate channels labeled as Left and Right, or L and R.”

That should clear it up for everyone, but…

If you still have any questions on this (or anything else for that matter), just comment below or send an email to taylor@caraudioadvice.com.

I’ll do what I can to help.

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