speaker relay wiring

Here's the setup.
6 speakers in a 25 foot boat.

1 Infinity Reference 4 channel amp

When we're in the boat I want to power the 4 speakers inside the boat.
When we're on the beach I want to power the 2 rear speakers in the boat and the 2 speakers I have on the back of my engine hatch facing the beach.

Currently I've got a simple 12 volt relay where I've got the positive speaker wires from the head unit feeding the relay. When I hit a switch on my dash it flips from the front speakers to the rear speakers. I'm just using a common negative wire for the 2 pairs of speakers.

My question is, what do I have to do different now that I'm adding an amplifier? I'm guessing I could just add another of those relays and then put positive and negative wires on the relays?

I was just going to run the front speakers from the head unit and the other 4 off the amp but it's kind of pointless to have the speakers on the back of the boat running when we're inside the boat so I'd like to keep my relay setup. I'm just confused on what the best way to do it is.

Can my relay handle the additional power from the amplifier?

This is the type of relay I'm using right now.

https://www.aquahub.com/store/12voltspdtrelay.html

With an external amp, yes, you will have to run dedicated negative and positive speaker wires, and switch all four wires. (If only switching one set i.e. the rear signals for internal speakers vice external speakers.)

Those relays will work just fine. Add one more pair, to disconnect simultaneously the internal fronts, or even add a second swich to selectively connect internal fronts or not. LOTS of options here! ;)

EDIT
Just re-read... Switch between the front cabin speakers and the external speakers using one pair of relays. Easy.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."

The part that's got me hung up is the power ratings on the relays. They say 10a for the contacts.

If my amp is pushing 75 watts RMS at 12 vols that 6.25 amps. So that should be ok. However, the peak watts would equate to 18 or so amps. Will these relays be OK? I'm just not smart on the ratings.

I think I understand that adding a second relay and just doing 1 relay for left and 1 relay for right would work find. Then I go from the amp to the relays and wire the two seperate sets of speakers. When the switch is off the relays are passing the signal to the front speakers. When I hit the switch it powers the relay coil and switches the contacts and sends the signal to the external speakers. Exactly what I want to do!! Just want to make sure the relays can handle it is all.

The relays I have say the contacts are rated for 10a. So I'm guessing I need to find some new ones.

Those relays will work perfectly. The current rating is usually a SWITCHING rating. Are you planning on switching the speakers while running the amp WFO? If not, then don't worry about it.

tedmond wrote:

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a relay can handle 30amps and 40 max. You can purchase higher rating relays for sure. The thing is running speaker wire through a relay might cause some noise.

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1: Not all relays will handle 30 or 40 amps. I have seen reed relays rated for 100 milli amps. I have also seen relays (and you did mention that they exist) rated for literally 1000A. The starter solenoid on the firewall of older Fords? That's just a relay rated for 300A or so.

And it is HIGHLY unlikely that there will be any noise induced onto the speaker leads by a relay. I have switched speaker leads MANY times with no noise, ever.

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."