Powered speakers???

T

tmh

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Sep 8, 2006
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I'm not familiar with older boat/auto stereos and I have a question. My 1985 boat has an AM/FM simple stereo and two speakers. We bought two new speakers and split the old wires from 2 "out" to 4 "out" for each + and - leads. However, the new speakers do not make sound. They do work - we tested on our home stereo.

Could it be there is no Amp on the stereo and the current speakers are powered some way? We only see one set of wires coming into each speaker which we assumed were simple speaker wires (no power). Waht are we missing?

Any help appreciated. We will likely get a newer stereo later on, but we have spent enough alreay for now. Thanks.
 
As you add speakers in parallel (+ to +, - to -) the total resistance (also called impedance or Z) decreases. Most amplifiers are rated to drive a 4 or 8 ohm load. The closer the impedance gets to 0, the harder the amplifier has to work.Usually you don't want to go below 4 ohms with consumer amplifiers. Most speakers are 8 ohms. Two 8 ohm speakers in parallel = 4 ohms. The best way to wire four speakers to a zone and keep the impedance at 8 ohms is to use parallel/series wiring. Wire both of the pairs in series, then parallel them together at the amplifier.
I'll try to explain this more clearly:
From the amplifier, the red (+) goes to the + of the first speaker, the black (-) of the first speaker goes to the + of the second speaker, and the - of the second speaker goes back to the amplifier. You now have two speakers wired in series. Repeat for the other pair of speakers and you now have two pairs wired in series and paralleled at the amplifier. Your total Z will be about 8 ohms, which is ideal for most amplifiers. You can use this parallel/series wiring scheme to add as many speakers as you want, as long as you keep the total Z around 8 ohms.
 
If you are replacing speakers check the impedance rating on the new and old speakers. I dont understand how you changed the wires. you had 2 speakers and still have 2 so why did you add wires??? do you mean you are trying to add 2 additional speakers?? if that is the case you have overloaded the output and might try connecting the 2 on each side in series instead of parallel though the power will be 1/2.
 
OK, thanks so far. I'll explain better...

We added two speakers...did NOT remove the two existing ones, for a total of 4 speakers. I understand what you're saying about overtaking the amp with 4 in parellel, but shouldn't we hear at least something from the new ones? The old ones sound just like they did.

Just thought of something - maybe the old speakers were already wired in series, then we did NOT actually tap into a + and - like we thought. I'll check that out then post any new info gained.
 
Problem solved. The existing wiring was just a huge mess and I couldn't be sure what went where. So I ripped it all out and wired from scratch and now all 4 speakers work fine. It took all of 20 min. or so, MUCH easier than trying to get rolls of electrical tape of tangled up wires.

Thanks for the help.
 
Is it not amazing what a little organizing of wiring bundles will do?

G
 
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