battery/speaker question

[robertmark]

My 69e barn find has had the engine and tranny removed for rebuild. I'm wanting to replace the speaker in the dash. I am needing to power up the radio of course. However, I have not yet put power to the car. Can I just put one battery in the car to test the radio? If so, would it be the passenger side? Also, the speaker from the factory has a soldered connection on a plate which I will have to remove to put on two female adapters of different sizes. I assume it matters which wire goes on which post on the speaker? Sorry for what are probably simplistic answers, but electrical, among other things, has never been my strong point. See attached pictures. Thanks Guys!!!

[darrin]

will let somebody else chime in on the power issue. If the radio's only powering a single speaker, polarity of the speaker (which wire goes to which terminal on the speaker) will not matter. Polarity is only significant if you're using multiple speakers, as you want them to both push and pull their drivers in unison -- if two speakers were out of phase (different polarity), they'd start canceling out bass.

[blucille]

agree with Darrin on speaker polarity.

in terms of power, yes, any 12v battery attached anywhere in the system will do the job, assuming the OTHER battery connections are insulated against touching each other, or the positive cable touching the chassis ground.

that plate is broken off the old speaker, the wire on the right in the last photo has a 'rib' in it, that often means it is the + side, you can see on your new speaker a + and a - mark, but the larger connector is +....again, it doesn't really matter.

[spuggy]

You could probably hear the difference from out-of-phase stereo speakers in your living room, with good-quality equipment. In an air-cooled 911 with the motor running? Yeh, not so much...

With a mono speaker, makes no difference. I'd probably just solder wires to the plate, and terminate the wire ends with the appropriate connectors for the harness.

If the 69 is 12V and both the batteries are 12V, then connected in parallel - and connecting either would power the system. If the 69 is 12V and the batteries are 6V (count the cells/caps - each is ~2V) then they're connected in series (e.g. stacked, like in a flashlight) and need both connected to make 12V.

Personally, with an unknown car I'd lean towards initially using a small cheap bench power supply with selectable power level (and a fuse) for the first connection, rather than a honking lead acid battery that'll deliver 600+ Amps on a dead short...

[Coastr]

Agreed with spuggy above. Rather than power up the entire car circuit with wires disconnected, just power up the radio directly. I bought a 12v power supply off amazon for ten bucks which was for led lighting. It has a pair of screw in terminals which is perfect for bench testing 12v equipment like radios. You can unplug the radio from the wiring harness and find the positive and negative, and hook your power up to that.

[robertmark]

Thanks for everybody's input. So the wire with the rib is typically Positive, or always positive? Also, why the two different size connections on the new speaker? Is that in the event there would be more speakers? Sorry if the questions are on the ignorant side. Just trying to learn. Besides the engine and tranny rebuild, this speaker will be the only new item on the car.