I recently bought a different car (a 1999 Sunfire GT) and I thought all the speakers worked at first, but then after awhile the front driver's side speaker quit working and the rear driver's side speaker wouldn't work. Then after awhile the rear driver's side speaker would work now and then. So when I got my empeg and amp installed I thought they would all work, but they don't. is there anyway to test the speaker to see if it works?

A D cell battery connected to speaker leads will cause the speaker to buzz.

My guess would be that the battery isn't providing a constant voltage, maybe due to a varying load on the battery as the speaker moves. That is, some sort of feedback loop. Obviously the battery never causes the speaker to move on both sides of the equilibrium point, but it might cause it to oscillate on the positive side (or the negative side if the polarity is reversed).

No you won't! You'll get a small click or thump when you make, and then break contact with the battery.

A hum implies an AC voltage source: batteries are pretty well known for being DC

I'm going to try this tonight with a c-cell and an old Subaru speaker in the basement. I'll let you know. I'm with the pop-on-contact-no-sound-otherwise camp.

However, one way in which this may make sense: a battery is a dc device, however the chemistry can only convert electrons so quickly. A speaker is essentially a short circuit to DC power, meaning that the DC voltage would drop quickly, perhaps there would be variations in voltage/amperage which cause the speaker cone to vibrate about a DC biased position, making noise.

-Zeke

I used to work for a guitar/bass/PA amplifier manufacturer as a designer. The test done on speakers for phase and functionality was pretty much the battery test described above. A "Thump" signified a working speaker and while watching the speaker you could verify the phase by the direction the speaker went when the test was run. This was especially useful for large PA speakers and subwoofers. The same effect often happens when the remote turn on of a car's amp is done wrong and there's a "Thump" through all the speakers when the amp is turned on when the car is.

The person speaking of a buzz is probably dealing with speakers with a bad speaker surround. Often the paper that actually joins the cone to the metal starts to wear and this is probably what is buzzing. I've had it happen with my own cars with rotted out speaker surrounds. They changed the design now on a lot of speakers to get rid of that issue i've seen, but they still make them with the paper surround. But as someone stated, DC with what is essentially a transducer sends the voice coil one direction only and to generate sound, it must be an AC type input. Currently I am working on designs in ultrasonics which are essentially voice coils that send the vibrations through metal at above hearing frequencies as opposed to a speaker which transmits audible sound through a cone to air.

As predicted: thump, then no sound unless contact was interrupted or partially modified (dragging wire along terminal of C cell).

I used a 9V, which gave a nice thump and pinned the voice coil. The C cell (1.5V) was gentler, but still had the same result. I didn't keep either battery attached long enough for the battery to become warm or hot to the touch.

Any 'buzzing' would have to come from intermittent contact.

I've also seen the 'rotten surround' buzz. I replaced some surrounds on my old AR410's with newfoam.com (warning- nasty yellow website design). It wasn't inexpensive, but if you have otherwise functioning speakers that are worth keeping they gave me great service & a quality repair. I reconed & refoamed two 4" mids & two 8" woofers. They now sound as good as ever and are ready for their next 20 years of service.

-Zeke