JBL tweeters cut in and out

Hi there,

I've been on a mission to get my 2005 Prius with JBL speakers back into shape. Over the years, a tweeter or two died along with a door speaker. I recently replaced the head unit with a Kenwood DMX907S - everything else is stock (JBL speakers, JBL amp, etc.).

Now, the front left tweeter cuts in and out at normal playback volume. I think it does it more when the volume is turned up. By "in and out" I don't mean it shuts off completely, it gets very soft for a 10 seconds, goes back to normal, and repeats this over and over again. It also doesn't seem to happen with all types of music.

I replaced the tweeter as well as the JBL amp with OEM replacements and the problem persists. It also doesn't seem to happen when I output signal to one corner of the car at a time. This leaves me with the remaining three suspects:

Poly switch: I've been reading "poly switches", a protective system in tweeters that lowers volume automatically to prevent damage.
Bad wiring: I accidentally messed up the wire during other modifications (sound deadening etc).
Underpowered stock amp: The JBL amp cannot handle the new high power coming from the head unit. I don't know much about speaker audio but I find this unlikely as I would assume the Metra TYTO-01 digital interface I used to handle these constraints.

I'm going to try running a wire directly from the amp to the speaker to test the wiring theory. In the meantime, does anyone know if the OEM JBL tweeters have this "poly switch" feature and have experienced something similar?

Thanks for your time!

 

Listening more carefully, it seems like both the front two tweeters are affected, but the back two are not. And it's not just high volume that causes the cut-outs, it happens particularly when there is a high level of bass. A great test is "9 Piece" by Rick Ross, as soon as those first 808's hit, the tweeter volume drops significantly. Without knowing any better, I might try an aftermarket tweeter to see if the problem is in the tweeter or if the JBL amp crossover is performing some kind of overload protection.