Installed an Alpine deck with an Arc Audio KS125.2, running 2 Hertz HCX 165's on a Harley. My problem is they have a distorted midrange sound. It almost sounds like the singer is under water. The amp sits on top of the deck in the front fairing. I have tried a new amp, bypassing the deck, changing the speakers and new wiring to no avail. Has anyone heard of this problem or something likes this? most of the product was new (the deck was out of the customers car but we tried with just running an ipod into the amp)

 

Is your speaker under water? lol... just kidding. Are you sure you're getting both channels and not just one to both speakers for some reason?

 

Also, might have polarity reversed on one of the speakers? Other than that, i dunno what to tell you

 

Is the low pass filter turned on on the amp? It shouldn't be.
That's all I can think of that would make it sound "underwater".

 

Just went through the same thing with a customer's bike & it ended up being a blown tweeter in one of the HCX 165's. Some sound dampening in the fairing will also help.