I have a 2001 Ford Expy with supposedly a Clarion receiver and some
pretty nice JBL speakers and a sub. Supposedly this system was sold as
a MACH system by Ford and offered 290 or so watts of overall power.

For the last few months I noticed that I lost everything in my sub
(bass, sound everything). As time went on it seems as though I have
lost ALL bass in my four other speakers. No matter which speaker I
fade or balance towards there is still no bass / low freq.

I tore into my panel housing my amp and sub. The sub speaker looks in
tact nothing obliterated there. The amp has a four wire connection to
somewhere (headunit?) and another two or three wires running to the sub
a few inches away. There is no fuse on the amp?

I disconnected the amp and the other speakers sounded the same so I
think the amp was strictly for the sub and the head unit handled any
cross over or other function.

Do any of you experts have some suggestions on troubleshooting? Thanks.