Hey guys. I'm working on a friend's '88 convertible and due to it's age and previous owner the car has a lot of interior issues. Most notably is the sound system. Here's the story to the best of my ability to describe:

The speakers worked when he got the car (except for having headrests from a coupe or the possible option of a convertible not coming with them) but he loaned the car to a friend for an extended period and when he got it back the audio did not work and the speakers had been replaced with new Pioneer units. I took out the console and radio bezel and removed the factory head unit. The antenna was not plugged in all the way so I plugged it in and turned the key to the "on" position and I got noise. It sounds like crap though. Now just about every search I have done mentions the various amps failing and I don't really know how to test that and I certainly don't want to spend my money trying to troubleshoot someone else's car. Is there an efect created by a failed amp? I seem to get just bass out of the doors which makes sense as they are a small, dedicated woofer. Searching for convertible info makes it seem that this was the factory setup as well. The left, front speaker has very faint crackling sound coming out of it and oddly, when I go over lane markers or a rumble strip I can make the front speakers emit a horrible noise. Knowing this info, what do you think the problem is and what should be my course of action to fix it. If the problem is obvious, then I have no problem spending money or having him do it. Thanks!

 

sounds like a badly done install.
better off running new wires to all speakers off the headunit if its not a stock unit.
much easier than tracing wiring faults.

 

The only thing that has been replaced is the speakers. The headunit, amps(at least the one behind the front driver's speaker which is the only one I know the location of) and wiring are all factory.

 

The "crackling" sound is indicative of a blown speaker, so the first thing I'd do is test the speakers, even though they have been replaced. Connect them to another source, see if they work properly. IF they are blown, chances are the amp/head unit caused it, especially if the "friend" turned the stereo up too loud. If you turn the factory (25w) system up all the way you will destroy the speakers quickly. You can take those same speakers, connect them to a 50w amp, turn them up to 25 w and they'll run all day long without being damaged. Why? Because if you push a 25w amp to 25w it produces a lot of distortion, which eats speakers. A 50 w amp delivering 25w is "clean" power, which not only sounds better it does far less damage to the speaker. I have 2600w in my car, not so I can blow everybody away, but because when I turn it up to 500 watts I get crystal clear sound.

I agree with Brodie on the wiring too. It's easier to run new wires than it is to deal with the crappy wiring harness in this car. The Mazda engineers used wire that is way too small to handle the current demands of many systems in the RX7, especially the FD. I don't know if the FC has this problem as much, but I'd guess it probably does.

 

I am having issues with my 91 vert as well. I get VERY little sound out of my left door speaker, none from rear speakers and very little from headrest speakers. Let me know if you have any suggestions. I am running the stock pioneer setup that came with the car.