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1990 Repair of Stereo System


Guest mosley1961

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Guest mosley1961

I just bought a 1990 Reatta that is about 90 percent restored. The previous owner had it painted (nice job) but put a plug in the antenna opening and discarded the power antenna. The radio works after a fashion as it does pick up public radio on FM. I have bought an aftermarket power antenna and think I'll get decent reception after it's installed.

The real problem I have is the rear speakers are blown. I'm no expert at auto sound systems, hence this post. I bought two 6" by 9" coaxial speakers with 4 ohm impedance to replace the blown rear speakers.

Will this work? This appears to be the correct speaker size - am I right? Is the 4 ohm impedance going to be a problem? Any advice?

Edited by mosley1961 (see edit history)
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Do you get loud crackling/popping noise coming from the rear speaker(s)? Because, they may not be blown, but rather the capacitors in the radio are crapping-out.

There's lots of information about people replacing these capacitors. I need to attempt that repair myself.

FYI, the crackling/popping noise happens regardless of the volume setting or even if muted.

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Guest mosley1961

The speakers sound as if the base has been blown out - there is no crackling noise at all. My assumption is someone cranked up the hard rock too much and blew them out - my only term for this sound.

I assume the 6" by 9" size is correct for the 1990 model year. That's what they look like, anyway.

I've got the parts and am going to have them installed tomorrow, based upon the impedance issue appearing to be OK. I'll advise as to success or failure.

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The factory front system in 4 ohms, the rears are 10 ohms. I have no idea why they did it this way. Maybe due to efficiency differences with the drivers and their enclosures?

My rear 4x10 speakers sound like garbage too. Probably foam rot. Note that even high end home systems can suffer from foam rot as they age. (Like my old McIntosh speakers did...) The speakers can be saved by replacing the edges. But I'd be surprised if anyone made edge kits for Delco 4x10s.

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The real answer is mylar speaker cones. These were just becoming available in 1990. Incidently 4x10 was a very common GM front speaker even forty years ago which explains the 10 ohm impedance. My Fieros have 2.

It is not the cones themselves that are the problem. Paper cones are fine - as long as they are protected from sunlight and are fairly stiff. (Flexy cones tend to color the sound more than stiff ones.) It is the foam surrounds that rot. They can disintegrate into dust - just from time. Kinda like the rollers in our Reatta headlight motors...

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Depends on where you are. I have removed paper cone speakers that had almost no cone remaining. Edge seperation is common. Just replaced a front speaker in an '86 Fiero that had this problem. I imagine that in different parts of the country, the expectation may be different.

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Guest mosley1961

Good afternoon -

Just had the new power antenna and the new speakers installed. The system appears to be running exactly as it should. Sound quality is good and the antenna works perfectly.

Thanks for all the input. This forum is very helpful for a new owner such as myself.

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Depends on where you are. I have removed paper cone speakers that had almost no cone remaining. Edge seperation is common. Just replaced a front speaker in an '86 Fiero that had this problem. I imagine that in different parts of the country, the expectation may be different.

Well, speakers that are exposed to the sun will certainly suffer - no matter what cone material. So cars with speakers in the dash and rear "hat shelf" are particularly vulnerable. Not really the case in the Reatta.

I pulled one of my 4x10s this evening. (Note: man were those screws in tight!) Besides the normal speaker grille, the speakers themselves have a black cover over them. I presume this is to further protect them from sun and dust. Maybe even rain? The paper cone and the foam surround look to be in good shape. Surprisingly large magnet. It will start to affect my computer CRT from almost 3 ft away!

So now I am wondering why my rear channels sound so lousy? Will be interesting to try them again when I get my head unit back.

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... So now I am wondering why my rear channels sound so lousy? Will be interesting to try them again when I get my head unit back.

Hmm. Pried the black cover off the front of the speaker, and sure enough - the surround is split. (Couldn't see it from the rear by peering through the holes in the basket.)

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