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Stock amplifier, rear speaker circuitry?

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Old 03-06-03, 07:03 PM
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Stock amplifier, rear speaker circuitry?

As I understand it, there's an amplifier stock in the rx-7? I think it's behind the passenger side front speaker.

A year ago when I put in my cd player I just wired it up to the speaker wires from the amplified speaker outs. I imagine this is undesirable, since you're basically amping an amped signal.

It sounds fine to me, I'm not picky But is this a potential electrical hazard in some way?

Also, when I was installing aftermarket speakers today, I got the fronts (4"ers) in just fine. Even though best buy said to get 6.5"ers for the rear, and the haynes manual has a picture of 6.5"ers in the rear, when I pulled mine out the mounting bracket had 4" speakers in there. That sucked. Also, the previous owner of the car had spliced a wire and installed what I can only assume are stock 4" speakers from a mitsubishi (they have the mitsu logo on the back). Why someone would do this is beyond me.

Anyway, so that's a heads up if you were going to replace your rear speakers. Some RX-7's (like my 86 GXL) have 4s in the rear, too. Be prepared to use a dremel, and if you don't have one you can order replacement speaker mounts that fit 6.5" speakers from crutchfield for $10 + shipping. If you don't want to do that, you can pay someone to cut them for you, but the local car audio place wanted $50 to cut the plates and mount the speakers, what a rip.

Also, what is the circuitry that's in the rear speaker housings? Is it some kind of crossover setup? Is the official stance that it should be bypassed, too?
Old 03-06-03, 09:17 PM
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Depending on the model and options there could be up to three amps in the vehicle.

Wiring up a high powered radio (25+ watts a channel) can lead to a blown amp. The stock fronts and rear amps are designed for around a 7 watt input. More than that can and will overload the system, causeing blown speakers and/or amps.

The rear speakers on a GXL are tuned powered/amplified enclosures. The 4" speakers are matched to the equalization in the amps. Again they should not be driven with more than about 7 watts RMS, or damage can occur.

So in your system from the factory you would have a front amp (which drove both front speakers) and then an amp in each rear speaker assembly.

Mitsubishi and Pioneer built the OEM speakers for Mazda. Mitsubishi used to sell car stereo much like Pioneer or Alpine. The speakers you found were likely OEM.

And $50 for custom rear speaker mounting plates is not unreasonable.

Last edited by Icemark; 03-06-03 at 09:20 PM.
Old 03-07-03, 09:25 AM
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Originally posted by Icemark
Depending on the model and options there could be up to three amps in the vehicle.

Wiring up a high powered radio (25+ watts a channel) can lead to a blown amp. The stock fronts and rear amps are designed for around a 7 watt input. More than that can and will overload the system, causeing blown speakers and/or amps.
Do you mean blown OEM amp or blown amp inside my stereo? Either way I should probably run my own speaker wires. Thanks much for the info, though.


The rear speakers on a GXL are tuned powered/amplified enclosures. The 4" speakers are matched to the equalization in the amps. Again they should not be driven with more than about 7 watts RMS, or damage can occur.

So in your system from the factory you would have a front amp (which drove both front speakers) and then an amp in each rear speaker assembly.

Mitsubishi and Pioneer built the OEM speakers for Mazda. Mitsubishi used to sell car stereo much like Pioneer or Alpine. The speakers you found were likely OEM.

And $50 for custom rear speaker mounting plates is not unreasonable.
No, it's not out of the ordinary if they all rip you off to that extent. But it IS unreasonable. I could cut and mount those rear speakers in 15 minutes. If I had customers lining up to do this, I'd privately make $50 every 15 minutes, bill $200 an hour and make $400,000 a year.
Old 03-07-03, 10:09 AM
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Originally posted by Deathbots
Do you mean blown OEM amp or blown amp inside my stereo? Either way I should probably run my own speaker wires. Thanks much for the info, though.
Both could be damaged, and no, there is no need to run your own wires, just bypass the amp at each amp.

No, it's not out of the ordinary if they all rip you off to that extent. But it IS unreasonable. I could cut and mount those rear speakers in 15 minutes. If I had customers lining up to do this, I'd privately make $50 every 15 minutes, bill $200 an hour and make $400,000 a year.
Ah there is more to that then you seem to know.

What about the cost of the tools, to make it?

what about the cost and time of the materials. Having to run down to the local metal supply place and pickout and purchase the sheet alumiunm or plastic??

What about even the electricity used to operate the tools to cut it?

Or the experience with the tools to do it correctly?? hell there are a good number of people here that can't even change their oil, well alone I would trust to operate a sabre saw, or router.

See, you might think it is a rip off, but if you don't have the tools, location, utilities, gumption and experience (all of which are part of the price - and it sounds like you don't as you asked them to do it in the first place) then you shouldn't be knocking them, or the cost to do something.

and if they were mounting the speakers as well as cutting the plates, then $50 was a screaming deal.

I didn't see that as a rip off at all. You shouldn't either!
Old 03-07-03, 10:39 AM
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I just wired in my aftermarket Sony deck with so so output and left the stock amps/speakers in place..

Sounds pretty decent, but certainly not great. I wont be surprised if I blow the amps.. LOL - lasted almost a year so far now.




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