akman360

Hi Guys,
I have a 1980 Mazda RX7 (20th Anniversary Edition) that I'm restoring. I have a problem with the speakers. The only channel that appears to work is the rear right channel. I have traced all the wires back to the head unit, just to make sure they're not shorted, and they aren't. I think the head is connected to an amp, which then goes to the speakers. I'm wondering if it's possible to separately test the head unit or the amp to see which one needs to be fixed. Also, the rear left channel does work, faintly, but only when the volume is turned up about half way or more, and even though it works, it is very distorted, and only loudest of tones comes through. The volume and seek ***** work fine, so I don't think that it's a bad potentiometer. Any help would be greatly appreciated.
Thanks!

mazdaverx713b

iTrader: (91)

possibly a bad amp...

akman360

That makes since. Do you think it would be possible to replace it with a newer amp and still achieve the same effect? Or are these amps relatively easy to fix? I would like to keep the stock radio.
Thanks

7aull

iTrader: (2)

akman
fbksman here (I'm in Fairbanks...)
XX 80 RX7? Congrats!! I know the radio head you have and -yes- there probably is an amp. Its either under the passenger seat or behind the radio console panel I believe.
This recent post dealt with SA radio wiring:
https://www.rx7club.com/forum/showthread.php?t=706402
tho it is likely for the simpler am/fm units the standard GS RX7 had, so keep that in mind. Funky speaker sound could be a bad speaker. Is it the OEM one? These are pretty crappy (not to mention old!). I have kept the stock radio too but upgraded to Polks - much improved sound (tho an amp will be my next addition)
Post some pics of your car!! Don't see many XX's
cheers
Stu Aull
80GS
Alaska

djessence

IF the amp is your problem:

You would need to find an older amp i think because if you stick a new amp in you will probably be providing waaaaay too much power to the speakers. I am willing to bet they are probably 5w speakers, new amps run 20w rms per channel roughly or more. If you were to replace speakers at same time as amp you would have better luck.

You should be able to test the channels on the amp simply by using a volt meter across the + and - halves of each channel. Another good test would be to hook up the working speaker to the bad channel (or side that doesnt work) and see if good sound comes out, that would tell you its the speaker.

akman360

Ok, so I narrowed it down to a bad amp. I took out the amp, and tested the wires from inside the amp (where the wires are soldered onto the circuit board) to the four pin plug, and there is good continuity. So now I need to find a different amp that will work, probably off of eBay. I just replaced the rear speakers with some new kenwood ones, and i'm probably going to do the same to the front ones, as they are stock and don't sound that good. I did "cross" the connections and all the speakers do work fine when connected to the channel that actually works. I'll post some pictures of it, after I reassemble the interior. That'll probably be later in the week.

Aaron
Anchorage, AK