I picked up a nice AM/FM radio for my 71 GS. I did the two speakers in the dash trick (Thanks Tim), and bought a new 6" x 9" for the rear compartment. After a few trys, I got the front ones to work (not too loud, kinda weak); but, I cannot get the rear speaker to work. The fader control seems to work, full front speaker fade to no (a little sound from the front) front speaker. My though is there is not enough power to run both (all three) speakers with my 12 Volt power supply. Any help? Second question: I would like to verify all the wiring is working before I start installing the new interior and dash stuff. How do I get the necessary power to the fuse block without installing all engine stuff, ie, starter, alternator, coil and such? Thanks, in advance, for your help. Len :3gears:
Post more info on the radio and speaker setup. Is it an original type of radio or is it a modern radio? The internal amplifier on the radio should have the power to drive 3 speakers. If it is a modern radio, you will probably need to rewire all of the speakers because the original speakers usually have common ground wiring. Are these brand new modern speakers as well? I don't think I understand what you are asking in the second question although I would think that your wiring harness will have something that plugs to the fusebox.
It is an original radio (I think it is out of a '72). The speakers are new Pioneers (4" round); two in the front. The rear is a single 6 x 9, old style. As for the second question, I have the fuse block installed under the dash and the wiring harness that goes into the engine compartment has numerous leads that go to the starter, alternator ect. I want to hook up a battery to the cables to check the wiring throughout the car without having to hook up the engine components. I need to have proper grounding and power lead to make it work. I tried hooking my power supply to the system but did not get any juice. Len
I know that the original radios had a pretty high impedance, as did the speakers. The original speakers I took out of my stereo were 10ohm speakers, and I don't think those would have played correctly with my stereo.
There are 3 likely causes. 1 mis-matched impedance, 2 your aftermarket speakers are looking for more wattage than the radio produces or 3 your radio is broken. 1) Impedance: The original radio expects speakers with an impedance of 8 or 10 ohms, modern speakers usually have 4 ohm resistance and this is the most likely reason for the weak sound. Here's where it gets a little weird, if you hook 2 speakers up in parallel you get 1/2 the impedance, if you hook them in series you get twice the impedance. Parallel is taking the two positive wires from 2 speakers and connected them with the positive from the radio and doing the same with their negative wires. That's parallel, 2 4 ohm speakers give you 2 ohms impedance, not what you want. If you hook the positive from your radio to the positive of speaker A, then connect the negative of speaker A to the positive of speaker B, then connect the negative of Speaker B to your radio (or ground) that is Series. Like a daisy chain. Hooking 2 4 ohm speakers in Series will give you 8 ohms resistance and you should get nice clear sound. Try it as an experiment and see what happens. If it works both speakers will be playing 1 side of the stereo. You'll need 2 more speakers to play the other channel. Instead of speakers I think you can add a 4 or 6 ohm resistor (in series) to create the expected load. 2) Wattage requirements if your speakers are expecting 100 Watts from your stereo they'll be disappointed. A 300 watt speaker can't make good sound on 8 watts. I don't know what wattage the OEM radios put out, but it's nothing compared to modern radios. As long as your speakers are rated for anything under 100 watts, this isn't your problem. One important note: It's easier to blow 100 watt speakers with a 25 watt amp, than it is to blow the same speakers with a 200 watt amp. Sounds backwards but it's true. A weak amp putting out a clipped signal will blow speakers faster than overpowering them with a clean signal. 3) If you wire your speakers in series and it sounds good your radio is fine, if not you can try with some 10 ohm speakers (check radio shack) and see if that works. In a convertible you need a lot of power to hear the music on the highway with the roof down. You can find filters that reduce the radio's output to line level which can then be amplified. Hide a nice 4 channel 75 watt amp in the trunk and you'll have lots of lovely sound while still retaining the stock head unit. You won't win contests with such an arrangement but it'll still sound fine and can be heard on the highway. Good luck, John
John; Thanks for the lesson; its always good to learn from people that know what their doing. I did wire the speakers correctly (only because the local radio place made me aware of this) and finally got the unit to work. It sounds ok. The fader control was not making contact to the rear speaker. I kinda fixed it. I'll end up changing it in the future (it used to have a nice, powerful Audiovox unit back in the early 80's. Len
