[Loffen]

Originally Posted by johnta1

Loffen was your car from the Washington state area?

Well this is where it get's funny, it was orderd by McCoy Auto Co Inc (25 280),Po Box 1628, Vancouver, WA 98660. date shippied 09-28-70

And sold by aggesell Pontiac Co (25 427), 660 Liberty street N.E, Salem, Oregon 97308. 5-10-71

The first owner was Marion car rental co, 195 commercial st S.E, Samem , Oregon

And the build date on the tag is 08 C-70...

[johnta1]

Thanks for the info.

Do you have a scan of the PHS showing them?

[Loffen]

Originally Posted by johnta1

Thanks for the info.

Do you have a scan of the PHS showing them?

Yes, I will post it in restoring my -71 vert tread later, think we are way over the top in this tread

[YNOBIL]

Originally Posted by Loffen

Yes, I will post it in restoring my -71 vert tread later, think we are way over the top in this tread

Loffen, You're right. This thread has drifted a long way from Stereo Radio Speakers.

[Shiny]

old thread, maybe new questions


I bought a 71 AM/FM stereo radio off the forum, going into my 70 if I can get the radio working.


Is it true these 71 radios were the first year to have a built-in multiplexer?


And as I understand, the left and right channels were, for some reason, originally routed front and back in an A body, with no option to add a 2nd rear speaker, correct?


I think that sounds wacky, given the idea was to provide left and right separation.


It makes more sense to put two speakers in the back and use them for left and right to me.


If I do this, is there any reason not to use a dual-coil front speaker and wire the front and rear speakers for each channel in series? I know the load on the radio was designed to be 10 ohms, so I'm thinking two 4-ohm speakers in series would be close enough...

Any red flags? I know I won't have a front/rear balance control off the radio, but it might sound like stereo instead of frontreareo...

[Shiny]

Also, on the topic of rear speakers..

When a car had dual rear speakers (full size?), but both shared one channel, how were they wired? I don't see how the load was balanced on the radio. I assume they were put in series (20 ohms) rather than parallel (5 ohms), which would be hard on the output. If it was 20 ohms, did this reduce the volume?

If I did that with today's speakers, but kept them both on one channel, would it be better to have 2 x 4 = 8 ohms or 2 x 8 = 16 ohms ?

[north]

70 was the changeover for the multiplex and it occurred during the model run. 69-72 Stereo radios came standard with a front and a rear speaker on A bodies but the B and G bodies used two rear speakers with that stereo radio. Also if the car was ordered with an 8 track you also received the rear speaker standard.

The right bezel tells you the story (assuming the car is unmolested); an AM or AM/FM mono radio without a rear speaker option will have a right bezel labelled "Select", if it has a factory or dealer installed rear speaker the bezel is labelled "Speaker" and if the car has an AM/FM stereo then the right bezel is labelled "Balance". Note that if a car had a non stereo radio but also an 8 track then the right bezel on the radio is always marked "Select" but the balance knob on the 8 track worked when playing the radio as well.

Any closed car ordered with a factory installed rear speaker would come with a mesh style rear package tray liner that concealed the speaker, cars without factory installed rear speakers had a plain cardboard that would be cut for dealer speaker installation and then a metal or later plastic speaker cover. (it seems that assembly plants did not follow this rule religiously).

I'm not sure about second gen Firebirds but 69's were a major exception, like other features on first gen Firebirds they used a Chevy style radio system. Mono radio were the same deal with a single dash mounted front speaker with an optional rear speaker option available. But if the car was ordered with a stereo radio and/or an 8 track they would have a 4 speaker system installed ala Chevrolet. This meant two kick panel speakers up front and two in back, the balance was a cross style: left was the LF and RR speaker while right was RF and LR.

[Shiny]

Thanks North!

Did the b and g bodies with dual rear speakers also have a front speaker?

Were dual rear speakers wired with separate (L & R) channels or tied together? If tied together, I want to understand how, since the speakers are supposed to be 10 ohms. If L & R, then the question does not need an answer.

[north]

On the B and G cars with a stereo radio and or 8 track had one front speaker on the left track and two rear speakers for the left track. The two rear speakers are wired in series.

I don't know how that works with ohms but that's how it was done. For example here is the A and G schematic for 69 out of the shop manual.

[Shiny]

Thanks again

I appreciate the time you took to chase that down and post the scan

[north]

No problem