68/70Vette

I have both Stereo AM/FM radios. The 70 is original to the car, the 73 is from ebay. Both radios have their speaker wire outputs buggered since they were butchered up to certainly drive aftermarket amps/speaker combo's etc.

First Question for the 70 radio: I know the 70's had in dashboard speakers. I still have those original speakers. Did the 70's AM/FM Stereo radios also power before the door floor speakers that are present in the 68 and 69's? (My 1970 AIM is at work, and I'm at home...will look tomorrow). From what little I can tell, the 70 AM/FM Stereo only drove the dash board speakers and there weren't any 68/69 style floor speakers (?).

For the 73 radio: The ebay radio only has one set of speaker leads protruding from it. Don't know what happened to the other speaker leads. Does anyone know of the speaker configuration for the 73 Stereo?


Background Info for People who are still interested!!: In 69, 70, 71, 72 stereo radios were a kluge. The mono radio was mostly used in addition to another outboard "box" about the same size of the mono radio. The left speaker(s) were powered by the modified mono radio and the right side speaker(s) were powered by the outboard box. In 1973, Delco finally got their act together and made an AM/FM Stereo radio in the same box size as the original mono radios.

Ok, OK...for restoring my 70, why don't I just re-install the 70 AM/FM Stereo and just only ask for it's speaker configuration? Because I'm installing a Vintage Air AC in the 70. The AC unit is under the passenger's vertical dash panel. There's a large mass of hoses to route air to the defroster, the side panels, the center console, etc. I'm afraid that if I install the 70 AM/FM Stereo, I afraid I won't have room to install that "outboard" box it requires. At this stage, I'd prefer to install the 73 AM/FM Stereo. Why am I installing a Vintage Air AC? The stock unit is very inefficient and takes up a great deal of engine room and is constraining if you want to install headers on your BB. Also, a complete, zero time/like new restore of the stock AC is very expensive.

More background information on working with these early C3 Delco's. They used non-standard speakers. The speakers have 6 ohm DC resistance. That is unusual and repro speakers often don't duplicate this impedance. For instance, on must normal radios, you'd expect that with the volume turned all the way down, there'd be 0 volts across the speaker terminals. On the early C3's the speakers always have a 5 (?) DC voltage across them. The 6 ohm speaker load is a part of the output power transistor's bias...use different impedance speakers, vary the bias currents and the radio lifetime may be shortened. So anyhow, wiring up an early C3 Delco radio means you have to be careful with speaker impedances. Finally one last factoid...In 1969 the factory AM/FM Stereo option (same radio as the 70) cost about the same as the 435 Hp tri-power BB engine option!!... $400+ A lot of money in 69/70 for a poor quality radio.

Thanks!!!

Alan 71

Hi 68/70,
Your right, in 1970 there were only the 2 dash speakers, even if the radio was the stereo model.
Regards,
Alan


I'm old enough to remember when stereos (home, not car) went to 4 speakers, and 4 channels, and the system was known as a quadraphonic system.

Tom73

The 73 stereo radio also used a remote "multi-plex" assembly. The mono was a single unit. Note that both used a small remote heat sink assembly.

68/70Vette

OK, maybe got it wrong, maybe what I think was a 73 is a 74....somewhere at that time, Delco was able to get the entire AM/FM Stereo inside the original C3 mono box. About the remote heat sink assemblies...they were called "convectors" by Delco. The mono radios had an external extruded aluminum heat sink with a single power transistor. The Stereo units had a convector with two power transistors.

Tom73

From the 73 service manual.

Believe the change in radios came with the new interior in 78.

Tom...

Easy Mike

You had to wait until 1977 before Corvette got the new design Delco stereos.

68/70Vette

Then it looks like my all in one chassis Delco AM/FM Stereo is a 1977.

Thanks
....................

Since I haven't decided which one to use yet, ordered speaker wire harnesses for both from lectriclimited. The speaker harnesses for both radios were buggered by probable bubba aftermarket stereo installations. At least I've the original 70 speakers in good condition.

Easy Mike

Could be. Is the old service label still on it? The label lists the model number. If it's 8-track or cassette, you can count on it being 77 and newer. Neither was available 68-76.

gbvette62

All 68-76 Corvette radios, are basically the same. They all used the heat sink, and stereo units all used the multiplex (though 68's multiplex was slightly different looking than later ones). 68-71 radio faces have numerals with a green tint, while 72-76's have white faces.

76 was the last year that GM used the multi piece radio. In 77, the dash was redesigned to accept a standard GM radio.

The 73 radio you bought, should look just about identical to your 70 radio, except for the white vs green tint faces.

stevelischynsky

My original 73 stereo only has the heat sink on the right. It does not have the 2 heat sinks as shown in your diagram.

Steve L
73 coupe since new