1977 C10 Rear speakers??

[hueydriver]

I have a 1977 C10 step side with original stereo. The truck has one speaker in the dash. I’m wanting to put some rear speakers in and need to see if the stereo can support it. I looked in the back and think that maybe there is a row above the green a black wires(dash speaker) that may be for rear speakers. Trying to find a harness that can fit it but I’m having a difficult time. So first wondering if there is a rear speaker connection, second is there a wiring harness that I can use to fit that connection.

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[Ricko1966]

If it has a single speaker,it is not stereo. If someone installed a stereo and hooked up only a single speaker the chances are 90 percent that only one channel works now. We need better pics of front and back of what you have,but I'd bet you are going to need to buy a stereo and probably 4 speakers.

 

[hueydriver]

I’ll get better pics of the stereo. I was wondering if it was capable of connecting more speakers to it since it looked to me from a diagram that it had the leads but they just were not hooked up.

 

[mcarlo86]

@Ricko1966 is trying to help you understand the terminology also. You are referring to your radio as a “stereo.” A lot of older AM radios and even some AM/FM radios were “mono” radios, meaning they only had an output for one speaker (or maybe 2 if there was a single front and a single rear). A “stereo” radio would have two outputs for a left and right speaker that then could support “stereo” sound. So like Rick said, need pics of what the radio looks like to help determine what you have.

 

[hueydriver]

You’re right, I should just say radio. I have no clue if it’s a “stereo”. The more I look at the back the more I feel like I can’t run rear speakers from it. I do t really want to switch out the radio so not sure what other options are available if I want to run rear speakers.

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[fast 99]

Below radio will fit opening without cutting and is stereo. Wiring is different so will need to adapt. Have sold about a 100 of these over the years but they have dried up. Don't have one now. Do be careful what you buy. As other have said they were available in both stereo and mono. Appearance is identical other than the inner right shaft were the knob slides on.

Not much that goes wrong with these radios other than dirty controls, easily fixed with electronic contact cleaner.

Not mine just a sample of what you need.

General Motors 7898450 AM FM STEREO RADIO UNTESTED GM Oldsmobile | eBay

This is a General Motors 7898450 AM FM stereo radio, untested and without warranty. It is a black color radio with features of FM and AM. The manufacturer part number is 7898450 and it is made in the United States.

www.ebay.com

 

[hueydriver]

Thank you. So on this radio when I adjust the left outer ring it does adjust the sound. Is that the balance or fade? It definitely makes the speaker sound different. So sounds like this is a mono radio, but my question still is can the radio support rear speakers? Even if it’s mono?

 

[fast 99]

Can't answer that for sure may be someone else can.

Many years ago I added additional speakers to a Ford AM radio without issues. No idea what that does to the internals or if it will shorten the life or not.

If you do update to the newer stereo radio I have extra sets of wiring. Send a PM if you want it.

 

[Ricko1966]

Thank you. So on this radio when I adjust the left outer ring it does adjust the sound. Is that the balance or fade? It definitely makes the speaker sound different. So sounds like this is a mono radio, but my question still is can the radio support rear speakers? Even if it’s mono?

If it doesn't have connections on the radio itself,it gets complicated as to whether or not you can add speakers. Example if it has 1x 10 ohm output you can drive 1x10 ohm speaker,1x8 ohm or 2x4 ohm speaker wired in series for an 8 ohm load. You need to find out what you truly have. The consequence of adding speakers is say you add 2x8 ohm speakers to a jack that's supposed to run a single 10 ohm. Wired parallel your output transistor is only seeing a 4ohm load not a 10 ohm load and very susceptible to burning up. It is a probably a 10 ohm single channel in which case if you want 2 speakers I'd run 2x4 ohm Wired in series for an 8 ohm load. If you wired those same 2x4 ohm speakers in parallel it would only be a 2 ohm load,way to low.

 

[hueydriver]

If it doesn't have connections on the radio itself,it gets complicated as to whether or not you can add speakers. Example if it has 1x 10 ohm output you can drive 1x10 ohm speaker,1x8 ohm or 2x4 ohm speaker wired in series for an 8 ohm load. You need to find out what you truly have. The consequence of adding speakers is say you add 2x8 ohm speakers to a jack that's supposed to run a single 10 ohm. Wired parallel your output transistor is only seeing a 4ohm load not a 10 ohm load and very susceptible to burning up. It is a probably a 10 ohm single channel in which case if you want 2 speakers I'd run 2x4 ohm Wired in series for an 8 ohm load. If you wired those same 2x4 ohm speakers in parallel it would only be a 2 ohm load,way to low.

So that was part of my question. It has other terminals in the back and I was wondering if it can support rear speakers. If you look above the green and black wires there’s some more terminals.

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[Ricko1966]

So that was part of my question. It has other terminals in the back and I was wondering if it can support rear speakers.

We don't know. We haven't seen the radio you are talking about get us good pictures,front and back,maybe we can figure it out. The amount of information you are giving us is Like me telling you I found a pair if blue sneakers,will they hurt my feet if I wear them?

 

[bucket]

Move that vacuum hose or cable out of the way and try to get a better picture. The wiring terminals and functions are stamped right on the case of the radio. GM was good about that.

 

[bucket]

Also, one of the "outer" knobs should be tone control. That's the sound change you were talking about. If the other "outer" knob moves and you can make the sound go away completely, then the radio can be used with more than one speaker.

 

[hueydriver]

Move that vacuum hose or cable out of the way and try to get a better picture. The wiring terminals and functions are stamped right on the case of the radio. GM was good about that.

As soon as I get home I’ll move the hose and take a picture. Good call. Thank you.

 

[hueydriver]

Also, one of the "outer" knobs should be tone control. That's the sound change you were talking about. If the other "outer" knob moves and you can make the sound go away completely, then the radio can be used with more than one speaker.

Ok yeah the sound definitely doesn’t go away completely. So it must be tone control. Thank you for the insight. So Ilol take another pic of the back but it sounds like this radio probably can’t be used for multiple speakers