91 Suburban Rear Speaker - Which Ohm?

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creich68

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I've been getting some static on the right channel (front and rear) of my suburban recently. Not quite sure if it's the original radio head unit causing the issue or original speakers finally biting the dust. Pulled one of the rear speakers out to see if it listed what ohm it was rated for, but doesn't show it (picture below). I hooked up the positive/negative terminals to a meter and it leveled out at 9.7. Did GM use a 10 ohm speaker in 1991? Most of the aftermarket 4x10s I've found are 4 ohm. The LMC catalogue doesn't list what their replacement speakers are rated for either. Just seeing what options are out there that would work with the factory AC Delco head unit? I'd rather not mess with replacing the entire head unit.

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Yep, I've had several Delco radios that produce static in one channel. Some times you can play with the balance knob a bunch and clear it up for a while.

Iirc, the factory speakers are 8 or 10 ohm.
 

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I remember 4 or 8 ohms, but my memory is $#!t any more.

Tuner cleaner, or elec contact cleaner might bring it back. But, if it's doing that now, it will eventually get worse. Sorry.
 

creich68

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Sounds like a classic case of dirty control potentiometer in the radio
Hmmm that could be possible considering the static is on the same side/channel, and adjusting the left/right knob did help some. Adjusting the back/front didn't appear to affect it as much.

Yep, I've had several Delco radios that produce static in one channel. Some times you can play with the balance knob a bunch and clear it up for a while.

Iirc, the factory speakers are 8 or 10 ohm.

It's only happened once (last night) and what was odd is that increasing/decreasing volume using the knob didn't change the volume of the static. Looks like I have some investigating to do.

I remember 4 or 8 ohms, but my memory is $#!t any more.

Tuner cleaner, or elec contact cleaner might bring it back. But, if it's doing that now, it will eventually get worse. Sorry.

Looks like I should pull the head unit out and try some cleaner in the knob area and other crevices. Would CRC QD Electronic Cleaner be okay to use or too aggressive on the internals?
 
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CRC QD Electronic Cleaner is okay to use. Spray it into the controls (after you get the head unit out) and work the controls back and forth. That should do the trick.

p.s., I've known factory speakers be 4 ohms as well.
 

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Ya'll are probably correct about the ohms. I'm not an electronics guy.
 

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We replaced all the factory speakers in my sons 91 Yukon with aftermarket speakers. We also sent the factory radio off for repair (3 times!) each time it came back with a different issue. Don’t use M&R electronics in Michigan for your delco radio repair!! The radio itself seems ok, they just can’t get the tape deck to work right.

Anyway, the sound level sucks with the aftermarket speakers. I didn’t think about it at the time, but if the factory speakers are 4 ohm, the replacement speakers are 8, we just effectively cut the radio power in half. This might explain why.
 

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We replaced all the factory speakers in my sons 91 Yukon with aftermarket speakers. We also sent the factory radio off for repair (3 times!) each time it came back with a different issue. Don’t use M&R electronics in Michigan for your delco radio repair!! The radio itself seems ok, they just can’t get the tape deck to work right.

Anyway, the sound level sucks with the aftermarket speakers. I didn’t think about it at the time, but if the factory speakers are 4 ohm, the replacement speakers are 8, we just effectively cut the radio power in half. This might explain why.

Like I said, I'm not an electronics guy, so I can't explain or give good reasons as to why, but several times I have used a factory Delco radio with factory 4x6 fronts and aftermarket 6x9 rears. This was in Celebrities and Camaros. I was always very happy with the sound.
 

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Hmmm that could be possible considering the static is on the same side/channel, and adjusting the left/right knob did help some. Adjusting the back/front didn't appear to affect it as much.



It's only happened once (last night) and what was odd is that increasing/decreasing volume using the knob didn't change the volume of the static. Looks like I have some investigating to do.



Looks like I should pull the head unit out and try some cleaner in the knob area and other crevices. Would CRC QD Electronic Cleaner be okay to use or too aggressive on the internals?
get some contact cleaner, take the knobs off, spray around the shaft for around 3 seconds. Put the knobs back on and rotate them as fast as you can. Let it sit for about 15 minutes so the contact cleaner will dry. Crank it up and try it.
 

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There is also a product called DeOxit, and it works well to clean up the contact on a reheostsat (volume control speaker fader,etc,) or a slide switch.

IIRC, older vehicles in the 50s and 70s used mostly 8 ohm speakers, but at some point the industry transitioned to 4 ohm speakers. I don’t know why it changed.

Using speakers with too low impedance may also sometimes damage a radio because the power amp starts to put out too much power at high volume. It can happen if you connect the front and rear speakers in parallel, because two 8 ohm speakers in parallel will become a 4 ohm load. This was common if you had a radio with only one set of outputs, and you tried to add rear speakers by just splicing into the left and right outputs.
 

creich68

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get some contact cleaner, take the knobs off, spray around the shaft for around 3 seconds. Put the knobs back on and rotate them as fast as you can. Let it sit for about 15 minutes so the contact cleaner will dry. Crank it up and try it.
Picked up some contact cleaner last night. Going to give it a shot this weekend and see if there is a change.
There is also a product called DeOxit, and it works well to clean up the contact on a reheostsat (volume control speaker fader,etc,) or a slide switch.

IIRC, older vehicles in the 50s and 70s used mostly 8 ohm speakers, but at some point the industry transitioned to 4 ohm speakers. I don’t know why it changed.

Using speakers with too low impedance may also sometimes damage a radio because the power amp starts to put out too much power at high volume. It can happen if you connect the front and rear speakers in parallel, because two 8 ohm speakers in parallel will become a 4 ohm load. This was common if you had a radio with only one set of outputs, and you tried to add rear speakers by just splicing into the left and right outputs.
That's what made me hook up the meter to measure the ohms across the positive/negative terminals. I didn't want to further damage the radio by hooking up a speaker with the wrong ohm rating. I'm going to try the contact cleaner first to rule out a head unit issue. My burb has the Delco "symphony sound" style radio so I'd like to fix it before considering a replacement. The cassette player doesn't sound the best, but still works haha.

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creich68

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Well - gave it some contact cleaner and worked the knobs. Seems like I have an issue with the radio itself as it's still making sporadic static/popping noise on the right side. More so in the back right speaker than the front right. I tried pulling the entire radio out, but it was not cooperating. Couldn't see if it was hanging up on a wire or something else.

Thanks for the suggestions folks. It was worth a shot!
 

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There is likely a support bracket in the back of the radio.
I've used 8 ohm speakers to replace the stock ones with no issues for years.
 

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:yawn:
Y U NO 6X9s
What's with all you dudes and 4x10s lately? They suck SO BAD!

boing! boing! boing!
Get some effing A-Dapters , man!

You could put an 8 inch WOOFER in 4x10 hole FFS!
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