Questions Re Replacing Head Unit & Speakers

[DuderMcMerican]

I posted this in Shine and Sound yesterday but no takers. Can anyone help?

Hey guys,

I have a 1990 LX with premium sound. I just bought a new head unit and speakers and tried to "plug and play" with the wiring setup that went with the PO's aftermarket head unit, which crapped out a while back, but the sound is terrible. I read it's a good idea to bypass the amp and wire straight to speakers to prevent that, so here are my questions:

1) The amp in my car is a Kenwood, so I assume that's not factory. I think one of the POs had it set up with a subwoofer and all, but I'm just looking to do a basic head unit/speaker replacement. Should I still bypass the amp and wire straight to the speakers? The Kenwood amp doesn't appear to have the same wiring setup as the original, but the system doesn't work when I unplug the amp, so I assume the PO hadn't wired straight to speakers. It still had the original speakers, so I guess his wiring through the amp still made sense..

2) I tested out the head unit-straight-to-speaker concept by just hooking up the red, back, and yellow wires and one single speaker (I cut the rest of the speaker wires off--plan to reconnect with solder). Thing is, the new speaker I wired straight to the head unit STILL sounded like crap. Is that an indication that I ended up with a bad head unit or speaker?

3) If I should still wire straight to speakers, what's the best way to get the new wires to the door and rear speakers? I know there's a boot that encases all the wiring to the door and whatnot, and I assume I'll need todisassemble the door panel somewhat to route the new wires, but are there any tricks to make it easier? Also, I have no idea how to route the new wiring all the way to the back speakers. Any help is appreciated.

Thanks!

 

[prgt347]

It's been a long time since I've had a factory unit in my car but it also came with the premium stereo system with factory amp. I had to remove the factory amp to get the aftermarket system to work with the factory wiring. I'm sure there was a way to keep the factory amp but it wasn't worth trying to figure out. Sounds like you have an aftermarket system if the amp is a Kenwood. Where is the amp located? Is it under the stereo where the factory amp sat or somewhere else in the car? Did the PO run new wires anywhere or just tap into the factory wires at the head unit? Is the factory wiring harness with connectors still attached or have they been cut off?

When you tested the speaker (#2 above) - are you positive the wiring was correct? I would think so, just trying to eliminate possibilities. Did you hook up the other speaker to the same wires to make sure it wasn't just the speaker?

Before running new wires you can probably check impedance with an ohm meter to make sure there are no bad connections between the wire at the head unit and the speaker. If you do have wire problems and have to run new wires it is not too hard to do but will require removing several interior parts and digging up under the dash. You'll have to remove the door panels to install the new door speakers so running the wires into the existing door boot shouldn't be much more trouble. Not sure of any tricks to make it easier, other than using the factory wiring, assuming it is not faulty.

Feel free to send pictures of the amp, wiring, and anything else that may help figure this out. By the way, I grew up outside Manassas, not too far from you.

 

[General karthief]

Premium sound from the factory has the pieces, the two exposed units in the dash and one farther back hidden behind the radio/amp, they are useless with an aftermarket head unit.
You should be able to use the factory speaker harness for your aftermarket unit.
You should pull your door panels off to make sure the op didn't rewire the door speakers.
I used factor harness with aftermarket radio and speakers.
I think the speaker wires are green and black but it's been a while.

 

[Dan02gt]

What type of harness are you using to connect your head unit to the factory wiring in the car?

 

[DuderMcMerican]

Thanks for the info!

Sounds like you have an aftermarket system if the amp is a Kenwood. Where is the amp located? Is it under the stereo where the factory amp sat or somewhere else in the car?

Its under the passenger seat. The original was behind the head unit but was removed by PO.

Did the PO run new wires anywhere or just tap into the factory wires at the head unit? Is the factory wiring harness with connectors still attached or have they been cut off?

They just tapped into the original wiring harness. The harness is (was) still intact. I'm going to solder and seal the wires I cut.

When you tested the speaker (#2 above) - are you positive the wiring was correct? I would think so, just trying to eliminate possibilities. Did you hook up the other speaker to the same wires to make sure it wasn't just the speaker?

Yes, it was wired correctly. No, I only tested the one speaker wired straight to the head unit, but the other speakers I installednand tested sounded like crap, too. I'd assume they were wired straight, but the system stops working when I unplug the Kenwood amp.

!

Before running new wires you can probably check impedance with an ohm meter to make sure there are no bad connections between the wire at the head unit and the speaker.

I did check ohms all around, and all tested fine.

!

If you do have wire problems and have to run new wires it is not too hard to do but will require removing several interior parts and digging up under the dash. You'll have to remove the door panels to install the new door speakers so running the wires into the existing door boot shouldn't be much more trouble. Not sure of any tricks to make it easier, other than using the factory wiring, assuming it is not faulty..

Okay, thanks. Figured it wouldn't hurt to ask about a shortcut. Haha
!

By the way, I grew up outside Manassas, not too far from you.

Manassas is cool. Not a big fan of wood bridge/dale city. Trying to get back to PA at some point, if possible, but the jobs are in NoVA.

Thanks again!

I'll post pics when I get the chance. Might not be until after the holiday, though.

 

[DuderMcMerican]

You should be able to use the factory speaker harness for your aftermarket unit.
You should pull your door panels off to make sure the op didn't rewire the door speakers.
I used factor harness with aftermarket radio and speakers.
I think the speaker wires are green and black but it's been a while.

Yeah, I am 99% sure the factory wiring is intact. The speakers I pulled out were original--only the head unit im replacing was aftermarket. All the door speaker colors match, but I'll take a look for rewiring once I get in there. Thanks!

 

[DuderMcMerican]

What type of harness are you using to connect your head unit to the factory wiring in the car?

i was just trying to plug and play with the factory harness like the PO had done. I know its all wired correctly, and all of the speakers sound like crap, so I'm thinking maybe I got a bad head unit? The previous head unit played fine with that aftermarket amp. I guess because the speakers were factory, yeah?

Not sure exactly how the amp is wired-in. All I know is I pulled a couple of banana plugs from it and the whole system cut off. This is my first time trying to do audio. I was just going to bypass the amp and run the wires straight off the head, but that test I did running the speaker straight has me all tripped up. I'll try a different speaker like a precious poster suggested.

I'll report back after i have the chance to mess with it some more, and ill take some pics.

 

[a91what]

Take pictures of what your working with. It's easier to help you if we know what stuff is

 

[Dan02gt]

i was just trying to plug and play with the factory harness like the PO had done. I know its all wired correctly, and all of the speakers sound like crap, so I'm thinking maybe I got a bad head unit? The previous head unit played fine with that aftermarket amp. I guess because the speakers were factory, yeah?

Not sure exactly how the amp is wired-in. All I know is I pulled a couple of banana plugs from it and the whole system cut off. This is my first time trying to do audio. I was just going to bypass the amp and run the wires straight off the head, but that test I did running the speaker straight has me all tripped up. I'll try a different speaker like a precious poster suggested.

I'll report back after i have the chance to mess with it some more, and ill take some pics.

I used the Metra plug and play harness with mine and it was horrible. My car had the base system but what I found was that the speaker connector from the car was wired way different than the Metra harness. The Metra harness was wired logically and done something like this: RF+,RF-,LF+,LF- and so forth. The factory connector was not logical at all and wired something like this: RF+,LR+,LR-,RF-... I ended up finding a fox body stereo wiring diagram and re-pinned the factory connector to match up with the Metra harness.

 

[DuderMcMerican]

Hey, guys. I had a chance to take some pics.

The first is of the speaker and power plugs. Here I have all the speaker wires cut and prepped to reconnect with shrink tube butt connectors I forgot I had. They're all cut from when I tested ohms. When I had tested the wire-straight-to-speaker setup, I obviously had two of them connected to a speaker.


The second pic is of the backside of the new head unit showing the power wires (still connected) as well as the banana plugs that run to the amp.


The third and forth are of the cavity behind the head unit where the factory amp once lived.

The fifth and sixth are of the left and right door speakers, respectively. The factory wires are shown, and they match the color codes for the '90 and '91, which leads me to believe they haven't been messed with inside the door. Here's the factory wiring color code scheme:
https://www.the12volt.com/installbay/stereodetail/891.html

Also, the aftermarket amp I mentioned is a Kenwood KAC-622. The seventh pic shows it's schematic.

Finally, the eigth image is of a funny drawing I did during a super boring meeting at work today

 

[General karthief]

You are sooooo talented

 

[DuderMcMerican]

You are sooooo talented

 

[prgt347]

Thanks for sending pics. Appears PO ran aftermarket RCA wires from the head unit to the amp, then must have run aftermarket speaker wires from the amp back to the console to tie in to the factory wiring for the speakers. That's a good way of doing it, assuming factory wiring is in good shape.

It makes sense that the sound goes out when you disconnect the amp. By unplugging the amp sound is being blocked at the amp and cannot continue to the speaker wires for you to hear sound through the speakers. But it doesn't sound like the amp is the problem.

Going back to the possibility of your new head unit being bad...When you hooked up the speaker directly to the head unit you said it sounded like crap...do you mean distortion or tinny sound, etc.? Keep in mind most head units only push about 15 watts to each speaker so the sound is going to be very limited. And if the speaker is just sitting out (not installed in the door, etc) it won't sound as good as it would inside an enclosure of some sort. But should still sound decent at low-mid volume, just distort if you turn it up too loud. I don't guess you have another head unit or one you could borrow just to hook up to see if it sounds the same?

Although I've never seen a new head unit do this in the 25 years I've been installing stereos, it is certainly possible. I'd say to eliminate the possibility of the head unit being bad before spending your time on any other parts of the stereo system. If the head unit is bad the rest of the system could be perfect and it would still sound terrible. You could even test it outside of the car - just hook the stereo up directly to the battery and one or two speakers to see if it still sounds bad. Just to make sure there isn't something inside the car that could be causing it. Doubtful there would be any difference, but again, just trying to eliminate possibilities.

Let us know...

 

[DuderMcMerican]

..When you hooked up the speaker directly to the head unit you said it sounded like crap...do you mean distortion or tinny sound, etc.? Keep in mind most head units only push about 15 watts to each speaker so the sound is going to be very limited. And if the speaker is just sitting out (not installed in the door, etc) it won't sound as good as it would inside an enclosure of some sort. But should still sound decent at low-mid volume, just distort if you turn it up too loud. I don't guess you have another head unit or one you could borrow just to hook up to see if it sounds the same?

Yuup. It sounded all tinny and distorted at all levels of volume. It did this when I wired the head straight to a speaker as well as when I wired it into the PO's amp setup.

No, unfortunately i dont have another head unit to swap it out with.

I dont know if this matters, but the head unit that went kaput was an aftermarket pioneer, and the new one I'm installing is also a pioneer. I figured it would be an easy swap-out with the PO's wiring scheme, but I guess not. The old head unit suddenly stopped working altogether. The new one "works" but it sounds all tinny and distorted no matter how I wire up the speakers.

I'd say to eliminate the possibility of the head unit being bad before spending your time on any other parts of the stereo system. If the head unit is bad the rest of the system could be perfect and it would still sound terrible. You could even test it outside of the car - just hook the stereo up directly to the battery and one or two speakers to see if it still sounds bad. Just to make sure there isn't something inside the car that could be causing it. Doubtful there would be any difference, but again, just trying to eliminate possibilities.

Let us know...

Okay, thanks, prgt347. I'll try it and report back.

 

[DuderMcMerican]

Welp, looks like I found the culprit. It was a bad speaker. I ran the unit straight off the battery, and it still sounded crappy. Then I wired up the other speaker, and it sounded fine. I also wired it up inside the car, and all was well. I should have tried that before, as someone suggested. Now to exchange the speaker set and get to wiring it up. Thanks, guys! I learned a lot.