Car stereo wiring question

unix-guy

unix-guy

Master of RTFM
Just throwing this out there since we have a broad user base with a wide range of knowledge.

I have a 2007 Toyota Sequoia with a factory premium JBL speaker system and power amp.

The speakers have a known problem where the speakers deteriorate causing buzzing/rattling/distortion.

In addition, the speakers are non-standard: there's a tweeter mounted on the upper part of the front door window frame and inside the front door is a 7" woofer and a small (2" I think) midrange driver, both mounted in a special bracket.

Factory replacements run $350+ per door... And there are also kits you can buy to repair the speakers but they seem a bit fiddly and I didn't feel like messing with that.

So I bought aftermarket coaxial 6.5" speakers with replacement mounting brackets and a replacement speaker wiring harness from Sonic Electronix.

All of this is part of a "set" designed for this purpose.

Got everything disassembled, reassembled and mounted in the door.

Go to connect the factory speaker connector to the wiring harness... No go!

Then I noticed that the factory connector has 4 wires: 2 for the woofer and 2 for the mid driver... But the replacement speaker only needs 2 wires as it's a coaxial design with a built-in crossover.

More research and it appears the factory amp (maybe) sends independent signals with different frequencies to the woofer and mid driver.

Found a post where someone suggested connecting both positive signals to the speaker positive and both grounds to the speaker ground.

I did a lot of searching for wiring adapters and all the ones that are supposed to be for my car are only 2 pins and 2 wires...

I did find a couple others that might also be supported by not a lot of detail. For those, they do actually appear to combine the signals as described above.

Since I'm comfortable with soldering wires, I could actually do this on my own by cannibalizing the wiring harnesses from the original speakers.

So, that's a long wind up to ask if that seems like it's safe?

Or if anyone has any first hand experience with reworking these Toyota + JBL systems.

Also, the original speakers (woofer / mid driver) are each 3ohm. The new coaxial is 4ohm total.
 
I've only installed 5 larger car stereos (largest was 16 amps), the last being over 20 years ago. In other words, I am NOT even close to being an expert.

So, I'm not going to be much help. About the only thing I can say with any semblance of accuracy is that the difference between 3 ohm and 4 ohm isn't going to hurt anything, probably won't even be able to notice it, as the different speakers also likely have different sensitivity ratings which you will be able to hear.

Now just guessing, the 4 wires from the factory amp could mean the factory head-unit could have been bi-amping the lows and mids, probably more like tri-amping the whole channel low/mid/high, but you're still using the high amp for the tweeter. However, this could be just the output from a crossover, too.

The question I'd have is, first, are the 4 wires coming from a crossover or from a bi/tri-amped system. If it's a crossover, it'll probably be safe to just connect the two pairs. If it's from multiple amplifier channels, then I'd want to ask whether it is safe to bridge the low and mid amps. If so, isn't most bridging (in PA applications at least) done in series (e.g. positive speaker to ch.1 positive and negative speaker to ch.2 negative, with a switch that bridges ch.2 positive to ch.1 negative and (possibly) phase reverses one of the channels so it can work in a push-pull arrangement.
Going to guess you've had some experience with setting up and using PAs? If so, it's pretty accurate to think of car stereos as a PA system for a car, same basic principles of sound reinforcement apply.

I might suggest taking a look at the Chilton repair manual (or similar) for your car, the ones that the mechanics use. You should be able to get some more information about the what the wires are for (crossover, tri-amping, special else entirely). Used to be able to find them in libraries, not cheap to buy, probably all electronic by now, so might be difficult.

Maybe ask a dealer or a mechanic if they could tell you more about what those wires are actually for, too.
 
Ok, so looking on the Crutchfield site and I come across a note in the installation instructions that says the speaker wires used send only the bass frequencies, the mid speaker wires must be cut/taped and not used and that you lose the midrange frequencies from this location.

Ugh!

Why didn't the Sonic install details mention this?
 
+1 for Crutchfield. I just ordered a replacement system for one of our cars, and they provided a lot of useful information about replacing the factory system, which integrates climate controls and diagnostics. I haven't purchased a car audio system from anyone else in a long time.
 
Well... I decided to go with the foam surround repair kit.

My buddy did this in his Sequoia and said it works great and was relatively simple to do... And cost is $30!

On a positive note, the speakers and speaker wiring harness do fit my Scion xB, so looks like I'm upgrading the factory speakers there!
 
TwinbornAxis said:
Long shot this might help but maybe a chance there's related info or similar wiring/parts that could be of use to you...I was looking to install a sub in my Venza, the thread lost me and I gave up on the idea lol but seeing your post reminded me a I had it bookmarked still.

https://www.toyotanation.com/threads/venza-lx-sound-upgrade-subwoofer-install.1696068/
Click to expand...
I've read numerous threads on that forum and others related to both Sequoia and Tundra (same basic setup).

Unfortunately nothing much that helps other than I originally found out about the separate bass and mid signals from a post there.
 
Combining the signals should work, but be mindful of potential impedance mismatches affecting your amp. Double-check the wiring diagrams to ensure correct polarity and avoid any short circuits. If you’re comfortable soldering, go for it, but consider an aftermarket DSP if you encounter audio quality issues.
 
Thesse said:
Combining the signals should work, but be mindful of potential impedance mismatches affecting your amp. Double-check the wiring diagrams to ensure correct polarity and avoid any short circuits. If you’re comfortable soldering, go for it, but consider an aftermarket DSP if you encounter audio quality issues.
Click to expand...
Thanks... I've decided to just do the speaker repair for now.
 
Before foam surround removal:
IMG_6183.jpeg

After surround removal and scraping/cleaning foam and glue residue (about 3 hours of work):
IMG_6184.jpeg

New surrounds glued in place.
IMG_6185.jpeg

They are now mounted in the speaker assembly brackets and the gaskets are glued and drying.

Tomorrow they go back into the car.
 
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