3rd Gen rear door 6.5" speaker upgrade

[Scramble]

My 4Runner Amp goes to 11. :bounce: (JL Audio)

If I can make one comment. The pics in the first post are too big & makes for hard reading when you have to scroll left & right. (I didn't read)
You can fit 6.75" in the front with no mods.
I agree that you need all 4 speakers working for full sound and keeping the same brand will give you a smoother sound.

 

[Hoye0017]

Quite the contrary; setting the gain on an amp properly is done with math.
It should be measured and set to match the RMS of the components/speakers.
Google "How to set gain...", and you'll find plenty of threads/articles/videos on how to properly set gain.

Your explanation is not quite right. Though I have no doubt that your understanding of it comes from googling that phrase. Unfortunately your results will come mostly from people who do not understand the nature of gain.

It's not an art, so I agree there. But it is also not a power knob or volume control as it seems to be at first glance. Car amplifiers have an input stage and an output stage. The gain control in this type of amplifier is an input gain control, not an output control.

Input gain is used to match the output of the head unit's line level signal to the level that the output stage is looking for.

It's true that gain can be used to limit or increase the power output at a given head unit volume level but a properly set up system lets the head unit/processor determine the output. Gain is just there to allow you to mix components of different output and input impedance.

Truly properly setting gain has nothing to do with the speakers. It's done with an oscilloscope at the input and output signals to find the maximum signal level before clipping/distortion.

I would say this article explains it pretty well:

https://www.extremeaudio.org/what-is-a-gain-control/

And with this in mind, I would say it's not true that the alpine power pack is "pretuned" if you are using it with a non-alpine head unit. It can't possibly be pretuned for every head unit ever made.

 

[Solidaxles]

Awesome write-up Snowden. Excellent.

I did pretty much the same mod but I used a Mainstays 5/16ths thick cutting board that you can get at Walmart for $10.00. I used a thicker one to keep the magnet closer to the inside of the door as possible.

I used the factory speaker holders to trace the shapes on the cutting board. I used the drill to drill the holes first, then used the cutout on the Kenwood KFC650 box to trace the speaker cutout hole. I used my dremmel to remove that material.

I went a step further and cut the hole in the door a little larger using tin snips and a file to smooth it down- just in case.

I used 3M 5/16 ths ribbon tape to seal the cutting board bracket to the door, and stretched out a piece to place in the speaker hole on the board to keep the speaker "clued" on the board. This not only seals the whole thing, but it helps keep the speaker in place when your mounting the bracket to the door.

And with the thicker bracket, I needed longer screws. I went to lowes and bought new stainless screws. 12 x 1 inch.

I also had to trim the inside of the door panel near the top part of the rear door map pocket to make sure nothing touches the speaker. You can stick your head in that pocket and see the speaker a little but you wouldn't notice it if I didn't tell you most likely.
I hope my contributions help someone make this mod a little clearer.

 

[Solidaxles]

Ok. My setup is complete. On my 2000 T4R I installed (4) Kenwood KFC 650s
And a Kenwood double din DPX502BT HU.

I'd start a new thread but I can't so I'll attach this info back on this thread.

There's a lot of talk of guys taking out the factory amp or bypassing it, and they don't give a reason as to why, but I'm letting you know that you can leave the factory amp in your 3RD gen 4runners if you want, and it'll work out great. You need Metra wiring harness 70-8113
The factory amp is 4 ohm if this helps.

I also left the factory tweeters hooked up on the front door and like I said, it sounds great enough for me. It's loud enough and clear enough. It fills the Stomper with sound. I'm not going to win a Slamology Contest with it, but it really sound great.

Here's one more time saver for someone I'm sure. On this Metra harness there's going to be a blue wire and a blue white wire. The blue wire is for if you have a power antenna. The blue white is the amp turn on. If you don't have a power antenna, then run the blue white wire into the stereos blue white wire. If you do have a power antenna then you're going to run the Metras blue wire and blue and white wire into the new head units blue white wire. If you forget to hook up the Metras blue white wire then you'll get no sound out of you speakers. How do I know this? Don't ask. :wow:

 

[2ndhandyotaman]

Pretty much how I made mine in my thread on fitting the 6.5's. I used 1/4" acrylic and hand fabbed them, then made a digital model and used a laser cutter to make a few sets that I've sold on the forum. I had to counter bore the lower mounting holes so that the speaker will sit flat on the adapter, did you have any fitment issues like that?

 

[superfrog]

Those alpine power packs are great. I was using one to power four speakers in my 2000 limited. I now just use it to power a set of tweets up front. Installed other amps for the rest of the speakers.

As stated the gain is simply the way to match the amp inputs to the source outputs. If the radio puts out 4 volts through the rca you set the amp gain at 4 volts and this will give you the amps rated power cleanly.
You can use an o scope but most people don’t have one but you can use test tones and a multimeter as well.

However, you can set an amp to make less than rated power for speakers with a smaller rms rating. Again, using test tones and a multimeter.

I believe sonic electronics has some videos about this using ohms law calculations and a multimeter.

 

[CircuitCircus]

I need to install new speakers in mine soon. This is gonna come in handy

 

[3dkustoms]

so those kenwoods are shallow enough to allow windows to fully roll down without hitting speakers?