As of 5/12/2019 this page is still a work in progress
The stereo that came in my Supra was far from impressive. The previous seller even acknowledged it in his for sale ad saying it "sucks". 20+ years of age has taken it's toll. I wanted to keep everything factory looking. After doing a lot of research this is what I came up with:
I installed the tweeters in conjunction with replacing my dash. My factory dash was peeling and was warped above the gauge cluster area. Unfortunately that is a common problem. I figured since they are still available from the factory I should replace it. I think it is possible to do this with the dash in the car, but it would be tricky and you'd definitely need to remove the gauge cluster stuff and the passenger airbag. The factory tweeters are screwed in from the underside of the dash so they can't be removed from the top.
Here is one of the factory tweeters. Both sides look like this. The tweeter is mounted to this bracket via a screw head bolt and some minor glue.
Start by prying the cover off with your bare hands. It will ruin the factory tweeter, but it was most likely never good to begin with.
Next separate the flat grill piece with what remains of the tweeter. If you look carefully there are 3 tabs that hold the tweeter to the underside of the grill cover. Use a tiny flat head to break the tabs and the rest of the tweeter can be removed.
Use a razor blade to cut the 3 supports out that hold in the plastic center piece. This is what the cover should look like afterwards. Notice the yellow screen looking stuff. If you use a 90 degree angled awl you can remove all of that. It's glued from the top side which you can't get to easily because the metal grill doesn't remove. The 90 degree awl allows you to get to it from the underside.
With the screen removed I enlarged the opening a little using a Dremel. The alpine tweeters are slightly larger in diameter than the factory tweeters so I wanted the opening to match it better. The Alpines came with some tweeter adapters as seen at the bottom. Snap off all the side mounting flanges.
With the tabs snapped off you'll have a mounting ring that can be glued to the underside of the factory speaker grills. I used some high heat hot glue that I bought years ago. When doing this pay attention to how the tweeters will twist into the housing. You want to make sure the wiring will exit the tweeter on the front or back so that it will clear the factory mounting bracket that screws under the dash. Figure this out before you glue it.
My tweeter grills didn't look the greatest. Some of the paint had worn off and some of the holes were clogged with dust. I scrubbed them real good using a toothbrush and some soapy water. Then I blew them dry with my air compressor. I gave them a 5 light coats of paint using Rustoleum semi-flat professional paint. I let them dry for a few hours then twisted the tweeters in.
Then I cut the tweeter wiring to shorten it and I soldered in the Alpine Capacitors that came with it. I like these Alpines because there are no crossover boxes for the components. Everything is built into the wiring. I also soldered on the factory pigtails that I cut off the old tweeters so it will plug in just like factory.
Screw the factory mounting brackets back under the dash. The Alpine speakers came with 2 rectangular pieces of peal and stick foam which is convenient. I used 1 piece per side and wrapped it around the tweeter brackets. I figure this will prevent any vibration as I did not want to fasten the tweeters permanently to the brackets. This way they will sit in the dash opening, won't rattle, and can be removed from the top if needed.
Here they are installed. They fit nice and snug in the new dash. They were a little lose in the old dash, but that's because it was so dried up and vinyl around the opening had dried and shrunk some.
The front door speakers are easy to install. Dealing with recovering the grill is another story. I'll start with the speaker mounting. I purchased the polycarbonate 6.5" speaker adapters online (see part# at the top). After I removed my door panels though I realized my car already had some MDF adapters from one of the previous owners. I compared them to the polycarbonate ones and chose to use the MDF as it felt stronger. I'm sure the other ones would have worked fine though. Here's my Alpine speaker installed.
Now for replacing your grill. (The oem grill likes fade to a purplish color over time). If you flip over the door panel you will see the grill is attached via some plastic posts that stick through the panel and then have these metal grommet washers pressed on them. The teeth on the grommets dig in and only allow it to move one way. It's a really awful design. You cannot remove the metal grommets without breaking the posts. You can cut off the grommets though with a Dremel. However I found the heat from the tiny cutoff wheel would warm the grommet up so much that it would slide and melt the plastic post, practically cutting them off. It's really a lose lose situation. Since one of my posts was already broken I just cut them all off and hoped I'd find a better solution.
Once the grill is removed, you need to separate the backing plate. It also attaches by plastic posts, but instead of using a grommet; the end of the post is melted creating a flat heat that holds it tight. The cover itself is made of ABS plastic, and the backing plate is made of PE plastic. I used a razor blade to cut the sides of the mushroomed head off of each pin.
With the backing plate off, I found a better solution to the studs I cut off. The Alpine speakers came with some metal mounting clips. I drilled a hole where each post was. Then I slid a clip over each one. Every single hole I had to modify slightly. I had to Dremel away some of the plastic to allow the clip to slide on farther. Then just about every clip I had to hold to my bench grinder to shorten them. It will make sense if you are trying to do this yourself. Then I used some machine screws as studs. The head of the machine screws was too bulky so I flattened them all out on a bench grinder until I had just a tiny bit of a Philips head left to work with. I used a black paint pen to cover my work.
The factory speakers are smaller diameter and the holes in the speaker grill reflect that. Since I'm running larger speakers I wanted to add some more holes to allow more sound to escape. I did just that using a drill press. Then I placed it on the door to make sure it wasn't going to rub anywhere. I did have to trim some of the door panel material as it interfered with the rubber ring around the speaker cone. I didn't get a good picture of this. It will be obvious when you test fit the door panel with the speaker in place and the grill removed.
The speaker fabric I bought off eBay from a seller named baostoner16. It's title was "Speaker Acoustic Grill Cloth Stereo Fabric Speaker Cover Indoors Outdoors Decor". I figured something rated for outdoors would hold up better in a car. It came in a 36"x55" panel which is overkill and about 3x as much as I need, but for $10 I couldn't complain. I used 3M Super77 spray adhesive. I only sprayed the back edges of the grill. I didn't spray the face of the grill, and I masked off the holes so nothing would accidentally bleed through. It was very easy to do. After about 30 seconds you can press one edge down just to set a starting point. Then immediately tug the opposite side slightly and press that edge down. Then rotate 90 degrees and repeat. It is very forgiving. It may want to stick in the wrong place, but you can pull it apart multiple times and it will continue to stick when you press it back down again. It's not like contact cement where you get one chance. When it looks good from the front you can cut the fabric from the backside. I left about 3/4" wrapped around the back side.
I used a plastic welder and some abs filament scrap from my 3d printer to re-pin the plastic together. Then I bolted it back to the panel using some stainless washers and nuts. I cut each stud a little shorter so they wouldn't poke through to far. Then for good measure I added a dab of hot glue to each stud to keep the nuts from wanting to loosen up. The areas I circled in red is where I had to trim the door panel slightly. I talked about it up above, but never took a good picture from the front side.
It looks so much better now. I wish Toyota would have designed this better. 3000gts have grills that screw on.
The rear speakers were not as bad to do. For starters the grills pop off. You don't need to remove any panels. To my surprise, my car was missing the rear speakers. No wonder the previous owner said the stereo wasn't that great!
Toyota has a special rear ported housing that the speakers bolt into. The Alpines I bought were actually a little too deep for these openings. I could have dremeled out an area so they would fit, but I didn't want to do that. Instead I chose to bring the speaker outwards. The Alpines come with a mounting ring. Unfortunately one ring was not quite enough; I needed two. However the rings that came with my front speakers were identical so it worked out really well. I used some JB Weld plastic bonder to glue the rings together. You'll want to snap off all the mounting tabs on the side except for the two triangular ones. When applying the epoxy don't get it in the brass threads. The screw bolts that come with the speakers are meant to only go as deep as one mounting ring. I had some extra screws from a different speaker set that were a little longer and helped pull the ring together nice and tight while it dried. Alternatively you could just set something heavy on them.
Once the epoxy hardens you'll need to elongate the holds in the triangular mounting tabs we didn't break off. The holes are a little too far apart so you need to elongate them inward with a drill. Basically you want to mount the ring like this only using 2 screws horizontally.
Then you need to snip or grind the metal area on the actual speaker so that it won't interfere with those screw heads. You can cut a pie shaped area out. If you look closely you can see where I've marked it with black sharpie.
After the speaker is cut, attach it using the 4 screw bolts. Then Add another screw top and bottom. The top and bottom screw won't penetrate through the mounting ring (It will just graze the outside edge of the ring). But it will pull the metal speaker housing tight against it and clamp everything together. Now it's very secure. The red circles show where the screw bolts went into the brass inserts on the mounting ring. The blue area are where I used the long screws (which I had to trim about 1/2" off as they were too long) that came with the alpine speakers.
Afterwards I test fit the cover. It still fits perfectly with no rubbing anywhere. The tweeter in the center of the cone is about 1-2mm from touching the grill.
I cleaned up the grill and recovered it just like I did with the front speakers. For the rear I actually did spray the face of the housing as it was glued the same way from the factory. It looks so much better now. More importantly it should sound better than a set of missing speakers.
You can't have a decent stereo without some kind of subwoofer. What suits me best is a single JL10W3. I've used this in a few other cars as well. It doesn't take up too much space (only requires 0.625 cubic feet), pounds pretty good, and it is affordable. Wicked Cas also makes a Supra specific box for one that goes in the trunk and still allows you to use your targa holder.
I started with mounting the amp. The Alpine MRV-M500 amp is Alpines latest version of their 500W Mono amp. I have their older version in my Subaru. The new model is slightly smaller which makes it easily fit under the passenger seat of a Supra. Normally there is a factory amp under the seat, but mine was removed by the previous owner as the speakers are powered by the built-in amplifier of the aftermarket head unit. This makes putting the subwoofer amp under the passenger seat a no-brainer. The factory carpet is already stamped with cutouts for the amp wiring to pass through, and there are already some factory bolt holes I could re-utilize to mount it. I started with making a simple bracket out of a piece of aluminum. This will anchor the amp so it can't fly around.
Then I ran the wiring. For the power/ground wire I used a Rockford Fosgate kit (RFK4X). It's 4 gauge OFC (Oxygen Free Copper) wire. It is more expensive as it's OFC wire. Its important to use quality wire though. Some people will use CCA (Copper-Clad Aluminum) wire which is aluminum wire coated in copper. It's not as good. Tests have shown that the same gauge wire as OFC will provide less power to your amp and the wire will run hotter. The last thing I would want to do is burn down my car from trying to cheap out on something. For the RCA wire I used Mediabridge gold 6' wire. I'm very impressed with Mediabridge. Anything you buy from them is going to be good. I ran the RCA cables (and remote wire) through the plastic track that the factory amp wires normally go through. Then for the Amp to Sub wire I used KnuKonceptz 10 gauge copper wire. It's a true 10 gauge wire unlike some of the cheaper stuff that claim to be 10 gauge but just use a thicker coating.
I bought the box and woofer from Wicked Cas as a combo deal. It didn't come installed so I had to pre-drill and install the sub myself. I used a tiny piece of KnuKonceptz wire to go from the sub to the terminal plate on the on the box. The back side of the terminal plate is meant for female spade connectors. I found the male spades that stick out on the inside of the box kind of flimsy. So instead I used some small ring connectors and attached them to the posts that hold on the male spades.
The box does seem to fit well. When you install it the factory spare tire cover will no longer fit. Instead of hacking the stock one up I decided to make my own using some 3/16 hardboard from Lowes. The factory carpet drapes over the box. It's true the bottom 2" of the sub gets covered as the hole is rectangular. I thought about cutting it, but decided to wait and see how it sounds first. I may try to source another OEM carpet as a spare before trying anything.