I've installed a lot of speakers in cars I've had over the years and the E46 M3 is the most challenging because the speaker fitment. I have a few 6.5" speakers laying around from previous vehicles so I decided to try each out to see what is the best solution. I also read through all the DIY's over the past few years trying to get this to work and this is what I came up with.
The outcome of this project is I spent $150 on the radio, $150 on the Amp, $100 on wire and $250 on the speakers and the stereo sounds great. The basic error I see in most of the DIYs is an incorrectly size speaker which means the front of the speaker aren't isolated from the rear resulting in no bass and very little midbass.
Here is some background of the full install.
Radio: I recently upgraded to a Sony MEX-BT4000P because I have the same one in my truck and liked the interface and options. The radio cost $150 and does everything you could want it to do. It even has a color setting called 'M-Red' which matches the car. Mounting the mic up in the top left corner by the windshield gave the best sound quality to those listening while driving. I bought the PAC controller so my steering wheel controls work too. When you wire up the harness, don't worry about hooking up any of the speaker wires since you will use RCAs.
SiriusXM Antenna: The best placement for this is on top of the cabin filter box under the hood. You can only see the antenna if you look through the black grill by the windshield and you know it's there. The signal never cuts out and it took 10 minutes to run the wire into the cabin using a rubber seal in the ABS compartment.
Amp: Alpine MRP-F300. Run 2 sets of RCAs from the back of the radio to the amp. $175 for AMP and RCA wire. My car was stripped of his NAV setup before I got it so the main harness was all that was left. For the front doors I cut and labeled the 2 sets of wires that from the harness to each woofer up front. For the rear 2 speakers I ran new wires since it was simple to do. The amp itself is installed under the carpet with the flat tire kit.
Front Door: I went with Alpine SPR-60C Type R component speakers and you should be able to get these for $150 for the pair. As you can see from the pictures I had to cut 3 notches on the speaker with a dremel that the round OEM ring would fit over the frame. I have found on the rear set that one of those multi-tools with the flat blade works 5x easier and makes less of a mess.
It is very important to seal the front of the speaker to the thin ring that clips to the front of the OEM speaker and the speaker opening on the door. If you do not do this, the front of your speaker will not be isolated from the back of the speaker and it will sound like crap. What I used to seal it was the black sealant that holds the dust shield to the actual door. I was careful not to get it onto the woofer itself. I'm sure there might be a better material to use but it's what I had at the time.
At first these didn't sound all that great because the speakers just didn't have enough air space behind them. Using a dremel as per another DIY, I carefully cut a hole in the door itself. I unscrewed the window frame to prevent from cutting it since it sits very close to the skin. Also pictured is the factory wires to the front woofer with new connectors on them. I saw a few DIYs where you can mount the speaker to the door itself if you build a bracket, but this method made such a massive improvement with these speakers that I don't find it necessary.
Pictured here is the crossover and tweeter setup. I removed the factory mid and the tweeter fit in perfectly once I set the adjustment ring to the correct width. Make sure you lower the tweeter adjustment on the crossover or your highs will be too bright. I put some dynomat over the hole were the tweeter was(missing when I bought the car) since t's important to seal up the door panel from the cabin.
If you install just the fronts like this up to this point you will already have a good sounding setup. For a few weeks I just ran the front speakers until I got around to finding some rear OEM speaker baskets and speakers to replace my missing ones. It's very important to use the OEM speaker basket to once again isolate the front of the speaker from the back of the speaker.
Rears: The rears were pretty simple once I got the front's just right.
There were 4 metal tabs I had to bend then the speakers were easy to pry from their OEM mounting ring (this ring fits the front and back speakers FYI)
Here are 3 different fitments that should help clear up which speakers will fit without any adjustments. The first is a Alpine SPS-600 6.5" speaker. Note that the screw mounts stick out from the ring on the speaker. Because of this, the ring on the speaker fits inside the OEM bucket without modifications.
Here is a set of MB Quartz speakers I had laying around that I attempted to modify. They are also 6.5" speakers, but the ring extends to the edge of the mounting holes so you would need to trim these down. I started too then realized that the magnet won't fit in the baskets which is why I went with Alpine SPR-60 Type R spears. They are the non component version of the fronts that I used before.
Here are the SPR-60's from before just as a test fitment. As you can sit once you cut the 3 tabs out of them, they will fit in the front or rear. When I went to put them in the car I noticed the back rear deck fits very tight. It's best to trim a way a bit of the rear deck around the speaker so that it fits better. I used a hot glue gun to attach them to the ring. The easiest way to cut out the 3 tabs was with one of those multi-tools with the flat blade that oscillates.
After that just bolt the rears in like the stock ones came one.
Pictured is the MB Quarts PVI-216, Alpine SPR-60C, and Alpine SPC-600. The Alpine SPR-600C is the one with the smallest fit which makes the install easy. I tried all 3 sets and it's the best sounding bass wise by far. The crossover is easy to deal with too.
Here is an updated shot that shows how some 6.5" speakers don't fit through the oem mounting rings. You can see the one on the left is too large and doesn't sit flush where the one on the right does because of the frame behind the speaker.
The outcome of this project is I spent $150 on the radio, $150 on the Amp, $100 on wire and $250 on the speakers and the stereo sounds great. The basic error I see in most of the DIYs is an incorrectly size speaker which means the front of the speaker aren't isolated from the rear resulting in no bass and very little midbass.
Here is some background of the full install.
Radio: I recently upgraded to a Sony MEX-BT4000P because I have the same one in my truck and liked the interface and options. The radio cost $150 and does everything you could want it to do. It even has a color setting called 'M-Red' which matches the car. Mounting the mic up in the top left corner by the windshield gave the best sound quality to those listening while driving. I bought the PAC controller so my steering wheel controls work too. When you wire up the harness, don't worry about hooking up any of the speaker wires since you will use RCAs.
SiriusXM Antenna: The best placement for this is on top of the cabin filter box under the hood. You can only see the antenna if you look through the black grill by the windshield and you know it's there. The signal never cuts out and it took 10 minutes to run the wire into the cabin using a rubber seal in the ABS compartment.
Amp: Alpine MRP-F300. Run 2 sets of RCAs from the back of the radio to the amp. $175 for AMP and RCA wire. My car was stripped of his NAV setup before I got it so the main harness was all that was left. For the front doors I cut and labeled the 2 sets of wires that from the harness to each woofer up front. For the rear 2 speakers I ran new wires since it was simple to do. The amp itself is installed under the carpet with the flat tire kit.
Front Door: I went with Alpine SPR-60C Type R component speakers and you should be able to get these for $150 for the pair. As you can see from the pictures I had to cut 3 notches on the speaker with a dremel that the round OEM ring would fit over the frame. I have found on the rear set that one of those multi-tools with the flat blade works 5x easier and makes less of a mess.
It is very important to seal the front of the speaker to the thin ring that clips to the front of the OEM speaker and the speaker opening on the door. If you do not do this, the front of your speaker will not be isolated from the back of the speaker and it will sound like crap. What I used to seal it was the black sealant that holds the dust shield to the actual door. I was careful not to get it onto the woofer itself. I'm sure there might be a better material to use but it's what I had at the time.
At first these didn't sound all that great because the speakers just didn't have enough air space behind them. Using a dremel as per another DIY, I carefully cut a hole in the door itself. I unscrewed the window frame to prevent from cutting it since it sits very close to the skin. Also pictured is the factory wires to the front woofer with new connectors on them. I saw a few DIYs where you can mount the speaker to the door itself if you build a bracket, but this method made such a massive improvement with these speakers that I don't find it necessary.
Pictured here is the crossover and tweeter setup. I removed the factory mid and the tweeter fit in perfectly once I set the adjustment ring to the correct width. Make sure you lower the tweeter adjustment on the crossover or your highs will be too bright. I put some dynomat over the hole were the tweeter was(missing when I bought the car) since t's important to seal up the door panel from the cabin.
If you install just the fronts like this up to this point you will already have a good sounding setup. For a few weeks I just ran the front speakers until I got around to finding some rear OEM speaker baskets and speakers to replace my missing ones. It's very important to use the OEM speaker basket to once again isolate the front of the speaker from the back of the speaker.
Rears: The rears were pretty simple once I got the front's just right.
There were 4 metal tabs I had to bend then the speakers were easy to pry from their OEM mounting ring (this ring fits the front and back speakers FYI)
Here are 3 different fitments that should help clear up which speakers will fit without any adjustments. The first is a Alpine SPS-600 6.5" speaker. Note that the screw mounts stick out from the ring on the speaker. Because of this, the ring on the speaker fits inside the OEM bucket without modifications.
Here is a set of MB Quartz speakers I had laying around that I attempted to modify. They are also 6.5" speakers, but the ring extends to the edge of the mounting holes so you would need to trim these down. I started too then realized that the magnet won't fit in the baskets which is why I went with Alpine SPR-60 Type R spears. They are the non component version of the fronts that I used before.
Here are the SPR-60's from before just as a test fitment. As you can sit once you cut the 3 tabs out of them, they will fit in the front or rear. When I went to put them in the car I noticed the back rear deck fits very tight. It's best to trim a way a bit of the rear deck around the speaker so that it fits better. I used a hot glue gun to attach them to the ring. The easiest way to cut out the 3 tabs was with one of those multi-tools with the flat blade that oscillates.
After that just bolt the rears in like the stock ones came one.
Pictured is the MB Quarts PVI-216, Alpine SPR-60C, and Alpine SPC-600. The Alpine SPR-600C is the one with the smallest fit which makes the install easy. I tried all 3 sets and it's the best sounding bass wise by far. The crossover is easy to deal with too.
Here is an updated shot that shows how some 6.5" speakers don't fit through the oem mounting rings. You can see the one on the left is too large and doesn't sit flush where the one on the right does because of the frame behind the speaker.