I'm very pleased with the upgrade, done on my 01 540i6. Installation was relatively easy. The most time-consuming part was removing the rear deck and disassembling the old Nokia box to remove the connector (explained below). I now get tight and punchy bass that was non-existant before, with a nice thump on my back. This is a much cleaner solution than putting in a separate box and amp, keeping the car stock. I am surprised that the stock DSP amp is able to deliver this type of bass response. Unless you're a true bass-head who wants to be felt and heard from a mile down the road, I believe most people will be very satisfied with this inexpensive upgrade. Playing Celine Dione's Becaused You Loved Me (very deep bass in the beginning) at moderate level caused slight rattling to my garage windows and garage door, so I toned it down. Everything is now set to flat except for treble (all the way up, I like it nice and bright) and the higher frequencies on the EQ going up gradually. Overall clarity has improved at medium to higher volumes because I can set the lower frequencies and bass tone control to flat, relieving the mid-range speakers from producing (trying to produce anyway) the lower frequencies. The result is not unlike the two 10" Bazooka pushed by a Rockford Fosgate Punch 45 amp in my old car years ago.
I've listened to a new M5 with the M audio at my dealer, but for some reason that car didn't have nearly the punch that I'm getting now, albeit the fact that I had to keep it down in the showroom and I didn't adjust any of the tone controls. I wonder if bmw toned it down at the factory to prevent excessive rattling during very low-end bass reproduction. Yes there's some rattling under the rear deck, only happenes during very deep bass and mostly audible from the outside of the car only. Makes me wonder why bmw doesn't include this as part of the premium audio. Looks to me it'd be cheaper to install these two free-air 10" rather than the Nokia box and the extra trim used to cover it up.
Thanks go the Brian Lewis for his tips on the rear deck removal, and Cosmos530 for posting the part number for the subwoofer. Part number 65-13-7-894-047. Ordered from Pacific BMW for $186.84 each. The description on this part number is simply "subwoofer" if you ask
them, but it's the right part and as Cosmos530 point out, woofer/harness/bracket come as one unit.
One final note. Audio quality preference is a subjective matter. What is to me bright highs and punchy lows may sound dull and loose to you.
Here's an overview of the installation.
The subwoofer came complete with a harness. I believe there should be a cable with the proper connectors to connect the two subs to the connector that plugs into the Nokia box (as seen on a stock M5 picture at www.nextmill.net/bmw540/pictures/m5enhancedbass1.jpg), but I don't have that part number. If you can find that part number it will make it even easier and cleaner. So I cut out the connector and strip off about an inch of insulation from the two subwoofers.
I wanted to avoid cutting the harness inside the car that connects to the Nokia box, so I disassembled the Nokia box and removed the connector along with the small circuit board to which the speaker wires are soldered. Cut off the connectors that was plugged into the two 5" drivers inside the Nokia box, strip off 1" of insulation. The longer wires connects to the passenger side sub, the shorter ones to the driver side. There is enough wire for the
passenger side driver, but I had to add two pairs (the sub is dual voicecoil requiring two channels each) of about 20 inches for the driver's side subwoofer. The wires with the black stripe is positive.
Remove the rear deck. For instruction goto www.nextmill.net/bmw540/rears.htm. On my July built 2001 540i6, the mounting holes are already there. There are three mounting points on each driver, use 5mm bolt to mount. There was a fourth connecting point that looks like the clips used to mount the door panel, but was broken off inside the box. Probably broke off during shipping, the boxes had bmw's seal on. The three 5mm bolt are sufficient to mount each driver. I just let the drivers port through the existing holes for the Nokia box. The template is already stamped on the rear deck if you decide to cut the 10" openings; this could improve response and possibly alleviate some of the rattling under the deck. But it's good enough for me and I definitely didn't want to do any cutting to the car. Looking at pictures of Brian Lewis' car it didn't appear to have the holes
pre-drilled. I believe his car is a 2000. You may or may not have the mounting holes, but I suspect all 2001's should have them since this is an option on the M5 starting 2001. The subwoofer gets under-mounted, so I just used a box and a stack of magazine to raise it up to get it aligned with the mounting holes. Once aligned tighten from above the rear deck. You might be thinking to just screw it in from underneath the deck, and save the trouble of removing the rear seats and all. I definitely recommend against it. It has to be securely mounted so it'll seal properly to minimize leak (it's only a foam seal but does the job) and rattle. Plus YOu probably don't want to chance getting your groceries crushed!
Next route the wires that came off the Nokia box. You can easily tuck them away behind the panels in the trunk. Connect the speaker wires from the subwoofer to the wires coming from the connector removed from the Nokia box. The wires with the black stripe are the positive leads so reconnect accordingly. Wrap up all exposed leads on the circuit board with electrical tape. Plug in the connector to the harness in the trunk, secure with tie wraps and you're done! Before putting back the panels and rear seat, I would play a few tracks with good bass response and see if there's excessive rattling. Try to tighten things as much as you can before closing everything back up. Take care when remounting the parcel shelf that everything snaps back in place properly so it doesn't rattle.
I took a few pictures of the parts, go to http://photos.yahoo.com/andye39s to view.
Enjoy!
