This may be a bit long but hopefully will save someone the headaches I had as I was never able to find a clear how to write up on any forum I have access to. Maybe just my poor search ability or...
My 05 has the premium Infinity OEM sound system which has a combined amp/crossover (a.k.a. amp) mounted on (not part of, as some have said) each front door speaker. As with most OEM speakers the cones are paper and the surrounds are foam so of course my surrounds eventually gave out. The front speakers would still produce sound but they buzz at certain frequencies. I purchased an online repair kit (glue and new foam surrounds) which went on just fine and took care of the buzz. However, that is only a short term solution as it still leaves you with the foam surround which is likely to fail again someday.
Checked around (dealer parts manager I know; Google search; and Crutchfield). This confirmed that the only "new" replacement available would cost ca. $160 per speaker/amp assembly (e.g. $320 for both fronts). That option is nuts given 1) both my amps are fine and there is absolutely no need to purchase new ones when the old could be shifted to a new speaker so long as it had the mounting bracket via 2 bolts and 2 quick disconnect fittings and 2) that would only get me the not so durable OEM speakers. Crutchfield was most helpful and 1) confirmed that the OEM speakers are 2ohm; 2) recommended a quality Infinity 2ohm replacement (the ones I eventually got); and 3) confirmed that I could leave the amps in the circuit but did not have, no surprise, any wisdom to offer of how to wire or mount the amps.
So here is what I did:
1. purchased 4 (2 pairs) of Infinity 6032si 2ohm replacement speakers, which have durable composite cones and surrounds, from Amazon (Crutchfield was out of stock). The 6032si has a tweeter control on each speaker that I set to +3db. I'm guessing that setting only matters for the rear speakers and the high sounds in the front go to the dash mounted tweeters.
2. wasted way too much time worrying about +/- terminals and fiddling with the 1.5v battery trick to determine which is which to avoid out of phase speakers. FORGET all that and just get a Metra electronics harness model 72-6514 (Best Buy SKU 7994771 or available much cheaper via Amazon) for the rear speakers. That harness plugs straight into the OEM wiring and has quick disconnect fittings that plug straight onto the standard (as marked on the new speakers) + large male terminal and - small male terminal.
New rear speaker with Metra pigtail installed
New rear speaker mounted - Note "long" mounting tab on all speakers goes up.
For the front speakers I made a pigtail from a standard 2 wire flat plug (NAPA PN 755-1598 or any parts store) and 1/4" for + and 3/16" for - crimp on quick disconnects (female on speaker side and male on amp side) from Radio Shack (PN 6403132 and 6404040 respectively) to have enough working wire for installation and any future removal and used that pigtail to connect the red=+ and black=- terminals coming out of the amp to the speaker terminals. Be sure to wrap the amp side exposed portions of the quick disconnects with good quality electricians tape (not cheap hardware stuff).
Amp side of front speaker pigtail
3. don't bother trying to see if there is enough "meat" to simply drill 4 new mounting holes in the door frame. There isn't. Use the supplied adapter rings remembering that they are plastic and a bit fragile (yes I know now). On the adapter rings that came with my speakers I noted 4 correctly spaced holes in the bracket that could be threaded for a 6/32 stainless steel machine screw cut to 3/8" long which left just enough threads to add a nut, with a drop of Loctite blue, on the door side; just run the bolt down until it lightly bottoms and then flip things over and do the same with the nut. I padded the nuts, where they contact the door frame, with skinny stick on sponge rubber cabinet door bumpers, skinny stick on no skid carpet backing would work too.
4. The amps are held to the speaker by 2 Torx head bolts that may be a bit tight and connected to the speaker by quick disconnects. Disconnect the amps from the OEM speakers.
OEM front speaker with amp mounted
OEM front speaker with amp removed
I mounted the amp solid side facing the inside of the vehicle and oriented vertically (big OEM plug off to one side) with a slight tilt for ease of access to the plugs which put the "cooling" fins toward the window glass. To do so cut a rectangular piece of 1/4" ethafoam or similar padding and zip tie it to the long axis of the solid side of the amp routing the zip tie thru the Torx bolt holes with a bit of padding sticking below the amp to provide padding between the amp and the inside and bottom of the door frame.
OEM amp with ethafoam pad mounted and wireing pigtail installed.
Same as above but with exposed pigtail connections wrapped in electrical tape
Using a really long zip tie or several zip ties spliced together secure the amp to the door frame taking advantage of a couple of existing cutouts low on the door frame. Be careful to capture the OEM wiring between the door frame and the zip tie to keep it away from the window track. Before mounting the speaker be sure to test the up/down function of the window glass; it should clear the amp ok although it may be close.
OEM amp mounted inside door
New front speaker mounted in door
Worked out great and the new speakers are much better than stock. Setting aside the time wasted on trying to figure out + vs. - and time invested in figuring out how to mount the amps I only had one problem. For reasons that totally escape me when I first installed the new rear speakers (OEM fronts still in place) the sound was dramatically muffled. I pulled the new rears and remounted the OEM rears and had the same problem. In all honesty this condition may have existed for some time given my radio speaker settings and the lack of passenger use of the rear seat. Not knowing any better I pulled my Sony MEX BT3900U radio and double checked the wiring to the wiring pigtail Crutchfield had supplied when I bought the radio and cross checked that wiring to the factory wiring diagram. All appeared perfect. Put everything back together and what the "F" the muffled sound has been cured. No clue why or what as all I did was undo plugs and redo them; guess there must have been an imperfect plug connection somewhere.
EDIT RE MUFFLED SOUND - I don't know about other Sony's (mine is a MEX-BT3900U) or other brands but on my unit there is a RB Enh setting where setting"1" fakes the system into applying Low Pass Filter settings to rear speakers as if they were subwoofers. DO NOT DO THIS as it makes the rear speakers function like subwoofers so all you hear from them is a muffled base thump/thump. I suspect what happened is when I killed power to the Sony during the original install and restored power this setting defaulted to off; I then manually set the switch to "1" per some old notes; and got the muffled sound on my 1st sound test; I then killed power again and rechecked everything BUT on the 2nd sound test I did not reset the RB Enh switch so it would have been "Off" hence rear sound was fine. Of course after everything was fine I reset the head unit and reset that switch to "1". Haven't been driving much but I did recently note that the radio and iPod sound levels were different (low and "flat" on radio vs. high and "not flat" on iPod) so I fiddled with the fader setting and found the rear speakers muffled again. Messed with the Sony setting and found that setting RB Enh to "Off" cured my problem which probably has been around since I installed that Sony head unit but since I never sit in my back seat and the "Premium" speakers are not that great I never noticed. Sigh; electrical stuff is way over my head sometimes.
