: 98+ Bose 4.0 Speaker sizes [ and what size to replace with ]

05-22-08, 05:13 PM
ok. first off this isnt what youre thinking. ive searched thru' this forum [ at least 20 pages ] and still can not find deffinitive answers on speakers sizes, impedance, and replacement sizes. theres no one thread that can answer all 3...so im making one.

the intent of this thread is to detail the actual Bose speaker sizes, impedance, and what will fit in lieu of factory parts. please post only if you can offer proof from pictures, articles, or personal experience!

ok, now from what ive seen most people agree that the dash speakers are 2.5" units, the door units are 8", and the rears are 6.5". the wild card is the sub. the popular mechanics article clearly states 12" sub, but ive seen many people here say its a 10" sub. what gives?

for the impedance. i have read on the forum, that the speakers are most likely 1 ohm. is that all speakers to include the sub? along these lines, the availability of 1 ohm aftermarket speakers is virtually nil, so you have to go to 2 ohm units which is small but speakers are available from a decent amount of mfgs. additionally, if the sub is 1 ohm as well you can just grab a dvc 2 ohm sub are wire it down to 1 ohm. easy fix there.

ok, whats the deal with the dash speakers? apparently they have their own little box. AFAIK, there is NO aftermarket size 2" speaker. there are 3" speakers which are fairly rare, the more common 3.5" size, and the 4" size. what will fit and how much clearance is there to mount them?

door speakers. literature says theyre 8" midbass speakers. the real problem here isnt finding a speaker thats an 8, but how much mounting depth is available. im pretty sure you cant fit a standard 8" sub in there, so thats probably going to mean getting an adapter for a 6.5, oversized 6.5, or a 7" speaker assuming you can find them in 2ohm versions which shouldnt be that hard.

rear door speakers. nothing special here. standard size thats available in 2 ohm version from a number of mfgs.

sub. same issue as before. what size is it REALLY? literature says 12", people here say 10. mounting depth isnt much of an issue since it fires into the trunk area and theres plenty of room. i wouldnt recommend a really heavy sub as i have no clue how strong the package tray area is.

05-22-08, 05:22 PM
would like to add that since it did not occur to me to look for tweeters specifically for the dash units i feel a little dumb. there are 2" sizes available but the PM article doesnt make mention if the 2.5" units are tweeters or not so i didnt initially think about tweeters. im leaning towards not since they come in a little box and are described as tuned port. i really doubt anyone is trying to optimize midbass in such a small speaker but i suppose its not impossible.

05-23-08, 02:46 PM
Just personal experience here. The rear sub is an 11" :rolleyes: The Bose in the CTS uses the same sub IIRC. With some work a 12" will bolt in, or with sub ring, a 10" will work.

For the front 'tweeters,' my STS was missing them and only had one 3.5 speaker on the center (the Delco setup in the SLS). So I added a pair of Alpine Type-R crossovers and tweeters. Rigged them in there with a bracket. Tried to replace the center speaker with a 3.5" JL Audio TR350-CXi, but there is little depth to play with in the center, and of course it didn't fit, so I left the Delco speaker.

I am really pleased with the results. The highs are super bright. Have been told multiple times the ohm on the Bose is 1ohm and my Alpine are 4ohm, but they get just as loud and crisp as when I had them in a true audio setup. The stock Boses must have some good watts flowing in.

For the front 8", don't replace them with a sub. You need to look for an actual mid-bass, like this JL Audio piece (http://mobile.jlaudio.com/jlaudio_pages.php?page_id=215) or a Kicker SSMB8. Or if you really want to step you're game up, looking in to one of these: HAT Legatia's, Dynaudio, or the DLS Iridium.

05-23-08, 02:51 PM
the sub is not an 11 incher
it is actually LARGER than 12 almost 12.5
if you pull it and drop in a 12 it will not match up with the stock mount holes and it will have gaps unless you make a spacer plate

05-23-08, 05:03 PM
thanks for the input guys. CadillacSTS2003, if the sub mounting is larger then what would you suggest someone do for a drop in replacement? or, if a drop in isnt possible [ besides stock of course ] then how much fabbing would it take to get something to fit correctly. do you know if theres enough room for a MDF ring adapter?

Shawn4.0, i looked up the mounting depth of that speaker and the JL site shows 1.5" mounting depth and the tweeter requires .5" clearance above the speaker. how close was this to working?

also, the 8" midbass you showed me were pretty much the ones i were checking out as well. will those actually fit in the stock locations and allow the window to operate normally?

05-23-08, 06:25 PM
id recommend an MDF ring and using a shallow free air sub (Kicker and Kenwood make some)
you COULD get away without using the ring but you have to mount the sucker DEAD ON and youll have very little room for error when drilling mount holes as they are that close to the sub hole

also if you remove the bose boxes in the dash you can easily mount 3.5 inch speakers as there is already pre made screw holes for the 3.5 speakers in the delco system

05-23-08, 07:43 PM

my only questions now are: can anymore confirm that all the speakers are 1 ohm units and will a regular midbass speaker fit in the factory location. im pretty sure that 8" pancake woofer is like that for a reason but i cant be certain as i havent torn the door apart to see for myself.

05-23-08, 09:15 PM
1 yea they are 1 ohm
2 yea youll be fine with a mid there you can fit a 6.5 so im told but idk how never owned a non bose seville to look at it

05-24-08, 01:15 AM
I am fairly confident a replacement speaker will fit in the doors. There is a good bit of space behind the speaker and what's behind it is just soft insulation so there's even more room. And I know the grills are off the speakers a good bit of ways.

I would take the door off to confirm that it will fit, the only thing I can see is if the window glass goes down that far? I didn't have the windows down when I took the panel off. It's relatively easy to do, there are bolts behind the door lever behind that little plastic cover piece, and then one behind the pull handle (where you rest your arm). Lift up that bit of perforated leather at the bottom and it should reveal that bolt. And then there's the two obvious ones at the bottom of the panel IIRC?