my 1992 745T came with dash and rear door speakers, which the PO had hooked up to a decent JVC deck... Getting tired of the ok-but-meh sound, so I've been planning on doing a speaker upgrade for months now, and finally bit the bullet.

I determined that you can just squeeze a 6" into the front doors by trimming the panels, and that JL Audio's C2-600's would JUST barely fit in the door, so I ordered a pair, along with C2-525X coaxials for the back doors.

C2-600 - Car Audio - Evolution® - C2 - Component Systems - JL Audio
C2-525x - Car Audio - Evolution® - C2 - Coaxial Systems - JL Audio

I had to trim a 'flat' on the flange of the 6" woofer frames, and remove a rubber trim thing from around the magnet for them to fit.





I took the factory dashboard speakers apart, removing the magnet and grill and cone, and secured the tweeter inside, using RTV (silicone rubber adhesive), [sorry, no pictures], replaced the grill, and put them back on the dash. the crossovers are going under the drivers side dash, probably secured to the clutch pedal bracket (since my wagon has no clutch)

I'm holding off on the rear speaker install, I've ordered a pair of these:
PVC Speaker Adapters - CNC Machined - In Stock or Custom Made

anyways, I have a bit more wiring to do this afternoon...

 

and I finished the wiring, did a quick test, all seemed good, so I wire loomed the harnesses I'd added under the drivers dash, secured the crossovers to the metal arm for the clutch-I-don't-have, and replaced the dash, and did some more serious listening in my driveway.

oh, fawk. passenger side tweeter ain't tweeting. WTF?

pop tweeter panel, no, its wiring all seems rock solid....

ok, tear into drivers under-dash, again... hmmm, front speaker wires that I kinda thought might have been a little funky were just fine..., all the way back to the crossovers, hey, the right crossover is missing the jumper for tweeter gain! oh, wtf. find a jumper on a old scsi hard drive adapter I had in a junk drawer, and plink! its tweeting. reinstall dash and be happy!

road tested it while driving to San Jose Airport tonight to pick my wife up after a business trip to Portland. played "Three Ring Circle", sounds _goooood_. cranked up really loud, the acoustic bass on that album caused my doors to buzz. but at any sane volume, it just sounded good.

 

with hindsight, I probably should have gotten the coaxial C2-600X ... doing the seperate crossovers, with the tweeters on the dash was likely a mistake.

JL's guidelines suggest putting the tweet next to the woof, and putting both of them down low and forward on the front doors. putting the tweeters in the 740/940 dashboard mounts, bouncing off the windsheild, made the treble really front and center. the woofers in the doors, which are carrying a lot of midrange, are quite disconnected.

If I did the component thing again in this car, I'd look at mounting the tweeter in the door, and stashing the crossover there too. but I think coax would work just fine.

these 6" drivers have found some buzzes in my doors. I can see using some RTV and/or butyl tape soon. one of the buzzes might just be a speaker screw that needs to be shortened from behind.

 

Hi Pierce,
I just installed a set of speakers in the front doors of my 740, the wiring was already there BUT I get no sound from the speakers. The rear door and dash speakers still work. Do you have any idea if the front door wiring goes anywhere? The wiring diagram seems to suggest so.
Thanks,
Andrew

 

my 1992 had the doors wired to the amplifier under the dashboard, above where the clutch pedal would be, the dash speakers were direct to the speaker. My local stereo store had an adapter specific for this configuration, there was two connectors, one plugged in where the factory amp was, for the door speakers, and the other connector plugged in to the factory connector for the original radio/deck, this made my wiring MUCH nicer. I removed the factory amp, and thats approximately where my crossovers are mounted.

this was my wiring, including the crossovers to separate woofer/tweeters.
https://docs.google.com/document/d/1...6M1zjB8io/edit

if your 740 is older, no telling if its exactly the same, I only have wiring diagrams for 1991 and 1992 (and 940's from 91 to 95)

 

Nice. I wish I did the 6" woofers in the front of the 740.
5 1/4" in mine.
Here is how I did the Front doors



The rears are the same just required more door metal trimming and then I needed to creat a stand off for the speaker to mount to the door nice and solid.

Luckly the speakers I used had the tweeter mount with the woofer for a simple install package.

I ran all new wires when I swapped interiors, and have the head unit control my amp which drives everything.
More info in my thread.

Sorry for the thread jack.

 

hmm, I bet the door mounting is more solid than the panel mounting I opted for, as I'm still fighting some bass buzz at higher volumes. OTOH, my speakers have some BIG magnets, I'm not sure the window would have cleared if they were mounted on the door.

 

Yeah it is tight in there.


When I measured, I think it was like something like 2.5" - 2.75" of clearance from the down window to the door metal. I don't remember...


The solid mount is definitely the way to go. you lose some bass energy through the movement of the door panel if mounted to that.

 

the whole door almost does a bit of a subwoofer thing hahaha. that 6" driver I installed can pump some air.



yes, I tore the top of the paper gasket when I trimmed the speaker with a fine tooth sabersaw. after the picture, I treated the paper with some glue. the speakers are installed with some auto/marine clear silicone. I also used the silicone as a sort of locktite on the various 'screws' that hold the tray and handle to the door panel.

now that I've found the right settings, the tweeter in the dash with the woofer in the door is working pretty damn good.

I don't have a picture of the tweeter install, but they are mounted inside the original dash speaker plates, you can't tell they are there. we carefully removed the screen from the top, removed all traces of the original cone and magnet, wired the JL Audio tweeter to the original terminals, then put the tweeter on a nice bed of RTV right in the middle more or less where the voice coil was. put the cover back on, and reinstalled.

I'm thinking if I add a small subbox in back and roll the low bass off of on the doors, it will be perfect. I'll probably need an equalizer/amp, or a new deck to make it all work.

my tweeters:

 

Hey guys, thanks for the ideas. Pierce, I have a 92, so I will dig around under the dash to try to match the wires to your diagram. TIPSP, is that a crossover in your picture of the open door?
I will update if and when I get it all to work.
Andrew

 

Yep. You can fit a good sized crossover in that location. The door panel is open back there.