babydave

Hi;

Couple of queries if I may:

1. With the Bose stereo are the individual crossovers for the door woofer and midrange installed in the door? The mid range speaker in the drivers door isn't working - I'm assuming is a loose connection.

2. http://www.crutchfield.com/p_1207017...s.html?tp=2977 - will this work as a harness adaptor with the Bose system (or is this just for standard). I see a few people have used these on here.

Many thanks;

Dave

cliffyk

1.
Here is the schematic diagram for the 1998 MY Bose amplifier:



You can see that the left and right door speakers are represented as a group assembly with a single feed. I suspect you will find a simple capacitor only "crossover" on the tweeter; or it might be a piezo or other tweeter design that needs no low frequency blocking.


2.
As delivered the stock radio drives the Bose amplifier via it's 4Ω speaker outputs, the inputs on the Bose amp have internal shunt resistors to terminate the low impedance speaker signal. Because of this almost any aftermarket receiver having speaker outputs capable of 10W or more will drive the Bose amplifier to it's full output.

However the adapter you linked, the Metra 70-1786, is intended to link a receiver's pre-amplifier output RCA connectors to the Bose inputs. Pre-amp outputs are typically 600Ω impedance, and after the Bose amp's input shunt resistors have had their way with the signal it's voltage is reduced. So to use pre-amp outputs, to drive the Bose amplifier to it's full potential, those outputs must be rated for least 4.0V preferably 5.0V or more. This limits your choices quite a bit; for example although Crutchfield lists 95 single DIN receivers, only 13 have pre-amp outputs higher than 4.0V.

The Bose amplifier can be modified to eliminate this requirement by removing the input shunt resistors; however it much easier to just select a head unit with it's own power amplifiers and drive the Bose amp from the speaker outputs. The difference in sound quality will be negligible.

You can wire the RCA jacks on the 70-1786 adapter to the receiver's front speaker outputs using RCA male to bare wire pigtails, or cut off the RCA connectors, or use the Metra 70-1784 adapter which has bare wires...

SRHsl600

Yes the Crutchfield adapter worked on my bose system. But my head unit is the Clarion pop out screen. I am so limited on the wiring diagram, I would say "yes of course" and be clueless!
My system was good before with the clarion et al. but returned to spectacular with a bose rebuild from RadioMan. No more pops and fades in the speakers and great range of sounds ( with the hard top.)
My system is old, 1994 version.

babydave

Thanks for the responses Gents, very helpful. Will tackle the silent speaker first and then a new head unit. The car currently has the standard MB headunit from Japan so only Radio frequencies I can get is 76.9 to 89.0Mhz which isnt much use!

Strangely I have tried 4 or 5 MB original units and none of them will talk to the CD changer or raise the antenna? The exist Jap spec unit has a button marked ANT that raises and lowers the height of the antenna when the radio is on? Starting to think the Japanese cars are wired up differently....

brauhaus313

Am I reading the schematic right by saying the Bose amplifier drives all speakers via the radio's front speaker outputs only?

Is that why I don't have any front/rear fading ability with an aftermarket headunit?

cliffyk

Yes; it is for that reason that the front/rear fader in stock head unit (in the r129) is also ineffective. This is documented in the audio system owner's manual...

brauhaus313

Ah, I see. Wish my car came with that manual.