Alternative source for cheap functional Bose speaker amplifiers

[mike100]

As requested, I put together some pictures and part numbers for 95-99 Nissan Maxima and Infiniti I30 cars that use the same type of Bose amps as the C4 does. They are functionally swappable, but the exact speaker tuning may be slightly different. I found that they sound great in the C4 as they have a similar small/large front to rear (respectively) speaker arrangement.

History- At first I set off to buy a replacement amp for one in the rear that squealed. Once I got that working with a good used Corvette unit (that I parted with $50 for), I realized other amps were weak and another completely dead- I think I had one good one in the whole car. You just couldn't tell because the squealing one was very loud. After reading up on the how-to to replace the capacitors, I redid mine (with used caps from some junkers I procured). Not using new caps was a mistake, but I got 2 out of the 3 working again. One of them failed three weeks later, but I did realize that some would be serviceable. For awhile I was trying to keep it proper using exact oem parts like an NCRS collector would do, but after having taken apart the enclosures a couple times too many, and having spent money for little gain, I considered the information I had found on the Nissans that used this same amplifier.


Nissan front amp- marked 'Sigma 975':


front amp opened:


rear amp:


rear amp side-by-side with oem C4 amp:


note on the last picture that some of the electrolytic caps appear missing on the Nissan part, but they are still there, just in different locations as the board had a layout revision. They work and I was hard pressed to hear a difference. You can tell bass/treble tuning if you swap a front to the rear and visa-versa so it is important to get that straight, but they are a good match for the vettes IMO.

I have been able to get mine from a local pull-it-yourself dismantler for $7 each. They are newer than the ones in our cars, and few people care to restore maximas, so this is the prime age for finding tons of these cars in the scrap yard. I have been able to find at least 4 amps each time I visit my local spot. (No, I have not been buying more).

[Dynomite]

Thanks for the information

[Corbusa]

Ditto Thanks for that info..! I have 3 out in my 89 Z51

[mike100]

Originally Posted by Corbusa

Ditto Thanks for that info..! I have 3 out in my 89 Z51

I understand that the 90-96 cars use this style of amplifier with the 6-pin header connection. I don't have a link, but i seem to recall it is possible to retrofit newer amps into older vettes if you are willing to cut and solder the original wiring into the proper location on the newer amp.

[scottfab]

Really good stuff.
Paying $7 for these is a steel.
And it is likely since they are 95 and newer vintage that the
fault found in the mid to late 80s caps will not be there.
There was a world wide defect of capacitors in the 80s that
was well understood by anyone in the electronics industry.
They found there way into the Bose amps.

The main problem with the caps is related to temperature.
They were rated at 85deg C and that was a lie and even at 85deg that
it was too low.
When using new caps the you want to find >100deg C.
@ $7 per amp why bother.
Next time I am by a U-pull it I'm going to look for some spares.
Good find indeed.

[Starman]

Bose has, or at least did have, a remanufacturing service for our speaker/amp modules. You have to send them the complete module and they will send you a remanufactured unit with a warranty. I did all 4 units in my car about 4 years ago for $75 each and it sounds better now than when I bought my car. I have a Pioneer DVD head unit and the Bose speakers really rock with the clean input from iPods, SD Chips, etc.

I have a call in to Bose to get updated information and will post ASAP.

[RHanselman]

Very good to know... I've 4 vettes and all but 1 have speaker issues... $21 per car is much better than $80 per speaker amp...

[Fully Vetted]

Originally Posted by Starman

Bose has, or at least did have, a remanufacturing service for our speaker/amp modules. You have to send them the complete module and they will send you a remanufactured unit with a warranty. I did all 4 units in my car about 4 years ago for $75 each and it sounds better now than when I bought my car. I have a Pioneer DVD head unit and the Bose speakers really rock with the clean input from iPods, SD Chips, etc.

I have a call in to Bose to get updated information and will post ASAP.

Thanks for running down this info.

[Vetman]

My radio and speakers were out and in a box when I purchased the car. I have the radio head unit, what looks like an amp. About 12 inches by 4 inches, and the four speakers. Are there additional amp's for each speaker?

[mike100]

Originally Posted by Vetman

My radio and speakers were out and in a box when I purchased the car. I have the radio head unit, what looks like an amp. About 12 inches by 4 inches, and the four speakers. Are there additional amp's for each speaker?

The box you describe might be the CDM or radio tuner module...although it isn't quite a foot long. The amps are near the speakers themselves.