KJL

I am trying to understand the system configuration. I know there is the head-end unit, CDM (Under the dash) and speakers which I believe each speaker has its own amp. I have a 92 ZR1 and the rear speakers don't work and pop loudly even of the balance is set to have all the sound going to the front speakers. This happens at both speakers. The front speakers sound a little "thin" as well. I suspect it is the CDM.

What I am confused about is there also appears to be a module between the CDM and the rear speakers on my 95 located behind passenger seat. I did not see this on my 92. Is this another amp? My plan is to test everything with working stuff before I replace the CDM.

Thanks

Pa'svette

Check internet for www. carsterohelp.net/troubleshooting/Corvette Bose.htm

KJL

Thanks however the link does not appear to be working.

WVZR-1

The CDM is just in a different location. The CDM still provides the same function regardless of location in the car. There's NOT anything additional in your '95 IF it's still the way the "General" assembled it.

KJL

So the CDM was move to behind the passenger seat on later model C4s?

Also, I just swapped the speaker amp from my 96 into one of the 92's rear speaker and it worked. Going to check passenger side now. Ecklers is running an 18% off discount on anything until midnight. Figured I would jump on the deal and get a couple of new ones.

csthews

Correct. And the loud pop you hear is from bad amps on the speakers, and not from an issue with the CDM.

KJL

I know the rear amps are a known issue for these cars but what about the front speakers?

BTW, both amps were bad. Ordered two new.

softwarejanitor

All the amps in those Bose systems are known to fail. Keeping them running can be expensive and while they are state of the art back in the day they lack a lot of modern features. A lot of people swap the entire Bose system out when it fails which you pretty much have to do since their parts are not easily compatible with anything else. If you do that you should box the Bose parts up and retain them for when you sell the car.

WVZR-1

Not actually - many make regular trips to the "Pick a Parts" to gather components from anything Bose and most all of the components will swap directly(with little effort) to the C4 Corvette. There's very little reason to scrap the Bose if you can do the work yourself and have maybe mid - to higher understanding of most anything audio related. Some actually suggest that the later components might sound better than original. Maybe because it's been less than optimal for a while .. who knows. The capacitors etc that failed have certainly been improved through the years so just "tossing it" seems somewhat foolish.

Listen to the tunes and pay attention to the road ... you don't need all of the rest of the "killer" electronics that everyone worries so much about having.

kenpeindl

Here are some useful links for repairing Bose amps if you are handy with a soldering iron. Also the amps out of a 95-99 Nissan Maxima and Infiniti I30 will work and are a lot cheaper.

http://www.zr1.net/forum/showthread.php?t=20380

http://www.zr1netregistry.com/Portals/0/Bose2.pdf

https://www.corvetteforum.com/forums...audio-faq.html

http://zr1corvette.blogspot.com/2011...aker-amps.html

KJL

Thanks, installed new boards in the rear and they sound great. The front sound OK but a little thin. I am keeping the old amps and may try to repair.

eldertek

I shipped each speakers Amp to www.carstereohelp.com and had them rebuilt.
All 4 work great now.
About $250 total for all 4.

kenpeindl

Here's a list capacitors and their symptoms.

C4 Bose Amps

Capacitor C172 affect volume and sound quality
Capacitor C7 & C8 worling and squealing
Capacitor C31 poping sound
Capacitor C203 Base disortion
Capacitor C16 Poping & squealing
Capacitor C19 & C 25 Generally don't go bad

The rest will make the squeaks and squeals

HGUNHNTR

For under $400 you can re-wire and install a modern stereo and speakers that will sound much better than the two decade old Bose. It's the best thing I've done to mine. Budget a Saturday, and you can have it done in time for an evening cruise.

pcolt94

Main difference between the front and rear speaker amps is the equalization. Main components and circuitry is pretty much the same. I ended up repairing all 4 of mine over the years. Filter cap were the main problems.

https://www.corvetteforum.com/forums...-and-more.html

softwarejanitor

My 1984 C4 had the lower end Delco AM/FM/Cassette instead of the Bose... but I've been really happy with the modern Kenwood KDC-BT762HD deck I put in along with Sound Storm Labs speakers... SSL GS-246 4x6" 2-way in front and SSL GS-369 6x9" three way in back. The head unit will play MP3 from the CD drive, has Bluetooth, HD Radio, front USB, AUX jack and is SiriusXM ready. All features you won't find on a 20+ year old unit. Cost for all the hardware including a wiring harness and antenna adapter and a mounting kit was under $300.

KJL

I guess these amps are all crap. The brand new units I just replaced in my 92 are already starting to pop and now the rear amps in my 95 are starting to POP as well. I am really surprised that Bose couldn't figure out how to make a decent car radio back in the 90's. It is not like that was the dark ages for pete's sake...where all we had was AM through vacuum tube radios. I am pretty sure "transitorized" radios have been around sense the 70's.

whalepirot

the lauded (by some) Blose 901s were assemblies of lots of cheapish drivers all equalized to hell and back. An A/B listen against some high quality speakers demonstrates this quickly and definitely. I did that with a pair of Klipsch LaScalas (a hundred years ago) and still remember the impact. The Bose ad budget is killer and effective. the sound, IMO, horrible. The optional sound system in the '84 was quite a revolution, however, from the ultra-crappy previous options, so the lauding and legend was given new life. the company was always mass market and hence, of middling quality for those who demand an excellent listening environment, not than any car will truly be audio nirvana.

I recall my Dad's Zenith transistor radio from the '60's.

I can barely listen to any Blose sound but grin ever time my upgraded Corvette system is fired up. Some days I get nothing else done, with the help from a battery charger and the good leather Corvette seat!

KJL

What system are you currently using?

whalepirot

Pio head,4x100W MBQuart,Inf 8"+6.5", from my signature. ' Pio' is the head unit, which I am not a huge fan of, for their mediocre support, but I do like the sound retrieval for mp3s. It was NOT done in one day, with mbQuart low-profile amp under the pax seat and self-made speaker enclosures for the door 6 1/2" and the 8" sub in the rear, not to mention the new, large speaker wires. I like Infinity products, but other high-end is good.