91 Bose System Noise
Thread Starter
Burning Brakes
Joined: Aug 2006
Posts: 1,123
Likes: 1
From: Rockland County NY
91 Bose System Noise
I recently purchased a 91 with a Bose system in it. It plays faint music but squeals like a stuck pig. Is this a common problem or is it time to upgrade? Also, is an upgrade as easy as pulling out the old unit and replacing it with something else? Help! It's hard to drive without music!
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
Bose Speaker Amp Repair - 94 (and more)
So I have spent lots of time on the internet and in the Forum and put together some info from my experience and research. The three best links are; and the first being the best with most detail.
http://www.zr1netregistry.com/Bose2.pdf
https://www.corvetteforum.com/techti...D=91&TopicID=2
https://www.corvetteforum.com/techti...D=58&TopicID=2
You can find more info using Bose or schematics as key words to search in the Forum but this I think is some of the best information. (You will need to look at the links to follow me).
My particular journey started when I had popping in my right rear speaker. I followed the instructions and replaced all 8 capacitors. Analyzed some of the circuitry because I’m a electronic teck turd and returned it to service fixed. Realized that speaker now sounded much better than the one that had no problem (the left rear). So I removed the speaker assembly and repaired the amplifier. Did not have C19 and C25 which are the ones that are a pain to physically install and decided to leave them alone since I felt like they were OK. Reinstalled the unit and had much more base and volume out of the speaker. The point is just because it does not pop, squeak or squeal does not mean that it is working properly after 12 years.
For those are interested, C31 gave me the pop and C172 will cause the poor sound quality. C7 & C8 will cause a worling squealing sound. Most of these are decoupling capacitors and don’t really carry any signal except C172. Capacitors really have to go bad and change value radically to cause a ill effect (most of the time and depending…..). Actually my C7 & C8 both measured about 47 umfd. Out of the 3 – 10 umfd & 4.7 umfd per board, 6 of the 8 capacitors did not measure anything as read on a capacitance meter (not ohm meter). So these 6 really went south, but I have better sound now.
http://www.zr1netregistry.com/Bose2.pdf
https://www.corvetteforum.com/techti...D=91&TopicID=2
https://www.corvetteforum.com/techti...D=58&TopicID=2
You can find more info using Bose or schematics as key words to search in the Forum but this I think is some of the best information. (You will need to look at the links to follow me).
My particular journey started when I had popping in my right rear speaker. I followed the instructions and replaced all 8 capacitors. Analyzed some of the circuitry because I’m a electronic teck turd and returned it to service fixed. Realized that speaker now sounded much better than the one that had no problem (the left rear). So I removed the speaker assembly and repaired the amplifier. Did not have C19 and C25 which are the ones that are a pain to physically install and decided to leave them alone since I felt like they were OK. Reinstalled the unit and had much more base and volume out of the speaker. The point is just because it does not pop, squeak or squeal does not mean that it is working properly after 12 years.
For those are interested, C31 gave me the pop and C172 will cause the poor sound quality. C7 & C8 will cause a worling squealing sound. Most of these are decoupling capacitors and don’t really carry any signal except C172. Capacitors really have to go bad and change value radically to cause a ill effect (most of the time and depending…..). Actually my C7 & C8 both measured about 47 umfd. Out of the 3 – 10 umfd & 4.7 umfd per board, 6 of the 8 capacitors did not measure anything as read on a capacitance meter (not ohm meter). So these 6 really went south, but I have better sound now.
