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Beating a dead horse.


Well-known member
Jul 25, 2001
2008 Silver Coupe
I have a horse named 'Bose Gold' I keep in a stable called 1990 Coupe.

About a year and a half ago,I had the CD/Cass rebuilt and replaced all four amps and speaker units.With the addition of a Bazooka Bass Tube,it sounded very,very good.:dance

Lately it's requiring more twist on the volume knob to get loud.I pretty sure the amps are dying.:cry

The question(drumroll please)

Will the capaciter repair procedures listed on this site and others bring back the loudness I had when it was freshly renewed?Or am I stuck with the obvious alternative of replacing all amps again?;help

Like I say,it sounds good,but it sounded just short of awesome(believe it or not)a year and a half ago.Those Bass tubes make a helluva difference.:_rock
rdgfx3 said:
Lately it's requiring more twist on the volume knob to get loud.I pretty sure the amps are dying.:cry

I'm not sure exactly how to approch this in a politically correct manner so here goes...
How high of a level do you normally listen to your stereo at?
If your deck was recently rebuilt(within the last few years) the power supply caps should not be drying out, unless you are running the amps at eccesively high levels.
In a past life, I worked for a large manufacturer of car audio components, and currently work with several hearing assitive device manufacturers and here is the catch 22 that I've seen for some in the past.
If the amplifiers are being run at a high enough level to boil the oil in the caps, which would shorten their life, the acoustic output of the system is probably high enough to cause long term hearing loss with repeated use.
I have seen examples of customers coming into install shops every six months to a year claiming that their stereo was not putting out as much as it used to "I have to turn the knob farther to get the same volume as before." In many cases installers will measure the output of the system each time the car was brought in, nad low ans behold the stereo wasn't changing. It was permanent hearing loss to the user.
I'm not saying that this is the case in your situation, but a good rule of thumb is if someone can hear what you are playing with your windows rolled up, its probably too loud.
A good place to check for infomation on sound)noise exposure is the OSHA web site. While these are requirements for employers only, its interesting to apply the formulas to your daily noise exposure in and out of work to see if you are at risk...most people are. Additionally, since only employers must adhere to these standards, manufacturers consitantly produce audio systems that are capable of causing long term loss in nearly all cars, depending on the length of exposure each day.
Sorry for the long reply, hope it may be of some help.

O.K.Let me try this approach.

What took 1/4 turn of the volume knob before now takes 1/2 turn.

A Bose system in one of these cars is not gonna bust an eardrum.
fair enough.

Are you low on level all around or just on individual drivers(sorry I should say speakers in a car forum)?
Are you using the bose amp to power the tube?
Does the tube have its own amp?

If all 4(5) speakers are dropping at eqivalent volume levels its unlikely all of the amps will be failing at the same time at the same rate. That would then point more towards a head unit problem.
Yep,self powered tube.It also has it's own volume control.

I don't know if they are losing volume individually or not.I have just noticed it as an overall loss in loudness but I will check that out.
Is it possible that the SCV (Speed Compensated Volume) Control on your Bose is acting up or not in the position you usually have it? :confused

That can have quite an effect on the relative position of the volume knob for the same apparent loudness.
SVC is O.K. Thanks for the input,though.

No single speaker is noticeably louder than any other,so it is a head unit problem,I presume.:confused
It would seem it's a problem with the Radio Receiver Box under the RH side of the I/P. :(

The Radio Electrical Diagnosis Section states the Radio Control Head sends all the control signals (including volume) on the data line to the Radio Receiver Box which decodes the signal and performs the function selected (I.E. Fade, Volume, Station Select).
"The Radio Receiver Box amplifies the audio signals that are sent to the speakers."

Good Luck, Don't you just love Bose! :hb
As I get older I am finding I need to increase the volume more.
When my passenger blocks their ears I figure its just on my side that the volume is low.;) ;)

Also as my tires accumulate miles the growl beings to appear. I have been using that as my latest excuse.

Even at home my TV doesn't go as loud as it did before. ;)

With all of the channels putting out similar levels it looks as though your problem is either in the "radio receiver box" as steel half shafts stated or your controller is sending out an incorrectly coded signal(highly unlikely). I'm not certain how all of the audio-electronic processing is split up between different components in the car, but it looks like your amplifiers and speakers are still ok.
Welcome to the world of modern OEM car stereo systems.

Just think the automotive manufacturers started splitting up the electronics and using digital bus controlable components to save money on the copper :Silly that was being run from the old fashioned all-in-one head units to the speakers. All of these problems for want of a little copper.:(

I am going to hook an amp and sub to the 90 stereo pretty soon.

Seems like there is no problem taking the stock output to the actual speaker, then running that through the high in input on the amp.

Montanabob has some great advise and also some terrific background in this field. I guess I just want to clarify where you hooked yours up. This particular 90 has been plagued for a long time with a host of noise in the stereo system. It has a new one now where something whines at a high pitch, then kind of winds down in the first minute or so that the car is running. You can only hear it when the stereo is on, and at any volume level. It sounds like a hard disc on a home computer spinning up.

I have not had a chance to call MTX. I need to try that next week as well. In the long/short run I am just hoping to use the parts and pieces I already have to get more kick out of the system. That 10" sub rocks the Metro to my liking. If I can get 3/4 of that in the 90 I would be thrilled.
Whipping that horse for good

One word. Pioneer. Luckilly when I bought mine it already had a pioneer cd player installed. Not only does it thump, it is trouble free (knock wood) and it looks cool with all those flouroscan displays. It even has outputs for subwoofer and a host of other stuff. It isn't stock but who cares, it works great and it fits the dash (1.5din).
noise in high level input

69myway, that is one of the problems with using a high level input to an amplifier, regular speaker wire is not shielded and the run from the bose amp to your new amp can pick up all sorts of noise along the way. Low level input cables are shielded to varying degrees. A couple of possible sources could be automatic antenna, rear defogger, or that pump that starts up a few seconds after you start the car and makes the annoying whirring sound under the hood. And motor power line running near your speaker line could be a culprit, but its hard to tell without actually hearing it.:hb
Does the high frequency noise change in volume when you turn the radio's volume control up and down?
I guess the first stupid question that i forgot to ask is...is the whinning coming out of the speakers?:Silly
Just a thought

You have a Stock deck (rebuilt)
And New(er) amps and speakers


How do you have the Bass tube wired in is it off a speaker wire then to converter for the signal to your Bass tube?

I noticed when I bought my car some guy did some very wierd things with the wires to make to stock system work with add ons tell me about your wiring layout I might be able to help here (Hopefully):TALK
this strange whine does not matter the volume level. It can be overcome with volume, and it is on the passenger side.
I'm assuming that you still have the stock stereo in (without the tube) and are getting this noise(of course i know what assuming can do:)) If that is the case, and you can overcome with volume, it sounds like power supply noise. Check the factory connector on the passenger side for corrosion or loose wires if that is not the problem it could be the power supply capacitors drying out.:(
If it is not the stock set up it could be other things as well.

OEM stereo components are cheap pieces of #$%# regardless of whose name is on them. But if these amp power supplies fail at the rates that it sounds like i'm hearing, the C4 amps are truely pitiful.

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