I have a idea for the factory Radio woes, I need advise from radio experts

[ReggieD]

I reviewed the schematic and wiring diagram. I am wondering if this idea will work. The vette has 4 speakers.
Each speaker has its own amp. The amps are powered thru a power relay. Each amp takes a pre-amp input.

Purchase a nice sounding AM/FM CD Player with RCA outputs (same as pre-amp output). Connect the RCA inputs into a passive equalizer that has a four channel output. Make sure the equalizer output levels are pre-amp levels. Let the equalizer drive the four factory ampified speakers. Connect the amps power relay to the antenna power output lead that comes from the radio. That same lead should also power the equalizer.

THe radio opening on the dash is pretty big. The opening should be able to accomodate a CD player and an equalizer.

Can this idea work or is there something special about trying to use the ampified speaker with an aftermarket radio?

I need input from the radio specialist on this forum;worship

 

[Ken Anderson]

None of the stock components will corrrectly interface with an aftermarket system. I assume you are discussing a 90-96 car.. What's wrong with repairing the stock system?

 

[Magmotor]

The Impedence needs to be matched thru out the entire system which I doubt it will. Also you shouldn't connect another component to the radio antenna pwr wire. Your asking for a blown fuse everytime you turn the radio on. Maybe just fix the system you have on it??

 

[ReggieD]

Have any of you tried this or are you just guessing.

As for the antenna power wire, all you need to do is connect that wire to a 10-Amp contact relay and let the relay power everything else. Plus the amount of current that the existing amp relay draws is very minimal; so, in this case, I will not need an extra relay. The 4 separate speaker amps are being powered by one relay which can be controlled by the same wire that triggers the antenna to go up (500mA - 1A max). An antenna draws about 150mA-300mA, the relay that powers the amps draw about 100mA-250mA. How do I know this? I already measured both of them in my vette by using a multimeter. If you look at the vette wiring diagram both the power antenna and speaker amp relay are all being power by one wire from the vette radio control box,

My wife owns a 1993 525i BMW. Her radio went out two years ago. I purchased the schematic for her car. Her sound system is similar to the vette where each speaker has its own amp. Also the amps are powered by a relay. I did the same steps as stated earlier and it has been two years and it still sounds very good. I installed a Kenwood tape player with CD changer in trunk using her existing amplified speaker. Her factory antenna is separated into 5 different types of antennas in her rear window. The antennas are all coupled together and powered thru an antenna multiplexer amp. All of it is powered thru the Kenwood's antenna power out wire. (The antenna amp and all four speaker amps)

I am looking for someone who has tried this with their vettes. The BMW people told me, it could not be done with her car, but as you can see they were wrong. I asking here in the forum because I know someone had to have tried this with their car.

My CD player is working fine now but I noticed that the clear sound quality is not there. My car is a 1992 so this CD player is from the old design. The laser is old technology. I want the new clearer sound with a clock display while the CD is playing.
Are you completely sure that the impedance matching is a problem or are you guessing base on theory? I find this hard to believe because the signal to an amp should have a high impedance. The output from a radio with RCA jack is a high impedance. What is mismatched?

My current speakers sound great but the CD player is not so great. I am looking for input to this task. I am going to try it and if it works I will put out the wiring instructions plus model number of radio/CD player. Plus pictures.

My reason for this task is there has to be a cheap way to upgrade your sound system with a great sounding system.

Car electronics is my hobby since I was 16 years old. Now I am 40.

 

[Ken Anderson]

Obviously you want to be different and must have a Kenwood. First the CD deck is replaceable in your Bose system for around $250 and it will work just like the Kenwood, because a deck is a deck is a deck. Second the BOSE speakers have only 1 ohm impedence, so make sure you get the righr amps if you going to use them. Finally, I would suggest you purhase a set of factory shop manuals for $125- they'll give you everything you want to know for this and future projects.

 

[ReggieD]

$250 where?

I read that I will spend around $500 plus to replace my head unit. I also read threads that if I get my CD head unit replaced or repaired that the system will go out again. I read though many threads and I noticed that no one had anything very positive to say about the CD factory systems in the 92 vette. Why spend over $500 dollars and the system still has problems two years later? I believe the laser is exposed to dust fairly easy.
I do have the GM factory service manual for 1992 Corvette, very thick book. This is how I got the idea to change just the head unit.

Your comment "BOSE speakers have only 1 ohm of impedance". My plans are not to connect to the Bose speakers directly. I am going to drive the factory amp that drives the speaker. I am sure that the speakers should have lower impedance because they sound so good. The amps that drive them should have a preamp input which has a high impedance input.

$250 for a head unit sounds very good to me. Do you have more information about this system? As for Kenwood, the one I placed in my wife’s car I found from a friend upgrading his system. I have no preference but to have a great sounding system for around $300 dollars that should last a great while. If I change my entire system, (head unit, amps, speakers, rewiring, etc) I would spend over $1000. If I can get a better head unit with a clock that displays while a CD is playing for $250 then I am in.
You have my attention. $250 is the magic number. Where do I go?
:BOW

 

[Magmotor]

Car electronics is my hobby since I was 16 years old. Now I am 40.

I've had a degree in electronics since college. Now I'm 54. Impedence must match or one unit will eventually burn out due to high current draw.

 

[ReggieD]

I agree

Impedance matching is a concern but I am pretty sure that the reason corvette split up the different module that make up the sound system was mainly due to space limitation. I reviewed the service manual block diagram and schematics. The existing speaker amps are perfectly matched to the speakers at which they drive. The radio control module is nothing more than a preamp driving the speaker amps. In mostly all cases the input to the speaker amp are high impedance. The output of an aftermarket radio with RCA jacks are designed to drive a high impedance input (The RCA jack portion only).
Ken Anderson mentioned that the speaker impedance is around 1 ohm. Yes this will damage a radio/amp that usually drives a speaker at (2 ohm -subwoofer, or 4 to 8 ohms woofer/mid-range speakers, or in some cases 10 to 20 ohms for tweeters/GMAC factory speaker/Ford factory speaker, etc). Higher impedance devices will not damage an amp or radio.

I am planning to install an aftermarket CD/Tape/radio that has a low signal, high impedance output to drive the existing Bose speaker amplifiers. The existing speaker amplifiers will continue to drive the existing speakers. The only problem I can foresee is if mismatches occur between the radio to amp I will only have a power problem, meaning less power. Less power will not damage anything; it will only lead to less volume on the bass end. I can compensate for this by turn up volume control. If I turn the volume control to high I will then introduce more distortion. So yes you are right about matching the impedance. Maybe someone can give me the input parameters for the Bose amp. This information is very hard to obtain. This is really what I am looking, the parameters. The service manual will not give up Bose’s specs.

I love chatting with EEs. This is how I check myself. I am not an EE thru school but I know my stuff. I have been in R&D for 24 year and I know my stuff. My wife is an EE.
I am just trying to save money. Bose is a nice system. I have other thing to fix on my car. I can't afford to spend $1000 dollar on just the sound system.

CD players are designed much better now days. My car has a 1992 CD player. This is the old stuff. The laser is not state of the art. Look at all the problems people are having with their CD players. If this works I will put the entire process on the forum with pictures. Maybe this can help someone who can’t afford upgrading their system but has an old radio lying around the garage.

 

[Ken Anderson]

$250 in Suwanee, GA @770-932-0867. Much better CD decks, yes, but the stock system has a life of about 10 years-give or take the number of potholes hit. And, it came with a 3 year waranty-which no aftermarket system has. I appauld your creativity for using stuff laying around to fix up your car, but the question is will it work?
My point is that it won't, unless you know exactly what you're doing. For instance, most stereo shops cannot successfully add aftermarket accesssories to a C-5 and I can assure you you will not replace your C-6 radio and still be able to drive your car. These cars are more complicated than the cars of the 70's, both mechanically and electrically. The days of "plug & play' are limited, and the only way to drive the Bose amps is with a Bose matched radio receiver. A miswired Bose amp has burned up many a car.

 

[Magmotor]

"The only problem I can foresee is if mismatches occur between the radio to amp I will only have a power problem, meaning less power. Less power will not damage anything; it will only lead to less volume on the bass end. "

This is not correct. You will have a "Signal" loss, not power. The greater the mismatch the more loss of signal or noies will occur. If a mismatch occurs you will never get a clear sound. If the internal structure of a component is known, its impedance can be computed using the same laws that are used for resistances: the total impedance of subcomponents connected in series is the sum of the subcomponents' impedances; the reciprocal of the total impedance of subcomponents connected in parallel is the sum of the reciprocals of the subcomponents' impedances. These simple rules are the main reason for using the formalism of complex numbers. There are many formulas to figure out Impedance. If your wife is an EE I would think she has the books or knowledge to help you out with this.

I gues the bottom line is go ahead a dive in. That's what R&D is all about. Should be fun anyway to find out what happens. Let us know if ya get to rocken & rollen down the hyw while listening to your new system....

 

[jsinga]

I replaced the radio in my 87 with an Apine unit.
The older cars have a common grounded speaker system and I re-wired the plug at the back of the radio.
As for the speaker and amps, mine measured about 1.8ohms as I remember. Since I was convinced there were problems in some of the amps I cut the wires to the amps and spliced the output of the reciever directly to the speakers.
Even with the low speaker impedence I haven't taken out the reciever amp yet, in almost a year.
I got a reciever that plays MP3's so I don't swap disks any more.

Issues I know of:
Amost all radios are DIN size
Climate control display dimmer on early cars is controled in the radio
you still will have old speakers

js

 

[ReggieD]

Thank you for answering my question

Issues I know of:
Amost all radios are DIN size
Climate control display dimmer on early cars is controled in the radio
you still will have old speakers

I am looking for vette owners who have actually tried similar things to what I am trying to do. My existing amplified speaker appears to be OK at this time. The CD player is skipping more each day. Some of the better radio/amps of today can easily drive the lower impedance speakers so that was a good idea of yours to just removes the amp and drive them directly.
I will use an after-market radio kit to get around the mounting issues. I will look further into the climate control issue to make sure I have no problems. If so, I will look for a way around it and post it. The older speakers may still be a problem but I will fix that once they go out.
My reason for keeping the existing amplified speaker is because they sound so good. The amps are tune to work perfectly with the speakers and the acoustics of the car. Thanks for your help and let me know if you think of something else. I will post my findings once I am complete.

 

[Gorgon]

Reggie, this is a great thread. But to help with one thing you are looking for, press the volume knob in a couple times. It will cycle between track number, track time and clock. I hit the button a couple times to get the clock reading.

Good luck with the change.

Leon

 

[ReggieD]

Rough-schematic before job begins, What do you think?

DO NOT TRY THIS UNLESS YOU HAVE SOME UNDERSTANDING ON CAR ELECTRONICS AND INSTALLATION OF CAR AUDIO EQUIPMENT.

Give me a chance to first detail the entire process. The schematic enclosed is for me to received input from other experts to fine tune my process for safe installation for others. Keep in touch and maybe this can be my way to give back to Corvette Action Center "CAC" for this forum has been very good to me

 

[69MyWay]

Reggie,

Crutchfield sells a little gadget for about $100 that will adjust the input/output of an aftermarket stereo to match the needs of the bose. So, you can install anything you want, and still run the stock amps/speakers.

If I may though...I have had experience with these, and have found it best to remove ALL of it if you are after more powerful, dynamic, and clear sound.

The weak link in the stock systems is the whole system! We have blown speakers, amps, head units, and the crazy little module under the passenger dash that is actually the brains behind the head unit that you see, touch, and feel. The stock system is great for people that like to hear something better than what they hear in their stock pick up truck, passenger car, etc, but it just does not hold a candle to what you can do with some extra time and parts.

 

[Eagle85C4]

Welcome to the CAC family...

Got some nice toys on the web site Reggie. I see from one of the license plates that you are a traveling man...been to the East?
I am having fun reading this thread and am looking forward to seeing the results of your labors. Good Luck...

 

[ReggieD]

Crutchfield is more proof that this might can be done

I am slowly purchasing the stuff to pull off this task. So bear with me because this is going to take some time.
I went to www.Crutchfield.com only to find more proof that my idea might work.
Crutchfield has a built-in search engine that locates the items you can install in your car. I entered 1992 - Chevy - Corvette - Coup - With bose system. The search engine located all of the radio/CD/tape players for my car which works with the Bose system. Each radio listed had a similiar feature. THe feature was a 4-volt "three/four pre-amp" output. The same outputs that I have mentioned several times that I think will work.

I am getting hustle money together to purchase one of these systems...stay posted also send me more ideas.

Plus, I want to say thank you to Gordon. I had recently complained about not having the time displayed when the CD is playing in my car. He wrote me about my secret button on the corvette radio. "Press the volume control button" boy I feel like an idoit. :Silly
Good news...I can now see the what time it is while listening to a CD.
:dance

 

[Gorgon]

No problem Reggie. I had the same complaint when I first got the car. Not sure how I discovered this feature, but I'm glad I did.

Leon

 

[Skant]

I hate to break it to you, but it's not going to work. If it was that easy, a lot of folks would be doing it. You're not the first to have that idea.

To do what you're talking about, you need to buy the above mentioned adapter. It's somewhat expensive and the sound quality is said to be somewhat poor. If you hook it up without the adapter, it won't work right. You'll just hear a very very low volume sound. And even if that weren't the case, the spectrum response for the bose speakers are also weird. Which is another reason they have to be matched with the special output from the head unit.

They're designed specifically to not be compatible with standard systems in any way.

The Crutchfield listing you see exists because not all vettes have the Bose Gold system. What you see is a replacement for the non-premium stereo, if your car were so equiped. But it's not. So that listing is not for you.

I've gone through all of this already. I saw the Crutchfield listing. I called them up and talked about it. I researched it all.

It just doesn't work.

Trust me on this, okay? You're gonna frustrate yourself and waste money.

Either stay with the stock system completely or replace the whole system with aftermarket. These are the only real choices. Any thing else either works poorly or doesn't work at all.

Here are the pros and cons of either way...

Stock system
- It's the original equipment for matching numbers folks
- It's smaller than an equivalent aftermarket setup (because it produces subwoofer like bass without a subwoofer)
- It has serious reliability issues
- It's sound quality is not up to modern standards
- No modern abilities like mp3 play, multi-disk, etc

Aftermarket system
- Expensive special installation in a vette (requires extensive rewiring and alteration)
- Subwoofer (if you want one) will eat some cargo capacity
- Sound quality is far better than stock system
- Modern abilities (mp3, multi-disk, anti-shock buffers, satellite radio, etc)
- Once the car is converted, upgrading/replacing again later is easy.
- Standard radio installation will leave you a little cubby hole to put things in (the vette radio aperatiure is only a little more than 1 and a half radios tall. The extra space is used for a cubby hole)


Kenwood makes a direct replacement for the head unit. I don't really see the point in that. It won't give you quality aftermarket sound, nor will it cure the reliability problems (the individual amps will still die). I think it's just a cheapo replacement for the stock head unit if you don't want to spend the bucks for a real one when it dies.

So I hope this information helps. I hate to rain on your parade. But like I said, I've already been through it. And I'm just hoping to spare you the effort and frustration.

- Skant

 

[ReggieD]

Skant

I trust you because you actually tried this before. Your points make sense to me. I will probably now just replace the entire system. I was looking for someone who may have tried this and you are that person. Thanks for stepping in before I jumped into the money pit. Others hinted the same message but you actually tried it before.

Thanks again....I guess I must spend the big money and replace the entire system.

THE FAT LADY SINGS......