Ok, I have a 1991 Thunderbird, and want to put in a new deck, however someone told me that there is a factory amp that is located somewhere in the car, and that installing a new deck will not work and if it does, it will sounds like crap..... is this true?
If true, and if anyone would have experience with this, where would I find this amp to bypass it, where in the 91 Thunderbird would it be located?
As far as running sound from a new deck into a factory amp is concerned, your friend is right. Often times the signal strength coming from after market decks is more powerful than the stock decks. But there are problems with input impedances, amplifier overhead and stuff like that that I won't get into for the sake of length.
Now as far as the location of the amp, I am not sure. Some common hiding places in other vehicles are up under the dash behind the glove box or the center console. My bet is that a Haynes, Chiltons , or even your owners manual would have this location listed.
But my instinct says that you would be better off running new (better) wire from you new deck to the speakers. This is where you may run into another problem. You will have to make sure the stock speakers can a.) handle the power and b.) are at least 4 ohms in impedance.
Reason for this is that some "premium" factory stereo's that use outboard amplifiers can have speakers with impedances of as low as .5 ohms. This will over draw current from your new deck rendering it useless.
So I would look into that as well and replace those stock speakers if the impedance is too low. Might want to anyway since they are stock and not meant to handle lots of power.
two options. you can get an adapter from metra-online or pac-audio dot com to adapt an aftermarket head unit to factory amp and speakers, or replace the factory head unit, and replace the factory speakers, wiring the new speakers directly to the head unit or an aftermarket amplifier, and totally disconnect the factory amp at the wiring harnesses to prevent it from drawing any unneeded current. if I recall on that tbird the amp is in the trunk, under a panel. I forget.. I mostly avoid fords, but in 91 I was working at the shop so I didn't get my choices then.
