Wendell Allen

I just finished installing a new head unit in my Mercedes. Seemed like a simple, clean install.

unit = Pioneer DEH-P2000
other amps = none
speakers = factory, two up front, two in the back
red wire = ignition
black wire = ground
yellow wire = hot all the time (memory)
blue wire = retractable antenna
speaker wire = two for each speaker, one negative, and one positive

Simple, right? But the heat sink, or what ever that cast piece is on the back of the unit really gets hot. So hot I can't even touch it. I'm really concerned. Is this normal? I'm afraid of it melting something back there.

The only thing I can think of that might be the cause, and I'm no audio expert, is the wiring to the speakers, or the speakers themselves. In this car, there was no balance adjustment on the factory unit. Only fade. So what I did was take the negative wires for both left speakers, and hook them to the left hand input on the car. Don't know if it was a positive or negative input, as I don't have a schematic. Didn't think it mattered as long as I hooked both sides up the same to avoid phase cancellation. I did the same for the positive on the left, and repeated that whole process for the right side. If I hooked the polarity on the speakers up backwards, would that cause it?

Also, I failed to verify the resistance of the speakers. Could that cause it?

Or am I getting alarmed for nothing? Please advise, as I'd like to know if I need to carry along a fire extinguisher!


:eek: :eek: :eek: :eek: :eek:

99HT

Never ever connect any of your speaker plus or minus outputs to each other or to anything but a speaker unless you know what you are doing. ALL decks that are more than 4 watts per channel use balanced or bridged power amplifiers. A balanced output consists of two seperate power amps per channel, each driven 180 degrees out of phase from each other. For example if you connect the minus output of one channel to ground, you will probably damage that minus amp. If you connect any minus OR plus output to any other minus OR plus output, you may blow both amps.

Wendell Allen

So by hooking up the positives from both of the right channels (front and rear), and tying them into the one speaker lead from the car (and doing the same with with the negatives), that could blow the amp?

My intent is to leave the factory speaker system alone for now. So the assumption is that I need to leave either the front's or the rear's from the head unit out of the equation completely to do that. This brings up the question, assuming my train of thought is correct, is the "information" from the head unit to the fronts and rears on each respective side the same? So the electrical signal to the right front is the same as that sent to the right rear, etc?

I'm trying to decide whether I should hook up the fronts only, or the rears only, or whether or not it matters as long as I do the same for both sides.

And just to verify, this is the way to go, given my goal of using the existing speaker system, and won't blow anything up? Or is this not the right way to go?

Thanks so much!

JoeyG

Connecting both rear speakers or front speakers in parrallel to one side of the output of the radio Will cause damage to the amplifier section. By the unbalanced load given to the amplifier. If possible trace each speaker wire to it's location. Then knowing the speaker location connect that speaker to it's respective output on the radio. When in doubt try a local stereo shop that has a certified mobile audio tech. Good luck

Wendell Allen

:crazy: :crazy: :crazy: :crazy: :crazy: :crazy:

What a pain. Seems my simple install is turning out to be a not so simple install.

I have the factory schematic for it. Looks like they ran one wire from the radio directly to both speakers on one side, "Y"ing it at a point somewhere unspecified in the middle. And the other wire for that side runs from the radio to a fader on the center console. For that channel, a seperate wire then goes to each of the speakers.

And I'm tellin' ya fellas, the front speakers are a gritch to get at. To get at the left front for example, I have to remove the entire instrument cluster! And running the individual wires to the back is another matter all together.

Oh well, if that's what I gotta do, I'll do it.

Thanks for your help in preventing me from burning up a perfectly good stereo. I owe ya, but I don't know the first thing about audio obviously. I'd send a check, but I'm unemployed (the stereo was given to me)!