Contour Enthusiasts Group Archives Forums Modifications Audio factory amp

Does the factory head unit send pre-amp voltage signlas or speaker level outputs to the factory "premium" amplifier?

The installer claims the factory amp has pre-amp inputs.

The kid who installed my system, even though I said he needed to BYPASS the amp with the MET BYPASS harness when I dropped off the car, used a "line level convertor" harness.

I figured that meant he took the speaker level outputs from my new head unit, and sent them into the factory amp, so I checked with the installer. He admits he did not bypass the amp and will redo the work (the manager chewed his ass out).


I hope the Sony 7050's amp (19W RMS, 50W peak) will be louder (I hope the factory amp is only 10W RMS!!!).

There is no noticable distortion even with the volume maxed out - nice. But, the somewhat low volume makes me wonder if the installer used preamp outputs into the factory amp, but should have used speaker level outputs.

The system sounds great (4 Polk dx7's and a so-so Sony 12" sub with a 140w RMS, 300W peak amp (pretty much all the sub is rated for) in a sealed box. It's just enough bass, which is a little disappointing.

The factory amp is using "speaker level" inputs, NOT "pre-amp" level inputs...


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-Steve
www.sweetsvt.com
SweetSVT99@aol.com

Thanks - I thought so.

That kid was bull****ting me, but I did not fall for it. I think he just plugged in whatever harness he could get to fit.

I'm just not sure then what the line level convertor is for then. Maybe it is due to the fact that after market radios are too powerful to feed into the factory amp?

Maybe that is why my system is loud enough, but not as loud as I thought it would be.

The jerks also did not mount the amp on the sub enclosure (I figure that is wasted space anyhow). He put it on the back side, and had the amp pushed against the seats - it was pretty warm. So they have some rework to do Wednesday morning...

At least he did not bang up the interior at all, which is why I had them do it.

I've heard too many horror stories about REALLY BAD installs. As a matter of fact, before I got my Alping I had Best Buy install my Old JVC CD Deck in my SVT...they screwed it all up! That is the first and last time I will ever have anybody install my equipment for me. Usually the installer is "some high school kid" (I have a lot of room to talk, as I'm only 19) doing the install. They don't have any respect for the person's property, or how they want the install done...


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-Steve
www.sweetsvt.com
SweetSVT99@aol.com

The managers were good. When I dropped off the car, I mentioned to the installation manager that the salesman's harness number (Met 5512) might not be the right one. He made sure they had it and the one I thought they needed (5513) in stock before I left the car, and they did.

He wrote down I wanted the amp on top of the box.

The installer, like I said, used the wrong harness, and installed the amp on th eback of the box so it was against the seat. And they did not give me any manual or warrantee for the amp, but I got them for everything else. Just sloppy work...

The box they used is over 1.2cu ft versus Sony recommends 1.0 +/- 15%. Probably close enough I suppose.


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1999 Contour Sport
V6 5 Speed

ok....i'm a bit confused. so, your head unit's speaker outputs are running through a line level converter to the factory amp's "speaker" inputs? this really doesn't make much sense. but i could have it all wrong. if you're bypassing the amp, you shouldn't need line level converters at all! just run the pre-outs from the head unit to your amp in the trunk. right?

also, since this installer sounds like he was ON CRACK when he did your work....check to make sure they ran the power cables for the amp seperately from the signal line. you'll get a much cleaner signal that way. they should never run parrallel and directly next to to each other for long distances.

lastly, you shouldn't notice that much of a difference with the extra .2 cu ft for the enclosure. the bass will begin to roll-off a little sooner than in a smaller box, but your sub is propably happier with more air. beleive it or not, the air inside a sub box can get pretty hot as you play your system louder. the more air for the sub, the longer it'll take the air to heat up, and (potentially) the longer your sub's coil will stay cool enough to run properly (less distortion).

I checked my receipt for the two harness numbers:

1) Made by Metra
#70-5512 ("Ford Premium Integrator") $26

2) Made by Al (who?) - has two numbers:
Model "FWH1" and serial number "701771" ("Low level adapter") - what the heck is that? $15

I think maybe the low level adapter are the ones I've seen advertised on autotoys.com and/or Crutchfield - they have a box hanging off the wires, which might just be a simple resistor voltage divider. But why would there be two harnesses...ARG! I'll search around the net and see if I can find more info on these harnesses.

I think the low level adapter resides between the head unit and factory amp. It does not make sense as you said since the factory amp's inputs are speaker level inputs (which is why I asked about that in my first msg).
Perhaps the aftermarket head units have more powerful amplifiers than the factory head unit, so the "speaker level" inputs of the factory amp will not handle aftermarket head unit outputs?

The Sony head unit has a small plastic surround, and I was told "keys" are needed to get it out, so I'm not sure if I can get the head unit out to see what he really did...

The Polk dx7's are great for mid and upper range, and sound great with my 12" sealed sub! They do have weak bass (I can not hear any different between the 80hz, 120hz, and no high pass filtering settings of the Sony head unit, so it seems they are weak below 100hz). They are rated for 45hz, but that might be at more than 3dB down as they do not specify.


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1999 Contour Sport
V6 5 Speed

The Metra harness they used is easy to find: http://www.carstereoreveiw.com/Cars/stuff/Ford/contour.htm
and http://www.carstereoreveiw.com/Installation/images/harnesses/70-5512.jpg

shows the Met 5512, which seeems to only plug into the square plug that leads to the external factory amp, and has bare wires on the other end to plug into the aftermarket radio.

The other harness is hard to figure out. I notice "AudioLink" makes a line level convertor (different part number though) to convert from speaker output levels to preamp levels. "Al" on my receipt probably is "AudioLink".

I do not see where they charged me for whichever harness they used to connect to the other plug (the wide one).

I think Met 5514 is what I need - it has the two plugs for the head unit and also the bypass harness.

http://www.tune-town.com/Installation/Harnesses.asp has many harnesses.

Met 5513 is the one for bypassing the amp.
Met 5511 has the two plus the the head unit.
Met 5512 connects to the harness going to the amp only (it is one of the two harnesses in the 5511 kit)
Met 5514 seems to have the 5513 and 5511 harnesses and is the way to go if available.

Am I correct???

about the keys...the installer should have given you these when he sold you the stereo. i would go back and get those. tell him you dropped m&ms back there and need to clean it out. they keys come with the stereo, so you own them.

as for the factory amp / aftermarket amp / head unit / harness fiasco....

i agree; since you have a new head unit and a new amp, i think you need 5514. what that should do is connect the power to the new head unit with one harness, connect the speaker wires to the speaker harness which runs to the amp, and then use the eliminator harness to bypass the amp. a line level converter should not be necessary since you're not feeding any signal to the factory amp, you're bypassing it! right?

then, the line-outs from your head unit should run directly to your line-ins on the sony amp in the trunk. the sony amp should have a dial which can be used to set the sensitivity for the line-in so you get a good match between the amp and the head unit.