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is oem head to amp spkr or preamp level?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=100748
Printed Date: May 10, 2024 at 4:05 PM


Topic: is oem head to amp spkr or preamp level?

Posted By: sum1snzeros
Subject: is oem head to amp spkr or preamp level?
Date Posted: January 04, 2008 at 2:15 PM

I have 07 Pacifica.

Can someone tell me is the signal from the OEM head unit to the OEM Infinity amp speaker or preamp level?
I would like to put in a preamp EQ (AudioControl EQL) if possible.

Or does someone have an easy way to determine such?

Thanks for any input!



Replies:

Posted By: KarTuneMan
Date Posted: January 06, 2008 at 1:40 PM
+12V DC Battery(Constant)RED / orange Pin 1 50 15 amp Power module in left front of engine compartment 
Switched AccessoryPink/orange Pin 2 25 15 amp Power module in left front of engine compartment 
Ground BLACK/ lt.green Pin 11 
Power Antenna Grey/orange Pin 13 
Remote Turn On(output) Dk.GREEN/ grey Pin 5 to pin 11 of DVD/CD changer; see notes for mp3 feature. 
Illumination ORANGE / grey Pin 3 
Dimmer ORANGE / tan Pin C2-9 
Steering Wheel Control Wire Gray/orange and gray/white  
Left Front + Dk.green Pin 10, line level to amplifier 
Left Front - Dk.GREEN/ brown Pin 9, line level to amplifier 
Right Front + Gray Pin 7, line level to amplifier 
Right Front - Gray/brown Pin 8, line level to amplifier 


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Posted By: sum1snzeros
Date Posted: January 07, 2008 at 10:17 AM
KarTuneMan, do you (?or anyone?) see any problems in taping into the OEM line levels to the amp with a preamp eq like an AudioControl EQL?

Thanks.




Posted By: tedmond
Date Posted: January 07, 2008 at 3:48 PM
doesnt not really matter where you tap your signals into. YOu can even do it from the speakers from the back if you would like. The thing is, sometimes tapping it off an amp, the hi to low converter cannot take the power rating of some stock decks. I have seen cases of people using rear speakers as an option to wire up a Hi - Lo for RCA output and ended up toasting the low output converter, unless you have a good output converter you should be good.




Posted By: sum1snzeros
Date Posted: January 07, 2008 at 4:02 PM
tedmond,

You may be misunderstanding what I am trying to accomplish. I want to intercept and EQ the audio signal after the OEM-head but before the OEM-amp at preamp levels. The AudioControl EQL only supports preamp not high-level(speaker level) input/output.




Posted By: tedmond
Date Posted: January 07, 2008 at 6:34 PM
getting a speaker leve input changing it to an RCA connection (PRE AMP)is done by using a Hi to Low output converter as i mentioned above. You can tap into any place and it wont be a problem




Posted By: speakermakers
Date Posted: January 07, 2008 at 11:40 PM
The last time I worked on one of these vehicles I found a few things that might be of interest to you. I was able to dissect and analyze one of these vehicles with an NTI acoustilyzer.
The infinity stereo in the vehicle that I worked on had a center channel that produced a signal that was derived from a combination of the left and right signal, Band passed, and equalized. This heavily modified signal also had shifted phase characteristics. The problem that I encountered was that the band width allocated to the center channel was missing from the signal being sent to the front door speakers. In other words there was no usable signal present in the front speakers.
The rear speakers however received full spectrum signal. This is where I taped my signal form to go to the EQX that I installed.
The vehicle also had a factory head unit that utilized a 2 channel balanced 16V non variable volume signal to transmit to the factory amp. All tone controls, balance, fader, and volume adjustments are done with a DSP unit built into the factory amp. The EQL cannot integrate with this type of arrangement. At least not at this point in the signal path. You will need to intercept the signal after the factory amp at its rear outputs. The EQL that you have is equipped with speaker level inputs that are far far superior to any HI-low converter that is made.
You will however have to add an aftermarket amp.




Posted By: sum1snzeros
Date Posted: January 08, 2008 at 10:48 AM
WOW speakermakers, Thanks for the input. That is !exactly! the info I was hoping for. So basically no-go on the EQL at least without the addition of more hardware.

That brings up another question then. I am planning to install a small after market amp/sub-woofer by tapping the front speaker signal into the after market amps built-in speaker level inputs. Are you suggesting that I should not tap into the front speaker signal and should opt for the rear signal? I personally do not wish to use the rears as I usually fade the rears down to open up the sound stage dramatically.

And a last question. What area of the Pacifica do the speaker wires run from the rear amp? Passenger side or center under the console? I am mounting the amp under the passenger seat and I want to know where to start looking for the best place to tap.

Again a BIG THANKS for the info!




Posted By: speakermakers
Date Posted: January 08, 2008 at 9:20 PM
Honestly I don’t remember. I work on over a thousand cars a year and this was about 2 years ago. After a while they all look the same. I only remember the signal processing setup in such detail because it was so far from the norm. When I tackle a vehicle I always like to have as much information about that vehicle as possible before I dive in. I usually call my local car dealership and get the diagrams of the amplifiers location. This usually includes a diagram that shows the entire audio harness and its routing in the car. This is usually free. If you have a hard time with the service dept. at the dealer there is another option. WWW.ALLDATA.COM is a pay service (20 bucks) that will supply you with the entire shop manual on line. This is the same information that the dealership has including all wiring diagrams and pinouts, disassembly instructions, the whole thing! Armed with that information you will save hours of work.
I don’t recommend taping off of the harness that goes from the B pillar to the rear door. It is to far from the source (amplifier) and will be a noisy signal. And that brings up a good point. You will need to either mount the EQL physically close to the factory amp (2 feet or less) or run a shielded signal cable that has its shield grounded to the factory amps chassis and not connected to any ground on the EQL end. This is not the type of cable that you will find at a car audio shop though (unless you chop up a good set of RCAs). I get mine from an electronic surplus store that we have in town. USB cable or something similar works well. It has three thin twisted conductors (red, black, white, use only two) and a braided shield. These are all characteristics that you want in a good signal cable. If you have more questions about that I will be happy to answer them.




Posted By: sum1snzeros
Date Posted: January 09, 2008 at 9:24 AM
speakermakers I really appreciate your assistance!

If I am not able to tap into the preamp signal between the OEM head and amp I am abandoning the EQL.

But I am still going to install an additional amp (Alpine MRP-M350 a class-D sub woofer amp) to drive a sub (JBL GTO804) that will be installed in a custom box located in what would have been the factory sub location.

Does www.alldata.com 's data include panel disassembly? If available I would like to get my hands on step-by-step instructions on disassembly and access to the factory sub location. I want to avoid breaking as many clips/fasteners as possible from disassembly experimentation if you know what I mean. :-)




Posted By: speakermakers
Date Posted: January 09, 2008 at 9:59 PM
Yes the information that you get from alldata is the exact information that the dealerships get. It has very specific instructions on how to remove any and all parts of the vehicle. It will even tell you how long it should take!




Posted By: sum1snzeros
Date Posted: January 10, 2008 at 2:15 PM
Again thanks for all your input speakermakers!





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