oem amp
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=14178
Printed Date: August 16, 2025 at 12:05 PM
Topic: oem amp
Posted By: NiceGuy818
Subject: oem amp
Date Posted: May 29, 2003 at 9:28 PM
Do most of the amps have orignally amplifier? How can you know if the car has it or not? I installed a subwoofer on my mercedes and the sub sounds like crap, why? I connected my RCA adapter to the back speakers is that ok? thanks
Replies:
Posted By: esmith69
Date Posted: May 29, 2003 at 9:50 PM
Umm kinda confused by your post. What kind of amp are you using, did you run the power and signal down opposite sides of the vehicle, did you test for correct polarity when tapping in to the rear speakers..... And what do you mean when you say it "sounds like crap"? Do you mean it's distorted? Not loud enough? Too loud? No bass? ------------- Ethan
-----
"Patience, persistence, and perspiration make an unbeatable combination for success"
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Posted By: NiceGuy818
Date Posted: May 29, 2003 at 10:41 PM
how can i test the polarity? I got a MTX mono amplifier 1500watts, I got the same thing in my honda sounds awesome. The batter of the mercedes is at the back so I connected there and the RCA adapter I connected from the back speakers since I wouldn't find the speaker wires from behind the headunit. When i put it up it give distortion and sound wierd can't really explain.
Posted By: wvsquirrel
Date Posted: May 29, 2003 at 11:37 PM
You can test polarity with a 9v battery. Hook up a wire from the + and - of the battery to what you think is the + and - of a speaker. If the speaker Pops outward (away from the magnet on the back) then the polarity is correct and you have correctly identified the + and - of the speaker. If the speaker Pulls in (towards the magnet on the back of the speaker) then you have the polarity reversed. This is how you can identify which terminal on the speaker is + and - when they are not marked (as most factory speakers are not marked). Now that you know which is + and which is -, do you still have the correct leads going to the + and - of the RCA adapter?
Another question, when you say "RCA adapter", are you referring to a Line Out Converter (LOC) like this one, or did you just splice an RCA plug onto the end of some wires for a homemade adapter? If you did the latter (homemade adapter) then you deffinately need to get a LOC. Even if the car doesn't have a factory amplifier, the headunit is still putting out an amplified signal (High Level signal). If you fed that signal into the RCA Low Level inputs of an aftermarket amp without converting it first, then that would cause a lot of distortion.
Third question, why wouldn't you find the speaker wires from behind the headunit? ------------- Squirrel
"No more Cpt. Kirk chit chat"
If its too loud, then you're too old
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Posted By: NiceGuy818
Date Posted: May 30, 2003 at 9:31 AM
I COULDN'T FIND IT BECAUSE THERE IS ALOT OF WIRES THAT ARE THE SAME COLOR.. I USED A (LOC)..
Posted By: wvsquirrel
Date Posted: May 30, 2003 at 9:08 PM
If the polarity is correct (meaning you wired the + and - to the LOC correctly), then you may have to adjust the gain settings on the LOC. It adjusts the signal to properly match the amp. ------------- Squirrel
"No more Cpt. Kirk chit chat"
If its too loud, then you're too old
Donate to the12volt.com
Posted By: NiceGuy818
Date Posted: May 31, 2003 at 8:31 PM
I checked everything was connected right at this point I'm thinking that since I connected the (LOC) to the back speakers right directly from the speaker, the factory amp may make it sound like this. What do you guys think?
Posted By: tom small
Date Posted: June 03, 2003 at 7:19 PM
Try unpluggling one rca with the system playing and see if there is an increase in bass. You may have the speaker level inputs out of phase on your loc. (the positive and negative may be reversed on one speaker input) Also verify that the subs are playing in phase with eachother. You can take a battery to the sub wires and make sure they both "pop" in the same direction. Does your car have the factory subs in the rear deck, and if so, did you tap the loc there or at the rear speakers? I have also seen factory components in the rear deck - verify you have tapped a woofer as opposed to a tweeter speaker wire. Good Luck!
Posted By: djfearny2
Date Posted: June 03, 2003 at 7:43 PM
what year mb do you have cuase all new style mb;s have factory amps now the back speakers alone are crossed over that is why you are getting crappy sounding outcome,. you have to connect to the front door speakers at the output wires of the amp when adding a after market amp and keeping the factory amp let me know i can help mail me.
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Jon
Installer/Help Technician
---coral springs florida---
mecp certification is not always needed. I have it and it has not helped me out at all. my experience out shines it.
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