need to wire subs to 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=40852
Printed Date: July 07, 2025 at 5:24 PM

Topic: need to wire subs to amp

Posted By: enwycee
Subject: need to wire subs to amp
Date Posted: October 14, 2004 at 12:20 AM

I need a way to wire my subs to my amp correctly. I have a Mtx Audio Thunder 2150X Amp. It is a two channel amp. The specs on it:

RMS Power measured at 12.5 Volts DC:
75 Watts x 2 into a 4 Ohm load with less than 0.05% THD+N
150 Watts x 2 into a 2 Ohm load with less than 0.1% THD+N
300 Watts bridged into a 4 Ohm load with less than 0.1% THD+N

Dynamic Power (IHF-202 Std) measured at 14.4 Volts DC
120 Watts x 2 into a 4 Ohm load
212 Watts x 2 into a 2 Ohm load
425 Watts bridged into a 4 Ohm load

I am wiring it to a Mtx Audio Thunder 5000 sub box, it has 3 10" subs in it.In the back of the sub box it has a black + and a red -, and on the amp it has terminals R , + and - ; and L + and -. Everytime I try to wire it the amp gets hot which I know is not good. What is the best way to wire it up and get the best power out of it? Also there are 4 terminals on the amp for hi-level speakers. what is that for wiring to? Any help would be appreciated.

Replies:

Posted By: stevdart
Date Posted: October 14, 2004 at 1:07 AM

I looked the subs up at the mTx site and saw that the 10" woofers were made in either single 4 ohm, 8 ohm and 12 ohm. Hope yours are the 12 ohm models. You need to pull the subs from the enclosure and check resistance across the terminals...find out what ohm resistance each of them are. The site shows that the DC ressistance of each is 9.02 ohms. Three 12's wired correctly, like shown, will give you a 4 ohm load, which is what your amp will work with.

posted_image

The other two possibilities, the 4's or the 8's, will not work for you, because three of those are wired to lower ohm loads.

You won't be using the high-level speaker inputs. Those are for use when you cannot use RCA's from the head unit. For wiring to your sub box, the amp should show a diagram for bridging. Neg should go to left neg on the amp...pos goes to right pos on the amp. If you have a total 4 ohm load with those three woofers, the amp should make a total of 300 watts, or 100 to each woofer.

Look at the wiring to each speaker, too. If you picked up that box/woofer combo used, you don't really know what you got. In fact, be sure those subs are actually MTX.

https://www.mtxaudio.com/caraudio/archive/thunderSub51012.cfm

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Posted By: 94legend
Date Posted: October 14, 2004 at 3:55 PM

Hey Stevdart, I can see that you are using the sounddomain Wirig Options as an example. Just wanted to say good lookin. LOL you biter. find your own source! lol j/k!

Posted By: stevdart
Date Posted: October 14, 2004 at 4:04 PM

Yeah, 94legend...I'm not above stealing something from you if I like it! lol

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Posted By: enwycee
Date Posted: October 14, 2004 at 4:46 PM

Thanks for the info, Stevdart. I am a fool to not have checked under my amp to see it shows where to hookup the wires. I hooked it up easily and it sounds great. By the way, the subs are MTX audio, i guess the guy just bought the 3 subs seperate and put em in a box. The amp gets a little warm, but not burning hot, like before. I guess thats just with use. Now my problem is how to keep the thing from moving in my trunk. thanks again.