hey all.  After a shitty day at work i hop into my truck and turn in the music, the only problem is with low volume the bass is nonexistant and with loader volumes it pops and just sounds like crap.  I hooked up a dvd player to the system to test it and it sounded the same.  It did fade from not to bad to worse and it is getting worse.  As of now i just have the sub disconnected from the radio cause it sounds like utter crap...  my question is does this sound like a problem with the amp (400W bridged MTX Amplifier) hooked to two 12" MTX subs (can't recall the specs on the subs) or the subs?

There are several things that might be wrong. The gains on the amp may not be set right. The amp may not have enough power to power the 2 subs. The subs may be wired to an impedance that the amp can't handle. The amp may be blown. The subs may be blown. The signal from the head unit to the amp may be bad. It could really be anything without having more information. Have they ever worked? Have they ever sounded good?

Stuff like this is usually a combination of crappy/worn speakers, poor input, and a cheap amp with no shielding abd poor tuning.

Disconnect the amp entirely and get the base system working propperly.  O'd replace all the components...whatever headunit you have is probably fine if it's an aftermarket piece (oem pieces usually don't have the tuning abillity suited for quality music)...if still stock get a decent pioneer or alpine piece.  Get one with audio ports to hook directly to your amp (standard issue any more).  Replace all your components to match the headunit's peak music power (RMS...NOT "max output").  AFter you get that done you need to tweak the headunit's settings until the speakers all sound good at all volumes.  Then comes time to setup your subs.

12" subs are too big for broad use...waaaayyyyyyy too big.  So what you'll want to do is tune your amplifier at whatever volume you prefer and setup a disconnect for other volumes.

I prefer not to use a large sub...I use a pioneer headunit and Harmon Kardon full range components...best sound ever and only ran $790.

well just got back from looking at the unit.  the amp is a mtx thunder 8302 and the woofers are mtx thunder 6000s  I can't see right now if they are the 8 or the 4 ohm model but i will look at that tomorrow.  They were working great untill a couple days ago when the quality of the output started to fade.  I have completely rewired the unit and tested it with an outside source for audio and they still sound like crap.  They are wired in the box in parallel and that is why they are run with a bridged connection.  Also the wires and connecting buits are all top quality gold plated rca cables and high grade speaker cable (10 gauge) if i had to guess ant the diameter.  so i think i am stuck with either a bad amp or subs but since they faded out over a couple days i am thinking it might be the amp.  Still open for suggestions or ways to test wither the subs or the amp.

test the speakers independant of the amp.  It's far more likely for them to blow than the amp it's self.

I have 2 kicker 12 inch L5's with a 1200 watt amp.  We blew 6 amps and 2 subs.  Yay for warranty, got it all fixed for free.  Cost 1600 though to get it put all in though    I didnt install it so I dont know why we were going through stuff that fast but the place that installed it got it all fixed though for us.  I dont have any input other than that I wanted to tell everyone of my big waste of money and brag a little.  Oh ya and my engines RPMS drop about 250 rpm every time they would "hit".

ok sp here are the details, the subs are 8 ohms wired in parallel so 4 ohm load together and 250 W RMS so in theory 500 W RMS in parallel.  The amp is bridged and pushes 425 W at 4 ohms.  my question is since the amp is acutally underpowering the subs would that make the amp more prone to go before the subs or does it matter.

I wouldn't brag about blowing subs/amps.. it means something's not wired right, or you're pumping way too much distortion through the system. Also.. if you're running that much power, for G-d's sake, get a Cap!

I notice that it's all Texas people replying to this post.

If they sounded good before, then it sounds like something is definitely broken/breaking. If the sound is slowly fading, I think it's the amp. Do you remember smelling burnt electronics recently?

In my experience, when subs break, you won't get anymore sound out of them. You can do a simple check on the subs. Take a multimeter and test the resistance to make sure it is actually 4 ohms.

I don't pump the juice thru them, i just use them as a bass souce cause the speakers in my truck are bass deficiant .  I didn't smell any burnt electronics but i will run the test on the subs iwth the meter that we have at work to see if it is actually 4 ohms still.  And i know they are wired right, they have worked fine in two vehicles for about three years, and i read the destructions cause i didn't want to blow 500 bucks and not get anything.  i will check the resistance tomorrow and get back, untill then i am one pissed off guy with no bass ........

You could be suffering from "cone drag" which I seriously doubt. It appears from your description that the "finals" (transistors) in the amp have gone South. The "finals" in the amp would be my first guess and cone drag (speakers) last. Also it could be pre-drivers but.............that still leads back to the amp. Hope this helps, OMW

thanks everyone.  I am going to test the woofers first thing tomorrow and i will post up what i find.

Quote from: NiceGuysFinishLast on November 15, 2006, 06:00:22 PM
I wouldn't brag about blowing subs/amps.. it means something's not wired right, or you're pumping way too much distortion through the system. Also.. if you're running that much power, for G-d's sake, get a Cap!

Well I didnt install it, got it done by the place I bought it from.  I think they must wire stuff in wrong or have something wrong because in my brothers old car he had an amp catch fire when it was in his trunk, he had it open though so he saw it catch so he could put it out.  In our other car though the trunk was so small that the amp sat right in the window and got baked from the sun and sometimes wouldnt work on real hot days and I suppose that it would over heat way easier when playing it.  But they hooked a fan up to it though to cool the amp and it works good now.    I know I know, bragging about breaking stuff, oh well, thats what I do!

MORON ALERT::: Locked keys in truck so can't test subs till i aquire another key from nissan, manage to get a freaking coat hanger to work, or break a window.  I hate my half sick self....

Quote from: natedawg120 on November 16, 2006, 07:50:27 AM
MORON ALERT::: Locked keys in truck so can't test subs till i aquire another key from nissan, manage to get a freaking coat hanger to work, or break a window.  I hate my half sick self....

For locked doors I carry a slim jim.  They sell them at my local dollar store.  Maybe check in your area?

yeah they don't have them in the stores around here.  I used to have one but don't know where it went in the last 8 moves.  i might try the old coat hanger trick but i don't think so.  As for now i am hoping that the Nissan dealer can make me a key from the VIN, but the web site that they have to look that crap up on was down when i went there.  So know i am just hoping...

ok i gave up on nissan and broke in.  Tested the woofers at the connection on the box and got 220 ohms resistance .  Either a wire has wiggled loose inside the box or i have one or two really bad subs.  Amp will be tested later to ensure it is still good.  we'll see how the volt meter bounces to some low volume bass.  more later....

WOO HOO!!!!!! I can defen myself again.  The amp tested fine it was putting out the vlotage with the beat of the music.  Removed subs and box and retested for resistance and got something between no connection and 180 ohms.  Took them in and took the plate off the back and low and behold the hot connection in the back of theh box had jiggled loose and was laying making a very loose connection and none at times.  tested the resistance there and got the correct reading of 4 ohms.  Reconnected and soldered them babies in, reinstalled and i am good to go.

Now where in the hell is my beer   

Glad to hear it was an easy fix.