Decibel Level On Subwoofer Fluctuating

[TeenWolf 10+ year member]

I've had a full aftermarket system system installed in my car for over two years. I have an MTX amp and sub box in the trunk for bass and it worked fine for approx 1.5 years. I'm now experiencing a problem whereby the bass level flucuates for no apparent reason. Sometimes I notice that very little bass is coming from the sub and all I need to do is push on the head unit and the bass comes back to its healthy level. I assumed that there was a RCA problem on the back of the head unit for the output to the trunk amplifier and when I replaced the RCA's, it seemed to solve the problem. Unfortunately, the problem arose again about three months later. I can manipulate the bass level by pushng on the deck. This is really starting to annoy me - Does anyone have any suggestions?

My amp doesn't cut out - just a lowered decibel level which appears to originate with the head unit or RCA's. Also, I have a dual 4 ohm sub that is wired in parallel to draw a 2 ohm load. Unfortunately, my amp (when bridged) is rated for a 4 ohm load. This is something that I only realized recently, but has worked fine for 1.5 years. My amp has never shut down. What problems could this create?

Also, I have 6 X 9 Infinity speakers in the rear and they rattle the crap out of my rear deck. I have sound damping ready to install, but I'm reluctant to believe that this material will solve all my problems. My car is pretty new (2003 Cav) so I'm thinking that I should be able to get distortion free sound.

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[johnecon2001 5,000+ posts]

i'll bet you have a detachable face huh? try cleaning the contacts between the face and the deck. also try checking all the connections behind the hU.

other than that, i would say that either your amp or sub are dying on you.

 

[TeenWolf 10+ year member]

Thanx for the input, but I already thought of that. I originally thought that it was the face plate connector b/c pushing on it would eliminate the problem. I cleaned the connectors several times with no luck. My HU is installed with a dash kit and I can get the bass back by just pushing on the dash kit. I really think the problem is with the RCA's or pre-outs. I took my dash apart and noticed that the RCA's moved when I pushed on the HU or dash kit. And the problem did go away for several months after replacing the RCA cable. I replaced it with Stinger, so expected a product life of more than 3 months!!

 

[TeenWolf 10+ year member]

Here are some of the things that I have tried:

- Replaced RCA cable

- Cleaned face plate connection (both face plate and unit)

- Inspected all wires

- Reinstalled the ground wire to ensure that it was grounded properly

What I think is possibly wrong:

- RCA cable keeps coming loose from preout plug

- Preout on HU is faulty

- AMP is unstable with 2 ohm load

Any suggestions?

 

[TeenWolf 10+ year member]

Tell me about it...Installing my system was a real pain in the ***!! I think they designed the car so people like us wouldn't alter anything, but they were wrong //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I will never buy another Cav again though.

Do you have any idea why my sub level would fluctuate?

 

[RandyJ 10+ year member]

It seems really obvious to me, its a connection close to the head unit that is falty. You have already proven this by pushing on the face plate to alter the sound.

It really is that simple. The hard part is finding out what behind the HU is retarded. I would say something in the RCA path is wrong as JMAC said. Maybe the outs on your HU are bad, dirty or just messed up.

I just re-read yoru post and you pretty much mentioned all of the things I just said, I would recommend having the HU checked by an electronics techie or prof. installer, whoever you think could help you the most. Know anyone in the Navy?? ]

Also, your amp not being stable @ 2ohms would have nothing to do with the HU. That is the one possibility I would rule out.

 

[TeenWolf 10+ year member]

Know anyone in the Navy??

 

[RandyJ 10+ year member]

Know anyone in the Navy??

Why yes I do, do you????

 

[Chevyaudio 5,000+ posts]

I was kinda having the same problem, turned out to be bad preouts, go get them looked at by a tech, or someone, it might be a simple fix.

 

[TeenWolf 10+ year member]

Thanx for the info guys. I will get the pre-outs checked when I get home. Yes, I know lots of people in the Navy including myself!

How easy is it to replace/fix pre-outs? How much could this cost?

 

[Bake 10+ year member]

I would think that you have a bad solder joint in your head unit for the pre outs. Ask one of the ET's on your boat to have a look. They could porbably fix it for you pretty quick.

 

[RandyJ 10+ year member]

Ask one of the ET's on your ship to have a look. They could porbably fix it for you pretty quick.

What I was thinking //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif The land shops have access to an amazing amount of equipment. And if you get someone who knows how to use it, they may be able to troubleshoot for you with some testing.

 

[JoseMCeee 10+ year member]

I kinda had the same problem but my sound on the right hand sound would cut out and I would push on the deck and it would solve the problem. This would only last like a couple of hours be4 it started again. I try push the rcas in as hard as I could but that also didnt solve it. Then I just switched to the Rear RCAs and it has never done it again. Im pretty sure it has to do with the deck pre-outs or the tips of the rcas.

By the way I have the same car as u and HELL YES it is a big fukin pain in the ***...

I cant stand that sht. Especially when your workin on the amps in the back, its hella small and everything always falls in between the seats. bah my next car will be a nice sized SUV for good spl and easy install.

 

[Bake 10+ year member]

Boat,,,,Ship whatever.....Either way it's haze grey. And underway alot if you are stationed on one. Wish you the best in your service. One other thing you might want to think about is those ET's have access to some really nice ocilloscopes. Might find one that can help you do some tweaking.

 

[TeenWolf 10+ year member]

Yeah, makes sense. I like the idea of having an ET taking a look b/c it will be a free service!