grounding question

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bassam_zaman

Member - Posts: 23

Joined: October 02, 2003

Posted: December 01, 2003 at 11:01 AM / IP Logged

what are the effects of improper grounfing? im asking because my mtx 801d is making realllly loud humming noises....like LOUD and whenever i press the window up/down buttons, sh*t gears etc. i hear it amplifiede in the sub ... and when the car is idle u hear it. ALso, when i turn it off(the deck) the amp turns off too (it has the smart engage function where it turn off when there is no signal and on when there is). The humming is soo loud , its shakes everything and then i have to turn the deck back on to stop it. Just to let you know, the gain is all the way up, the bass boost is all the way up too. Im using speaker leverl input and i grounded it to the seat fram which is quite big and has a big structure. This never happened with my old sony xplod 2165 gtx. PLZ HELP!

muppetmaster

Member - Posts: 36

Joined: November 11, 2003

Location: United States

Posted: December 01, 2003 at 11:12 AM / IP Logged

Your gain is set too high. Gain settings are not to be used as a volume or bass control. They are made to match the voltage of the preamp of your head unit. turn gains all the way down. turn up head unit to 85% volume. adjust gains until you hear distortion out of your subs, then back it down a couple of notches. Are there any other electronics? eq? another amp? if there is, you must use the same grounding point, or you will get grounding loops..

Ketel22

Silver - Posts: 976

Joined: August 23, 2003

Location: United States

Posted: December 01, 2003 at 11:13 AM / IP Logged

you shouldnt have you gains and bass boost up all the way first off. but also have you tried a new set of Rca's and are the rca's run the same route the power wire is. if so maybe think about changing that as well.

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forbidden

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Joined: November 01, 2003

Location: Alberta, Canada

Posted: December 01, 2003 at 1:06 PM / IP Logged

Still does not solve the ground problem. A seat bolt is actually a really bad grounding point, while it is the assumed way is to ground to something like this, it is in fact the worst possible place to go. The most important connection in car audio is the ground. Now Stephen and I battled back and forth on this and well we both won. What you are asking that ground to do is travel through who knows what blend of recycled metal that has sh*tty welds and mounts and is glued together in most unibody cars. This ground path provides nothing but resistance and a breeding ground for noise. If you have a meter, disconnect the ground wire from your amp, attach one lead to that ground wire, attach the other lead to the negative terminal on your battery. A reading in dc resistance (ohms) will show you what is going on, a reading of over .5 ohm means that you should be grounding direct to the battery. Do this and your amp will play cleaner, play louder, not heat up as much and eliminate a whole pile of potential noise problems.

Follow what Ketel is recommending, lose the bass boost and full gain, run the RCA's on a different side of the vehicle as the power and ground leads. You may also have a really crappy hi - lo level adaptor, is it built into the amp or is it separate? Post up some more info on your car make, model, year and exactly what you have for a system, ie: stock head + hi - lo adaptor + amp + subs.

Top Secret, I can tell you but then my wife will kill me.

bassam_zaman

Member - Posts: 23

Joined: October 02, 2003

Posted: December 01, 2003 at 3:38 PM / IP Logged

Hey forbidden, i have a 2002 chevy trailblazer, using factory head, mtx 8000 sub, mtx 801d amp, 4 gauge wires, the ground wire is less than 4 feet, using high level input which is already on the amp and im running the high level wires away from power and ground wires. But you guys didnt answer my question, does not rounding properly make the amp go crazy like that? whne i turn off the head unit, it takes a second the the sub goes brrrrrrrrrrrrrrrrrrrrrrrrrrrr really LOUD! But when i turn down the bass bost to like 75% , it doesn make that loud brrrr noise , but you can still hear engibe noise etc but lower. the amp is rated at 500 watts at 4 ohm and my sub is rated at 400 rms but the sub looks like it can take it no prob, but it lloks like its going crazy, the way it goes in and out !! its is a bandpass box. Thanks for all your help.

forbidden

Platinum - Posts: 5,352

Joined: November 01, 2003

Location: Alberta, Canada

Posted: December 01, 2003 at 3:49 PM / IP Logged

Yes a bad ground can cause all sorts of nightmares for that amp, it may have in fact already damaged the amp. In any GM vehicle I always recommend to ground to the battery due to the sh*tty design and construction of the vehicle. (no offence against your ride). Where did you hook the remote on lead from the amp up to? Where is he current ground run to?

Top Secret, I can tell you but then my wife will kill me.

bassam_zaman

Member - Posts: 23

Joined: October 02, 2003

Posted: December 01, 2003 at 6:49 PM / IP Logged

lol, ok i used the ignition wire under the steeing wheel, so when i turn my jey to the ON position, the amp turns on. I didnt understand your second question. The ground i connected it to one of the bolt in the back seat. I did this with my old amp and i had crystal clear sound.where do you think i should do it, i can make any whole or like sand anything down etc. its a shared car with my family member. Thanks,

forbidden

Platinum - Posts: 5,352

Joined: November 01, 2003

Location: Alberta, Canada

Posted: December 01, 2003 at 6:53 PM / IP Logged

Do you have a dmm?

Top Secret, I can tell you but then my wife will kill me.

bassam_zaman

Member - Posts: 23

Joined: October 02, 2003

Posted: December 02, 2003 at 7:00 AM / IP Logged

sorry whats a dmm?

muppetmaster

Member - Posts: 36

Joined: November 11, 2003

Location: United States

Posted: December 02, 2003 at 8:15 AM / IP Logged

digital multimeter, used to measure resistance, voltage, etc. If you don't have one, you should invest in one, they are really handy, and are quite inexpensive.

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