subs thumping out of tune

[jazer80]

the other day a box in my trunk disconnected the power wire going to my subs' amp, so i bent the terminal piece out so that it would fit (again) a 4 gauge wire, but when i hooked it back up, every time that i put my volume past a moderate level the sub just starts hitting every second, regardless of what I'm listening to. I turn the volume down to zero, and it's fine again until it hit's around 18, then starts again. I think either: the gold terminal piece connecting the power wire to the sub has just been used too long and is in too bad condition to properly transfer the power (this happens that something in my trunk pulls the wire out leaving the gold piece still connected to the amp); or, I broke my amp. any ideas/opinions (besides don't put backpacks in my trunk and drive so they slam around)?

[mjshort18]

replace that gold terminal peice and see what happens.

[frozen_Joth]

check all of your amp fuses.

[60hz163.5db]

try turning the gain down some if this is already down. Take the amp to a shop and have them bench test it on a load see if it does the same thing. This could be a form of motorboating if the instant loss of power/ground has happened more than once this may be so. It's something inside the amp which makes it discharge into the subs. Ie the subs hitting every second. Spikes or instant drops of voltage are very bad for amps.

[EclipseACCORD]

Maybe you have a strand of your power wire touching either the amp's casing or maybe even the ground terminal. Usually the fuse blows automatically but who knows.
To me it sounds more like speaker wires touching each other. I suggest you check all your wiring on the amp and the speaker wires on your subs. Maybe the box hit something else in your trunk as well.

[xjoeharperx]

FROM EXPERIENCE...You have shorted out the amp...sorry....take it to your local electronics repair and they should be able to fix it for around 50 bucks....always secure your equipment...velcro is cheap and easy..

[jazer80]

actually the amp was held down, but i always have a backpack in my trunk or something, and it slams into things. well, i got the new terminal - didn't work, amp was junk. now i got a new one, wired it all, and i have ANOTHER PROBLEM.... if i turn my stereo on everything's fine, as long as my car is in the accessory mode. when i turn on the engine i hear a distortion. it's can't be heard while music's playing unless you're looking for it or near the box, but inbetween songs you can hear it. the guy at my stereo store said it could be because my rca and power wires run down the same side of the car, but they were always like that. no matter what i fix in my car, something inevitably goes wrong.

[T!mmy]

haha yea I know what you mean...you get one thing fixed...get all excited and then BAM! another problem...I know you said it was always like that but I would say that would be the case as well...

[xjoeharperx]

The guy at the stereo shop is right ...the rca cables by the power cable will cause distortion,..the new amp is more sensitive than the old one to recieving this distortion..you can reroute these cables and/or put in a filter. if you dont want to reroute the cables, find a sheath that you can wrap or slide over the rca cables to provide extra shielding from electromagnetic interference...what i used to use was a rubber coating used for noise dampening. I would spray all the cables individually and let them dry. This stopped all interference between the cables and was a cheap and easy way to get a clean sound..

[jazer80]

thanks, now it's just a matter of getting out there and doing it. another thing is that i have new speakers throughout, and was running a 2 channel amp to the front 2. the new amp that i bought for my subs is the same exact amp, and it's running to my 2 subs. now i feel like my subs are seriously lacking ( these amps are only 50W by 2 ), and am not sure whether or not i can just take one of the amps off the front 2 speakers, and then bridge each amp to one sub. is it a problem that 2 amps are running to 1 box? the amps have 2 sets of terminals, and say 'bridged' and have a line connecting a "-" from one set of terminals to a "+" on the other set. only thing i can think of that is different is that there's one power wire running to the back into a block, which has 2 more coming out (1 to each amp) but they aren't the same gauge, since originally the larger one ran into a bigger amp and the smaller ran into the speaker one, which i now have 2 of. oh sorry so long

[xjoeharperx]

Are you trying to run the amp in a bridged mode? Im not sure of your setup that your desvribing in the post but try this out...Take one 12 guage speaker wire and run it from the "+" terminal on the bridged diagram, and run it to the first "+" terminal on your sub. Piggyback another wire off of that same terminal and feed it to the other sub on the "+" terminal. Now take another wire and come off of the "-" terminal on the amp and do the ssame thing to the "-" terminals on the subs. this will create parallel circuit and you should get more power from your amp (im assuming your amp can handle it). If you want to run both amps on the subs you are going to have to isolate the subs from each other on the box. But before you do all this check your polarity on the subs..make sure the positve and negative terminal and wiring match...this will make a world of difference..

[jazer80]

okay i'm confused; i may have described that wrong. basically i have 2 identical amps, and 2 identical subs. both subs are in the same bandpass box, and each sub has it's own set of positive/negative terminals. now each amp has 2 sets of +/- terminals, and are 50wX2. looking at one of the amps, under the 2 sets of terminals, it says bridged, and there are two lines going from the word bridged, to a positive from one set of terminals to a negative on the other ( which leads me to believe it is okay to bridge these amps). what i want to do is just bridge one amp to each sub, so each pair would be independent of the other except for sharing power wires (of varying gauges). is this okay? i think you meant to wire from one sub to the other and then back to the original amp, but i'm not sure. i think i have add

[xjoeharperx]

what kind of bandpass do you have? Im assuming you have a 3 chamber, one rear chamber for each speaker and a shared middle chamber. And also what kind of amp are you running?
You can run the setup you are describing. There are just a couple of things to remember, The bandpass setup drops the power handling of the speaker. It is very easy to destroy the speaker and not notice you are overdriving the sub untill its too late.
Both amps really need the same size power wires. The bandpass needs to run symetrically. If one woofer has less power than the other then the lesser woofer will become more compliant and react to the more powerful speaker causing distortion and damage.
you can achieve the same results by bridging one amp to both speakers and leave the other one to power the rest of the system. The power jump by droping the ohm load should be just about as much as using two amps. you will also keep the subs in phase with each other and avoid cancellation of the bass wave.

[60hz163.5db]

I don't think spray on dynamat will stop radiated noise. That stuff is pretty dense but actual tin shielding usually reflects electromagnetic/radiated noise although some high end rca's have thick rubber they also have more shielding than cheaper ones...

Word to the wise reroute the rcas this will solve your problem and won't cost anything but time. Bravo joe standing waves are a bitch. Also double check your subs if it's seriously lacking with the same amp you have probs make sure the are all good if one fries it will still move as a passive radiator but produce no pressure also if a sub goes it will change the impedence possibly dropping off some power.

[xjoeharperx]

Trust me..the rubber undercoating works wonders. Its not dynamat spray, its a rather thick rubber underecoating spray....Hmm..passive ratiator bandpass..never tried to make that one lol