subs thumping out of tune

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)?

replace that gold terminal peice and see what happens.

check all of your amp fuses.

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.

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.

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..

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.

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...

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..

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

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..

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

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.

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.

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 :)

alright i bridged both subs to one of the amps and now it's a lot louder. I moved the rca to the other side of the car and it's still making the interference noises. could it be the remote wire being close to the power maybe? this suks i hate this noise!!

Is the noise there when the truck is not running?
If so then it is most likely your alternator. This is normal and a sign of a healthy alternator.
The first step i would take is to get a filter and install it into the power supply to the head unit..
Make sure you have good connections and a good ground for the amps...Most people use the seat bolt for the ground..This is ok, just make sure you scrape all the paint from under the contact surface of the eye connector on the ground wire.. There is another piece called a "ground loop". This is a loop of wire that installs along with the ground wire on the grounding point and minimizes the interference..
Make sure you have good quality rca cables.. They can make a big difference in sound quality and help stop interference.
One trick I used to use was to run the head unit power off of the battery and use the factory power wire to operate a relay. The battery seems to filter out a lot of noise... Good luck..some of these problems can be a nightmare to get rid of...but not usually.. :)

What kind of headunit do you have kenwood or pioneer? Cuz i have seen the internal ground fade on pioneers before mostly on the screens but all you have to do to correct this problem is pretty easy. On an rca jack there is a pin in the center and a ring around it tape a peice of barewire to this outside ring. Connect the other end of this wire to chassis ground behind the headunit do this to all rca's. Or try a friends headunit in your car if it goes away then it's prolly something internal and the radio needs serviced or replaced. But really aslong as you have your rca's opposite power. A nice short ground at the amp. And has had a tune up this is sometimes overlooked spark plug wires sending out mad radiated noise. Make sure you have a good ground for your headunit also alot of times just regrounding the headunit straight to ground helps, moving the headunits power wire off the rca's. All little things that can cause pesky noise.

new rca's took care of the problem. now that i had a free amp i tried wiring it up to my speakers, and now i'm getting an even louder distortion noise from my door speakers. i ran new wires (for the speakers) from the trunk and connected them to my wiring harness behind my face. could it be that a larger wire connects to a shorter wire on the way to the speaker?

i don't know how clear that is - i mean i ran new wires that were kinda thick all the way up to the front and connected them to the really thing crappy stock ones that run from the head unit to the speakers.... damn distortion sucks. (i'm out in a parking lot with my stereo pulled out of the dash, disconnecting wires. a cop drives up, looks into my car, and asks me if i'm alright. i say yes, and he just leaves. now i know how my car got robbed right under a street light in mission hill<boston>)

Are you using a factory head unit?..if you are using the wires that normally power speakers and you are using them for signal wires then thats your problem...Go to the store and get a "line level adaptor" it will reduce the voltage and help quiet the distortion...If you have an aftermarket unit and using the speaker wires beacuse you only have one set of rca's then go to radio shack and get a splitter and run to the other amp...or split off of the sub amp and run to the mid/high amp with the other set..this is predicated on the fact that the crossover is built in to the amp..you can also do this with an active crossover..
here is a link.. http://www.crutchfield.com/S-2fiTpin31m0/cgi-bin/ProdView.asp?s=0&c=3&g=82600&I=489CX11&o=m&a=0&cc=01&avf=N

The splitter is probably the easiest route to go for right now..

i must have explained worse than i thought. rca's are all fine, i got new ones and they took care of the problem. my face only has one external out, so i'm splitting it into 2 in the trunk for the 2 amps. one amp runs straight to the subs, the other to the front 2 door speakers. the thing is that i put in new, large speaker wire from my speaker amp, and ran it up front to behind my face, and connected it to the thin speaker wire that is part of the factory harness. i was thinking that the distortion was coming because the sound signal was going through a thicker wire, then connecting to a thinner wire before hitting the speaker. i just wanna know if this is the case before i go and run new wires ( like an idiot i got a few feet shorter than what i should have) to the doors themselves, which i really don't want to have to do unless absolutely necessary because i've never taken the doors apart on this car and have too much studying to be out there for a while.

Rrunnig to the doors is the best way..you are probably picking up interference from the vehicles wiring harness...

you think so? i hope that's what it is, but this interference is so loud i don't know if it's just wiring. guess i'll try it i'm really getting sik of sttudying

okay i went and got more wire and was told by the guys at the stereo store that w/ such low wattage there shouldn't be a problem with connecting a larger wire to a smaller one creating distortion as loud as i'm getting. i also switched my amps to make sure it wasn't the amp, and it wasn't. i started trying to take my doors apart and am lost. is there any other things i should look at before i dive into rewiring it? i really don't want to have to go through all that trouble if it's not the problem.

where is the power for the amps coming from?

i'm running a 4 gauge from the battery to a distributor block, then i believe two 8 gauges run out of that, though it could actually be that a 4 runs into the block and comes out as another four and an eight. gg check it out, but unfortunately i won't be able to post til later, on my way to check out the jesus movie

okay i couldn't figure out where the distortion was coming from, so i continued to run only 2 midrange speakers (the front 2), powered by the receiver. today i went outside and wired the back 2 speakers to my extra amp. i turned it on and it worked!! i was so excited that i actually went out to my car to do something and had success; so, i put everything back in it's place, turn the key from the accessory position, and start the car. as soon as the engine turns over and the car starts, the stereo comes back on, and there's the distortion again! this time it's on the back speakers only (as opposed to the front ones that were doing it earlier). i know it's not wiring, because i wired them w/ brand new wiring, and the amps in the trunk so it's only like 2 feet of wiring. i know the amp is in good shape because i tried it on my subs and it hit fine. i have the gain as low as possible and that doesn't help. this is the same problem i was having with the subs way before (they would be fine until the engine was on and the alternator was running), but when i replaced the rca's it fixed the problem. now i don't know what to try. i'm splitting one amp pre out to two amps, could that be bothering them? i was told it wouldn't be a problem. they're also sharing a remote wire, but i don't see how that would be a problem. please help i'm sick of my stereo always being in a constant state of repair

you've broken most of the rules of good car stereo install ...and tried a lot of "voodoo" cures. Sounds like you have either a radiated noise problem or a ground loop problem. The radiated problem can be solved by using UTP (unsheilded twisted pair) RCA's. The ground loop problem is usually solved by grounding both amps at the same point. You have to face the possibility that the old amp may be bad.

Am i correct in saying that the distortion is comming from the speakers running off of the head unit??
If that is the case, get an inline noise filter for the power supply that feeds the head unit..

that may be right .... if you're gonna use your headunit's internal amps, you have to adjust your outboard amps to be consistent with the output of the headunits internal amps. Otherwise, one will distort badly when the other is in the normal operating range

sorry i explained it badly; it is the rear speakers, which are running off of the amp that are distorting. i recently got brand new rca's (which solved this problem when it was happening to my subs), so they should be fine. i'm gonna go check out the grounding, make sure they're grounded to the same place. i'll post a little later

okay they were both grounded to the same spot, and i checked it out and the ground is good. also i adjusted the front speakers (which get power from the receiver) and the rear speakers to get them balanced and this did nothing to lessen the distortion.

Okay I'm going to try and explain this as best as possible and simple as possible. If you have your power and rca wires ran on the opposite sides of the car and you still are getting a whinning noise and distortion then you have a ground loop problem and the best way to fix the problem is to put a filter on the device causing the problem. From what you have stated before you need a filter at least on your deck if you are running one rca from the deck to your amps. If you are running two rca's from your deck to both amps then you should first put a filter on the amp running your highs. sometimes you will need a filter at the deck and at the amps. In my previous setup in my 95 Maxima with 110 amp alternator, Deep Cycle battery, 600watt x1 Bazooka Amp, 200watt MTX Amp, 2-12" MTX Thunder6000 subs in a sealed box I had to use filters to get rid of the engine whine. Same setup in my 87 Honda Accord have to use filters. The nice thing about filtyers is that they are easy to install just plug the rca's into the plugs then plug the other end into the source. I don't know what audio shops you have but if you have a Wal-Mart just go pick up a ground loop isolator in the car audio dept. for about $13.00 plus tax. also a tip on amping your door speakers run you speaker wires from your amp all the way to your deck and the wire should be at least 16gauge you run that size wire cause the signal path is longer and you don't want to lose sound running smaller wire would be worst. Also for better sound run the amp on your front speakers and make sure you set your amp on high pass filter, you will like the sound a lot better and you may not need to even have a rear fill. there's a lot more I could say on how to hook up your system but I'll stop there. I have hooked up many systems so I speak from experience. If you have any questions post them here or email me at [email protected].

sorry i explained it badly; it is the rear speakers, which are running off of the amp that are distorting. i recently got brand new rca's (which solved this problem when it was happening to my subs), so they should be fine. i'm gonna go check out the grounding, make sure they're grounded to the same place. i'll post a little later

Dude, your problem has to be with your amps. You stated that before you had no noise and everything was cool until your backpack hit it and you replaced the amp. Then all of the sudden you have noise. You should never have to use those cheap filters and such. Those just tone done the noise. You just treat the symptom and not the cause. You never see a $20k system with filters all around. You did good things by moving RCA's around and away from power but with good quality RCA's you usually do not have to worry about that anyway. Now, one thing that it could be is your car's battery. If you've been working on your system with the battery still hooked up, you could have worn out your weak battery. Sometimes you can have a weak battery but not really notice it but it makes your altinator run like crazy. This high charging output will cause radio noise. To do an easy test, unhook the RCA's behind the radio and start the car. If you still have noise, you have something else going on. If you don't, then you know that it is with your radio or battery/charging system.

if the problem is the amp is it possible that the same amp works fine when i hook it up to my subwoofers? i'm pretty sure the amp's fine. i know my battery (optima) was very good a month or two ago, but i guess i don't understand how i would mess up my battery by working on the system with the battery hooked up? as far as unplugging the rca's and trying that, all i have to do is turn the radio off and the noise goes away. the noise is definitely coming from my rear deck speakers, so if i unplug the rca's, i disconnect their power and they turn off, and the noise is gone.

i'm assuming that since the noise is only present when the engine (and the alternator) is turned on, it has to be related to the alternator (i think). the last time i had this distortion, and it was only present when the engine was on, it turned out to be poor quality rca's. swapping them out fixed the problem. what other things do you want to check when the problem is in all likelihood related to the alternator

Of course the problem is with the amps and the reason you hear it in your speakers running highs is because the whine is a high pitch whine in which your subs cannot play. You have to remember that electricity has a humming noise that is with it. So when the power from your baterry is being transfered to your amps your amps is going to try and pass that noise off as a signal. You ask why it only happens when the engine is running and why it gets louder. The answer is simple when your car is in accessorie mode it is only sending about 12volts to your amps which most amps are able to surpress but when you turn on the engine you can be sending as much as 14volts to your amps in which all of the noise is not able to be surpressed and the higher you rev the engine the more power your alternator is putting out. That is why I say use a noise filter, the noise is not hurting anything except our ears cause we have to hear it when we are not listening to the music loud. There are other things you can do like change your amps out for some high end amps that have filters built into them to handle the noise, but that's a lot of money to put out just to get rid of a noise, the other thing is try a different deck but I have had Sony, Pioneer, and JVC and had the same problem with them all. Most $20k dollar systems have the best amps on the market, the best rca's, the best decks, upgraded auto electrical system, and the best wiring and even some of them have to use filters, but that is something that you wont read or see to often. There is a lot of things that are used in car audio to be sure to get a clean sound you have to be really into it to know it. I don't think that he worried about having a competition system he just wants to be able to drive around in peace except for the music coming from his CD's or radio.

alternator whine problems SUCK ...and you would be surprised how many high dollar installs use them because the installers don't know how to troubleshoot this problem.

oh i get it when you said it was my amps i thought you meant they were broken, but you're saying that they are just picking up the noise, and that higher end amps probably wouldn't, right? i guess i'll just have to end up trying the filters. hate solving problems that way but looks like i'm out of options. thanks for the input everyone

oh i get it when you said it was my amps i thought you meant they were broken, but you're saying that they are just picking up the noise, and that higher end amps probably wouldn't, right? i guess i'll just have to end up trying the filters. hate solving problems that way but looks like i'm out of options. thanks for the input everyone
Well, not too quick here. We need to make sure that the noise is actually being pickup or generated by the amps or the stereo. Do this, leave everything connected and put a jumper between the turn on and the 12v constant on the amp(s) in question. Then start the car with the radio off. Here you should have the amps on but the radio off. If you don't hear engine noise, you then now know that it is comming out of the radio and not from the amps or RCA's. If you do hear noise, unplug the rca's then and see what you get. If don't, there's the problem. If you do, then it's the amplifiers that are picking up the interferance.

Now, even the last being said your problem actually could be the altinator or battery. If your altinator is putting out major amperage for some unknown reason, you'll get noise each and every time no matter what system you got in your ride. I had that in my brand new car and it was driving me nuts. Here the altinator was already shot after 2k miles!!!! :banghead:

ponch, sorry but could you explain this like you would to a child, i really don't wanna blow sometyhing up; when you say connect the 12v constant to the turn on, does that mean to connect, via a speaker wire maybe, the power terminal to the remote turn on terminal? and when i do this, do i leave the other wires (remote and power wire) connected?

yo ponch....

ponch, sorry but could you explain this like you would to a child, i really don't wanna blow sometyhing up; when you say connect the 12v constant to the turn on, does that mean to connect, via a speaker wire maybe, the power terminal to the remote turn on terminal? and when i do this, do i leave the other wires (remote and power wire) connected?
YES :) The amp turn on input is a low amperage switch. It actually goes to an internal relay that "clicks" when it sees 12v+. Leave everything else on or hooked up (except the turn on lead from the radio since you will use a jumper wire). So then you will do the above steps to investigate where the noise is really coming from.

when you do this, you need to make some shorting plugs for the rca inputs. Every input on theamp needs one. A shorting plug is just an RCA end that has both poles or wires just soldered together. This will short the amp input, to prevent it from picking up stray noise.

OK, I run tow amps to two subs in one box, its perfectly fine and extremely loud, as for your noise problem, you can buy shielding for your sound wires in any audio shop that will prevent the noise.

uh i don't think that's the problem