Sub Noise
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=10945
Printed Date: August 14, 2025 at 7:08 AM
Topic: Sub Noise
Posted By: spyder1125
Subject: Sub Noise
Date Posted: March 15, 2003 at 6:36 PM
I have a 1989 Trans Am with power windows with an older Kenwood head unit (KDC-215s) with a self-amplified Bazooka tube, and from the pre-outs I have Monster RCAs running along the driver side to the trunk. I have the power wire running along the passenger side from the battery to the trunk, and my ground is connected to the chassis in the trunk, and is about 3 feet long. The problem I used to have is back. Every time I played the radio or CD I would have a loud deep noise coming only from the tube, even if I lowered the volume down to zero, the noise would still be there. I rewired my RCAs from where I used to have them going under the console by the fuses and all the car electrical, thinking that would be the problem, and ran the wire under the carpet, then along the driver side to the back. The noise went away for a little and now its back. What is wrong? Is it a bad ground somewhere or is something shot that needs replacing? Thanks for you help.
Replies:
Posted By: bberman1
Date Posted: March 15, 2003 at 8:38 PM
Start off by relocating your amps ground, make sure you sand down the area so you have nothing but bare metal. Sounds like you could also have a bad RCA cable. You might want to change out that rca cable and see what happens. Also what size power and ground cable are you using? But try those 2 things and post your results.
Posted By: dragonrage
Date Posted: March 15, 2003 at 9:29 PM
If you have any other preamp out sets on the head unit, try those. Otherwise... Relocate the ground and make sure it touches bare metal as bberman said. If that doesn't work, disconnect the RCA leads from the amp side short the inputs (not the power leads) on the amp. You can just do that with speaker wire if you want, but don't let it touch any other places accidentally if you do... If it still hums then it's either cables or the amp itself. You can try hooking the power up via a good set of jumper cables to see if the cables were bad, but beware, without some spare power wire that you can clip onto, the clips aren't going to go on the amp too easily... If shorting it does work, check/replace the RCA cable. If that doesn't work, you could try an isolation transformer on the RCAs. If none of that works, I think your best bet would be to replace the head unit. Be careful if you have T-Tops though!  ------------- 2009 Pontiac G8 in planning stage
HU: ?
Speakers: ?
Amps: ?
Posted By: spyder1125
Date Posted: March 16, 2003 at 10:35 AM
bberman: i relocated the ground cable, to the rear seat bolt i have a whole Monster amp wiring kit for the setup that's 8 gauge. dragonrage: i only have one pair of preamp outs i relocated the ground to the rear seat bolt which obviously is connected to bare metal...i'm a little confused on your shoring the inputs statement however...do you mean short the inputs on the wire going directly to the Bazooka tube, or do you mean to short them from the head unit, because i have the Monster RCA going from the outs on the head unit connecting to another set of RCA wires that are about 1' long coming from the Bazooka tube, however, I shorted the ones going directly to the bazooka tube, not by the head unit, and there was no noise, is that good or bad? Would I really have to replace the RCA cable? I spent so much money on the one I have... A side note, when i turned on the head unit the hum was really loud from the tube, I then went back to the trunk and moved around the wires a bit and it stopped, then i noticed that while i was playing a song or the radio the bass sounds really bad (like loud) sometimes, and sometimes it hits right. I also notice that while changing tracks on a CD, that little pause between one track and the other where your not supposed to hear anything, i can vaugley hear some sub noise, (this is when i moved the wires around and the noise stopped), but i heard some noise during that changeover. Just wanna let you guys know that my car is going to the body shop for the rest of the week so I won't be able to try your replies until next monday the 24th, thanks a lot for the help guys, sorry i wrote so much.
Posted By: dragonrage
Date Posted: March 16, 2003 at 1:45 PM
It means use a piece of metal to touch the inside of the RCAs on the amp (not the wire, the amp connectors) to the outside of the RCAs, but avoid touching the case of the amp (it may or may not be bad for it, better safe than sorry).
-------------
2009 Pontiac G8 in planning stage
HU: ?
Speakers: ?
Amps: ?
Posted By: spyder1125
Date Posted: March 16, 2003 at 5:27 PM
i'm still confused dragon, sorry, but there are no RCAs on the amp, there is a plug like the one pictured below, and from that plug are the wires to the RCAs. Now what I did is on those RCAs pictured below, I used a wire to connect one of the RCAs to the other RCA touching the inside only, and that produced no noise...also realize that the amp and sub are one unit in the box, and the casing is plastic 
Posted By: bberman1
Date Posted: March 16, 2003 at 5:35 PM
I know that you don’t have the car right now. But you should not use the seat bolt as a ground. If you move the wires around and the noise stops then you know your problem is being caused by one of those wires. Make sure that the signal and power (includes remote wire) are all as far from each other as possible. Once you get it back play around with those wires and connections and I am sure you will locate the problem of the interference
Posted By: spyder1125
Date Posted: March 16, 2003 at 5:43 PM
I also notice that while changing tracks on a CD, that little pause between one track and the other where your not supposed to hear anything, i can vaugley hear some sub noise, (this is when i moved the wires around and the noise stopped), but i heard some noise during that changeover. -what could that be? is that all with the bad ground? Also, what should I use as a good ground, I heard somewhere the seat bolt is the best...below is an older picture of it, now the wires are more tightier and they all have black plastic tubing around them, but notice the blue RCAs coming from the tube are going straight to the left side, while the ground is going to the other side, i don't know how much more i can seperate them. also, ignore that ground loop filter in the back, that was my old setup and it did noting so i removed it. 
Posted By: bberman1
Date Posted: March 16, 2003 at 5:48 PM
I cant view you pic i dont think you loaded it corectly. And as far as the ground where is your amp located?
Posted By: spyder1125
Date Posted: March 16, 2003 at 5:48 PM
Posted By: bberman1
Date Posted: March 16, 2003 at 5:53 PM
if you play with the connector right where the wires go into it dose the noise go away? Also what wire is that the blue one is going around ( the black wire) ?
Posted By: spyder1125
Date Posted: March 16, 2003 at 6:15 PM
if by the blue one you mean the remote going toward the right side it is the pos. wire. also realize this is an old setup, and they're no long tangled like in that picture, each one is wrapped in black splite wire loom. it appeared that the noise went away when i was messing with in, what would be toward the left of the picture, where the blue RCAs connect with the purple RCAs
Posted By: bberman1
Date Posted: March 16, 2003 at 6:25 PM
That black wire loom won’t do anything as far as preventing interference. But you say the noise goes away when you play with the rca cables. Are you using RCA Interconnects to connect the two cables? If so undo the connection and put it back together see if that helps. If the noise goes away when you play with the rca cables than you know that that’s the problem. If you can try and replace them one of them could have gone bad you would be surprised it dose happen.
Posted By: spyder1125
Date Posted: March 16, 2003 at 6:50 PM
i just remembered that the rcas came with a 3rd wire in the middle and said it could be used as a remote or ground islolator, i'm not using it as a remote but i know that i connected it to the seat bolt on the driver's side, but the other end of this wire is not connected to anything, wouuld that cause noise too? i still have the car in my garage, and just took some pics to help you out. i know the loom doesn't do anything, but i just cleaned up the mess to make it look nice to the cables aren't all crossed over each other. https://www.hpphoto.com/servlet/com.hp.HPGuestLogin?username=spyder1125&password=43656685 i just took these pics, hope they help to give you an idea of what is going on 
Posted By: bberman1
Date Posted: March 16, 2003 at 6:58 PM
Have not reviewed the pics but try and disconnect that wire and see what happens there is a possibility that it is causing interference.
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