Ground loop or bad rca's? dynamat atl.
04-11-2008, 07:51 PM
#1
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Ground loop or bad rca's? dynamat atl.
ok so i just changed my system up a little bit and put a new head unit in, and got a new sub (same amp) the amp wiring hasnt been touched at all... after everything was all said and done it sounded pretty good, except that you can hear noise comming through the sub now IE: turn signals,brake,windows etc... how can i have a bad ground if the amp is grounded to the battery? or do i just need some better RCA's that are shielded? because that is my only guess of what it could be.. also if thats the case where can i get some good RCA"s that dont cost an arm and a leg? also off topic what is a good/cheaper alternative to DYNAMAT? thanks chris
04-12-2008, 02:45 AM
#6
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Second Skin is a great alternative to Dynamat, but if you search there is a whole thread dedicated to Dynamat type products, their price per foot comparisons, and where to buy them.
04-12-2008, 02:55 AM
#7
Ok where to start...
Those RCA's from "Crappy Tire" are not shielded, which really doesn't matter because I don't think they have stores in Ohio, it being CANADIAN Tire and all, I could be wrong but it seems like a logical conclusion. I do agree with what you said about the stock power wires causing interference, some people don't realize that just because they are not running power wire from the front doesn't mean there isn't power wire there already.
While correct in theory this is not always true, if you take your multi-meter and set it to resistance,(the one that beeps) touch the neg. battery terminal with one probe and the bolt to your back seats with the other I know its going to singing to you, I know this because I have done it when looking for a ground, so yes the bolts for the back seats are a good ground but not always better than the neg terminal, it just depends on placement of the amp.
OK, that being said lets go with this, by process of elimination, if the sound was not there before and is now then the problem is coming from something you changed, if the amp is the same as it was before than I'm betting the problem is not your ground.
You replaced your head unit, how tight was the fit when putting it in?
Have you cut the plastic moldings out fron behind the radio? How about the metal bracket?
Alot of people have had to cut these out (myself included) to fit the aftermarket HU in. I was having the same problem as you, I also thought it was my ground. turns out my RCA were getting pinched right behind the HU due to lack of space, once I removed the moldings and the metal bracket the problem went away. In any case I think somewhere along the line either your RCA's are pinched or cracked. They are sensitive little suckers and must be treated with a little TLC when you run them.
I just finished using Hush Mat to do my deck lid, works really good, a bit easier to work with that dynomat is and its about half the price. IMO its a good alternetive to dynomat
canadian tire has some decent rca's. but if your looking for good quality go to soundsaround or the like.
Your amp shouldn't be grounded to the battery.....A good place to ground it is to a seat bolt for the rear seats
OK, that being said lets go with this, by process of elimination, if the sound was not there before and is now then the problem is coming from something you changed, if the amp is the same as it was before than I'm betting the problem is not your ground.
You replaced your head unit, how tight was the fit when putting it in?
Have you cut the plastic moldings out fron behind the radio? How about the metal bracket?
Alot of people have had to cut these out (myself included) to fit the aftermarket HU in. I was having the same problem as you, I also thought it was my ground. turns out my RCA were getting pinched right behind the HU due to lack of space, once I removed the moldings and the metal bracket the problem went away. In any case I think somewhere along the line either your RCA's are pinched or cracked. They are sensitive little suckers and must be treated with a little TLC when you run them.
I just finished using Hush Mat to do my deck lid, works really good, a bit easier to work with that dynomat is and its about half the price. IMO its a good alternetive to dynomat
04-12-2008, 03:11 AM
#8
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And for your other questions regarding whine, first don't ground it to the battery, ground it to the bolt thats right beside the battery. You're hearing EMI, which is electrical waves interfering with radio waves. It mainly comes from a bad ground or non-braided RCA wires. Fix your ground and get braided RCA cables like Monster or these Stinger's:
04-12-2008, 03:25 AM
#9
Sorry my bad I was talking about the bolt where the battery is gounded to, IMO that is the neg terminal since its what grounds the battery out. Wouldn't make much sense to use the actual neg post on the battery , thats like adding a middle man, and true to form middle men are always just looking for thier cut.
I had those exact same stinger 's running to my 4 channel front end amp, but I found them to flimsyand IMO thyey just didn't seem like there was enough shielding on them, this of course could possibly be my own OCD ridden head messing with me.
I use the blue stinger to my sub amps, with monster Y-jacks, and ended up putting in Monster 4 channel cables to run the front end amp, there really nice take a look,
http://www.monstercable.com/mpc/prod...0Interconnects
I had those exact same stinger 's running to my 4 channel front end amp, but I found them to flimsyand IMO thyey just didn't seem like there was enough shielding on them, this of course could possibly be my own OCD ridden head messing with me.
I use the blue stinger to my sub amps, with monster Y-jacks, and ended up putting in Monster 4 channel cables to run the front end amp, there really nice take a look,
http://www.monstercable.com/mpc/prod...0Interconnects
04-12-2008, 04:06 AM
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Yup Monster's look nice, but they're not any more shielded then Stinger. Each stinger RCA is double grounded, that's why you see 4 wires in each twisted braid. Monster cable just has a lot of thick rubber or plastic with sleeving to make the wires feel thick, but as long as the wire gauge is the same, underneath all the fancy exterior is the same stuff on the inside. Stinger is usually quite a bit cheaper then Monster, and you don't see the cable after you route it. Get Stinger, loom it or buy some braided wrap if you want it to look pretty, and you'll still save vs Monster. 
04-12-2008, 04:57 AM
#11
using seat belt bolts is one of the worst grounds you can do.... don't
What kind of rcas are you using? or better yet what headunit did you get? was it a pioneer?
Reason i ask is because even thou rcas will get interference they usually wont with sub amp... i did a lil test and wrapped a set of one of the crappiest rcas i could find around my power wire to see if it induced noise and it didn't. BUT unfortunately i know there are worse rcas out there
So while it could be the rcas i sorta have a feeling theres a bigger issue then them
What kind of rcas are you using? or better yet what headunit did you get? was it a pioneer?
Reason i ask is because even thou rcas will get interference they usually wont with sub amp... i did a lil test and wrapped a set of one of the crappiest rcas i could find around my power wire to see if it induced noise and it didn't. BUT unfortunately i know there are worse rcas out there
So while it could be the rcas i sorta have a feeling theres a bigger issue then them
04-12-2008, 03:59 PM
#12
Not the seat belt bolts
The bolts that hold the back seats in, no not the ones under the those huge brackets but rather the ones that are a bitch to get to on the sides.
If there is continuity between that and the bolt in which the batt is grounded to then how is it a bad ground.
James- I wasn't saying that stinger wires have bad shields but my OCD (Obsesive Conpulsive Dissorder) wont let me look past the size. It was more of a joke than anything. .
So if the only thing you changhed were the HU and the sub then the problem lies somewhere in and around the HU.
Like said already what kind of HU, RCA's and what did you use to interface with the car, or better said what wire harness did you use.
Even if you hooked the sub up backwards it wouldn't produce interference noise, it wouldn't sound so nice but still its not the problem IMO
The bolts that hold the back seats in, no not the ones under the those huge brackets but rather the ones that are a bitch to get to on the sides.
If there is continuity between that and the bolt in which the batt is grounded to then how is it a bad ground.
James- I wasn't saying that stinger wires have bad shields but my OCD (Obsesive Conpulsive Dissorder) wont let me look past the size. It was more of a joke than anything. .
So if the only thing you changhed were the HU and the sub then the problem lies somewhere in and around the HU.
Like said already what kind of HU, RCA's and what did you use to interface with the car, or better said what wire harness did you use.
Even if you hooked the sub up backwards it wouldn't produce interference noise, it wouldn't sound so nice but still its not the problem IMO
04-12-2008, 06:57 PM
#13
Senior Member
Sorry my bad I was talking about the bolt where the battery is gounded to, IMO that is the neg terminal since its what grounds the battery out. Wouldn't make much sense to use the actual neg post on the battery , thats like adding a middle man, and true to form middle men are always just looking for thier cut.
I had those exact same stinger 's running to my 4 channel front end amp, but I found them to flimsyand IMO thyey just didn't seem like there was enough shielding on them, this of course could possibly be my own OCD ridden head messing with me.
I use the blue stinger to my sub amps, with monster Y-jacks, and ended up putting in Monster 4 channel cables to run the front end amp, there really nice take a look,
http://www.monstercable.com/mpc/prod...0Interconnects
I had those exact same stinger 's running to my 4 channel front end amp, but I found them to flimsyand IMO thyey just didn't seem like there was enough shielding on them, this of course could possibly be my own OCD ridden head messing with me.
I use the blue stinger to my sub amps, with monster Y-jacks, and ended up putting in Monster 4 channel cables to run the front end amp, there really nice take a look,
http://www.monstercable.com/mpc/prod...0Interconnects
My guess is that he's got soemthing with the headunit screwey, maybe the RCA's are connected wrong? Maybe the headunit has noise in it, or maybe the output from the new headunit is less then the output of his old line driver and he turned up the gains on the amp so it matched the old output? He changed the sub out to, so maybe it's wired wrong, or maybe it's blown? There could be any number of things...
04-12-2008, 07:00 PM
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04-12-2008, 11:27 PM
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Ok where to start...
Those RCA's from "Crappy Tire" are not shielded, which really doesn't matter because I don't think they have stores in Ohio, it being CANADIAN Tire and all, I could be wrong but it seems like a logical conclusion. I do agree with what you said about the stock power wires causing interference, some people don't realize that just because they are not running power wire from the front doesn't mean there isn't power wire there already.
While correct in theory this is not always true, if you take your multi-meter and set it to resistance,(the one that beeps) touch the neg. battery terminal with one probe and the bolt to your back seats with the other I know its going to singing to you, I know this because I have done it when looking for a ground, so yes the bolts for the back seats are a good ground but not always better than the neg terminal, it just depends on placement of the amp.
OK, that being said lets go with this, by process of elimination, if the sound was not there before and is now then the problem is coming from something you changed, if the amp is the same as it was before than I'm betting the problem is not your ground.
You replaced your head unit, how tight was the fit when putting it in?
Have you cut the plastic moldings out fron behind the radio? How about the metal bracket?
Alot of people have had to cut these out (myself included) to fit the aftermarket HU in. I was having the same problem as you, I also thought it was my ground. turns out my RCA were getting pinched right behind the HU due to lack of space, once I removed the moldings and the metal bracket the problem went away. In any case I think somewhere along the line either your RCA's are pinched or cracked. They are sensitive little suckers and must be treated with a little TLC when you run them.
I just finished using Hush Mat to do my deck lid, works really good, a bit easier to work with that dynomat is and its about half the price. IMO its a good alternetive to dynomat
Those RCA's from "Crappy Tire" are not shielded, which really doesn't matter because I don't think they have stores in Ohio, it being CANADIAN Tire and all, I could be wrong but it seems like a logical conclusion. I do agree with what you said about the stock power wires causing interference, some people don't realize that just because they are not running power wire from the front doesn't mean there isn't power wire there already.
While correct in theory this is not always true, if you take your multi-meter and set it to resistance,(the one that beeps) touch the neg. battery terminal with one probe and the bolt to your back seats with the other I know its going to singing to you, I know this because I have done it when looking for a ground, so yes the bolts for the back seats are a good ground but not always better than the neg terminal, it just depends on placement of the amp.
OK, that being said lets go with this, by process of elimination, if the sound was not there before and is now then the problem is coming from something you changed, if the amp is the same as it was before than I'm betting the problem is not your ground.
You replaced your head unit, how tight was the fit when putting it in?
Have you cut the plastic moldings out fron behind the radio? How about the metal bracket?
Alot of people have had to cut these out (myself included) to fit the aftermarket HU in. I was having the same problem as you, I also thought it was my ground. turns out my RCA were getting pinched right behind the HU due to lack of space, once I removed the moldings and the metal bracket the problem went away. In any case I think somewhere along the line either your RCA's are pinched or cracked. They are sensitive little suckers and must be treated with a little TLC when you run them.
I just finished using Hush Mat to do my deck lid, works really good, a bit easier to work with that dynomat is and its about half the price. IMO its a good alternetive to dynomat
scratch that its fucked up again and im pissed! it was working fine and then 2night it started acting up again....... i went to turn the gain up on the amp (its wayy down because the sub is brand new and still being broke in) and its going crazy when i turn the gain up just rumbeling real loud and i know its because the rca's are bent back there!!!!!!! and idk what to do because i cant cut anything else away because there up against the heather vents in the dash! someone help!!!!!!!!!!!!!
Last edited by rockstarbass1; 04-12-2008 at 11:27 PM. Reason: Automerged Doublepost
04-12-2008, 11:55 PM
#16
Senior Member
find some 90 degree RCA adapters or some extensions with really small ends. (you might have to change out the RCA's if they were crimped bad enough too)
Last edited by SS SCHGD; 04-12-2008 at 11:57 PM. Reason: Automerged Doublepost
04-13-2008, 12:46 AM
#17
Turn the metra dash install kit upside down and mount it like that.
Cut the tabs off the top so it will fit in at the bottom,
There is more clearence at the bottom of the radio opening than the top.
You could just take the bracket out,, it has two screws on either side of it , you can just use a 7mm or 9/32 socket, or was it a 10mm I cant remember, there a bitch to get at but its an option.
In any case those RCA elbow adapters are hard to find but a good idea,
Cut the tabs off the top so it will fit in at the bottom,
There is more clearence at the bottom of the radio opening than the top.
You could just take the bracket out,, it has two screws on either side of it , you can just use a 7mm or 9/32 socket, or was it a 10mm I cant remember, there a bitch to get at but its an option.
In any case those RCA elbow adapters are hard to find but a good idea,
04-13-2008, 12:00 PM
#18
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where did u get that pic from? i found some online but they werent stubby like that.... they were kinda longer! and cheap looking..... also i thought i tried to flip it upside down and it didnt work???
04-13-2008, 12:18 PM
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04-13-2008, 04:01 PM
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well i went to circuit city and got a 80 dollar set of fancy rca's for 30 bucks
and went to radio shack and got 2 right angle things went home hooked it all up and i still got that crazy low pitch sound comming when i turn the gain up on the amp.... so i pulled out the manual for the head unit and saw that you can swich the rear output from full range to just a sub output (dont know why it has that feature when the head unit has a sw output) but any ways did that pluged it into the rear and boom all better!!!!
so im guessing its somethin messed up with the sw output on the headunit........ anyone have this problem before with a pioneer head unit? thanks chris
and went to radio shack and got 2 right angle things went home hooked it all up and i still got that crazy low pitch sound comming when i turn the gain up on the amp.... so i pulled out the manual for the head unit and saw that you can swich the rear output from full range to just a sub output (dont know why it has that feature when the head unit has a sw output) but any ways did that pluged it into the rear and boom all better!!!! so im guessing its somethin messed up with the sw output on the headunit........ anyone have this problem before with a pioneer head unit? thanks chris
04-13-2008, 04:59 PM
#23
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what would be grounded bad? im not getting any noise what so ever now... no interferance or anything..... i was just getting a steady low tone out of my sub when it was hooked up to the one set of rca's on the head unit. now that i put it in the rear rca, and swiched that to sw its fine........ bad ground on my headunit???
04-14-2008, 12:24 AM
#25
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if i said all the way up i didnt mean to..... past 3/8 ths to half.. and this wasnt a little hum its was like my sub was being fed a loud solid note...... but now that i have it in the rear output swiched to sw (subwoofer) its fine.. wich is good but weird and kinda sucks cuz now i cant run a 4 ch amp also because im using the rear for a sub instead of the sw output errr