Weird Audio Problem, Help!

GreenStangGT · Feb 4, 2008

So I recently installed a couple subwoofers and an amp in my 95 GT. I used the sub out on the back of my Sony headunit, and ran the other wires normally. Now, when the car is running I get some very unusual noises through the speakers. I even hear the sound of my turn signals through the speakers. Any ideas what could cause that and how to fix it?

Black95GTS · Feb 4, 2008

Depending on the system you can't run the signal wires next to the power wires. You're hearing the power draw of the various accessories impact the signal as it travels to the amp.

Don't know how much power you're running. When I put a sub in my F150 at 300W, I ran the power and signal together, but when we did 1200W in my friend Drew's Integra, we seperated it out.

I would conclude with saying do as I say, not as I do, and make sure your audio signal is run down the opposite side of the car as the power cable. Anything over 500W I'd look to a capacitor as well.

Adam

GreenStangGT · Feb 4, 2008

Thank you for your reply, but the separation of power and signal is not the issue. The wires are run seperately on each side of the car.

Additionally, the pitch and volume of the noise seems to correlate with the engine speed. I believe this might be some electromagnetic interference issue.

Thank you for any more help.

Zero Signal · Feb 4, 2008

Don't run high level inputs, you need to use shielded RCAs. Otherwise you're going get lots of buzzing with engine RPM and popping. The power cable should be run separate but it's the signal cables that are critical. If your deck has no RCA outputs, I'm not sure what to do, I've never used one that didn't.

Edit: I re-read your post, I guess you aren't using high level inputs. Try changing the ground on the deck. You probably used the black wire on the stock harness. Try changing it to a short chassis ground. If that doesn't fix it, try running a new 10 or 12ga power wire to the deck from the battery or splice it with the amp power cable near the battery but behind the fuse or breaker, whichever you used.

GreenStangGT · Feb 4, 2008

Zero Signal said:
Try changing the ground on the deck. You probably used the black wire on the stock harness. Try changing it to a short chassis ground. If that doesn't fix it, try running a new 10 or 12ga power wire to the deck from the battery or splice it with the amp power cable near the battery but behind the fuse or breaker, whichever you used.

Hmmm. It doesn't sound like there is anything wrong with this advice, but it makes me wonder. Why would this new noise start right after I installed the new subs and amp? This noise was never present before they were installed and none of the original wiring of the headunit was changed when I completed this new installation. Any ideas?

95BlueStallion · Feb 4, 2008

Check your ground on your amp, and make sure your RCA's are plugged in securely and dont have any major kinks when you reinstall the head unit. Ive had buzzing that goes along with RPMs with both of these issues.

Zero Signal · Feb 4, 2008

It just happens. I think it's some kind of feedback. I've always been able to fix it by running new power cables to the deck along with new grounds (for the amp as well as Nick pointed out). I always cross my fingers when installing things, because I never really know if it will happen or not.

Nick's advise on making sure there are no kinks in the RCA cables should go without saying, but definitely make sure. Sometimes people cram the hell out of the deck to get it to snap into the bracket, but that only leads to kinked RCAs and bent posts which is never good.

Black95GTS · Feb 4, 2008

GreenStangGT said:
Hmmm. It doesn't sound like there is anything wrong with this advice, but it makes me wonder. Why would this new noise start right after I installed the new subs and amp? This noise was never present before they were installed and none of the original wiring of the headunit was changed when I completed this new installation. Any ideas?

Hmm. Hearing the RPM issue, I'd say you have a ground loop. Make sure the connections are good. I make a point to scrape both sides of the ground connection with a pocket knife until I can see bare metal before I reef it down.

Can't hurt to check the RCA connections either.

Electrical gremlins are misery...

Adam

iwashmycar · Feb 4, 2008

def sounds like a ground issue....or really cheap RCAs

turbogt · Feb 4, 2008

first check ground... then you can start the car up and use an Ipod or mp3 player plugged into your amp with a 3.5mm headphone jack to rca cable and determine whether it's from your source or rcas....

GreenStangGT · Feb 4, 2008

I know for a fact that the amp is well grounded. I sanded the chassis and secured the ground firmly.

Something odd, it does seem as though the noise only occurs when the 'auxillary' input is selected on the headunit, and not when the radio is playing. It's possible that I just have more difficulty hearing the noise with the radio on though.

HISSIN50 · Feb 5, 2008

My first thought was also an issue with the amp's grounding pathway. The common sourcing of grounds to one spot helps with this (along those lines, John's advice about running a new dedicated HU ground was very good).

When I got the 88, you would hear squealing through the amp channel when I broke the rear tires loose. It was so puckin annoying. Some re-running of power cables fixed it.

One last thing is that some RCA outputs have grounding issues (one can mechanically ground them). I dont know if your deck is like this though (it's another line of decks which are known to have this issue).

Good luck.

GreenStangGT · Feb 5, 2008

So basically I should re-ground the amp and see if the problem goes away? And if it doesn't I need to re-ground the deck too?

95BlueStallion · Feb 5, 2008

I would re-ground both amp and deck, and depending on the quality of RCAs, maybe replace them if they are cheap. Good quality RCAs will help your sound quality if nothing else, especially if you used some cheapies. I know this cause my first few stereos I used cheap wiring and learned my lesson.

turbogt · Feb 5, 2008

95BlueStallion said:
I would re-ground both amp and deck, and depending on the quality of RCAs, maybe replace them if they are cheap. Good quality RCAs will help your sound quality if nothing else, especially if you used some cheapies. I know this cause my first few stereos I used cheap wiring and learned my lesson.

Difference between expensive RCA's and Cheap ones.....................SHIELDING

ANYWAY, since you say your problem is only when the deck is on aux, I would reground the deck and personally, pull the SONY out and run over it multiple times... When using RCA's for a sub amp, you can get away with a pair of $5 rca's and be just fine...

GreenStangGT · Feb 5, 2008

turbogt said:
Difference between expensive RCA's and Cheap ones.....................SHIELDING

ANYWAY, since you say your problem is only when the deck is on aux, I would reground the deck and personally, pull the SONY out and run over it multiple times... When using RCA's for a sub amp, you can get away with a pair of $5 rca's and be just fine...

I will have to look into regrounding the deck, but I'm still confused as to why this would have happened only when I put in the new stuff. Nonetheless, I'm going to try it when I get a little free time. Hopefully tomorrow.

As for running over the Sony... I think I'll pass. I've had three Sony decks and have gotten awesome performance out of all three. Hands down better than the other decks I have tried and even better than the much more expensive decks a couple friends of mine have. This is the first oddity I've had, and I don't really think it's the fault of the deck.

95BlueStallion · Feb 5, 2008

GreenStangGT said:
I will have to look into regrounding the deck, but I'm still confused as to why this would have happened only when I put in the new stuff. Nonetheless, I'm going to try it when I get a little free time. Hopefully tomorrow.

Thats what makes me lean toward your amp ground, or the RCAs. It started after the install of the new stuff. So it pretty much has to be something not secured correctly, ground that isnt quite up to par during the installation, or a faulty piece of equipment.

GreenStangGT · Feb 5, 2008

95BlueStallion said:
Thats what makes me lean toward your amp ground, or the RCAs. It started after the install of the new stuff. So it pretty much has to be something not secured correctly, ground that isnt quite up to par during the installation, or a faulty piece of equipment.

Unfortunately it is neither of these problems. The sound still occurs when the RCA's are unplugged, and I re-did the ground with no change.

Am I to the point of re-grounding the H/U?

Chythar · Feb 5, 2008

I had a similar problem on my 94 V6, I was told the problem was the spark plug wires being "worn" and allowing electrical interference. At the time, I replace the wires and the buzz went away; but only for a short time. It always returned. I haven't had the problem for years, so apparently I changed something that fixed it.

You altered the electrical drain on the system when you added the sub and amps, so you may have revealed a problem that was already there. Your Sony head unit may be able to filter out the interference, but the sub and amps can't.

Here's a GREAT article I just found on eliminating noise from a car stereo:

http://www.termpro.com/articles/noise.html

GreenStangGT · Feb 5, 2008

From the sounds of things here, as well as after reading that great webpage, it sounds like I have a ground loop and need to re-ground the H/U. I'll post here after I do that.

Weird Audio Problem, Help!

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