After my audio upgrade, I am having a serious issue. Engine noise!

When driving I get high pitched noise coming from the speakers. It goes in accordance with me revving the engine. (e.g. if I give it gas it gets louder).

It is such a pain to troubleshoot. I appreciate any advice you might have to fix.


Some causes of engine noise:

1. Bad ground for the amp
2. Bad ground Line Level Converter box.
3. Too long a ground wire for Amp
4. Too long a ground wire for Line Level Converter.
5. Running power cables along side speaker wires.
6. Running power cables along side Processor or Line Level Converter.
7. Running RCA cables near power cables.
8. Using RCA cable that crappy?


Some potential no-no's / problems I had:

1. I was running my amp power cable along side my right channel speaker wires and RCAs. I separated them but it did not solve the issue.

2. I was running amp power cable along side re-q5 module. Separated, did not fix.

3. I ran 16 gauge speaker wire to power the re-q5 (line level converter). This was recommended by the re-q5 guys (I called them). I ran the 16 gauge wire along side the amp power cable to the battery. I connected the positive lead to the pos, and the ground to the negative. I thought perhaps the ground was too long, so I cut this ground and tapped the ground wire closer to the modele (just 1 foot away to a grounding plate). Did not solve problem.


Also, here are some things I learned:

1. The noise plays through all 4 speakers.

This wields out the possibility that just the right side speaker cables were picking up sound from power cable.

2. The noise plays even when the car stereo is off.

Not sure what this means. The amp will still play music when the car stereo is off. The car stereo is just an "input" at this point. (For instance, the re-q5 has a line level input which will play independent to whether stereo is on). High pithed noise will also play when line level input is off.


Other info about my setup:

The ground for my amp is only 3 feet long and runs from the amp (in the boot) through a hole, under the car and attaches to a bolt on chassis. I scraped away the metal with a screwdriver to get a clean connection. I think it is pretty good.

I cut 8 speaker leads at x9331 and soldered connections to 8 x 16 gauge cables (taped together and ran) to the req5 in boot. I ran it up drivers door side, across base / front of back seats and up to right corner of boot.

I ran speaker cable from amp in boot up to crossovers under each of seats and from there through the doors to speakers.

I bought standard RCA cables from an electronic store. They are not special but are decent. I heard something that the RCA cables should be "encased." I am not sure whether they are encased (to protect from ouside noise pickup), but right now the RCA cables are completely separate from any other wire runs.


Don't know what else I could tell you. Thank you for your ideas and advice.

Update

Perhaps I need an in-line noise filter.

Could that actually solve my problem?

Something like one of these these:

http://www.crutchfield.com/S-rTAWG4H...e-Filters.html

Thanks.

 

The first thing I would try is re-doing the power and ground for the system. The ground especially. First, I wouldn't have the ground attached under the car... exposed to the elements? Not sure if it would cause a problem but I'm guessing it might. No reason to leave that to chance. Attach it inside the car somewhere. Second, instead of just scraping away paint with a screwdriver, use a rotary tool with a wire brush attachment (like a dremel, drill, or grinder) to clear away the paint. Poor ground connections cause the majority of these type of problems. Make sure your end connectors on the power and ground cables are crimped nice and tight. If all else fails, try a power line conditioner.

Oh yeah, and you also might try grounding the re-q5 and the amp to the same point. If the re-q5 has an output adjustment **** (increasing the voltage sent to the amp), I highly recommend cranking that up to the maximum that doesn't induce clipping. Then, reduce the gain on the amp. This should help also.

 

why did you feel the need to ground the amp outside the car? There are plenty of good grounding locations inside the boot.

Where is the re-Q grounded?

Does the amp have speaker level inputs? If so i would try bypassing the re-Q.

I would spend the time to solve the ground loop before putting a filter in line..they tend to roll off the highs too much for my liking.

 

I had everything grounded right and was setup well.

I needed to install a noise filter however, like these:

http://www.sonicelectronix.com/viewc...469&f_745=2823

I got a 15 amp one. I have the power run for my line out converter / bass restoration module (re-q5) ran directly off the amp. I took the amp power cable and the re-q5's power cable and plugged them into the same spot on the amp (power line in port). (I also did this for the ground). The power wire for the re-q5 leaves the amp, goes through a small fuse, then through this unit (the noise filter), and finally to the re-q5.

Totally fixed my high pitched (oh my god im gonna lose it) noise.

YES!! I can put my car back together now and enjoy the sweet sounds of paradise toonage.

Thanks for your replies. Hopefully this information can help someone with the same issue in the future. Let me know if it does.