Alright got my system all ready to go and wired for tuning.

 

First i set my gains using an oscilloscope on my sub mono amp.  All went well.

 

Then i set my gains on my 4 channel amp.  All went well.

 

I plugged in the speakers, and i am getting high pitch scratching noises that vary and change intermittently.

 

When I turn off the subwoofer rca output from the headunit to the rear, the sub no longer gets any signal obviously..

 

but if i have rcas plugged into the 4 channel amp...... the sub then starts playing music!

 

could this be my twisted pair rca cables?  should i switch to coaxial?

Wow, that's interesting.  Can you post up a pic of the amps and the way they're wired?  Something definitely seems off.

More info... just ran a set of regular coax RCA's to the back... not the issue.

Tried 2 other amps I have laying around.... not the issue.

Set all gains as low as possible to check for clipping... same thing.

I do get an amplifier whine on top of the noise I am getting.

Big 3 is done...

What HU are you running?  When you say you tried two other amps and not the issue, what exactly happened when you hooked them up?  Whine on top of everything else is an indicator of a ground issue in most cases.

I tried other 4 channel amps.... same exact noise

Its a Kenwood x895 I've used it in another car it was great.. same amps in fact too no issue. I'm uploading pics now.

Does the noise come from the speakers without the RCA's hooked up?  It seems as though it does, which leads me to believe it's a source issue of some kind.  Try connecting an MP3 player or iPod DIRECTLY to the inputs on the amps, if the noise goes away and you get clean music then the issue must be with the source.  I've seen a few vehicles that the factory ground wire in the harness behind the stereo was crap, you could be having a similar problem.

Here are my 2 pioneer amps on the top shelf.

 

Here is how my crescendo is wired both 12v and ground directly to battery.

 

here is the wiring for the 4 amps i have total.. the 4 8awg wires on the left go to the pioneer amps.  my 4th amp is not on the rack as of right now im having it serviced.

 

this is my relay for switching all the amps on, it also switches on my lcd volt meter in the dash.

 

 

this is the ground wires to the wall of the trunk

 

no the sound stops coming from the speakers if i disconnect the rcas...  

 

let me go try hooking up my ipod directly to the amps... gotta hook everything back up give me a little bit

You need to sand the paint off that ground location, get it down to bare metal.  In fact it would probably be beneficial to try to find a better place to ground to.  The frame is preferred, but due to the uni-body design of today's cars pretty much impossible to get.

no the sound stops coming from the speakers if i disconnect the rcas...  

 

let me go try hooking up my ipod directly to the amps... gotta hook everything back up give me a little bit

 

No hurry dude.  Take your time, ensure you don't make any mistakes.  That's much more important than being in a hurry to get back on here with any answers.

What car is it? Maybe someone with experience with the same car can chime in on a better ground location.

On my mobile now... 04 intrepid

How would I get ground to the frame safely?? Drill???

Those grounds look kind of shabby. Try relocating your grounds to a solid, clean, oem bolt location.

For instance, I used my trunk latch bolts for my grounds.

You need to sand the paint off that ground location, ...

 

Make sure to always sand down to bare metal where ever you decide to ground the amps.

Grounds are fine... I ran rca from my ipod through the RCA's I had hooked to the radio.. gotta be a source issue.. this is clean with no head unit

How do I go about grounding the HU better?

When the key isn't on (in the accessory position) I get a hum in the speakers.... bad hu?

Edited May 6, 201312 yr by Patrick Danesky

Yeah, something is up with the HU it sounds like for certain.

That sucks... I loved this hu. I'm gonna try turning it on without the factory harness direct to the battery..

 

still getting the hum

Edited May 6, 201312 yr by Patrick Danesky

Well alton, id just like to say thank you for everything...

 

the box you designed pounds.  i was playing a 25hz tone at full blast earlier... my garage windows were shaking, and the roof was flexing like crazy.

 

thanks again bro, youre the best.

Well alton, id just like to say thank you for everything...

 

the box you designed pounds.  i was playing a 25hz tone at full blast earlier... my garage windows were shaking, and the roof was flexing like crazy.

 

thanks again bro, youre the best.

 

Thanks man, and you're welcome, I'm glad you're liking it.  Feel free to hit me up anytime.

In one of your photos I've noticed that you have 8AWG positive wires with no fuse. Yes, there is a 250A fuse on the main 0AWG lead, but if one of the smaller cables short on an amp case or something, the big fuse will not blow! I'd really recommend a distro block with 60-80A fuses when reducing the cables' cross-section.

Edited May 5, 201312 yr by groowe

I figured an amp that had visible fuses on it didn't needed to be fused additionally.