Featured Whining noise in Speakers

[97obs]

I have a 1997 Chevy C1500 OBS. Currently running Alpine ILX-W650. Audison SR-4.500 Mid/High Amp. 2 DC Audio A3 1.2KW. Pushing 4 6-1/2s 2 sets of Pro Audio Tweeters. 2 Deaf Bonce Apocolypse 10” subs under back seat. I have a X-Brand 360w alternator. 2 XS 3400 Batteries. Everything is wired with Sky High Car Audio 1/0 OFC Wire. I have SHCA premium rca cables. Amp's are mounted behind rear seat on wall. Right now I have 1 battery on each side in engine compartment. I have grounds run from DS battery to distribution block that also has alternator run to frame. It’s also tied into Ps battery also ran to distribution block grounded to frame and engine. Power is ran from DS battery to PS battery via a SMD fuse block. Power from amp is also tied into this fuse block. Power to starter also comes from this fuse block as does the power to amps. Behind the seat power is fed to a SMD fuse block to each amp. Ground is from distribution block to each side of frame under truck and to each amp. The head unit in dash is also grounded to the frame via an 8 gauge wire. I am getting a real bad alternator whine. Is there something I have connected wrong. How
Can I isolate the amps from getting this noise? I am only getting it in the mids/highs. I am at a loss.

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[Doxquzme Premium Member]

RCA's on the MID/HI amp? Shielded/twisted?

Are you able to feed the MID/HI amp with an outside signal to see if it is the amp that is picking up a noise signal? Use your phone or laptop, feed the MID/HI amp directly off the phone/laptop and see if it goes away.

 

[97obs]

RCA's on the MID/HI amp? Shielded/twisted?

Are you able to feed the MID/HI amp with an outside signal to see if it is the amp that is picking up a noise signal? Use your phone or laptop, feed the MID/HI amp directly off the phone/laptop and see if it goes away.

They are shielded. How do you recommend using my phone to feed the amp? I only use my phone currently as the source. I have tried Bluetooth and wired Apple car play.

 

[Doxquzme Premium Member]

Directly into the amp with this. Bypass the RCA's in use to isolate the source of the noise. Turn the car on, plug this directly into the amp from your phone, see if the issue is with the other RCA wires.

https://www.amazon.com/gp/aw/d/B09GFQHRFW/?_encoding=UTF8&pd_rd_plhdr=t&aaxitk=935a1f1366c1d0de1758212b9c4eca4f&hsa_cr_id=4265783540901&qid=1718577184&sr=1-2-9e67e56a-6f64-441f-a281-df67fc737124&ref_=sbx_be_s_sparkle_mcd_asin_1_img&pd_rd_w=8PXqE&content-id=amzn1.sym.417820b0-80f2-4084-adb3-fb612550f30b%3Aamzn1.sym.417820b0-80f2-4084-adb3-fb612550f30b&pf_rd_p=417820b0-80f2-4084-adb3-fb612550f30b&pf_rd_r=4TDC221NYTYDHWNRYQVZ&pd_rd_wg=ne6r0&pd_rd_r=dfeb69cd-e17a-45a7-872a-351fe92e7b7e

If you are using your phone are you also using any kind of aftermarket EQ/DSP/LOC type of signal distribution in the loop?

 

[97obs]

Can it be the way I have alternator hooked up in the circuit?

 

[Doxquzme Premium Member]

Not likely. Again, do you have and EQ/LOC/DSP or anything else but your phone in the signal path?

 

[97obs]

Not likely. Again, do you have and EQ/LOC/DSP or anything else but your phone in the signal path?

My phone is hooked up via USB cord to alpine hu. Then from hu to amps via Premium Shielded SHCA rca cables.

 

[1aespinoza Premium Member]

I am only getting it in the mids/highs. I am at a loss.

To what radio volume are your gains set? I used to have my gains set to 10 on the radio. When I changed out my starter, something went screwy and I started getting whine out of the alternator. I had to set my gains with the radio at 75% volume.

 

[97obs]

To what radio volume are your gains set? I used to have my gains set to 10 on the radio. When I changed out my starter, something went screwy and I started getting whine out of the alternator. I had to set my gains with the radio at 75% volume.

I used a SMD Distortion Detector to make sure I had clean sounds. HU clean up until 31. Gains were also set on amps with DD and none detected at 30. I have had 3 different amps. All did it. Multiple sets of RCA cables. Everything wiring wise is SHCA. Nothing cheap.

 

[1aespinoza Premium Member]

. I have had 3 different amps. All did it. M

Would you run a power and ground from the amps to the radio and test it out? OEM radio wiring may also cause the issue.

 

[97obs]

Would you run a power and ground from the amps to the radio and test it out? OEM radio wiring may also cause the issue.

I will certainly try that. So just instead of connecting hu to factory power wire. Connect it and the ground to distribution block at amps?

 

[1aespinoza Premium Member]

I will certainly try that. So just instead of connecting hu to factory power wire. Connect it and the ground to distribution block at amps?

Yes.

 

[maylar 10+ year member]

You have read the whine-and-ground-loop sticky here, right?

I've only had alternator whine in one install, and it was nearly impossible to eliminate. A 1985 Oldsmobile and Pioneer deck. Pioneer was famous for whine back in the day. Problem comes when the ground for the HU is at a different zero-voltage than the amp's ground. RCA cables have a shield that is at ground potential, and when you tie amp and HU together you get a "ground loop", where current flows through the shields.

In this car, the deck was grounded to the dash through its case, and it didn't matter where the ground wire was attached. Amp was grounded via heavy cable to the body in the trunk, and that was different from the HU ground. Years of rust between body panels helped to make the ground points different.

The solution was to use a ground loop isolator on the RCA cables. If your whine goes away when the RCA cables are unplugged, this may be a solution for you.