Wehan Posted September 24, 2015 Report Share Posted September 24, 2015 Car is a 2007 Chevy Cobalt coupe. Setup Head unit: Sony DSX-S300BTX, Grounded with my amps and power from same power distro as amps. Mids/highs: Crescendo C1100.4, Polk components front, polk 6x9's rear. Lows: JL 1000/1v1, 2x Alpine Type s 12's Electrical: (+) Stock 115a alternator 5' run of 1/0 from battery (+) to distro block splitting to a 3' run of 4ga to the JL and a 6" run of 4ga to the Crescendo, 12' run of 12ga too head unit. Electrical (-) 2' run of 4ga for both amps to one bolt all paint scraped/wire wheeled off to bare shiny steel, 12' run of 12ga for head unit. 5' run of 1/0 from amp grounds to battery (-), 1' run 1/0 from alternator bracket to strut tower. All power/ground wire is Kunkonceptz OFC Rca cables: Soundrive HF 17' to crescendo and Knukonceptz Karma SS 6m to JL. If the JL is getting this noise obviously the crossover or differential inputs are killing it so for the remainder of this when I reference the "amp" I am speaking of the Crescendo. I have run my rca cables every witch way possible and I still get it. If I unhook the rca at the amp its gone, if I unhook the rca at the head unit its gone. I don't have a spare head unit laying around to rule this out as the problem but it is looking like it is because if I understand correctly if the noise was penetrating my rca cables then it would still be present with the head unit disconnected correct?. Also I unhooked the antenna from the back of the head unit and tried grounding the rca to the head unit chassis and still had noise. Any help is greatly appreciated. One thing I am curious about is in this pic of a Chevy cobalt dash you can see the steel frame around the stereo bay. Directly under that and attatched to the steel frame is the fuse pannel and a bunch of other wires. I wonder if steel cage is acting as a transmitter antenna and directing all that noise from the wiring on it into my head unit and if there is anything I can do to stop that or rule that out? Maybe ground the head unit chassis to it? Link to comment Share on other sites More sharing options...
BigManAC Posted September 24, 2015 Report Share Posted September 24, 2015 Easy way to rule out the amp is by connecting an RCA to AUX into the inputs of the amp. If there is no noise then it is coming from the front end. 2001 Saturn L200-Sony MEX-BT4100PFRONT STAGE:- (4) Crescendo PWX 6- Cadence XA250.2SUB STAGE:-Fi Audio BL 15 (Sealed Off)-Crescendo BC2kELECTRICAL:- Singer 240A alt - XS Power D3400- SkyHigh OFC power/speaker wire- Big 3 with SkyHigh 0gaugeBuild Log: Click HereScores: 146.5db @ 29hz Outlaw Link to comment Share on other sites More sharing options...
Wehan Posted September 25, 2015 Author Report Share Posted September 25, 2015 Easy way to rule out the amp is by connecting an RCA to AUX into the inputs of the amp. If there is no noise then it is coming from the front end. Did this, no noise. Any Ideas on how to troubleshoot the head unit or do I basically need to replace it and hope for the best? Do those inline power filters I've see actually work or are they just BS? Link to comment Share on other sites More sharing options...
Deeznutz Posted September 25, 2015 Report Share Posted September 25, 2015 When you remove the cd player from the dash (isolating the radio from the chassis), I mean sitting on the shifter if you have one, do you still get noise? Since you're talking about the cresendo amp, did you try disconnecting the polk speakers, and bringing the speaker directly to the cresendo amp and connecting it to rule out the speaker wire or passive crossover as the culprit? -Frank Link to comment Share on other sites More sharing options...
Deeznutz Posted September 25, 2015 Report Share Posted September 25, 2015 As far as I know, an in-line noise suppressor acts as grounding the rca's to the chassis. You asked if the noise would be able to penetrate the RCAs even if the radio is disconnected, I would have to say no. When your radio's RCA output are connected, electrons are flowing. If you're talking about electromagnetic interference you would need the electrons flowing across the RCA to be able for the interference to be picked up. -Frank Link to comment Share on other sites More sharing options...
deathcards Posted September 25, 2015 Report Share Posted September 25, 2015 skip factory ground on your head unit, and make your own see if that help skar sk2500.1 0 gauge power and ground kunukonceptz alpine HUvxi65 components on BA gt-275new build log -> http://www.stevemeadedesigns.com/board/topic/150642-project-d-kon-deathcards-build-log/#entry2148821 2 x-15 sundowns singer alt, odyssey bat, and maxwell ultra caps Link to comment Share on other sites More sharing options...
Deeznutz Posted September 25, 2015 Report Share Posted September 25, 2015 Wehan, when you connected the RCA's to the radio, was the radio turned off when all connections were made? I was always told "never connect a live RCA from the radio to the amp because the shielding in the wire could be damaged". How true this is, I am not sure, I just never connect/disconnect RCAs without turning off the radio power supply. -Frank Link to comment Share on other sites More sharing options...
Wehan Posted September 25, 2015 Author Report Share Posted September 25, 2015 Yup, everything powered off when connected/disconnected. Noise still present if I pull the HU and set it on my center console. Head unit is already grounded at my amps ground. Link to comment Share on other sites More sharing options...
Deeznutz Posted September 25, 2015 Report Share Posted September 25, 2015 If you tried the AUX RCA trip like AC suggested, than yes it could be your radio. I purchased an old school Sony (Mobile ES series from the 90's) SQ unit for $40.00 last year. When I brought it home to test, it made noise whenever the motorized parts would move. Go to Wal-Mart, pick up a cheat radio, test it, and rule it out, return it! -Frank Link to comment Share on other sites More sharing options...
Wehan Posted September 25, 2015 Author Report Share Posted September 25, 2015 Actually I have an old Panasonic in my project Jeep I forgot all about, I'm going to hook that up and see what happens. Link to comment Share on other sites More sharing options...
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