new amp installed - whine help!

[jcraft 10+ year member]

Hi all,

Need some troubleshooting assistance here. I have a Sony HU installed for a couple years now. From the HU I am using RCA outputs running a non-shielded rca cable back to a JVC amp. this amp feeds a 12" sub in the trunk. four speakers are then fed from the HU. Now I purchased another amp (50x4) to run the 4 speakers. I put the 4 channel amp in the trunk also. I ran a separate # 8 wire to the new amp and also another # 8 wire and grounded to the same point as the sub amp. I then ran two 4 cond. # 14 cables ( on the other side of vehicle not near the power wires) from the new amp in the trunk back up to the dash and tied all the speaker wires in there. Now to test I used the rca cable that fed the sub amp ( pulled it from the amp) and used it to feed into the new amp. Now, when vehicle is not running and I turn HU/amp on, there is a very slight whine but as soon as you turn the music up even a bit you don't hear it. However, as soon as you start the car, there is a god awful whine coming from all the speakers. As you accelerate it increases and decreases with speed. Funny thing is I never got any whine from the sub/amp I had. I tried running a separate ground from the HU ( i only had a piece of 22ga. wire and ran it back and grounded it to the same point as the other amps). This kind of deadened it a bit but not much. Any other ideas on how to solve/troubleshoot. Hoping it is not the new amp. I also tried disconnecting each rca wire individually to see if anything changed but it didn't. Any other thoughts on what to try. Maybe I should use the RCA for the sub amp and run the new amp with the high level inputs. At present the HU only has one set of rear out/sub out outputs so I will need to put a bunch of Y connectors in to split to go to both channels of the new amp as well as one channel of the sub amp. Presently I have no Y's in the system though. Thanks for the help!!

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[maylar 10+ year member]

Why on earth would you use non-shielded RCA cables?

 

[pickup1 5,000+ posts]

Better rcas or maybe even bigger wire..

 

[jcraft 10+ year member]

I guess I am not sure if they are shielded or not. I bought them at radio shack and the seem to be a good quality. they look to be a gauge or two larger than the cheapest. in any event they are running the other amp/sub with no whine.

 

[maylar 10+ year member]

Sub amp won't play the whine frequency.

 

[jcraft 10+ year member]

Yes the sub amp will not play the whine frequency. I actually took the new one back and exchanged it for a new one of the same type. This one the whine was less pronounced but it was still there annoying as ever. THis is a cheap Boss amp I got from Advance auto. IT also sounded like crap when the car was off an I didn't have the whine ( hissing popping etc.) I transferd my front doors and deck speakers to the JVC I have running the sub and they sound great. I have ordered a Rockford Fosgate 300-4 which has great reviews and hopefully that will work nice and I'll return the peice of crap.

 

[maylar 10+ year member]

And get some good RCA cables. Something you can be sure of.

 

[nvturbo 10+ year member]

buying cheap components will lead to issues. Keep that in mind.

 

[ThatChevyGuy 5,000+ posts]

how long is your HU ground?