car amplifier makes weird noise

[api1243]

so i installed new speakers to an amp(4channels). i already had it with 2 speakers and a sub, i removed the sub and just wanted to install 2 speakers instead but while doing that my ground connector came loose from the am= i stuck it back in and the sound went weird basically thought something got fried like the speaker since i connected a new one instead of the sub and had still a place for 1 more since the sub took 2 channels . that ground came out and i stuck it back and secured it tightly i checked everything and basically it works like this: i can run 2 of the speakers either front or rear normally with either of them connected to every speaker line i want it to be RL +- RR +- FL +- FR +- all of them work and either RCA cables i set work for both the 2 for front and 2 for rear but the sound start when i try to connect anothr rca more then 2.. basically starting to use 3rd and 4th channels
dosnt matter what combination i try the 2 channels work wont matter what rca output(which channels i choose from the line in connections) i choose and which cables or speakers i connect to wherever its just gonna start making buzzing/humming noise together with the new 3rd/4th speaker when i connect their rca to channel 3/4 and i believe its just technically i hot wired the amp but it was already connected i just wanna know how can i fix the amp or try my solution for now all i did was make a new ground hole and drill it and connect it to chasis.

MY AMP is SP audio v15

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[1aespinoza 10+ year member]

just wanna know how can i fix the amp or try my solution

You can probably connect all 4 speakers with just two RCA inputs. No need to have all four RCAs in. The amp should have the option of just using Front RCA Inputs.

 

[audiobaun 5,000+ posts]

Make sure you have switched ch 3&4 back to FULL or HPF with the RCAs from the HU on Front or Rear connected to front and Rear ch being used for the amplifier in 4 ch Stereo mode with wires properly secured at the amplifier for the correct speaker and ch of left and right and poss and negative.

 

[audiobaun 5,000+ posts]

Make sure you have switched ch 3&4 back to FULL or HPF with the RCAs from the HU on Front or Rear connected to front and Rear ch being used for the amplifier in 4 ch Stereo mode with wires properly secured at the amplifier for the correct speaker and ch of left and right and poss and negative.

You can download your amplifier manual to view the settings and proper wiring of adding speakers usually for free. A Diagram will help you and you can view it as long and as many times needed

 

[api1243]

thanks for all the replys ill be on it asap and post an update maybe even a video

 

[api1243]

so an update:
basically i got my 2nd car which i just installed a car amp kit and routed all the wires so i thought to myself lets take this amp before i get a new one and test in the newly routed car. so i removed the good amp in my 2nd car and installed the amp that made the problems and all is working good.
later on i canceled the possibillity of the amp being bad since its good on another car and then i went on removed the headunit in my first car and decided to change rca cables without rerouting them ofc instead of the ones that are already installed. so i took 2 rca cables and connected the 4 from headunit side and the amp side and its still the same so that makes it clear... the head unit took some damage i guess?? amp is good cables are good ground is good and positive and fuse are good
so the thing i did is like that basically took 2 adapters from 1rca to 2rca and just used rear right are front right on the amp as front right on the headunit side and a rear left + front left to front left also connected to 1 singe rca on the headunit side. which now fixed it all.
the headunit just dosnt want to get more then 2 rcas
i have a nakamichi NAM5230 i got a month ago so the rcas over there are abit weird but dosnt matter as long as i can connect 2 rcas its enough 2 left are combined to front left and 2 right and combined to front right.(and yes i also tried powering the speakers from the headunit itself without any amp just straight 4 speakers to 4 speakers wire input on the headunit and all 4 works just not all 4 rcas.)
thx for all guys