Noise in my speakers

sharpee64 · 21st April 2010, 11:20 AM

hi guys,

i have just installed an amp in my ute, when i play music without engine running its fine but when the key is turned to the on possition there is a really high pitched noise. also when the engine is on i get alternator whine. i have tried many types of noise filters but if anything they make it worse. my power and rca cables are completly seperated aswel. my ground cable from amp is around 1ft to a bolt.

my front speakers are just connected straight to the head unit and they are fine. i have in front 4" fusion speakers and in back i have 6x9 fusion connected to an presicion audio amp 75w x2

Redshift187 · 21st April 2010, 02:58 PM

Could it be that the head unit isn't properly grounded?

I assume there is no paint or other coating preventing the amp grounding bolt to not actually be grounded?

Cal Weldon · 21st April 2010, 03:38 PM

Moved to Car Audio.

Perry Babin · 21st April 2010, 05:53 PM

You need to check the RCA shield ground on the head unit.
RCA Shield Repair

sharpee64 · 21st April 2010, 08:51 PM

how do i check grounding of head unit and the rca cables. but the front speakers connected directly to head unit work fine when engines on? its just speakers connected to the amp.

also could it just simply be a bad amp because it was second hand from a friend (he said he had it second hand also) and the brand ive never heard of?

Perry Babin · 21st April 2010, 10:27 PM

Click the link I posted.

sharpee64 · 24th April 2010, 08:46 AM

tested head unit (all normal)

today i wired the amp to a car battery charger and just plugged the rca's from head unit into amp and it works fine like it should even with engine on. But then when it put it back on battery i get noise again. what does this mean and what should i do now?

thanks

Perry Babin · 24th April 2010, 12:06 PM

If this is a bridgeable amp, disconnect the RCAs from it and measure the resistance from the input RCA shields on the amp to each of the non-bridging speaker terminals. What is the resistance?

sharpee64 · 24th April 2010, 12:21 PM

i dont think the amp is bridgable.

basically all i have is the two front speakers connected directly to head unit. and then an rca cable from head unit to the amp. then two 6x9 speakers connect to the amp. its only a two channel amp aswell.

i have also tried just connecting amp directly to car battery both power and ground, still makes the noise.

MikeHunt79 · 12th August 2010, 09:53 PM

I'm guetting similar problems in my car, but I think this is due to my choice of amp.

Anyway, here's something to try, does the volume of the whine increase when you increase the volume on your headunit or does the whine stay at a constant volume?

21st April 2010, 11:20 AM	#1
sharpee64 diyAudio Member Join Date: Apr 2010	Noise in my speakers hi guys, i have just installed an amp in my ute, when i play music without engine running its fine but when the key is turned to the on possition there is a really high pitched noise. also when the engine is on i get alternator whine. i have tried many types of noise filters but if anything they make it worse. my power and rca cables are completly seperated aswel. my ground cable from amp is around 1ft to a bolt. my front speakers are just connected straight to the head unit and they are fine. i have in front 4" fusion speakers and in back i have 6x9 fusion connected to an presicion audio amp 75w x2

21st April 2010, 02:58 PM	#2
Redshift187 diyAudio Member Join Date: Aug 2008	Could it be that the head unit isn't properly grounded? I assume there is no paint or other coating preventing the amp grounding bolt to not actually be grounded? __________________ Tyler

21st April 2010, 03:38 PM	#3
Cal Weldon Speakerholic diyAudio Moderator Join Date: Jan 2004 Location: British Columbia	Moved to Car Audio. __________________ Next stop: Margaritaville Some of Cal's stuff \| Cal Weldon Consulting

21st April 2010, 05:53 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	You need to check the RCA shield ground on the head unit. RCA Shield Repair __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

21st April 2010, 10:27 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Click the link I posted. __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


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21st April 2010, 08:51 PM	#5
sharpee64 diyAudio Member Join Date: Apr 2010	how do i check grounding of head unit and the rca cables. but the front speakers connected directly to head unit work fine when engines on? its just speakers connected to the amp. also could it just simply be a bad amp because it was second hand from a friend (he said he had it second hand also) and the brand ive never heard of?

24th April 2010, 08:46 AM	#7
sharpee64 diyAudio Member Join Date: Apr 2010	tested head unit (all normal) today i wired the amp to a car battery charger and just plugged the rca's from head unit into amp and it works fine like it should even with engine on. But then when it put it back on battery i get noise again. what does this mean and what should i do now? thanks

24th April 2010, 12:06 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	If this is a bridgeable amp, disconnect the RCAs from it and measure the resistance from the input RCA shields on the amp to each of the non-bridging speaker terminals. What is the resistance? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

24th April 2010, 12:21 PM	#9
sharpee64 diyAudio Member Join Date: Apr 2010	i dont think the amp is bridgable. basically all i have is the two front speakers connected directly to head unit. and then an rca cable from head unit to the amp. then two 6x9 speakers connect to the amp. its only a two channel amp aswell. i have also tried just connecting amp directly to car battery both power and ground, still makes the noise.

12th August 2010, 09:53 PM	#10
MikeHunt79 diyAudio Member Join Date: Aug 2003 Location: Bristol, UK	I'm guetting similar problems in my car, but I think this is due to my choice of amp. Anyway, here's something to try, does the volume of the whine increase when you increase the volume on your headunit or does the whine stay at a constant volume?

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