help with nasty nasty noise. search yeilds nothing.

[d audio 450 10+ year member]

after waiting well over 4 months to get this crazy system of mine in.........i get 2 jl 4inchers in with the dub7 and jesus w. christ the noise is THE worst noise ive ever heard from a system in a car, and i'd say that actually says something, having worked as an installer. i thought the noise would primarily be from the three fans i have running to cool the amps......but nope. its gotta be the alt whine.....i was lookin in my parts express catalog and found noise suppressors for like 17 bucks a pop but they only handle 35amps....i suppose i could put three or four of em in parallel, but im not exactly sure how that filtering works, and paralleling them may change the parameters of the filters......not sure. bottom line is, i GOTTA get rid of this noise.....using what ive learned in school...i was wondering if the right assembly of capacitors might help filter out that whine....i have an o-scope that i was thinkin about hokin up but i wanna get some other opinions b4 i start goin at it alone....if anyone knows where i could even find schematics, thatd be awesome - im familiar with alotta shit, being a junior in temple u's EE program.

thanks for any help...

-pat

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[stones 10+ year member]

What you are suggesting is needlessly complicated.

#1 Try adding a cheap common noise filter to the HU power wires.

#2 Ground the RCA's by simply wrapping a peice of wire around the unsheilded part of the RCA and then grounding it to the chassis of the amp, HU or the car itself.

#3 Run your RCA wires further away from any noise sources.

#4 Try grounding your amps in a different spot.

#Do "the big three" http://forum.sounddomain.com/forum/ultimatebb.cgi?ubb=get_topic;f=5;t=007801;p=

Theres lots of stuff you can do with out buying a bunch of stuff, try my suggestions and come back.

 

[tRiGgEr 5,000+ posts]

If you're such a "master installer" you would know the cause is either the grounding point of your equipment, or faulty equipment. IE: Amp/HU...

 

[d audio 450 10+ year member]

stones, thanks a lot. good checklist. it's much appreciated. the grounding of the rca's seemed to kill 99% of the noise, im definitley going to redo the grounding of the the batt and alt as well, as the big 3 says. again, much thanks.

trigger, is it me you mock with the quotation of "master installer"?

-pat

 

[AVSTANG02]

Grounding the RCA's seems like a band-aid fix???

whats the cause of having to ground the RCAs ???

 

[d audio 450 10+ year member]

Grounding the RCA's seems like a band-aid fix???
whats the cause of having to ground the RCAs ???

if im understanding what your asking.....there was crazy mad noisage. buzzing and hissing and such....liiittle bit of it was from my fans i got running (to cool off my amps)....but when i turned those off to see there was still a real hefty bzzing noise goin on. first check i did was the grounding on the headunit- saw a buncha peoples badmouthing the grounds on pioneer headunits......did nothin when i regrounded it (understood that if it were inside the h/u it wouldnt really matter anyway)....so outta chance i just tapped the grounded wire to the rcas and that shit was GONE. i suppose it makes sense to me, but i was under the impression that the noise was injected via the instability of the exact voltage of the power lines....like tiny ripples caused from minute changes in current pull...or something.

so there thats the cause of having to ground the rcas. have a splendid day.

-pat

 

[stones 10+ year member]

Grounding the RCA's seems like a band-aid fix???
whats the cause of having to ground the RCAs ???

Ground loop.

Info on ground loops-

Basics

A good power distribution system is essential for proper operation of audio system. Professional audio systems just doesn't work well with normal extension cords running hundreds of feet to a stage. Besides the power feed the good grounding of thw whole system is essential.

Ground loop is a condition where an unintended connection to ground is made through an interfering electrical conductor. Generally ground loop connection exists when an electrical system is connected through more than one way to the electrical ground.

When two or more devices are connected to a common ground through different paths, a ground loop occurs. Currents flow through these multiple paths and develop voltages which can cause damage, noise or 50Hz/60Hz hum(variable in cars) in audio or video equipment. To prevent ground loops, all signal grounds need to go to one common point and when two grounding points cannot be avoided, one side must isolate the signal and grounds from the other. (Grounding the RCA connects the two components to share a ground eliminating the stray voltage -stones)

Usually ground loops are an after-the-fact type of problem in which the end-user blames the installer, the installer blames the manufacturer, and actually nobody is at fault. Neither the manufacturer nor the installer can usually predict where a loop will occur. Only after the system is installed can it be determined if a problem will exist.

Ground loop problems can be corrected and avoided. It is important for the dealer, isntallee and the end user to be aware that this problem can occur. It is a good idea to design the system to avoid most obvious source of this kind of problems, and then be prepared still to face some problems when starting to use the system. A ground loop problem may occur at several points in the system, and each occurrence of the problem must be corrected individually.

more-

http://www.epanorama.net/documents/groundloop/index.html