Page 4 of 6 FirstFirst 123456 LastLast
Results 31 to 40 of 56

Thread: Ewww, ground noise finally isolated, now wut!?

  1. #31
    Constant Bitrate Specimen's Avatar
    Join Date
    Jul 2005
    Location
    Los Angeles, CA
    Posts
    153
    Quote Originally Posted by proph
    Man everyones thought process, and plans of action can really vary.
    I guess too many cooks does spoil the soup
    PROGRESS [==========-] 99.9% <- Are we ever really actually done with our carPCs?

  2. #32
    Raw Wave tj!2k4's Avatar
    Join Date
    Oct 2004
    Posts
    3,294
    Quote Originally Posted by TheLlama
    try getting a noise isolator at wal-mart for $15. I think they are made by Scotsche or something. It is basically two big coils that pass sound from one to the other via inductance. It may degrade sound quality some, but it is a good test. For $15 you can keep it if it fixes the problem and sounds good or just return the thing.
    You mean, like the first item I have for sale?

    tj!2k4's FS Thread [US/NY/Westchester]

  3. #33
    FLAC sdashiki's Avatar
    Join Date
    Aug 2004
    Location
    Floreeda
    Posts
    1,085
    So I need to do what exactly, wills post

    "cutting a set of RCAs to a couple inches and shorting the inside wire to the outer shield. Plug em into the amp and turn em on."

    make only a little sense to me.

    I need to get some RCA plugs (L/R pair) and cut off one end so all I have is 2 RCA plugs and 2 bare wires?
    Then what?
    IM stoopid about this I guess.
    (All done)
    iPad Mini 128GB, RF 600.5 amp, JL12W0V2, 8 Infinity Components

  4. #34
    Constant Bitrate Specimen's Avatar
    Join Date
    Jul 2005
    Location
    Los Angeles, CA
    Posts
    153
    Na, you’re not stupid it’s a hard idea to grasp. Let’s see if I can explain this a little. What makes the actual sound from the speaker is the voltage difference between the positive connector of the RCA (inside) and the negative connector of the RCA (outside shield). Ideally the negative should be at 0 Volts and the Positive will fluctuate from + to – Volts to push the speaker in and out. Now the issue with a ground loop problem is that the negative connector is not at 0 Volts ideally but is rather a slightly positive voltage or is fluctuating. If it fluctuates you will hear a whine change as you rev your car. If you hear a buzzing that means the ground is not at exactly 0 Volts (bad ground). So if two components are reading different ground values say +.5 volts on the amp and +.9 volts on the Head unit, they are both going to get different values when subtracting ground from the Positive connectors, introducing a buzzing or whining noises as it passes through the components to your speaker.

    Now the reason why we short the positive to the negative on the RCA plug is to keep both the positive connector and the negative connector at the same voltage. If the ground is fluctuating in voltage, that same change will be sent down the positive part of the RCA cable into the amp. Same voltage on both line means when you subtract them, you get a difference of 0 Volts or silence in the speakers. By doing this, you should ideally not hear anything when you connect a speaker directly to the amp audio output. That’s why they’re called mute plugs cause its like you muted your system.

    From there we start to narrow it down as to what might be the cause, your amp, or the rest of your setup.

    The reason why everyone is saying to scrap off the paint is because anything that provides resistance (loose connection, wire that is not think enough, etc) will change the GND reference from 0 Volts to a slightly positive voltage causing ground loop issues.
    PROGRESS [==========-] 99.9% <- Are we ever really actually done with our carPCs?

  5. #35
    FLAC sdashiki's Avatar
    Join Date
    Aug 2004
    Location
    Floreeda
    Posts
    1,085
    to short out RCAs just clip one end off and connect the wires inside?

    oh and if this matters, when you turn the key to start the car (all electronics off, even with the RCAs disconnect but the remote-on wire still to the HU so as to turn on the amp) you hear a WHIIIIRRRR in the speakers like its listening to the alternator turn and rev up?

    which is weird because the amp isnt "on" and the HU hasnt told it to come on while the car is starting...so nothing should come from the speakers at all but there is something carrying over into the speakers even during starting.
    (All done)
    iPad Mini 128GB, RF 600.5 amp, JL12W0V2, 8 Infinity Components

  6. #36
    FLAC sdashiki's Avatar
    Join Date
    Aug 2004
    Location
    Floreeda
    Posts
    1,085
    I got a couple of these lying around:

    Name:  DSC00222.jpg
Views: 265
Size:  47.1 KB

    which gave me this out the end:

    Name:  DSC00223.jpg
Views: 229
Size:  14.3 KB
    (All done)
    iPad Mini 128GB, RF 600.5 amp, JL12W0V2, 8 Infinity Components

  7. #37
    Constant Bitrate Specimen's Avatar
    Join Date
    Jul 2005
    Location
    Los Angeles, CA
    Posts
    153
    yes

    where is your "remote on" connected to on the amp. Is it connected to the HU "amp on" wire? Also where is your "remote on" connected to for your crossovers? Same as the amp?
    PROGRESS [==========-] 99.9% <- Are we ever really actually done with our carPCs?

  8. #38
    FLAC sdashiki's Avatar
    Join Date
    Aug 2004
    Location
    Floreeda
    Posts
    1,085
    crossovers are passive, came with the infinity components kind of deal.

    the "remote on" is connected to the "Blue/White wire which is for 'system control terminal of the power amp or Auto-antenna relay control terminal'" out of the head units wire harness.

    HU to amp with a long wire....which could be frayed and shorted to the chassis maybe somewhere...its an old long wire and pulled alot thru the car if I recall correctly...is this starting to make sense or somethign?
    (All done)
    iPad Mini 128GB, RF 600.5 amp, JL12W0V2, 8 Infinity Components

  9. #39
    FLAC
    Join Date
    Sep 2004
    Location
    Falls Church, VA
    Posts
    904
    Twist all of the wires together to form a muting plug. You will want one for right, one for left.


    I wonder if he is getting RFI through the passive crossovers? Just a thought...


    I have a 4 ohm speaker on a 2 foot piece of wire. I tinned the ends with solder and use it as my test speaker. If it were me, I would use the plugs and one test speaker. Turn the amp on and carefully attach the test speaker to each output channel, one at a time. If the sound is still there, its the amp. No way around it.

    Do you have the amp mounted to metal using metal screws?

  10. #40
    Constant Bitrate Specimen's Avatar
    Join Date
    Jul 2005
    Location
    Los Angeles, CA
    Posts
    153
    if the Blue/White or the frayed old long wire was shorted to ground, your amps wouldn't turn on at all.

    Just connect the white and black wire in the middle of the RCA together. The outer one is just a shield and probably doesn't need to be connected to anything.
    PROGRESS [==========-] 99.9% <- Are we ever really actually done with our carPCs?

Page 4 of 6 FirstFirst 123456 LastLast

Similar Threads

  1. The quest for no noise
    By mp31500 in forum General Hardware Discussion
    Replies: 26
    Last Post: 04-02-2007, 11:12 PM
  2. Noise!! AARGH!
    By sq_geek in forum General Hardware Discussion
    Replies: 23
    Last Post: 09-21-2004, 02:33 PM
  3. Learn and fix ground loop noise
    By 14.4vTech in forum Car Audio
    Replies: 3
    Last Post: 07-03-2004, 09:55 PM
  4. stupid ground noise!
    By EvilInside944 in forum General Hardware Discussion
    Replies: 2
    Last Post: 08-14-2002, 11:29 PM
  5. Alpine / PC Challenges all around...
    By acitrano in forum General Hardware Discussion
    Replies: 5
    Last Post: 11-10-2000, 08:45 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •