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Thread: extra buzz, audio/power connections

  1. #1
    Variable Bitrate
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    extra buzz, audio/power connections

    I ran all my power down one side of the car, and the audio down the other. Lets start with the power issue...

    I took a cig adapter to an inverter and cut it in the middle of the wire. I added extra wire to increase the length to run the inverter to the trunk. Because it required both a pos and neg lengthening I'm thinking it could be a grounding issue. The extra noise here is not that the inverter is running, the fans don't bother me, but the subs seem to be constantly moving (low bass, but not loud, just barely audible to be annoying). This continues even with the inverter unplugged from the cig lighter, and cd player turned all the way down. I also have my laptop opened (it didn't like turning on when closed, it did once in a while though?), power cord wound up and taped so as not run throughout the trunk, and mounted behind the subs so it can't be seen. Is there too much power stuff going on by the amp/subs to create a clean environment, would it even get better with extra grounds?

    The second issues is with the audio...

    I ran an 1/8" (headphone) extender from the jack on the laptop to the non power wire side of the car. I also had to run an extender off of this to reach the aux input on the front of a new headunit. Doing this creates a whine/buxx sound that gets louder as volume is turned up. I figured this is because of the connections where the 2 connectors plug into each other. If get rid of the connection and splice them together would the whine/buzz continue, get worse, or better? If someone might know, if these are spliced together, would this also be better off getting grounded as well?

  2. #2
    Newbie p3rlphr33k's Avatar
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    buzz kill

    The power inverter is the culprit. The power that comes out of it is a modified square sine. If its not a high end inverter it will create a lot of interference. Not only does this create annoying buzz sounds, but this is actually very hard on the equipment after a long period of time. This is just my opinion on the issue, I cant be sure without assessing the problem but, If you want to kill the buzz sound look into these:

    http://www.google.com/search?sourcei...+loop+isolator

    Install this between the PC audio out put and the head unit input. This should do the trick, good luck!

  3. #3
    MySQL Error soundman98's Avatar
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    so your inverter is still plugged into the cig. lighter?

    cue 2k1 toaster artwork:



    from what i get from reading between the lines, part of the problem is going to be where everything is getting power, and is grounded to.

    cig. lighter plugs are notorious for having poor power and ground connections-- look into at least hard wiring the inverter to the battery(make sure to fuse within 12" of the battery!!)..

    if your radio, sub amps, laptop, and inverter all are grounded to different locations, this could also be a cause-- try to combine some of the ground points to the same spot, so they all have a similar ground plane.. also, make sure to sand the paint away from the ground point to prevent the paint from interfering with the connection.


    for the laptop audio cable-- it is not usually the splice point that causes problems but the way the devices get power..

  4. #4
    Newbie p3rlphr33k's Avatar
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    Inverter info

    Pure Sine Wave Inverters
    The power supplied by the national grid (found in a typical households) is 230V 50Hz AC - or alternating current. The current effectively 'switches direction' 50 times every second. There in no positive or negative as there is with a battery. The change is smooth and gradual conforming to what is called a 'sine wave'. Pure Sine Wave inverters are the most efficient and highest quality inverters available, producing a sine wave. Because Pure Sine Wave inverters produce little distortion, they are able to run even the most sensitive electronic equipment.


    Modified Sine Wave Inverters (also called Modified Squarewave)
    Designed to emulate a sine wave waveform, Modified Sine Wave are cheaper than Pure Sine Wave inverters. They mimic the sine wave shape in large steps (much like that of a stairwell). Lots of simple appliances like light bulbs and electric motors will work fine with a modified wave inverter...though they produce more noise and heat. As these inverters do not produce clean sine wave power, it is not recommended you use them to run electronic equipment like TVs, stereos and computers. Clocks and other timing devices can run either fast or slow.
    Attached Images Attached Images  

  5. #5
    Newbie p3rlphr33k's Avatar
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    cig plug

    I do agree with the comments regarding the cig plug. They are not suitable for powering such devices for the reasons listed above and because the gauge of wire used is not meant to carry the current required to power this equipment without getting hot and melting it not fused properly. Otherwise, you will blow fuses or melt something or worse, starve your devices for power and cause them to prematurely die.

  6. #6
    Neither darque nor pervert DarquePervert's Avatar
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    Quote Originally Posted by soundman98 View Post
    cue 2k1 toaster artwork:
    Seems this masterpiece is getting lots of use of late....
    Have you looked in the FAQ yet?
    How about the Wiki?



    Under normal circumstances, a signature would go here.

  7. #7
    Variable Bitrate
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    I have to admit, I even saw the artwork earlier in the day in another thread /facepalm...

    The only thing that is powered from the inverter is the laptop. I got the inverter because in the future I wanted to use the other set of hookups for it that will go to the battery (with a switch in between so not to drain it). It also has 2 outlets on it and I was gonna extend one of them to the front to mount.

    If the inverter is really the cause of the problem and since only my laptop uses it, would it be beneficial to look at the dc-dc laptop cables. I know I've seen them linked before, but if someone has feedback on them before I spend the money on that as well and have the same issues that would be great. I will also try getting one of the ground loop isolaters and see how that helps.

  8. #8
    Raw Wave
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    Perl, consider that sinewave output does not mean no interference from the input, or from the case.

    But yes, it can cause problems with some loads - whether general operation, or longer term damage (overheating from harmonics).

    Though SMPS inputs should not care (ie, shape nor actual peak voltage is not that important to a modern SMPS).


    And I hereby upgrade 2k1toaster's artwork from big-deal to award nomination.
    Yes - it has grown on me (like too much recently!).
    But there is something about its realism that has really impressed me...!

  9. #9
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    If it's a laptop, it is easy to test the issue. Run the laptop on battery power, then start the car and run the system. No noise = inferior inverter.

    If that's the case, use a DC-DC laptop adaptor cable and you should clear up the problem.

    You may still be able to use that inverter for *other* stuff by connecting it to the battery, and you may be able to power the laptop that way as well, but the most common noise culprit in a setup with an inverter is the inverter.
    Quote Originally Posted by ghettocruzer View Post
    I was gung ho on building a PC [until] just recently. However, between my new phone having internet and GPS and all...and this kit...Im starting to have trouble justfiying it haha.
    Want to:
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  10. #10
    Variable Bitrate
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    Well I just ordered a 3.5mm ground loop isolater, hoping that will take care of the audio issue. I did hear that they degrade the sound quality/signal coming through as well, has anyone experienced this before?

    Didn't even think about trying to run the laptop from the batter to see if that clears up inverter problems, maybe because I don't have a battery for it... So that is on order to and hopefully that will clear up another issue for me.

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