Stopping Speakers from poping

Discussion in 'General Electronics Chat' started by iONic, Nov 5, 2011.

  1. iONic

    Thread Starter AAC Fanatic!

    Nov 16, 2007
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    I bought a piece of cheap electronics crap...an alarm clock/radio/MP3 player.
    I've been going over all the faults to it and deciding if I should return it for some other flawed alarm clock device. And by the looks of the reviews on Amazon I can see too many that do not have multiple flaws of their own.

    For example:
    1) No battery backup system. It seems that many of SONY's alarm clock/radio's do not have battery backup. WHAT!??

    I thought it would be easy these days to find an alarm clock that could play MP3 music from a memory device as apposed to a CD or a bloody iPod/iPhone.
    It's not easy, but I found one that accepts a memory card or USB device.

    But with this cheap device there are also many flaws.

    1) FM radio is usless....no reception
    2) Runs on a rechargeable battery only and no way to know when it needs charging. (Does have Bat. Backup)
    3) The temp was set in Centigrade and the lousy instruction did not explain how to change it to F, not that the temperature matters. By happenstance I presses two buttons in a sequence and it changed to Fahrenheit. Go Figure!
    4) The volume of the the alarm (Radio/MP3) audio is set too high and is not adjustable.
    5) Each time the MP3 or Radio is initiated there is a pop on the speakers. (Makes for the rude awakening I was trying to avoid in the first place)
    6) There is no line out for headphones or external speakers.
    7) No backlight for nighttime viewing

    It is #s 5 and 6 that bring me here.

    If I do decide to take surgical action, how might I stop the speaker from popping, a capacitor? What kind and value.

    To make a line out would I merely have to wire in a audio jack from the two speakers?

    To compensate for Loud Volume on wakeup I have to decrease the volume of the MP3 file to 35% of it's original volume.


    Thanks
     
    Last edited: Nov 6, 2011
  2. tom66

    Senior Member

    May 9, 2009
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    The popping is caused by the amplifier not having a click/pop suppression circuit, which removes the click/pop when the power is lost or mute is initiated.

    A capacitor would not remove the click or pop, it would just act as a low pass filter making the audio sound muffled.
     
  3. iONic

    Thread Starter AAC Fanatic!

    Nov 16, 2007
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    Thanks tom66. Ive found an IC by Maxim-IC MAX9890 that might be what are referring to as a pop/click suppression circuit, but was hoping for a simpler solution.
     
  4. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    There should be a FET that switches power to the audio amplifier. The amp power is switched off when not playing to conserve battery power.

    The FET is probably a larger SMD device and will be connected to the V+ rail, so if you post a photo we should have some hope of identifying it.

    One solution would be to add an RC between the microcontroller and the FET gate, so when it turns on power to the amp it "ramps" on over say 0.5 seconds, not 0.5 microseconds. :)
     
  5. iONic

    Thread Starter AAC Fanatic!

    Nov 16, 2007
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    Thanks RB.

    I've actually decided to return the product to the merchant as the problems are just too many. Sure, I could add a wall power supply and a line-out plug, fix the audio pop and add some small light so that I could see at night. I could re-record the audio for the memory card so that it doesn't blow me away as it wakes me up...
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Yeah I hear you. They make some nasty junk these days. Of course we're a big part of the problem, we all want 50 cool high-tech features in a device that costs $9.95.
     
  7. iONic

    Thread Starter AAC Fanatic!

    Nov 16, 2007
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    You know your buying crap when there is no mfg. website and you can not find an instruction guide as a .pdf. In this day of fancy featured electronics (ex. iphone) I thought that some of the features I wanted ought to have been done over and over again. Guess not.

    I'm willing to double the price or more I I could find one that had what I think are fairly basic features, but it doesn't appear to be out there. Everyone's building stuff for the iPod, iPhone, iThis and iThat. I personally do not own own an iAnything and do not want to either. Apple's to stuck in their proprietary world..............but they are getting rich!
     
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