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Thread: Amplifier Noise

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    Default Amplifier Noise

    Hoping to get some help here,

    Bought this amplifier () connected to a a horn speaker from Jayacar as well, however with no source on the amp there is some white noise,

    So far have tried a second amplifier and second speaker and mulitple power supplies all the same issue, some white noise. Also tried to use some noise suppressors on both the power and the speaker lines but these did not help.

    Also tried some power filtering as well,

    Just trying to stop the noise without any input, would anyone have any ideas



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    yep shielding ? sure as eggs you may have to go to a coaxial cable to the inputs and these need to be as short as possible

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    The noise is from no input connected to the amp.....

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    so thats where the pickup of noise is generated . Do you have a oscilloscope ? Because its open circuited the amp it trying to work at amplification of any signal within its grasp ? isnt that what amps do ? thats why its called a AMPLIFIER , lets straighten the though process unless the input to the amp is short-circuited it will try to amplify to minimise this effect you have to sheild any electro-magnetic generated "noise" or short the input so it cant amplify .IE no input no noise- reduce noise to a minimum shielding this wont remove it but it will stop most of it getting to the amp got it ?

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    You need to define the input impedance ~ your signal input should look like;



    edit: 10K potentiometer
    Last edited by wotnot; 02-05-21 at 10:47 AM.

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    We had the setup as per the diagram and still there was noise unless the potentiometer was turned all the way down, then if we applied an input there was no output, as the potentiometer was turned down,

    the RCA cable was a shielded cable when the input was applied, the manufacturer jsut replied it is noise, and a ground loop issue, but with both the ground loop isolater and shielded cables made no difference

    If we replaced the amp with a car audio amplifier, using the same power supply there is no noise (without an input) if we then connect the source (using shielded cables) there is no noise.

    The only thing we can work it is is something with the amplifier,

    I dont have an scope to measure the intererence, was hoping there was some type of filter we could use on the speaker side to filter out this noise,

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    Why dont you use a plug that is a short until the other half is connected like a phono plug used in studios they all short to ground to stop hums and loops occurring if you want to filter it out on the speaker side haha good luck many have tried and failure is assured as its not possible under these circumstances , as you said yourself the noise isnt there when the pot is turned way down because the input is short circuited. sansui had a system where they rectified the input and switched a transistor taking the input leads to ground but it wasnt very successful and was soon dropped as it caused more problems than it was worth and instead supplied a rca plug with a 10 ohm resister built in to hold them at ground levels but that was in the 1970s ? most phone jacks have a switch on them to allow for grounding or you could try some sort of decoupling with say 10uf cap series with a 0.1uf to ground might reduce it quite a bit and isolate the dc area input good luck Don

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    so if i short the input there should be no noise on the speaker?

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    the circuit dia is not the same as the one on the module and it says its a balanced output so you cant ground the speaker wires or didnt you read that ? If you do you create a low impedence path thru the speaker to ground and its likely to let the smoke out of it

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    We have wired it as per the diagram on the module, and then as per the diagram here (downloaded from the site) there is always noise on the speaker, even when the input is connected to a source and the source is not supplying a signal,

    If we swap out the amp, the car radio amp has no noise so it has to be the mini amp, wanted to use this amp due to its size but with the constant hushing will not work for us, with my tinnitus it will drive me mad

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    Odd....and can't find any schematics of the amp module, but there's multiple suggestions it's using a TDA2010 chip ~ if this were the case, they may not have included the input coupling capacitor in the module? Also, the quoted 84mV input sensitivity seems very low, as typically this should be near 200mV ...

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    All amplifiers create noise.
    Even low noise circuits and components still create noise.
    Every resistor creates noise, particularly carbon film which you would likely find inside those simple modules.
    A little module like that would have around 100x gain, that means the noise of the components appear a 100x louder.
    You are using a horn.
    Horns are often 5x or more efficient (louder) than a dome tweeter. So you can multiply the acoustical reproduction of white noise by another 5x.

    You are regulating the signal with that 'volume' pot on the input of the amp, so that 500x gain of the noise is always present, no matter how low you set the volume.
    Even with an expensive Yahama amp when you turn everything up to max you will always hear noise, predominantly hiss from a powerful horn tweeter.

    The reason why it is quieter when you close the pot on the input is that you are shorting the noise created by the input components that usually has a higher impedance.

    The only way to avoid this noise is to use a preamp and regulate the volume between it and a power output stage that does not have such a high voltage gain.
    Last edited by Uncle Fester; 02-05-21 at 03:00 PM.
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    the input to the car radio amp has a low impedance input the amp you are trying to use has a much greater input impedance so thats why the difference I suffer from tinnitus so sympathsize in that quarter the only way i can see of overcoming this is to pull the kemo down so a transformer is the most practical way and will give you dc isolation as well similar to CAT.NO:MM1900 but smaller type ? do some research on radio spares or farnell etc

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