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Old 2nd September 2012, 10:14 PM   #1
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Default HUM From an amplifier

I am facing problem of hum. When i turn my volume control to its lowest position then hum increases, but when i position it to the middle it decreases also when i remove ground connection from the volume control then it disappears completely and there is no hum from the woofer.I tried to increase the power supply capacitors but no change. I am using split unregulated 16-0-16 (5 Amp transformer )power supply and my amplifier is running in bridge mode using TDA2030A ic(Ckt is given in TDA2030A datasheet). Also there is no device connected to my amplifier. I am unable to understand whether this is the problem of power supply or anything else.Electrolytic capacitors are used in power supply (4700u).
Please help me.
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Last edited by samm001; 2nd September 2012 at 10:43 PM.
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Old 3rd September 2012, 12:35 AM   #2
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Hi,
Do you have the inputs isolated from the chassis?
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Old 3rd September 2012, 02:14 AM   #3
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Have you used a star grounding system ?
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Old 3rd September 2012, 03:56 AM   #4
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Hi
Just in case attached it is a star ground sketch so you can compare it with your ground wiring.
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Old 4th September 2012, 03:56 AM   #5
seanvn is offline seanvn  Viet Nam
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Some of those IC amplifier chips don't have good supply rejection. For example those designed for use in cheap car audio systems such as the TDA2003. I would guess that is why you are hearing hum. I don't think there is any easy answer to your problem. You can try the other things suggested such as star wiring. If that does not work then you are looking at having to use a voltage regulator chip or some kind of supply line finessing. Hopefully it is just some kind of wiring or shielding problem.

Last edited by seanvn; 4th September 2012 at 04:05 AM.
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