Amp Noise

Thread Starter

dkester13

Joined Aug 14, 2013
7
Hey, i soldered the velleman k4001 amp. when a play music though it, it sounds pretty clear and nice, for such a cheap amp. The problem is when i remove the input, the noise is huge!!!

Can someone help me? it should be something with ground, but i have no idea, since when connected to the pc the noise disappears. Maybe because it is grounded with the pc ground??

I need to remove this problem because i want the amp to be mobile, so plugging and unplugging wil happen a lot. And i don't want that noise.

Thank you
 

jerluwoo

Joined May 17, 2014
5
With the input disconnected the input trace of the pc board acts as a sort of antennae conveying all electrical noise into the amplifier. The high gain setting of this kit, only 40mV in for full output, makes it worse than most. Adding a volume potentiometer to the input will help considerably and help make the amp more compatible with different input sources such as direct line in from a cd player with no volume control. Choose a dual 10kohm logarithmic type potentiometer.
 

#12

Joined Nov 30, 2010
18,224
Pretty much, yes.

Radiated noise doesn't have much power, so a resistor to ground loads down the voltage quite a bit.
 
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