Preamp Ground Loop Problem

Vipul Kumar's picture


Joined: Jan 05, 2019

Replies: 0
Preamp Ground Loop Problem
January 5, 2019 - 4:22pm

i recently built a preamp but one problem is very critical that when i amp connecting microphone to the preamp along with the laptop in charging mode i am getting a very static strong ground loop or hum noise.

Case1- when all things connected just removed charger from laptop noise goes away 

case2- when all then are connected just make volume all the way down noise goes away 

case3- when all thing connected just mic is removed then all noise goes away 

can any one here who can help me i went so many forums but no one able to give me solution which could solve my problem this forum is my last hope WhatsApp Image 2018-10-14 at 8.20.30 PM.jpeg open this to see what the noise

Aswinth Raj's picture


Joined: Aug 16, 2016

Replies: 810
Ground isolation
January 7, 2019 - 12:03pm

Hi Vipul,

Your video does not show the hardware connections. So the questios are

1. What is your laptop doing here? Is it powering the circuit through the USB or providing arduino signal instead of the microphone?

2. How is the output speaker connected? Does it also have its power source or it just a simple speaker?

This should very likely bee a isolation problem. the reason why no was able to help could be because of the lack of hardware information.