Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Chip Amps Amplifiers based on integrated circuits

ESD noise from finger and volume control
ESD noise from finger and volume control
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 11th January 2012, 09:54 AM   #1
elvischan917 is offline elvischan917  Hong Kong
diyAudio Member
Join Date: Nov 2006
Send a message via ICQ to elvischan917 Send a message via MSN to elvischan917
Smile ESD noise from finger and volume control


I built some TDA7293, LM3886 and discrete but all of them suffer one same problem. Everytime I touch the volume control and turn it, I heard some glitch noise on my loudspeaker. I don't want to connect signal ground to the case to solve this problem as it may cause a ground loop. What should I do? Can I connect two diodes from the ground toward the power supply?

Can anyone help?

  Reply With Quote
Old 11th January 2012, 03:23 PM   #2
johnr66 is offline johnr66  United States
diyAudio Member
Join Date: Mar 2009
I always solder a jumper from the signal ground lug on the control pot to the case of the pot. No more glitch and buzz when touching the control. If the pot is already in contact with a metal chassis, there should not be a noise unless the case is not grounded. I'd ground it at least at one point.

Last edited by johnr66; 11th January 2012 at 03:26 PM.
  Reply With Quote
Old 13th January 2012, 06:28 PM   #3
pacificblue is offline pacificblue  Germany
diyAudio Member
Join Date: May 2008
If the pot case is not grounded, you get hum or buzz. If you follow johnr66's advice you won't create a ground loop.

If the pot is DC-coupled to the amp input, you can get crackling noises as you adjust the volume, due to the accompanying change of DC offset voltage. A coupling cap between pot and amp will help, but don't forget to add a resistor to ground after the cap.

In general you can have noises, when the pot is either cheap or old (or both), because the wiper loses and makes contact. You can cure that temporarily with contact spray or for longer by replacing the pot with a better one.
If you've always done it like that, then it's probably wrong. (Henry Ford)
  Reply With Quote
Old 12th May 2012, 04:55 PM   #4
portreathbeach is offline portreathbeach  United Kingdom
diyAudio Member
Join Date: Jan 2010
Location: Cornwall
elvischan917, I usually connect a 10 ohm (2 watt) resistor and two diodes (in opposite directions) in parallel, between protective ground (main earth) and power ground. And then I connect another two diodes and resistor from power ground to signal ground:

Click the image to open in full size.
  Reply With Quote
Old 12th May 2012, 05:01 PM   #5
AndrewT is offline AndrewT  Scotland
diyAudio Member
Join Date: Jul 2004
Location: Scottish Borders
Originally Posted by elvischan917 View Post
.................I don't want to connect signal ground to the case to solve this problem as it may cause a ground loop. .............
The Signal Ground must be referenced to the Main Audio Ground (MAG), somewhere.

The MAG must be connected to Safety Earth, somewhere.

The Safety Earth must be connected to PE, somewhere.
regards Andrew T.
  Reply With Quote


ESD noise from finger and volume controlHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Volume Control, ToneStacks, Potentiometers and noise TheGimp Instruments and Amps 28 5th January 2016 11:44 PM
Volume control on DVD player remote. Lose resolution at low volume? Circlotron Digital Source 2 10th June 2011 07:20 PM
Replacing broken volume control with digital volume control Gunawan W Solid State 19 15th December 2010 10:46 AM
volume control hum/noise cbutterworth Tubes / Valves 6 8th April 2007 07:47 PM
Help me regarding very low Supply Ripple output noise DC volume control unit electronist Parts 0 31st December 2003 09:29 AM

New To Site? Need Help?

All times are GMT. The time now is 03:40 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio