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

Audio Sector Kits & PC boards from AudioSector

Thread Tools Search this Thread
Old 16th April 2012, 04:31 AM   #1
imperion is offline imperion  United States
diyAudio Member
Join Date: Jun 2007
Default LM3875 kit troubleshooting

I am having some issues with my amplifier and was wondering if I could get some advice. I have been getting some high frequency hums/noises when I hook it up to my computer. I plan to use my PC as my source. Hopefully this is not too much of an issue.

Unplugged from the PC-source, it is dead quiet. When I attach it to my Ipod Touch, it is also very quiet with only a small hum when I press my ear to the speaker. When I hook it up to my computer, the hum/noises is almost as loud as the music (it does not get louder if I adjust the volume through windows). I have no pot or volume control on the amp.

Using a single transformer and rectifier board to power two amplifier boards.

Currently I am using your power star ground configuration (I think):
Earth ground
PG+ from rectifier board
PG- from rectifier board
PG+ from both amplifier boards
PG- from both amplifier boards
CHG from both amplifier boards with a 8-10 Ohm resistor (although its shorted now, so I don't think the resistor is doing anything. I read somewhere that it was supposed to help...)


I also read somewhere that you want to put a capacitor on each RCA connector. So I believe I have a 1 uF (not sure of value) under the heatshrink. If this is an issue I can verify by cutting the heatshrink.
  Reply With Quote
Old 16th April 2012, 05:52 AM   #2
gmphadte is offline gmphadte  India
diyAudio Member
Join Date: Jul 2003
Location: Dona paula, Goa
You have a ground loop problem due to Earth connection of the PC.

Gajanan Phadte
  Reply With Quote
Old 16th April 2012, 06:00 AM   #3
DigitalJunkie is offline DigitalJunkie  United States
diyAudio Member
Join Date: Apr 2003
Location: Portland,Oregon
Send a message via AIM to DigitalJunkie
It could be ground loop related,to an extent.

PC's are full of noise. I would add a volume control to the amp,and then turn up the output of the PC,then use the pot on the amp to adjust the volume. Otherwise the signal is just going to be buried in the noise from the PC.
The idea here is to try and increase the signal to noise ratio coming out of the PC.
  Reply With Quote


LM3875 kit troubleshootingHide 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
Troubleshooting the decware se84 kit crappyjones123 Tubes / Valves 4 2nd November 2009 02:23 AM
LM3875 troubleshooting Grandma´s_SUB Chip Amps 39 20th January 2007 05:24 PM
lm3875 kit + other bits jimbo1968 Vendor's Bazaar 0 9th December 2006 04:29 PM
BrianGT 3875 kit troubleshooting ejn327 Chip Amps 18 18th February 2005 03:46 AM
FS: BrianGT gainclone kit. LM3875 Dual Mono Kit mattjk Swap Meet 3 16th November 2004 01:24 AM

New To Site? Need Help?

All times are GMT. The time now is 03:23 AM.

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