Hum through speakers using GC & Laptop - Page 2 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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
Reply
 
Thread Tools Search this Thread
Old 9th August 2010, 06:30 PM   #11
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
the weight of evidence is against me.

I wonder what I have seen in the past. They all looked like two core mains flexible.
__________________
regards Andrew T.
  Reply With Quote
Old 9th August 2010, 08:35 PM   #12
diyAudio Member
 
Join Date: Aug 2008
AndrewT, I have seen many older laptops with 2 wire (isolated) power supplies. We use them exclusively at work. That said, I've also worked on laptops that friends own that are 3 wire power supplies.
__________________
Tyler
  Reply With Quote
Old 10th August 2010, 03:42 AM   #13
gootee is offline gootee  United States
diyAudio Member
 
Join Date: Nov 2006
Location: Indiana
Blog Entries: 1
Quote:
Originally Posted by zebra100 View Post
It is a three pin PSU. So what can I do about the hum, aside from removing the ground (which I really don't want to do)?
Gfiandy and abraxalito both gave you other suggestions. Have you tried them?
  Reply With Quote
Old 10th August 2010, 12:31 PM   #14
diyAudio Member
 
Join Date: May 2008
Have you tried muting everything in the sound card settings? If hum goes away unmute one at a time. I have seen this issue if you have a built in mic.
__________________
My adventure: http://www.1414audio.com/
  Reply With Quote
Old 10th August 2010, 03:08 PM   #15
diyAudio Member
 
tangmonster's Avatar
 
Join Date: Jul 2007
Location: Cape Town
I also thought laptops only had a 2 prong connector. then i went to look at one.

Most laptops i have seen use the "for EU plug" in this image.

Click the image to open in full size.

Nobody has the correct adaptor so basically nobody uses earth on them.

The only time i ever found a problem with buzzing noise on the headphone out was when the laptop went into sleep mode while power supply was plugged in.

three options i see:

1) Disconnect earth and make the problem go away A short on laptop side will propably put the powersupply in safety switch off mode. You are using a dc blocker cap on your amp input?

2) if a friends charger solves the problem get a different charger

3) Only connect amp with power supply plugged out
  Reply With Quote
Old 10th August 2010, 03:49 PM   #16
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
to fit a UK socket outlet (to match a BS1363 plug top) one must open the protective shutters over the Live and Neutral receptacles.
This is done with the third prong of the plug top. But that third prong does not need to conduct, it can be all insulating.

The clue is in the cable. Is it a flattish oval with two cores, or a round cable with three cores?

Pics of the cables would be more informative, than pics of the plug tops.
__________________
regards Andrew T.
  Reply With Quote
Old 10th August 2010, 07:27 PM   #17
diyAudio Member
 
Join Date: May 2008
Quote:
Originally Posted by gootee View Post
Gfiandy and abraxalito both gave you other suggestions. Have you tried them?
Yes, sorry should have said. The input ground is connected to the star earth, and I have tried a ground lift in the past, athough I have taken it out.

I think it could just be that the amp doesn't agree with SMPSU's.

Chris.
  Reply With Quote
Old 10th August 2010, 07:32 PM   #18
diyAudio Member
 
Join Date: May 2008
I think I may have to try something radical such as a USB D/A converter (like this one Behringer UCA202 U-Control USB Audio Interface (GAK)) for use with the laptop.

Chris.
  Reply With Quote
Old 10th August 2010, 09:15 PM   #19
diyAudio Member
 
Join Date: Feb 2010
Location: Bucharest
Send a message via Yahoo to Th3 uN1Qu3
Quote:
Originally Posted by zebra100 View Post
It is a three pin PSU. So what can I do about the hum, aside from removing the ground (which I really don't want to do)?
Not much. Removing the ground shouldn't have any adverse effects, it's not a computer with exposed metal parts. Anyway, if you haven't tried yet, run the laptop on battery to confirm that the problem is within the laptop PSU.

If removing the ground doesn't work either, most likely the main filter capacitor inside the laptop's power supply has dried and needs replacement.
__________________
"Audio grade" components simply means that they failed at a more critical job.
  Reply With Quote
Old 22nd August 2011, 01:53 AM   #20
diyAudio Member
 
Join Date: May 2007
Buying a USB DAC won't work as they are grounded through the laptop USB port anyway (unless you hooked it up via an optical out on the laptop but it shouldn't be this difficult surely). I'm not quite sure what the deal is with laptop power supplies as I have the same problem on my 2 DIY amps but not with my comercial (Yamaha) amp and only with a laptop that has a grounded power supply. Ones with no ground work fine.
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
How to removing the ******* HUM sound from our GC?? thomgun_lc Chip Amps 64 13th June 2008 08:20 PM
3875 GC Hum Crash&Burn Chip Amps 5 7th September 2005 10:12 PM
Amp needed for measuring speakers with laptop JohanH Multi-Way 7 24th February 2005 06:28 PM
Help!!! GC hum when input attached HawkeyeStoob Chip Amps 6 6th December 2004 08:29 AM


New To Site? Need Help?

All times are GMT. The time now is 09:02 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2