LM3886 DC offset and hum - Page 3 - 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 3rd October 2012, 10:22 PM   #21
gootee is offline gootee  United States
diyAudio Member
 
Join Date: Nov 2006
Location: Indiana
Blog Entries: 1
Quote:
Originally Posted by Pemo View Post
Hi Tom,

This is very interesting!!!
Could you pleas further explain this to us. This is the first time I hear about it.

RGDS

Pemo
Pemo,

Here are some links to similar explanations that I posted in the past, possibly with more details or better information:

One more LM3886 PCB

Odd grounding problem

Thoughts of apparent noise on ground - due to power tx?

Cheers,

Tom
  Reply With Quote
Old 3rd October 2012, 11:09 PM   #22
WSJ is offline WSJ  United States
diyAudio Member
 
WSJ's Avatar
 
Join Date: May 2009
Location: GILROY, CA
Quote:
Originally Posted by bcmbob View Post
Does that transformer introduce noise as compared to a toroid or R-core?
As seen in my pic, the twisted power supply wires are right next to the transformer.
The wide band amplifier output noise is only 430 uV RMS.
What is your speaker output sound level at 430 uV RMS?

Here is a sales pitch for Toroidal Transformers.

Toroidal Transformer - Toroidal Transformer Home

The superior design of a Toroidal Transformer results in a power source product which offers many advantages over other transformers utilizing standard, laminated, power. Several powerful advantages offered by a toroidal transformer include the following:

Low, stray, magnetic fields.

Quiet, efficient, operation.
  Reply With Quote
Old 3rd October 2012, 11:14 PM   #23
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
Thanks, I have only used Ts and Rs but I continue to see the laminated in a lot of posts. Why are they so prevalent in tube amps? Is that a completely different ballpark?
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."
  Reply With Quote
Old 4th October 2012, 12:11 AM   #24
WSJ is offline WSJ  United States
diyAudio Member
 
WSJ's Avatar
 
Join Date: May 2009
Location: GILROY, CA
Michael,

Make sure the inputs are shorted when making a noise test, the amplifier input wires act as an antenna when left open.

With an HP lab power supplty at +/- 25 V, I measured a LM3875 on a PCB with the input shorted, the output noise was 270 uV RMS.
  Reply With Quote
Old 4th October 2012, 01:32 PM   #25
Pemo is offline Pemo  Mexico
diyAudio Member
 
Pemo's Avatar
 
Join Date: Dec 2009
Location: Echegaray, Naucalpan, Estado de Mťxico
Quote:
Originally Posted by gootee View Post
Pemo,

Here are some links to similar explanations that I posted in the past, possibly with more details or better information:

One more LM3886 PCB

Odd grounding problem

Thoughts of apparent noise on ground - due to power tx?

Cheers,

Tom
Thanks Tom, Iīll be reading.
  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
DC offset and gain on GC LM3886 Xerxes75 Chip Amps 19 9th October 2012 10:02 PM
LM3886 - DC offset problem luis.jimenez Chip Amps 22 10th April 2010 11:34 AM
LM3886 RC filter + DC offset questions. blackboy Chip Amps 2 27th April 2007 06:16 PM
Moved+changed preamp and now got hum and dc-offset whith chipampkits MiWi Chip Amps 1 4th August 2006 04:40 PM
Same old story LM3886 and DC offset officeboy Chip Amps 11 24th June 2004 02:51 AM


New To Site? Need Help?

All times are GMT. The time now is 05:42 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