Searching for a PCB for a BR100 - Bridged LM3886 - 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 18th October 2008, 12:02 AM   #1
seebaer is offline seebaer  Germany
diyAudio Member
 
Join Date: Sep 2008
Default Searching for a PCB for a BR100 - Bridged LM3886

Hi,

I'm looking for a PCB to build a bridged LM3886 as shown in AN-1192 from National. Where can I find a PCB? I didn't find one in the typical gainclone shops.

Thanks, Bernd
  Reply With Quote
Old 18th October 2008, 12:17 AM   #2
diyAudio Member
 
Join Date: Jan 2008
Why would you want one? Buy a stereo pair from one of the usual sources, and knock up balanced line driver around DRV134 (or around a pair of opamps, see http://sound.westhost.com/project87.htm ) to provide the necessary inputs.

DRV134 is a seriously easy chip to implement, the only necessary external components are the supply decoupling capacitors (and, obviously, the +/- 15V power supply). Alternatively, there exist suitable transformers that can do the job, see http://www.shine7.com/audio/bpa300v2.htm

These are both better solutions than the 1-inverting, 1-non-inverting setup described in the application notes.
  Reply With Quote
Old 10th August 2011, 07:04 PM   #3
ST7677 is offline ST7677  India
diyAudio Member
 
Join Date: Sep 2008
Quote:
Originally Posted by TheSeekerr View Post
Why would you want one? Buy a stereo pair from one of the usual sources, and knock up balanced line driver around DRV134 (or around a pair of opamps, see Balanced Transmitter and Receiver II ) to provide the necessary inputs.

DRV134 is a seriously easy chip to implement, the only necessary external components are the supply decoupling capacitors (and, obviously, the +/- 15V power supply). Alternatively, there exist suitable transformers that can do the job, see DIY BPA300 v2 6x LM3886 300W audio Amplifier

These are both better solutions than the 1-inverting, 1-non-inverting setup described in the application notes.

Is there any difference in the above two approaches? i.e. is one approach better than the other? Why?

The LM3886 bridge application note AN1192 suggests using an inverted and a non inverted configuration to bridge. Most people seem to be looking at BPA using DRV134. Is it because they are using 6 LM3886 instead of just 2?
What is the better approach to bridge just 2 LM3886 chips?


I am building a 3+3 channel amp. Each channel will have 2 LM3886 in bridge configuration. So looking for the best approach to bridge.
DRV134 adds to complexity and real estate issues considering that there are 6 amps to be bridged. I am wondering if there is any sonic benefit of taking that approach.
  Reply With Quote
Old 11th August 2011, 06:51 AM   #4
diyAudio Member
 
Join Date: May 2008
Try the Simplest Ever Bridging Adapter for Amplifiers. Cheap, simple and the result is the same.
__________________
If you've always done it like that, then it's probably wrong. (Henry Ford)
  Reply With Quote
Old 11th August 2011, 11:11 AM   #5
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Does ESP's inverting amplifier operate at unity gain?
What does ESP's 100r on the +IN of the inverting amp do for the circuit?
Does the "added resistor" give any significant noise problem?
__________________
regards Andrew T.
  Reply With Quote
Old 11th August 2011, 06:22 PM   #6
diyAudio Member
 
Join Date: May 2008
I don't see why it should not work at unity gain. On the other hand the LM3886 does not work at unity gain, so that circuit need not work at unity gain either. What use is a BTL power amp with unity gain?

Quote:
originally quoted from 'http://sound.westhost.com/project20.htm'
The input of the second amp should be grounded as shown (using a 100 ohm resistor), to prevent noise pickup.
100 Ohm is in most cases smaller than even the tolerance of the feedback resistor. Its Johnson noise can therefore certainly be regarded as insignificant.

That resistor should also have a cancellation effect on the bias current which should in theory reduce THD, and it will limit the current that flows into the amp input thus providing some protection during start-up and shut-off.
__________________
If you've always done it like that, then it's probably wrong. (Henry Ford)
  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
My Bridged LM3886 robertj88 Chip Amps 12 31st October 2010 03:47 PM
My LM3886 Board Based On BR100 Schematic gcds Chip Amps 3 8th January 2009 09:08 PM
Bridged LM3886 (again ?) Puffin Chip Amps 24 14th February 2008 08:10 AM
Looking for a PCB for bridged LM3886 zafira1981 Chip Amps 1 29th March 2006 03:39 AM
LM3886 Bridged Amp soundNERD Chip Amps 1 20th January 2006 01:36 PM


New To Site? Need Help?

All times are GMT. The time now is 01:22 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