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

My Version of Mauro Penasa's LM3886
My Version of Mauro Penasa's LM3886
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 30th December 2006, 12:12 PM   #21
Nico Ras is offline Nico Ras  South Africa
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Quote:
[i]
I use parallel series 0.47R because I haven't found non-wirewound power resistor.
Thanks for help [/B]
I don't understand the need for .23 ohms in series with the speaker, what does it do?
Besides wirewound resistors are not inductive, if this was a concern.
  Reply With Quote
Old 30th December 2006, 02:05 PM   #22
Russ White is offline Russ White  United States
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Quote:
Originally posted by Nico Ras


I don't understand the need for .23 ohms in series with the speaker, what does it do?
Besides wirewound resistors are not inductive, if this was a concern.

It is actually there to sense current for feedback.

Please read this Nico: http://www.diyaudio.com/forums/showt...645#post702645
__________________
Less pulp more juice Twisted Pear
Audio
/Twisted Pear Audio Blog
  Reply With Quote
Old 30th December 2006, 02:36 PM   #23
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Quote:
Originally posted by Nico Ras
.....Besides wirewound resistors are not inductive......
wire-wound resistors can be made two ways.
inductive or less inductive.

The way they are wound determines into which category they fall.
The easy, cheap way is to wind a coil on a former and weld on the lead out wires. This is inductive.

The alternative methods involve winding coils that oppose each other to cancel the magnetic field. This cancellation will never be perfect but a substantial reduction in inductance can be achieved. Anything better than 90% reduction will cost more than the inductive wound type.

BTW,
1uH has a reactance of 0.13ohms @ 20kHz.
Imagine (or calculate/simulate) what effect this might have on emitter resistor feedback when the Re is of similar resistive value.
What happens when the frequency of interest is one or two decades higher?
Even 1nH starts to become significant cf 0r22.
__________________
regards Andrew T.
  Reply With Quote
Old 30th December 2006, 03:26 PM   #24
Nico Ras is offline Nico Ras  South Africa
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Quote:
Originally posted by Russ White



It is actually there to sense current for feedback.

Please read this Nico: http://www.diyaudio.com/forums/showt...645#post702645
Dear Russ,

very interesting reading thank you.

Kind regards

Nico
  Reply With Quote
Old 30th December 2006, 03:28 PM   #25
Russ White is offline Russ White  United States
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Quote:
Originally posted by Nico Ras


Dear Russ,

very interesting reading thank you.

Kind regards

Nico

You are most welcome, its not exactly easy to find. It is very good read though. I have actually done several Howland pump type amps, one using discrete components(not chipamp).
__________________
Less pulp more juice Twisted Pear
Audio
/Twisted Pear Audio Blog
  Reply With Quote
Old 30th December 2006, 11:52 PM   #26
Stanley Drake is offline Stanley Drake
diyAudio Member
 
Join Date: Oct 2006
Send a message via ICQ to Stanley Drake
I have soldered and assembled amplifier but it doesn't work
I think that this is due to SMD (very difficult to solder accurate) or burned LM3886.
I don't know what to do with this. I'm so tired from LM3886 (I already have made 2 amplifiers that work ok) but 3rd was unlucky one.
Maybe I should forget about that chipamp and try to make a discrete amplifier. What do you think about this?
  Reply With Quote
Old 31st December 2006, 12:27 AM   #27
Russ White is offline Russ White  United States
diyAudio Member
 
Russ White's Avatar
 
Join Date: Jan 2005
Location: Nashville, TN, USA
Quote:
Originally posted by Stanley Drake
I have soldered and assembled amplifier but it doesn't work
I think that this is due to SMD (very difficult to solder accurate) or burned LM3886.
I don't know what to do with this. I'm so tired from LM3886 (I already have made 2 amplifiers that work ok) but 3rd was unlucky one.
Maybe I should forget about that chipamp and try to make a discrete amplifier. What do you think about this?

Or you could use a PCB that is tried and true. I posted a single side PCB PDF file on the MyRef thread.
__________________
Less pulp more juice Twisted Pear
Audio
/Twisted Pear Audio Blog
  Reply With Quote
Old 31st December 2006, 01:31 AM   #28
Stanley Drake is offline Stanley Drake
diyAudio Member
 
Join Date: Oct 2006
Send a message via ICQ to Stanley Drake
Thanks for advice but I think it's time for something more complicated
My fault that I used SMD. I will never use SMD again in amplifiers I'm unable to produce a good looking PCB with SMT
  Reply With Quote
Old 31st December 2006, 01:41 AM   #29
pinkmouse is offline pinkmouse  Europe
diyAudio Moderator
 
pinkmouse's Avatar
 
Join Date: Apr 2002
Location: Rotherham, England
My Version of Mauro Penasa's LM3886
Stanley, by all means build another amp, but don't give up on yours. Learning to troubleshoot things like this is an invaluable skill, and can even be quite fun, (in a month or so, once the frustration has gone).
__________________
Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?
  Reply With Quote

Reply


My Version of Mauro Penasa's LM3886Hide 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
X-Calibre : Hot Rodding Mauro Penasa's LM3886 design rudi Chip Amps 171 19th January 2013 10:38 PM
my_ref revC group buy (Mauro Penasa LM3886 design) schro20 Group Buys 650 18th October 2010 12:42 AM
WTB: Mauro Penasa Ref C marginwalker Swap Meet 0 13th October 2007 06:28 PM
Mauro Penasa's INV GC/REF GC group buy. Russ White Group Buys 277 27th March 2006 09:57 AM


New To Site? Need Help?

All times are GMT. The time now is 12:46 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio
Wiki