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

is 40 Vdc ok for bridged?
is 40 Vdc ok for bridged?
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 23rd November 2003, 11:39 PM   #1
avenger is offline avenger  United States
diyAudio Member
 
Join Date: Nov 2003
Location: Boston
Default is 40 Vdc ok for bridged?

Hi Guys, I just found another transformer that after rectification and with a 56000uF cap I get 40Vdc , I know these (lm3886) can handle the 42Vdc as its limit, would 40V be ok? I have a 2 of these amps bridged(not paralleled) so that I can get 100W output into a 8 ohm load. Datasheet says I should get 50W with +/- 35V. I presume 40v should be ok....what you guys think, would this be ok?
Thank you in advance.
  Reply With Quote
Old 23rd November 2003, 11:44 PM   #2
SkinnyBoy is offline SkinnyBoy  Australia
Banned
 
Join Date: Nov 2002
Location: Adelaide, Australia
Send a message via MSN to SkinnyBoy
too high..
chip die..
cos ya running it into 4 ohms...
  Reply With Quote
Old 24th November 2003, 12:07 AM   #3
bigparsnip is offline bigparsnip  United Kingdom
diyAudio Member
 
bigparsnip's Avatar
 
Join Date: Apr 2003
Location: Cambridge
As long as you are going to be using a parralled bridge arangement (using at least four chips for one speaker channel, possibly more) everything should be fine as this voltage is just under the limit for the chip, and it will drop down a bit when you start to load up the transformer.
  Reply With Quote
Old 24th November 2003, 12:35 AM   #4
avenger is offline avenger  United States
diyAudio Member
 
Join Date: Nov 2003
Location: Boston
HI, maybe I wasn't clear, sorry, I will be running it into a 8 Ohm load, not 4...Thank you for the replies
  Reply With Quote
Old 24th November 2003, 01:11 AM   #5
Stu is offline Stu  Australia
diyAudio Member
 
Join Date: May 2003
Location: Wollongong
Since you are bridging it, you are effectively halving the load seen by each chip - this is because the current is doubled, so you effectively do have a 4 Ohm load.

As bigparsnip said, you can bridge and parallel 4 chips to split the current in each back to what it would be for an 8 Ohm load, but I would suggest changing the power supply instead - a 2V headroom is little smaller than I would be comfortable with.

There is a good spreadsheet on the National website for this, it should give you a good idea of the limits of the devices (it's called "Overture Design Guide" or something like that).
  Reply With Quote
Old 24th November 2003, 01:36 AM   #6
MWP is offline MWP  Australia
diyAudio Member
 
Join Date: Oct 2002
Location: Adelaide, South Australia
+-40V with a LM3886 gainclone will get you ~200W RMS into 8ohms as long as you can keep the ICs cool enough.

Ive got two 8chan bridged gainclone amps that have been running 40V for a few years now with no problems.
  Reply With Quote
Old 24th November 2003, 01:13 PM   #7
macboy is offline macboy  Canada
diyAudio Member
 
Join Date: Oct 2003
Location: Ottawa, Canada
Avenger,
that supply voltage is much too high for a bridged configuration, unless you were to use a 16 ohm load.

Please read the National Semiconductor application note on building high-power amplifiers using it's "Overture" (chip amp) products, which you can download here. They discuss bridged, parallel, and bridged-parallel designs, including how to determine the correct power supply voltage, which is a critical aspect of any amplifier design.
  Reply With Quote
Old 24th November 2003, 01:17 PM   #8
SkinnyBoy is offline SkinnyBoy  Australia
Banned
 
Join Date: Nov 2002
Location: Adelaide, Australia
Send a message via MSN to SkinnyBoy
thankyou for LISTENING to me in the first place...
  Reply With Quote
Old 24th November 2003, 09:07 PM   #9
avenger is offline avenger  United States
diyAudio Member
 
Join Date: Nov 2003
Location: Boston
Hi Guys,
I just tried the +/- 40V setup, with no problems at all, it works like its supposed to, I read average of 30Vac at the output with a 8 ohm load, the chips(2 of them) get barelly warm....what a great set up. Thank you guys for the support.
  Reply With Quote

Reply


is 40 Vdc ok for bridged?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
bridged amp please help Dan2 Solid State 5 27th April 2008 12:34 PM
Bridged (BTL) A75 Help please damacles Pass Labs 7 26th April 2008 01:34 AM
Bridged amp pt.2 Gabevee Solid State 1 24th July 2002 03:11 PM
bridged SOZ FBLEAGH Pass Labs 5 24th September 2001 01:32 AM
Bridged Zen gimpus Pass Labs 4 20th June 2001 09:15 AM


New To Site? Need Help?

All times are GMT. The time now is 10:39 PM.


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
Wiki