High input level LM3886 amp ? - 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 11th October 2006, 07:07 PM   #1
bibster is offline bibster  France
diyAudio Member
 
bibster's Avatar
 
Join Date: Aug 2004
Location: Lasbordes, 11400
Default High input level LM3886 amp ?

Hi all,

I've about completed my 5687 based linestage, finished my FE87e Fullrangers, so what's left?
Right: A (power)amp!
I've read about tubebufferd gainClones, but I don't want to something like that: My linestage will be to far away to implement series feedback, and:
My linestage has a (voltage)gain of about +26dB....
That is: 1v in, 20v out...
I don't want to keep the linestage's inputs verrrrry low, so I end up having 2v output (and a lot of noise... :-( ), so my question is:

How can I build a gainclone thinggy that accepts some 20V input?
(I thought of a simpel voltage divider, but there must be some more elegant way)

Hint welcome!

Cheers, Paul
__________________
Demagogue: One who preaches a doctrine he knows to be untrue to men he knows to be idiots.
H.L. Mencken
  Reply With Quote
Old 11th October 2006, 10:09 PM   #2
ReidK is offline ReidK  United States
diyAudio Member
 
Join Date: Jan 2006
Location: Los Angeles (a.k.a. Hell on Earth)
You don't want to attenuate (reduce) the level only to amplify it again. That will do nothing but increase the noise level.

The LM3886 can handle input voltages in that range (20V). You just need to adjust the gain to a low value (like 1 or 2). Gain, which is the factor by which the amplifier multiplies the input voltage, is set with external resistors.

There's one potential problem - like many op-amps, the 3886 has stability problems at low gain levels. In other words, it tries to stop being an amplifier and become an oscillator (tone generator). At best, this makes the amp useless. At worst, the chip can burn up, though the 3886's substantial protection circuitry would probably preven that. This thread had a good discussion of how to make a low-gain gainclone: Gainclone...No gain, YES pain.

Good luck.

Reid
  Reply With Quote
Old 13th October 2006, 07:13 PM   #3
juma is offline juma  Serbia
diyAudio Member
 
juma's Avatar
 
Join Date: Nov 2005
Location: Zemun
Hi bibster,
use OPA549 - there are some people who prefer it to LM38xx chips. It is known that it works better in low gain configurations (G=1 or 2) - it has wider bandwith when configured that way. No stability problems at all, other specs also very good. Take a look at:
http://focus.ti.com/docs/prod/folders/print/opa549.html
http://www-s.ti.com/sc/ds/opa549.pdf
  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
What should be the optimim level of Input Signal to a LM3886 based amplifier kuldeepsingh Chip Amps 9 14th May 2008 10:17 PM
UcD400 and high level sub input chrisb03 Class D 51 21st May 2007 12:20 PM
JBL Sub high level input only Dr Moreaux Subwoofers 5 22nd April 2007 03:04 AM
Sub-woofer high level input StalfoS Solid State 2 15th February 2007 11:00 PM
lesser of two evils, high level -> line level, digital volume control mazurek Solid State 3 19th November 2006 12:25 AM


New To Site? Need Help?

All times are GMT. The time now is 07:56 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