LM3886 loud pop when turned off - Page 2 - 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 5th October 2011, 07:27 PM   #11
nige838 is offline nige838  United States
diyAudio Member
 
Join Date: Dec 2009
Thank ya'll very much for the input.
I'm looking at the schematic that was posted and I think that I'm going to use it.
Speaker protection is a little beyond me at this point.

Here is my power supply, coming from a center tapped transfo.

From bridge rectifier.
55v+ 0 55v-
| | |
| | |
-----||------------||----
| | |
55v+ GND 55v-

Caps are 10000uf 80v.

Using this power supply and said voltage, would the supplied schematic be OK?
Attached Images
File Type: jpeg 30X AMP-2.jpeg (42.3 KB, 184 views)
  Reply With Quote
Old 5th October 2011, 07:30 PM   #12
nige838 is offline nige838  United States
diyAudio Member
 
Join Date: Dec 2009
Also, what are the values of caps:
5.6m
100n
?

Both are on the power inputs

Another problem that I have is that one side is significantly louder than the other channel. Why would this be the case?

Thank ya'll very much for helping me in this build..

Nicholas
  Reply With Quote
Old 5th October 2011, 07:46 PM   #13
diyAudio Member
 
Professor's Avatar
 
Join Date: Sep 2005
Location: Electrostal, Moscow region
Quote:
Originally Posted by nige838 View Post
Thank ya'll very much for the input.
I'm looking at the schematic that was posted and I think that I'm going to use it.
Speaker protection is a little beyond me at this point.

Here is my power supply, coming from a center tapped transfo.

From bridge rectifier.
55v+ 0 55v-
| | |
| | |
-----||------------||----
| | |
55v+ GND 55v-

Caps are 10000uf 80v.

Using this power supply and said voltage, would the supplied schematic be OK?
As i say, +-55 volts is too much for LM3875, using such big voltage this is strongly risk for your acoustic systems. You need +-27 volts
__________________
http://mymegahobby.jimdo.com/

Last edited by Professor; 5th October 2011 at 07:52 PM.
  Reply With Quote
Old 5th October 2011, 07:48 PM   #14
diyAudio Member
 
Join Date: Feb 2010
Location: Bucharest
Send a message via Yahoo to Th3 uN1Qu3
5.6m = 5600uF. Bigger is better so keep your 10000u ones. The 100nF caps must be placed as close to the IC as possible. Anyway, the one most likely source of your pop is the lack of a coupling capacitor in the feedback loop.

As for one channel being louder, your gain setting resistors probably have high tolerances, or you got the resistors wrong on one of the channels. Buy 10-20 resistors of the values you need for gain setting. You'll quickly find use for them in other projects anyway. Using your multimeter select the ones that are closest to each other from the batch, and use those for the feedback network of the amplifier (the resistor from output to inverting input, and the one from inverting input to ground).

And yes +/-55v is way too much. +/-40 at most. In fact, you're lucky they didn't blow up yet... and the protection on those chipamps sounds UGLY.
__________________
"Audio grade" components simply means that they failed at a more critical job.

Last edited by Th3 uN1Qu3; 5th October 2011 at 07:51 PM.
  Reply With Quote
Old 5th October 2011, 07:57 PM   #15
diyAudio Member
 
Professor's Avatar
 
Join Date: Sep 2005
Location: Electrostal, Moscow region
Quote:
Originally Posted by Th3 uN1Qu3 View Post
... and the protection on those chipamps sounds UGLY.
...but very helpful if you dont read datasheets =)
__________________
http://mymegahobby.jimdo.com/
  Reply With Quote
Old 5th October 2011, 08:06 PM   #16
kaos is offline kaos  United States
diyAudio Member
 
Join Date: Dec 2005
Location: Los Angeles
UGH! +/- 55 V on an LM3875! Youíre lucky the encapsulation didnít blow off on you. Wear goggles dude.
  Reply With Quote
Old 5th October 2011, 08:18 PM   #17
nige838 is offline nige838  United States
diyAudio Member
 
Join Date: Dec 2009
Not trying to sound ignorant, but the datasheet said that it could take up to 84volts.
I figured that 55v was WAY below to MAX.

Also, would this inductor work?

http://www.mouser.com/ProductDetail/...CP8ejQYbxjo%3d

I beginning to think that I'm in over my head. The reason why I chose the LM3875 was because I thought that it could handle the voltage that was available within the amplifier.

As for using the 55v, the amplifier sounds fine. It doesn't seem like it's too much voltage for it.

Last edited by nige838; 5th October 2011 at 08:21 PM.
  Reply With Quote
Old 5th October 2011, 08:19 PM   #18
diyAudio Member
 
Join Date: Feb 2010
Location: Bucharest
Send a message via Yahoo to Th3 uN1Qu3
84v total, measured from positive rail to negative rail, not from one of the rails to ground. +/-55v is 110v.
__________________
"Audio grade" components simply means that they failed at a more critical job.
  Reply With Quote
Old 5th October 2011, 08:22 PM   #19
nige838 is offline nige838  United States
diyAudio Member
 
Join Date: Dec 2009
Quote:
Originally Posted by Th3 uN1Qu3 View Post
84v total, measured from positive rail to negative rail, not from one of the rails to ground. +/-55v is 110v.
55 volts measured from positive rail to negative rail, not positive to ground.
  Reply With Quote
Old 5th October 2011, 08:28 PM   #20
diyAudio Member
 
Join Date: Feb 2010
Location: Bucharest
Send a message via Yahoo to Th3 uN1Qu3
Quote:
Originally Posted by nige838 View Post
55 volts measured from positive rail to negative rail, not positive to ground.
Then your earlier diagram was misleading. There is no problem in that case, so let's get on and tackle the pop. Insert a 22uF 50v cap in the feedback loop, lift the end of the 680 ohms resistor that goes to ground and insert the cap between it and ground.
__________________
"Audio grade" components simply means that they failed at a more critical job.
  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
Subwoofers too loud when barely turned up mfaughn Subwoofers 10 11th March 2011 01:08 AM
Gainclone makes my speakers go POP when lights turned off chylld Solid State 30 3rd July 2008 05:56 PM
'POP' sound when unit is turned off coki Car Audio 5 10th September 2007 07:56 AM
My amp only works after a while, or when turned up loud. boas Solid State 12 15th February 2007 10:16 PM
Pop when amp is turned off boostin1989 Solid State 6 10th October 2006 04:10 PM


New To Site? Need Help?

All times are GMT. The time now is 10:33 PM.


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