Can mute pin on LM3886 (etc.) eliminate popping? - 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 2004, 04:22 PM   #1
cm961 is offline cm961  Canada
diyAudio Member
 
cm961's Avatar
 
Join Date: Jun 2001
Location: Peterborough, Ontario
Default Can mute pin on LM3886 (etc.) eliminate popping?

Hi guys,

I have a 4 channel gainclone that I love, but when powering up and down the speakers, a lot of odd noises are heard. If I put a capacitor across the mute pin resistor, will this help?

What I'm looking for is an easy way to eliminate turn on/off thumps. I've investigated using relays, but it looks overly complicated and the datasheet says it has controlled turn on/off. So I'm probably doing something wrong. It would be nice to fix this problem with one capacitor. Do all other gainclones without relays thump on turn on?

Thanks,
Pete

P.S. In the LM3886 datasheet its listed as Cm. "Mute capacitance set up to create a large time constant for turn-on and turn-off muting". Sounds promising! Can anyone confirm this?
  Reply With Quote
Old 5th October 2004, 05:26 PM   #2
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
Using the mute function may do the trick. My LM3886 amp is totally silent, especially the "model 1" (of 6). The file below contains 6 different versions where only model 1 and 4 are tested. Model 4 isn't totally silent but pretty much.

http://www.sjostromaudio.com/hifi_fi...qrp01r0xls.zip
__________________
/Per-Anders (my first name) or P-A as my friends call me
Tube Buffered Gainclone in work |Thread || Diamond buffer |Thread for the group buy | Wiki
  Reply With Quote
Old 5th October 2004, 05:34 PM   #3
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Default Re: Can mute pin on LM3886 (etc.) eliminate popping?

Quote:
Originally posted by cm961
Do all other gainclones without relays thump on turn on?
Properly wired GC will not produce thump at turn on.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 6th October 2004, 01:09 AM   #4
cm961 is offline cm961  Canada
diyAudio Member
 
cm961's Avatar
 
Join Date: Jun 2001
Location: Peterborough, Ontario
Seriously? Wo. Well I'm using a 4 channel gainclone I made, I believe 2 are LM3886 and 2 are LM3875. I'm pretty sure all 4 pop on turn on. Pretty bad pop too, makes me concerned about the tweeters. The star grounds it are terrible. Yeah I said grounds. It's not that I did not know how to wire properly, just that I've never had a soldering iron which could actually melt solder until now.

Thanks for the tips.

Pete
  Reply With Quote
Old 6th October 2004, 01:24 AM   #5
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
The popping may be caused by improper grounding, PS wires routing. I had it at one time too, but later it disappeared when I changed layout.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 6th October 2004, 01:34 AM   #6
cm961 is offline cm961  Canada
diyAudio Member
 
cm961's Avatar
 
Join Date: Jun 2001
Location: Peterborough, Ontario
Ok, well now that I have an extremely hot (but crappy) soldering iron, I'm going to rewire it. I believe I gave each amp a "local" star ground, and then ran those to the main star ground. I know, terrible, but my iron couldn't melt the joints.

So I'll rewire and also add capacitors across the muting resistor.

Thanks again.

Pete
  Reply With Quote
Old 6th October 2004, 02:38 AM   #7
diyAudio Member
 
xplod1236's Avatar
 
Join Date: Dec 2003
Location: On the couch
Send a message via AIM to xplod1236
I never had success with the turn on delay. I have the mute pins of 4 LM3886s connected to one resistor and a 470 uf cap. The datasheet says to use a 100 uf cap for each chip, so 470 uf should take care of that. When I turn the amp on, I get sound immediately. Also, I don't get any turn on/off thumps.

What's the equation for figuring out the length of the delay?
  Reply With Quote
Old 8th October 2004, 01:06 PM   #8
cm961 is offline cm961  Canada
diyAudio Member
 
cm961's Avatar
 
Join Date: Jun 2001
Location: Peterborough, Ontario
I tried I think 470uF as well and it didn't seem to help.

I have a question about the grounding though.

My amp channels are all point to point wiring with everything connected right to the pins of the amp. Then the grounds are connected to one wire (where the +ve and -ve caps connect together) and then a thick wire runs to ground.

Also the speaker outputs -ve are connected to the main ground as well. Perhaps they should be connected to the channel's ground?

Do all grounds need to go to the star ground? If so, what happens when you use a PCB?

All four channels exibit the turn on, turn off thump (its a DC offset that fades away. Positive on amp start-up, negative on amp shut-down).

Pete
  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
LM3886, mute question... CJ900RR Chip Amps 6 6th June 2013 06:07 AM
lm3886 no mute rtill Chip Amps 21 29th August 2009 05:43 AM
LM3886 - regulator on the mute pin ? ash_dac Chip Amps 8 2nd September 2006 12:28 PM
LM3886 Mute richie00boy Chip Amps 6 18th August 2004 11:26 AM
lm3886 mute LED blabley Solid State 1 30th May 2002 05:51 AM


New To Site? Need Help?

All times are GMT. The time now is 12:17 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