Want to bypass power supply, but... - 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 17th November 2005, 12:08 PM   #1
beanbag is offline beanbag  United States
diyAudio Member
 
Join Date: Dec 2004
Location: california
Default Want to bypass power supply, but...

Hello,

I recently rebuilt the power supply in my LM3886 amp. Before it was a single bridge, and now I changed it to the double bridge design. Before, there was only a 1 Ohm, 100nF snubber directly across the terminals of the elctrolytic cap. There was a huge amount of HF noise (MHz), but the amp sounded fine. After the rebuild, I put one terminal of the snubber on the terminal of the elctrolytic cap, and the other terminal connected to the star ground. I made changes in other parts of the circuit, but anyway, the noise on the power supply is much less now.

However, the amp sounds different, I think. I am not sure, but it seems like female vocals sound more blurred or "stuffy". Again, I am not sure since I didn't listen to my amp for a few days while it was being upgraded. The reason I connected the other terminal of the snubber to ground was coz I thought you wanted to reduce high frequencies with respect to the star ground, not necessarily the negative terminal of the electrolytic cap. First question is, was this the right thing to do?

I'm also interested in adding some smaller caps near the actual LM3886. The problem is that due to the point-to-point wiring, the amp is about 4 inches away from the star ground. That means that I will have 100nH worth of inductance. At very high frequencies, it comes out to a reasonable fraction of an ohm. Any suggestions on what to do?

Finally, I don't really understand the idea of putting a cap between the + and - pins of the amp. I can do this locally, but doesn't it just couple the noise and signal from one supply to the other? What is the point?
  Reply With Quote
Old 17th November 2005, 04:47 PM   #2
diyAudio Member
 
Join Date: Apr 2005
Location: Belfort
Send a message via MSN to youyoung21147
Maybe you can make a star ground next to the chip, and wire the two chip's star grounds together on the PSU ground. I did this and it allows 1/2 inch ground path !
  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
Need advice on capacitors for power supply bypass (Hafler P-500) Aaron D Solid State 7 8th December 2009 12:35 AM
Effect of supply bypass positioning. Arx Chip Amps 10 10th June 2007 08:13 PM
Bypass caps on power supply digital desire Solid State 55 18th January 2007 04:15 PM
Best Op-Amp Supply Bypass Scheme psychokids Solid State 3 2nd January 2003 08:38 PM
Power Supply Bypass Caps dsrviola Solid State 1 3rd November 2002 07:15 PM


New To Site? Need Help?

All times are GMT. The time now is 01:52 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