diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   Chip Amps (http://www.diyaudio.com/forums/chip-amps/)
-   -   Buffered IGC and global feedback? (http://www.diyaudio.com/forums/chip-amps/21044-buffered-igc-global-feedback.html)

JoeBob 2nd October 2003 09:24 PM

Buffered IGC and global feedback?
 
I am currently using a opamp buffer for got an inverted LM3875 and was wondering what people thought of taking the feedback from the output of the LM3875 to feed to the opamp buffer? I know I would need a voltage devider for the feedback coming in, and wouldn't the feedback go to the + terminal since it would already be inverted? Hmm... was just thinking about it and was wondering if anyone had done it and what people thought the pros/cons were. Of course I would keep the opamp very close to keep the feeback path short.

Joe Rasmussen 3rd October 2003 12:23 PM

Re: Buffered IGC and global feedback?
 
Quote:

Originally posted by JoeBob
I am currently using a opamp buffer for got an inverted LM3875 and was wondering what people thought of taking the feedback from the output of the LM3875 to feed to the opamp buffer? I know I would need a voltage devider for the feedback coming in, and wouldn't the feedback go to the + terminal since it would already be inverted? Hmm... was just thinking about it and was wondering if anyone had done it and what people thought the pros/cons were. Of course I would keep the opamp very close to keep the feeback path short.
I wouldn't advise it... the total open loop gain would be humongous! Besides, what's wrong with nested feedback? In almost all cases (there may be some instances I can't think of right now) this should be considered advantageous. Far better (and easier) to use a UGS (Unity Gain Stable) IC as buffer, then experiment with an LPF (which won't do within a loop). Even better, use a tube:
members.ozemail.com.au/~lisaras. There is no easier or safer tube project than this.

Joe R.


All times are GMT. The time now is 09:24 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