Buss insert point question

[abechap024]

Hi,
I have a 8 buss Quantum 168 that I am adding buss insert points to. preferably I want the VU meters to be post insert point. My first thought was to put the insert point between the line buffer opamp and the transistors that buffer the VU meters, then I realized that their is a feedback loop connecting the two stages

as you can see
http://i872.photobucket.com/albums/ab284/abechap024/Modsqm168.jpg . My gut tells me this is going to open a whole can of worms, but can someone with more experience confirm? will this work just fine or is this going to not work. If it won't I'll just put the send/return post fader. Thanks in Advance!
AC

 

[abbey road d enfer]

Won't work. Feedback will fight against whatever you insert at this point; best case the FX you insert won't work, worst case the system will oscillate or stay stuck to one of the rails.

 

[sodderboy]

True.  You will need to put the insert before the opamp (which would eliminate the need for INA134) or after the R21 post transistor.
While you are at it, put buffers on your VU meters if they do not have them.  JLM has a good board.
Mike

 

[abechap024]

Great Thanks !
I will check out the VU buffer, It would explain the high(er) THD when I tested the boards without the VU, Still I'm excited about this board! Its almost done.
Regards
AC

 

[sodderboy]

Goodonya!  What are you using to measure THD?

Mike

 

[abechap024]

Rightmark Audio analyzer - its free and works great for people like me that don't have a nice testing set up yet. oh and I put those VU buffers in, I just used a tl074 wired as a unity gain buffer for each meter, and it works just fine. the THD is down a good bit now. Definitely a good move!! Every little bit helps in a console.