Stacking opamps by using Quads.
Feb 8, 2014 at 10:41 PM Thread Starter Post #1 of 2

backspace119

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I bought some quad opamps today to play with and after jamming a little bit after configuring the first two amps up as a normal setup I decided I would try to "stack" the amp by wiring the corresponding inpus/outputs to the ones on the amps already wired (all this was done on a breadboard so it was quick to setup and test). I have to say i think I noticed a difference (especially with bass distortion (there wasn't much to begin with unless I turned it way up (that may be due to my vgnd circuit using a /kind of/ cheap opamp as a buffer on the rail splitting resistors.))) but I'm not certain if there was one yet (fairly certain it was at least louder) I'll try to measure it on the shops oscope when i get back to school but until then I only have my subjective reports.
 
Does this sound like a good way to "stack" opamps rather than get 2 duals and literally stack them?
 
Thoughts and comments appreciated.
 
Feb 10, 2014 at 1:11 AM Post #2 of 2
no - doesn't often work - try the 1st hit when Googling parallel op amps  http://e2e.ti.com/blogs_/archives/b/thesignal/archive/2013/03/26/paralleling-op-amps-is-it-possible.aspx
 
op amps need individual feedback components per each, and then you can share the outputs by putting a low value R in series with each output (after/outside of the feedback) before tying them together
 
you can't stack op amps - you may have seen pics of unity buffer chips - their feedback is internal and some had enough output R to safely parallel without added parts - but it is not a general technique
 

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