Active Signal Summing/Mixing, Using Op Amps in Inverting Configurations (ECE Design Fundamentals)

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In addition to using this lecture for our Fundamentals of Electrical and Computer Engineering Design class, I also use this lecture in my Analog Circuits for Music Synthesis class.
This lecture frequency refers to my lecture on passive summing:
• Passive Signal Summing...

[@droningbrightness3403]

I've been following this series about op amps and learning so much. The clarification of what occurs in passive vs active mixing is exactly what i needed. thank you Aaron!

[@ninetailscosmicfox5585]

This is such an intellectual and professional way of telling us that op-amps are awesome because they change the game!
Also I really have to compliment you on how informative this really is. I'm watching this before your music synthesis with analog circuits series and seeing the differences between the passive and active summing functions is inspiring me!

[@Lantertronics]

Thank you for your kind words!

[@chthonicdevices7516]

Dude, your videos are excellent. If you had a book with similar content, I'd buy it. Your content sits wonderfully between having technical depth and being functionally useful for the intuition; no mean feat considering the subject matter.
I've been working in industrial controls for years, analog audio on the side. I find it difficult to get the joke, so to speak, of the analog audio books I have. Your content gets to the heart of the parts of audio electronics that I can actually put to use.
Thanks :)

[@jacobfaseler5311]

Khan academy for ECE. Bravo.

[@psynautic]

if you care about the phase, aka the fact that your signals are now inverted, is there any concerns with dropping another inverting op amp after the mixer?

[@DJ_Merkury66]

That's the general idea. Sometimes though it makes more sense to perform other tasks inside the circuit and leave it inverted until later. It just depends on what the function and complexity of the circuit is. In eurorack modular synths it has become more of less standard to have 100k resistors on the inputs and 100k feedback resistor to create a 1 to -1 gain. Then, as you state, put the inverted output through another 100k resistor and invert is back with a 100k feedback resistor.

[@psynautic]

@@DJ_Merkury66 ohh right that makes sense, this helps keep the inputs from loading the source

[@Lantertronics]

@@psynautic Shawn's reply is on target.