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Author Topic: Mixed Mode Feedback  (Read 1707 times)

pathfinder10

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Mixed Mode Feedback
« on: October 13, 2015, 11:45:36 PM »
I read about it in teemuk's book and im wondering what is the real advantage on it. I got a schematic and i want to try it to see how it sounds, but i want to know if i will need the RC filter (to prevent oscillation) on the amp's output because it doesn't show it on the schematic that i got, and do i need an output capacitor(to block dc)?

i attached the schematic.

J M Fahey

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Re: Mixed Mode Feedback
« Reply #1 on: October 15, 2015, 03:31:53 PM »
That's a simplified schematic to show the concept, in practice you add a 100uF capacitor (any electrolytic will do) in series with the 220r resistor.
The amp will also have the proper RC Zobel stability network in parallel with the speaker ground and the amp will certainly have some input to ground resistor, as a ground reference.
But details are usually not drawn in examples, so you focus on the main point.
Look at any commercial Guitar amp schematic (Fender/Peavey/Laney/Crate/Marshall), lots of them in this Forum,  to see what they actually do.

phatt

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Re: Mixed Mode Feedback
« Reply #2 on: October 16, 2015, 06:56:39 AM »
I'm wondering if it would even be noticeable on such a small amplifier. :-X

In my non expert experience but having done a bit of A/B testing with some feedback ideas it's a bit over rated for what it actually does. :-\
YMMV, but hey experiment with it and see what happens, you never know. :tu:
Phil.