Thread: Tone Controls
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Old 14th May 2019, 9:27 am   #33
Synchrodyne
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Join Date: Jan 2009
Location: Papamoa Beach, Bay of Plenty, New Zealand
Posts: 2,943
Default Re: Tone Controls

Quote:
Originally Posted by Radio Wrangler View Post
The FC38 diagram in post 23 is fundamentally different. The tone control elements (a full active Baxandall circuit in this case) is entirely in the forwards path, and there is flat feedback around the whole thing. If the tone control is used, the feedback system sees it as the same as unflatness in the power amp, and sets about improving (flattening) it. Essentially the feedback fights the tone control.
That's what I thought when I first looked closely at the FC38 circuit. It didn't make sense to me. Initially I thought that I must be missing something, but I guess that the real reason is that it actually doesn't make sense. To a lesser extent I think that the BS125/4 circuit, with overlapping feedback loops, might have a similar problem.


Cheers,
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