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How do I change this to a single supply filter?

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I used the TI filter pro to make the design of this filter, I set it to notch, why do you claim that its a bandpass?
Because it is called a Multiple Feedback Bandpass Filter on thousands of sites in Google.

also, what do you mean by feed?
What is the input, what feeds this circuit? A high impedance guitar pickup? A preamp circuit with a low output impedance?
 

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If its a bandpass filter how come it works like its supposed to? (it does cut the 400 and the 2.5K)

It's going on an effects chain so I guess high imped.
 
R3, R5 and R8 must have a very low impedance connection to ground which is best if they connect directly to ground.
Yes, you're right, there's no need for lots lots potential dividers, the inputs are capacitively coupled so it's fine to connected the resistors directly to 0V.
 
If its a bandpass filter how come it works like its supposed to? (it does cut the 400 and the 2.5K)
It passes mid-bass frequencies, passes mid-range frequencies and passes high frequencies. It reduces frequencies in between the bandpass filters and also cuts fairly low and very high frequencies.

It's going on an effects chain so I guess high imped.

The first filter must be fed from a very low impedance like the output of an opamp.
 
A friend of mine asked me to make him a filter cut for 400hz and 2.5khz to avoid feedback, my assumption that its caused by the distortion he is using, he wanted it to avoid buying a whole EQ set only to remove these freqs.
So I made one.
 
Feedback is caused by a microphone hearing the speaker it is playng through. If there are peaks in the response of the speaker or room then feedback will occur at those frequencies. Distortion has nothing to do with it.
If you notch those frequencies then feedback will be reduced, not avoided. The feedback will probably simply occur at another frequency.

A notch filter should have a fairly high Q (a narrow response) so it doesn't reduce too much of the program. Then it must be accurately tuned, not just guessed.

Can't you borrow or rent an adjustable notch filter to see its small effect on feedback?
If it works then you can make a real notch filter, not a bunch of bandpass filters.
 
My friend is a sound production student, I'm guessing he knows what freq. needs to be cut.
And I fail to understand why this can't work.
Also, if I use a buffer before the circuit, will it lower the impedance?
 
My local TV station got a new studio. Now their sound is terrible. It has no high audio frequencies so all the important consonant sounds in speech are missing. The word Police sounds like Olee, Face sounds like Ay. The new audio compressor is turned up way too high and makes speech sound like a robot.
You know what? Their commercials and off-site reporters sound perfect.

These guys are "professionals", not students. Maybe they are deaf?

Most buffers have a very low output impedance.
 
A friend of mine asked me to make him a filter cut for 400hz and 2.5khz to avoid feedback, my assumption that its caused by the distortion he is using, he wanted it to avoid buying a whole EQ set only to remove these freqs.
So I made one.

Sorry, it won't work - feedback frequencies are different in every room, and with slight changes in every room - even when a single person moves it can change things.

The Behringher Feedback Destroyer works by dynamically (and automatically) notching out troublesome frequencies - I've got one I was given, but I've never used it. Modern microphones are amazing, feedback is mostly a thing of the past - just take normal sensible precautions.

As AG says, if you want to try and do it (nut it wouldn't be any use) make a variable notch filter, the bandpass one you're looking at it useless - you want a sharp deep notch.

Or better still try a Behringer Shark, which is pretty cheap.



The one I have is more like this though:
 
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