Equalizer with band-pass filters

Thread Starter

zoom

Joined Jul 11, 2014
29
I've been playing around with an IC named MSGEQ7 which returns the amplitude of seven different frequency bands. To be able to utilize it, I use arduino.

Now I want to make the circuit permanent but I realised that I really don't need to use this IC with an Arduino, instead I can build separate band-pass filters to get the amplitude of the desired frequency band.

So, what I want to do is designing a band-pass filter with a varying capacitor or resistor so that I can shift the center frequency of the band-pass filter. But I really don't need the amplitude of the frequency instead I want to get HIGH or LOW if there is this frequency in the given signal.

I am planning to connect the output of each filter to base of an NPN transistor to drive some LEDs.

So, all in all I need help for designing the band-pass filter. I want to use op-amp to make it easier (I think it makes it easier, right ?) But I don't know much about it. Googled it but could not find a proper design, especially with a varying parameter to be able to change the middle frequency.

Appreciate if you guide me.
 

Thread Starter

zoom

Joined Jul 11, 2014
29
It's likely you can't get such a wide frequency range with a single filter expect by switching capacitors. Would that be acceptable?
Why do you want to build you own filters when that MSGEQ7 will do what you want much simpler? :confused:
No, actually I am planning to use 7 different filters for each range, not a single filter for whole range.
Well, the msgeq7 I have is defective and also I need to spend one arduino nano to use it on a permanent project. That's why I want to achieve this project with my own filters, also it's a good practice :)
 

GopherT

Joined Nov 23, 2012
8,009
No, actually I am planning to use 7 different filters for each range, not a single filter for whole range.
Well, the msgeq7 I have is defective and also I need to spend one arduino nano to use it on a permanent project. That's why I want to achieve this project with my own filters, also it's a good practice :)
The msqeq7 is called an "equalizer" but it is really just a set of seven filters with sample/hold to detect the maximum signal in each band - then transmit those levels to the Microcontroller. It does not adjust (equalize) the various bands.

What is your goal? Build filters to sample and display - or - build filters that adjust and equalize and audio signal?
 
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