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Description: The seven band graphic equalizer IC is a CMOS chip that divides the audio spectrum into seven bands. 63Hz, 160Hz, 400Hz, 1kHz, 2.5kHz, 6.25kHz and 16kHz. The seven frequencies are peak detected and multiplexed to the output to provide a DC representation of the amplitude of each band. No external components are needed to select the filter responses. Only an off chip resistor and capacitor are needed to select the on chip clock oscillator frequency. The filter center frequencies track this frequency.
Other than coupling and decoupling capacitors, no other external components are needed. The chip supply can be between 2.7 and 5.5 volts with 5 volts providing the best performance. The device has very low quiescent current (less than 1ma typical) for portable audio devices. the multiplexer is controlled by a reset and a strobe, permitting multiplexer readout with only two pins. The multiplexer readout rate also controls the decay time (10% decay per read), so no external pins are needed for this function.
Based on 6 ratings:
I stumbled upon this convenient chip when creating an LED cube. I wanted to turn the cube into a visualizer for music and thought I would have to create individual filters for different frequency bands, BUT I happened to find this beauty and it worked pretty well! It isn’t very hard to get it to work. The only downside is that it is fairly expensive with shipping.
The fall off rates for each filter are smooth and even, as shown in the datasheet. When analyzing audio sources, there is a lot of distinction between each frequency band, so this makes for a nice 7 band graphic equalizer display. This chip blew my expectations away, making the steep price worth it.
I was happy with speed of shipping. It did not take 1 month like other suppliers.I as like how cheap and small this chip is.
For a while ive been wanting to make a simple Spectrum visualizer. but to do that meant i would i either have to mess with a lot of bandpass amplifier circuits or have to realy on digital filters using Fourier which i lacked the knowledge to do.
This little chip solved the issue pretty well. instead of lots of analog circuitry or digital wizardry i just use this single chip and i get the information i need with enough precision for some fun experiments involving lights and patterns.
Everyone knows what this thing is for - and it works as advertised. If you want a spectrum analyzer without doing all the fancy math in-code, get this thing.
Beware, however, of noise and input sensitivity. I had this champ hooked up to an Arduino with the BOB-09964 microphone and COM-12999 addressable RGB LEDs.
First, the LEDs turned on and permanently burned my retinas. Once I could see again and adjusted the brightness, the “output” was still all over the place. This is due to the sensitivity of the microphone - the chip was just doing its thing. So taking the raw-input from the MSGEQ7 and subtracting 127 eliminated most of the noise. Except for the 63Hz band.
I fought this for hours. Replaced the chip three times, turned off my TV, radio, fans, everything I could think of, but the 63Hz band kept flickering even in the quietest room I could make it.
While sitting there, cooling off from frustration, I hear the soft click of my refrigerator’s compressor turning off - which was in the other room. The 63Hz band light stopped flickering.
Moral of the story - just because you can’t hear it that well, doesn’t mean your device will have the same problem.