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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.

 

Features:

  • Low Power Consumption
  • Only Two External Components
  • On Chip Ground Reference
  • Switched - Capacitor Filters
  • 3.3 or 5 Volts Operation
  • 20 dB of Gain
  • On Chip Oscillator
  • Output Multiplexer
  • Variable Decay Time
  • 8 Pin DIP Package

Documents:

Replaces: COM-10024

Comments 22 comments

  • Wrote a tutorial that may be of interest: http://tronixstuff.wordpress.com/2013/01/31/tutorial-arduino-and-the-msgeq7-spectrum-analyzer/

  • Where can I find this in a smd package?

  • just a warning: don’t buy these chips on ebay even though those are cheaper. I bought two and they were both defective. Each channel was broke (tons and tons of noise, completely unusable). Someone else had the same problem, so my guess is that an ebay vendor (or a few of them) is selling defective chips. at any rate, stay away from them. I wasted days trying to troubleshoot them.

  • Is the MSGEQ7 DIP package eagle part available in the sparkfun libraries? I found a MSGEQ7 but I am not sure if it is surface mount of DIP.

  • I’m trying to hoop up the msgeq7 to electret microphone (I’ve tried both sparkfun’s adafruit’s microphones).

    I’m hooking it up as follows:

    Pin 1 - 5v (.10uf between pin 1&2) Pin 2 - Gnd Pin 3 - A0 (Arduino) Pin 4 - D4 (Arduino) Pin 5 - .1uf cap to OUT/AUD of the electret microphone Pin 6 - .10uf cap to GND Pin 7 - D5 (Adruino) Pin 8 - through two 100kohm resisters to power, 33pf cap to 5v

    I’m getting numbers from 40-200 on channel 0 and 6 and number around 830-930 on channels 1-5.

    that seems pretty constant regardless of my music volume

    Any clues?

  • When using a 200k resistor and 33pf capacitor to select the oscillator frequency, what frequency should I be measuring on pin 8? Would I see 165khz like specified in the datasheet? Or is that frequency only present somewhere else internally on the chip?

    • Note: The MSGEQ7 chips I ordered from eBay were all defective, replacements from sparkfun worked perfectly. Be careful, or you might waste time troubleshooting defective chips!

      • I second this. The 2 chips I ordered from ebay had ridiculous amounts of noise on each channel that made them completely useless, despite adding noise filter caps. Both chips had the same problem. I spent days trying to get them to work. Anyway, I realized what happened thanks to your comment. I bought 2 new chips from sparkfun after reading this. Hopefully they’ll work much better than the ebay ones -_-

  • Put it in stock literally the day after I bought it from eBay. Too bad for you guys I guess :(.

  • can you change the frequencies this chip detects?

  • Does anybody know how to run this off 3.3V? Every schematic I can find has 5V for VCC.

  • I made a project with this. Got it onto Hack a Day
    =)

  • The link to the MSGEQ7 tutorial created by J Skoba is broken, but I have posted a copy on my site at:
    http://nuewire.com/info-archive/msgeq7-by-j-skoba/

  • Is the datasheet here outdated? This is the latest one from the Product Page: http://www.mix-sig.com/datasheets/MSGEQ7.pdf
    The capacitor that should be on the input pin is now 0.1uF as opposed to 0.01uF?

    • That’s exactly what I was thinking when I saw the old data sheet I thought to myself “that .01 uf cap is probably gonna clip my bass response a little.” So I decided I would use use a .1uf when the time came. Then here I see your post and I go look at the new datasheet and lo and behold! They read my mind!

  • I’ve been playing with these and yes you should be able to drive the LM3914 series of chips OK. Each output is fairly linear over 25db. But be aware that the output is refenced at around 500mv, so for best results use an rail to rail opamp to ground reference the output. You would connect the output of the MSGE7 to the positive input of the op amp. Place a 1K resistor from opamp output to negative input. Then connect a 50K pot from negative input to +5V, adjust pot for 0 volts out with no audio input to the MSGE7.
    If you want to run standalone (no micro), things become complicated. You would need to use an analog switch to demux the output into seven outputs. Each output would drive a separate LM3916. This would require a 1 of 8 decoder to drive the analog switch and a divide by seven counter circuit to drive the 1 of 8 decoder (eighth output is not used). The counter would divide the strobe pulses from the timer.
    The timer which drives both the counter and the MSGE7 strobe input could be a LM555. To avoid flicker, set the timer to produce a low duty cycle positive pulse. To adjust decay of display adjust the timer frequency higher for faster decay.

    • No need to drive separate LM3916s. Just use one and a multiplexed 10x7 display (or two 5x7 dot matrix modules) with the anodes driven by a decoder. This is the same method used in the now (sadly) discontinued Velleman Spectrum Analyzer Kit. One bargraph driver and a 1-of-10 decoder (in that design, a CMOS 4017 decade counter). Less parts.
      But still, the design is complex with passive ICs only (no-microcontroller.)

  • If I wanted to use this in an analog audio spectrum display, sending the voltages for each frequency band to power 7 LEDs for example, is there a demultiplexer I could use, instead of reading the values with an Arduino?

  • What’s a “DC representation of the amplitude”? An analog DC voltage between VDD and VSS? That datasheet is pretty rough.
    It looks like this would work great with a set of LM3916s and a demux to make a simple spectrum analyzer

  • This listing is same as COM-10024 which is marked as retired now. What gives? We just lost those 14 comments.

    • This new package is RoHS compliant, while the old one wasn’t. You can still see the comments on the old product page, linked to above.


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