DIY myDAQ Audio Equalizer

[Eric_K]

Introduction

The  attached VI uses the Audio Input Jack on the myDAQ to acquire a stereo  audio signal from an iPod or other audio player, alters the signal in  software, and then outputs the signal to the Audio Output Jack on the  myDAQ.  The effect on the audio signal can be changed by sliding the  volume and level sliders on the front panel.  Alternatively, white noise may be chosen as the signal source so that the effects of the equalizer can be observed and heard in the absence of a music audio source.

As seen in the block diagram below, a DAQ Assistant VI is used to  acquire the audio signal from the Left and Right audio channels on the  myDAQ. After the signal is acquired, it is passed to three Filter  Express VI's that separate the audio channels into bass, midtone, and  treble waveforms.  After the signal is split up, the three audio  components are multiplied by the corresponding controls on the front  panel.  The signals are then added together and multiplied by the volume  control on the front panel.  Finally, a second DAQ Assistant Express VI  is used to output the final left and right audio streams to the Audio  Out Jack.

The Audio Input? slector allows the user to switch between the Uniform White Noise source and the DAQ Assistant audio input.

Steps  to Complete

To use this VI, you will  need:

1. An  NI myDAQ
2. An audio source such as an  mp3 player
3. A cable to connect the  audio source to the audio input of the myDAQ
4. Headphones  or powered speakers to connect to the audio output of the myDAQ

With  these materials, follow the following steps:

1. Connect  the myDAQ to your PC and set it up as DEV1 in Measurement &  Automation Explorer
2. Connect the output of the  MP3 player or audio source the the Audio In Jack on the myDAQ
3. Connect  the headphones or speakers to the Audio Out Jack on the myDAQ
4. Download  the myDAQ Equalizer VI file attached at the bottom of this page
5. Press  play on the MP3 player or other audio source
6. Run the myDAQ  Equalizer VI
7. Move the sliders on the front panel and listen to  the audio change!

Additional  Notes

1. Note  that while this VI runs fine on most systems, it does require a large  amount of CPU time.  If other programs are running on the PC at the same  time, it greatly increases the chance of this program stopping and  throwing errors.
2. Note that the stereo Jacks  on the myDAQ are configured to measure and output from -2 V to 2 V.  If  connecting an audio source that supplies move than 2V, an error will be  thrown.