There was a really good thread on tuning parametric equalizers
but for those who rely on the more common graphic equalizer there isn't a similar thread for setting it up.
I took ideas from that thread and started applying them to graphic equalizers.
Let's take the classic 10 band EQ with bands at 31, 62, 125, 250, 500, 1000, 2000, 4000, 8000 and 16,000Hz.
Apart from tuning by ear on music, one method some people tried was to play sine tones at those ten frequencies and adjust the EQ until all the tones sound equally loud. There are two problems with this approach:
1. The human ear does not hear tones of the same SPL at different frequencies as having the same volume. This is explained here:
2. A band on the graphic EQ affects more than the labelled single frequency. The 10-band equalizer is also known as a 1-octave equalizer because each band affects a whole octave. Within that octave, especially in high frequency bands for headphones, there can be wild ups and downs in the frequency response of the headphone-ear system. So a tone at 8000Hz may be very unrepresentative of the loudness of the EQ band which spans e.g. from 6000 to 12000Hz. (I don't know the exact start and end frequencies, but the latter is double the former.)
To fix both of these problems, I designed the following test tones. Pink noise is filtered through an EQ matching the equal loudness contour at a musical volume, then it is bandlimited at different ranges of frequencies corresponding to the 10 EQ bands to produce 10 test sounds. You just need to adjust the EQ until the ten test sounds all sound as loud as each other at the volume you usually you play your music at, and the result should be a well compensated headphone frequency response.
The sounds are labelled 10-xxx.wav, where xxx stands for the center frequency of the corresponding EQ. There's also a "10 bands" file, which is just all the 10 test sounds put together, going from 31Hz to 16kHz.
There's a zip file that contains all the test tones:
I recommend starting with 10-1000 and adjusting the volume until it sounds about as loud as you usually play music. Then go through the other test sounds adjusting the corresponding EQ sliders until they all sound equally as loud as the 1000 test sound. For safety's sake I recommend turning down the 8k and 16k EQ sliders before you start, as with treble-happy earphones the test sounds for those bands can be really piercing. Also if your EQ has a preamp slider, push it a ways down before beginning the calibration; this will give you headroom to boost frequencies without clipping.
I have also made a 5 band version of the test sounds for the 5-band Android Equalizer app:
although for this first version I made the top band seems too hot so you may end up EQing the 14kHz band down too much by referencing these test tones. Use these test tones to calibrate Equalizer by loading the tones into a media player, disabling the media player's EQ, enabling Android Equalizer, then play the test tone in a loop.
Edited by Joe Bloggs - 3/19/13 at 10:00am