From the manual:
The Eris E5/E8 provides three EQ controls in its Acoustic Tuning section: High, Mid, and Low Cutoff. (There’s also an Acoustic Space control, which is covered in the next section.) In general, setting the High control to 0 (no boost or cut) will produce the best results. However, if the sound is generally too bright or shrill, try turning this control down below 0; if the sound is too dull and lifeless, try turning it up above 0. It’s always better to cut than to boost and to use the smallest cut or boost needed to get the job done. The Mid control is a mid-frequency peak filter that boosts or cuts frequencies centered on 1 kHz and extending about one octave above and below that frequency. Again, setting this control to 0 will generally produce the best results. If you want to emulate a car stereo, try turning it down below 0 to approximate the common “smiley face” EQ curve. On the other hand, if you want to emulate a cheap portable radio, try turning it up above 0. Try not to boost much, since this can add noise to the signal.
