Hi Bobby. First question is can you hear any changes at all when you turn the Gain controls? I ask this as the FX configuration is a bit quirky so need to confirm if it's actually affecting the audio. If it isn't then I've misunderstood you so ignore the following
If you can hear some EQ changes, then the graphical display is a pretty nice addition to the machine as it shows what the controls do, and the EQ on/off toggle button is useful for comparing 'before & after'. The horizontal axis shows the full range of frequencies you can hear (20Hz to 20KHz for a young'un!), and the vertical axis shows the gain or cut applied to those frequencies.
If you press the EQ Flat button you can start with a clean slate. The graph is a flat line so no frequencies are boosted or reduced and you'll hear no change when you toggle the EQ on & off.
Each Gain/Freq pair of controls allows you to boost or cut a specific range of frequencies, so even without altering the Freq controls, you already have control over 3 (preset) bands of freqs. As you turn the Gains up & down you should see the bands which will be boosted or reduced as humps or dips in the graph; the Low affects the bass freqs, the High affects the treble freqs, and the Mid affects the middle.
If you turn one of the Gains up full, then turn the Freq control, you should see the hump move left or right. This shows the gain or reduction is being applied to a different band of freqs, allowing you to override the preset ranges. The amount of movement overlaps to some degree for High/Mid/Low, but you can see they are designed for their own part of the frequency range or spectrum.
There's an extra control for the Mid section which controls the width of its hump, i.e. the range of freqs affected by the Gain control.
Note the gain or reduction for any band of frequencies will only be audible if the original audio contains those frequencies. e.g. if you playback a high-frequency sound like a whistle, the Low controls won't make much difference. Vice versa if you play a bass sound and alter the High controls.
Each instrument used to create the original audio will generate sounds with certain frequency ranges - there are some charts somewhere on the web showing these in a nice graphical way. So with this information, you can tweak the Gain & Freq controls to emphasise or reduce the sounds for individual instruments and/or correct shortcomings in the recording, e.g. if the bass sounds too muddy, you could turn down the Low Gain and alter the Low Freq till you get a compromise between losing the mud and losing the feel of the music. If it sounds dull, you could increase the High Gain and adjust the Freq to add sparkle without adding too much hiss... alternatively, just twiddle till it sounds right! There's a bit more to it than that, but I'm sure there are others out there who can add their 2 cents if more info is needed.
White noise contains lots of frequencies so this can be useful for experimenting, and you may hear the EQ more easily... record yourself making a hissing sound, then try the the Mid & High controls (although this may not be so effective if your hearing is shot as it's the higher frequencies which tend to get lost first). Also try the Mid Q control - turn the Gain up first, then turn up Q to get a sharpish hump, then turn the Freq control to hear the swooshing effect as it boosts the different freq ranges.
May have completely missed your point here, but hope it helps someone
Phil.
