Boost or cut certain frequencies and add gain. Read the manual if you're not sure

So I suppose this question is about the general processing chain of a guitar amplifier. A guitar amplifier classically consists of the following components:

• A pre-amplifier, amplifying the high impedance instrument level signal to a low impedance line signal (also may include limiting or gating)
• An equalizer section, typically either 2-band (treble and bass) or 3-band (treble, mid and bass)
• Optionally an effect loop to allow for external effect processing
• An output amplifier, driving the speaker

These will give you different control options.

• Usually you would get a pot before the output amplifier to control how loud the output signal is. This is often labelled “Volume”. Can also be “Gain“ or as in your case “Level”
• Usually you’d also get a pot before the pre-amplifier, controlling how loud the signal hitting the pre-amp is. This is often labelled “Gain” or “Pre-Gain” or “Drive”
• 2-3 knobs for equalizing

Now, a general “Volume”-knob is not a weird thing. But why have a second control for the pre-amp? The reason is that the pre-amp is traditionally an amplifier that tends to distort and thus colors the sound. Here generally the lower the signal is the cleaner the amplifier will be. If signal is too high you’ll get heavy distortion. This is why you get the option to turn down the signal.

But sometimes people want a lot of distortion, but 100% signal won‘t give enough. So up came the concept of “overdrive”: You add another clean amplifier between instrument and preamp. This means you can drive the pre-amp harder and get more distortion.

For the equalizer there are two general ways an equalizer can work:

• A passive equalizer (only decreases volume for the band)
• An active equalizer (includes an amplifier and can also increase volume for the band)

Generally an equalizer consists of filters and volume adjustments. The neutral position depends on the type. On a passive equalizer the neural position is the pot set to the highest position, on an active equalizer it is usually with the pot set to the middle position.

If you look at the manual https://www.zikinf.com/manuels/rocktron-rampage-r10-manuel-utilisateur-en-28873.pdf you will find that on your model the eq is active.

So looking at your specific amp you get:

• Level: Volume of the output stage
• Gain: How hard the pre-amp is driven, thus how much distortion you get
• Overdrive (on/off): Increase input volume to drive the pre-amp harder
• Bass/Treble: Keep in middle for a neutral sound, turn left to decrease and right to boost bass and treble

Drive: Drive (or input) usually adjusts the signal level being introduced to an amplifier. More drive will push the signal closer to the overload region of the amp, introducing more (hopefully musical) distortion artefacts.Bass: A bass amplifier or "bass amp" is a musical instrument electronic device that uses electrical power to make lower-pitched instruments such as the bass guitar or double bass loud enough to be heard by the performers and audience.Mid: well the mid is the midrange and the treble is high, as the opposite of bass.Treble: It's obvious from the labels what most controls on guitar amps do: the Treble knob adjusts treble (high) frequencies, the Bass knob adjusts bass (low) frequencies, and so on.Presence: In an amplifier, a presence control boosts the upper mid-range frequencies to make the sounds of voices and instruments with similar tonal ranges seem more "present". On the television production studio's sound desk, there can be several presence controls, for several different, switchable, frequencies.Pan: Panning audio lets you distribute sound across the stereo or surround spectrum to create balance or a special effect. For example, you can place more sound in the right channel of a stereo clip or less sound in the centre channel of a surround clip.Reverb: Reverb occurs when a sound hits any hard surface and reflects back to the listener at varying times and amplitudes to create a complex echo, which carries information about that physical space. Reverb pedals or effects simulate or exaggerate natural reverberations.

Yup!!! Treble = High Mid = Mid bass = Low

^{simulate this circuit – Schematic created using CircuitLab}

Figure 1. Preamplifier to power amplifier connection is simply a matter of connecting the outputs of one to the inputs of the other.

One odd thing is that the pots are wired backwards on the BA5406 schematic. Normally they are wired as shown in Figure 1 but this requires log pots (audio taper) so that loudness increases smoothly with rotation. The backwards pots may be a trick to use cheaper linear pots and still give an approximately log response. They actually short out the preamplifier when turned down to zero which is unusual but not dangerous.