Open an audio project in Cubase. At this point, your project should appear as a series of tracks, like horizontal bars stacked on top of one another, with each section of your recording (such as guitar, bass, keyboards or vocals) occupying a track. For some recordings, you may have only a single track.
Open your Cubase mixer by selecting (Window > Mixer) on your menu bar. Click the "Play" button, which appears as a triangle turned on its side, to begin playing your mix. As the recording plays in real time, pay attention to the vertical meter on each channel strip (column).
Lower the volume on any channel where clipping occurs. Audio clipping is a distortion process caused by excess volume and will ruin the quality of your recording. Clipping occurs when the vertical meter on a column turns red. Whenever you notice this happening, drag the volume fader downward on that particular column. Continue to do this until you successfully eliminate all clipping. If excessive clipping occurs, lower your main volume.
Click the column that reads "Stereo Out" on your mixer. This is your main mix, which includes all of your recorded audio. It typically appears on the far right side of your mixer.
Click the "Inserts" button on the left side of your main project window, the multi-track viewer. From there, select (Dynamics > Multiband Compressor). Compression removes the high and low volume peaks from a recording, resulting in a smoother and more consistent sound, and is essential to mastering. An article in Sound on Sound Magazine recommends setting your threshold (the volume at which the compression process takes effect) at -30 to -40 decibels. Experiment with this range but also use your own discretion if this range does not produce a desirable sound for your particular recording.
Click "Equalizers" in the left column of your main project window and select a multiband equalizer from the list. Equalizers (or EQ) allow you to smooth out your high, middle and low audio frequencies. If the bass (known as "low end") sounds thin or even non-existent, despite your mix containing a bass part, you can raise the bass frequency presence to improve your mix. If your high sounds (like guitar solos) have a sharp, piercing quality, you can reduce your high frequencies. Your low frequencies fall between 20 Hz and 200Hz, and your high frequencies fall between 2 kHz and 20 kHz. The frequencies in between are your mid tones. Use these numbers to adjust your frequencies on the EQ grid and add or subtract frequencies as needed. For best results, try to keep your adjustments as minor as possible. Too much EQ can ruin your entire mix.