Set up your multi-track jazz recording for editing in your mixing environment. Hardware and software mixing environments share the same terminology. In most cases, your mixing environment will include the ability to play all tracks, a combination of tracks or single tracks alone. Press the "Solo" button on the bass track's channel strip or track header so it will play back alone.
Insert or load a graphic equalizer on the bass track. Consult your mixing environment's documentation for details on inserting or loading an EQ. If you have a variety of EQs available, use the one with the most frequency bands for more detailed control of tone.
Zero all sliders on the EQ and listen to the bass track all the way through. Determine if it is too quiet or too loud, and if it lacks "punch" or presence. Listen carefully to the track and decide what it needs to sound better to you.
Boost frequencies in the 20 to 50Hz range if the bass track lacks depth or "bassiness." Frequencies in this range are the lowest the human ear can perceive. If the bass was recorded with a microphone not specifically designed for bass recording, the result will often be weak in the lowest registers. Be careful not to boost these frequencies too much. Excessive gain here will result in a loss of definition, called "boominess."
Boost frequencies in the 150 to 300Hz range to "lighten" an overly present or boomy bass recording. This will emphasize the bass's mid-range frequencies relative to the lower frequencies discussed in Step 4. Boosting these frequencies can also help to emphasize some of the subtle performance details captured on the recording, such as the clacking of the strings when struck.
Avoid cutting frequencies above 1,500Hz unless necessary to eliminate static or other unwanted, high-frequency sounds. Some of the most characteristic performance details in jazz bass occur at these frequencies, such as the sound of the player's fingers sliding over the strings. Reduce frequencies above 1,500Hz if these details are over-emphasized in the recording.
Press or click the bass track's "Solo" button to un-mute the other tracks. Press "Play" to hear the equalized bass track with the other tracks. The initial equalization pass is often sufficient, but you might need to make further adjustments to help the bass track mix well with the others.
Pan the bass track to the left or right if desired. In some cases, it will be appropriate to pan the bass somewhat to one side to create room in the audio field for the kick drum or other low-frequency sounds. However, bass is usually center-panned because panning it to one side can be disorienting to the listener, depending on how integral the bass line is to the overall track.
Add compression to the bass track if it contains very pronounced dynamic contrasts that interfere with its ability to mix well with the other tracks. For example, the recording might have brief sections that are too quiet or too loud. Adding compression will make the louder parts quieter and the quieter parts louder, making the overall volume of the track more consistent.