Audio Recording

In audio mastering, you will be dealing with three major adjustments: EQ, Compression and Limiting. This tutorial will highlight common audio frequency issues in mastering. By knowing these frequency ranges, it will be easier to do frequency adjustments either using a parametric equalizer or in multi-band compressor.

The Bass Frequency Regions (20Hz to 200Hz):

The bass frequency spectrum is commonly found in 20Hz to 200Hz. If you are mastering, a mix down material has two possible scenarios in the bass region:

Scenario1: The kick drum occupies the higher bass frequency range as compared to the bass guitar.
Scenario2: The bass guitar is mixed and placed at the higher bass frequency range compared to the kick drums.

Scenario1 is more common in rock, alternative, grunge and some pop music. Scenario2 is more common in ballad rock, country and jazz. You can read more about this in the mixing bass guitar tips.

Common frequency problems include:

a.) Too strong or weak lower bass. 35Hz to 75Hz
b.) Too strong or light upper bass: 75Hz to 200Hz

Recommendations
1.) If you have a reference material, you can benchmark using the technique illustrated in getting the right bass level in mastering.

2.) For scenario1 and scenario2, use a parametric equalizer and do adjustments using this range:

For lower bass adjustments:

Center frequency: 50Hz
Q=1.0
Cut or boost= from 1dB to 3dB

For higher bass adjustments:

Center frequency= 135Hz
Q=1.0
Cut of boost= from 1dB to 3dB

3) If you find out that the entire bass regions are lacking, apply low shelf filter boosting mode. Boost around +1dB to +3dB and use your ear to judge the level.

4.) If you find out the upper bass to be lacking in clarity because of mud, try this:

Center frequency= 200Hz
Q=1.4
Cut= -3dB

The Mid Frequency Regions (200Hz to 5000Hz):

The most common problem is the lack or too much presence in the 500Hz to 4000Hz range. The instruments here are the vocals, guitars and other instruments like piano keyboards. Use your ear to do the adjustments:

1.) If you find out that the vocals are too strong, apply parametric EQ in these regions:

Center frequency: 2500Hz
Q=0.8
Cut or Boost= -3dB to -6dB

Bear in mind that by doing frequency adjustment in mastering can also affect the levels of other instruments. For severe cases, the material needs to be re-mixed.

2.) If you find out the vocals are weak, do the same range in #1 but boost around +1dB to +3dB.

3.) If you find out that there is a complete lack of “mid range” presence, then apply parametric EQ:

Center frequency: 2000Hz
Q=0.5
Cut of Boost = +1.0dB to +2dB

The High Frequency Regions (5000Hz to 16000Hz)

Common problems are:

1.) If there is an observed sibilance/harshness in the vocals, cut at these range:

Center frequency: 8000Hz
Q=1.4
Cut= -1dB to -3dB

Do not over cut at this range as it will drastically reduce the high frequency response of your material.

2.) If you observed that hi-hats and cymbals are too weak or too strong, you can either cut or boost at this range:

Center frequency: 12 KHz
Q=1.0
Cut or Boost= from 1dB to 3dB

3.) If the high frequency region is extremely lacking compared to other frequency range you can implement a high shelf filter in boosting mode. Boost around +1 to +3dB and use your ear to judge the level.

Final Note: Do not apply too much cut or boost (typically exceeding 6dB) in mastering.
If this is the case, you need to consult the audio mixing engineer and request for a re-mix of the material. Explain to the audio mixing engineer that the material is experiencing serious audio frequency problem that can only fixed in the mix. The audio mixing engineer will be happy to hear your suggestions and more likely will re-mix the material. In return, the mixing engineer will also learn from his/her mistakes.