Whether we like it or not, audio post production is part of our daily lives. Common sonic symptoms include audible noise, hiss and rumble, boomy unintelligible dialogue, clipped or distorted recordings, low quality DSLR audio, over compressed dynamic scenes of crowds to name just a few.
The good news is: One Golden Rule prevails in the murky, waxy realms of audio for post production –
Is Your Friend
If your project’s audio is suffering from any of the sonic symptoms above then the good news is: the majority of audio related issues can be tamed, masked and in some cases completely eradicated with the use of EQ.
No. 5 – Clean Up
Audio can feel stuffy, bloated and lacking in clarity when frequencies below 20Hz or above 20,000Hz are present in coded audio information. Essentially, these frequencies are taking up unnecessary sonic space as we’re unable to hear them and yet they do effect the quality and intelligibility of other frequencies.
- Insert an EQ plugin at the very beginning of your plugin chain on your audio channel.
- Most Equalisers in NLEs come equipped with ‘shelf’ EQ also know as ‘High Pass‘ EQ and this is where you can cut everything below 20Hz
- Set the Center frequency to 20Hz
No. 4 – Set Your Levels
(No, not with the Channel Fader)
Audio has a maximum. Not just a maximum level, but in the apparent ‘room’ that audio has left to move into. This is called ‘headroom‘. Try to keep your levels 3db lower than you would normally when EQing, especially if you are increasing frequencies rather than removing them.
- On your Master Output look to reach -6db as a limit. This depends on how many audio channels you have, but it’s a safe bet to begin with.
- If you’re increasing frequencies look to reduce the output level. Try to think in terms of ‘as above:so below’, so if you increase frequencies, then compensate by reducing output level.
- Reduce the output level not with the Channel Fader (this is not always the best way to control level) but instead, use the EQs output gain. This is called gain staging in the audio world and effects the quality of processed audio.
No. 3 – Scoop Out the Mess
Mid frequencies, and in particular low mid frequencies are picked up by DSLR cameras and even high quality shotgun mics when conditions aren’t right for recording. This can occur when using too much input gain on the mic during recording or the influence of small rooms and reflective spaces. These frequencies bloat audio feeling muddy, boxy and boomy.
- Insert an EQ plugin onto your audio channel or clip. You’re looking to affect frequencies from 250Hz to 500Hz.
- Set one of your frequency bands to cut @ -8dB and whilst playing back your audio sweep the frequency control from 500Hz down to 250Hz slowly.
- Listen carefully for the audio to lighten, open up and sound clearer as you scoop out the muddy, boxy frequencies.
No. 2 – Brighten
Increasing intelligibility and clarity in audio is not the only consideration. Inbuilt camera mics in particular have harsh compression and noise cancellation which can make things sound less brilliant and in effect less natural
- Using the same EQ plugin as in Step No. 3 (no need to over process using multiple EQs) head to the far right hand side of your EQ and engage the ‘High Shelf‘ EQ
- Frequencies between 10,000Hz (10khz) and 14,000Hz (14Khz) are airy and give audio a ‘lift’, without effecting more harsh, sharp frequencies.
- Apply a + 3db lift somewhere between 10Khz and 14Khz to brighten, and air out audio suffering from dullness and that underwater effect.
No. 1 – Gain Up
As above:so below. When taking away, give back proportionally. If after a large scoop in the boxy mids and cutting everything below 20Hz you then gain up, audio left over can be emboldened and made starker to the ear. The effect is enhanced clarity and presence.
- Using your EQ plugin set the ‘Output Gain’ to between +0.5dB and +2.5dB. Use your ears. You don’t need to use the channel fader for level adjustments in processing – faders are primarily for mixing a number of audio sources together, not level adjustments after processing.
- It’s by no means a rule that follows the mantra ‘louder is better’ but it’s a tool, along with the steps above, that molds audio shedding more light on the things your ears like.
EQ is the Alpha Tool
With EQ most problematic audio issues can be addressed, low quality audio improved and in fact sweetening, embellishing and brilliance can all be achieved by confidently wielding Equalisation as a correction tool. These 5 simple tips can be applied to any source audio from dialogue to street scenes, live music to loud crowd scenes, natural location recordings and many more.
I hope you find these DSLR Audio EQ tips useful… let me know how you get on!
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