• Sol Barnes

Gain Structure for DJs: Avoiding the Redline

This article is a practical guide aimed at DJ's of all skill levels, explaining how to correctly set levels on the DJ Mixer for the best possible sound quality and volume. This is called “Gain Structure”.


For those that would like to get into the technical aspects, I have included a list of further reading materials at the end of the article.


What is gain structure and why should I care?

All sound equipment has a sweet spot when it comes to the sound level going in and out of the equipment.


If it’s too loud the music will distort, if it’s too quiet and the music will become noisy (hiss).

It is important to remember that while the Sound Engineer can correct the music volume (level), they will not be able to remove the distortion or noise and if the signal is very distorted, they will have to reduce the overall sound level to protect the equipment.


Clean audio, at a consistent level will sound better for the people coming to listen to you play. They will enjoy the event and leave the show having had a great experience.


A typical DJ mixer such as the DJM 900Nxs2 has 4 locations where the volume (gain) can be adjusted and it is up to you to manage these while playing your set.


Where are these controls?

For this we will take the DJM 900Nxs2, however the same can be broadly applied to any DJ mixer or controller.


Control 1: Channel Trim (or Gain)

Channel trim is the first place that the volume (gain) must be set and is the foundation for your ‘Gain Structure’.


Where is it?

The channel trim control can be found at the top of each channel strip on the mixer and is labelled ‘Trim’, (it may also be labelled as ‘Gain’ on some mixers and controllers). See Fig.1


What is it for?

The purpose of this control is to correct for different level music sources, for example an old record maybe quieter than a new one.


How do I set it?

This volume (gain) control needs to be adjusted for every tune you play during your set and should be set before you begin to mix it in.

  1. Skip though the tune to find a loud section of the music (just after the first break is typically a good location).

  2. Set the EQ controls so they point directly up (no EQ applied).

  3. Finally adjust the Trim control until the LED level meter shows 1 orange light (0db).

See Fig.1


Will I need to adjust this?

Yes

  • You must repeat the above process for every tune you play during your set.

  • You may also need to adjust this control mid tune, for example if the tune gets louder or an EQ boost is applied.


Fig.1: Channel Trim (Gain) control and LED Level Meter, Correctly set to 0dB.

Control 2: Channel EQ

The Channel EQ controls are one of the areas that needs to be approached with particular caution. These are volume (gain) controls that only affect part of the sound, typically split into Bass, Mid and Highs.


Where is it?

These controls are found under the Trim control on each of the channel strips. See Fig.2


What are they for?

These controls have two functions.

  1. They are used to correct for tunes that may have weak bass, mid or highs. By allowing you to give a slight boost to that part of the sound.

  2. They can also be used to transition from one tune to another. Typically, by cutting parts of the sound on one tune while mixing it into the other.

See Fig.2


How do I set this?

The default position for the EQ controls should always point directly up (no EQ applied).


The EQ control should only be boosted if the track being played requires a boost in a certain part of the music, for example the bass is weak and requires a little boost to match the other tunes being played.


  • Important Note: If you boost any of the EQ controls, you must check the channel LED meter, you may need to adjust the Trim down to compensate for the EQ boost. See Fig.2

Will I need to adjust this?

Yes:

  • You may use this to correct tracks that have weak Lows, Mids or Highs.

  • During your mix you may use these controls to cut parts of the sound. (Typically, you should not adjust the Trim control if you have used the EQ to cut some of the sound, as you will be bringing it back later in the mix).


Fig.2: EQ Section, Shows the effect of boosting EQ can have on the overall channel volume (level).

Control 3: Channel Fader

The channel faders allow you to mix two tunes together by bringing up and down the volume on each tune.


Where is this?

These can be found at the bottom of each channel strip. See Fig.3


What are they for?

They are used to control the volume of each tune going to the master output.


How do I set this?

These controls are called ‘Attenuators’, they do not make the music louder, they can only turn it down.

  1. When playing a single tune, the fader should be set to the top (maximum) position.

  2. As a second tune is brought in, it maybe necessary to move the fader down a bit as the music from the two tunes can combine increasing the overall volume (level) being sent to the Master output.


Will I need to adjust this?

Yes

  • You will adjust these as you mix.


Fig.3: Shows the channel faders.

Control 4: Master Level

The master level is the last volume (gain) control that you need to monitor during your set.


Fig.4: Shows the Master Level correctly set to 0dB on the Master LED Level Meter

Where is it?

This control is found near the top right side of the mixer and is labelled ‘Master Level’. See Fig.4


What is it for?

This control is used to set the volume being sent from the mixer to the sound system.

How do I set this?

Providing you have set the channel levels correctly. The master level control should be set so that Maser LED meter shows 1 Orange light (0dB). See Fig.4


However, while the above is technically correct, some Sound System engineers will assume that the DJ will ‘redline’ (boost the level beyond the sweet spot and into distortion) and set the sound system so that maximum level is only reached under those conditions (this is bad sound system practice, but unfortunately is quite common).


  • Top Tip: If possible, speak with the Sound Engineer to find out what level you should set the mixer at.


Will I need to adjust this?

Yes,

  • You should set this level at the start of your set.


  • Note: This control should not need regular adjustment; however, you should keep an eye on the level , if the LED meter is consistently showing the level to be above or below one orange light (0db), you should check your channel Trim, EQ and Fader levels, if these are set correctly, then you should adjust the Master Level control.


FXs

FX can have a dramatic change on the volume and is something you need to be aware of when using them.


Conclusion

Getting used to managing gain structure as part of your set is an important part of DJing and will improve your shows and gain you a good reputation with Sound Engineers who will be more happy to push there systems louder in response to knowing that the music will stay consistent and clean throughout your set.


Thanks for Reading

Sol Barnes - Mindscape Event Hire


Questions?

If you have any questions please leave a comment below and I will do my best to answer it.

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Further Reading

Bob McCarthy: Sound Systems: Design and Optimization: Modern Techniques and Tools for Sound System Design and Alignment, 3rd Edition: Chapter 3 - Transmission


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