HIGHPOINT STUDIOS

HPF1 Licence [Gain Structure]: Do's and Don'ts for Playing a Large Scale Rig

Having watched countless performers take the stage, I put together this set of do's and don'ts for DJs and artists getting ready to play a large scale rig. These are purely technical notes — it's taken for granted that you can beatmix, choose strong tunes, understand energy and movement, and read a crowd. The one thing you must learn before performing on a large scale stage is GAIN STRUCTURE.

Note: a 2dB increase or decrease equals twice or half the watts, while a 3dB increase or decrease equals twice or half the perceived volume.

Peak Gain vs RMS Gain

First, let's separate peak gain from RMS gain. Peak gain is the flickering peaks sitting above the meat of the audio — the highest voltage the waveform will ever reach. RMS gain is the average dB value of that meat. This guide refers to RMS gain.

1. Gain Structure: The Cup Analogy

Picture four 275ml cups. These stand for your input channels. In the input meter legend, 250ml equals 0dB RMS (green) and 275ml equals +24dB RMS (double red).

Your master bus is the 1L jug. Say you have poured 275ml from cup 1 and are now slowly mixing 250ml from cup 2, 260ml from cup 3 and 245ml from cup 4. Suddenly you are spilling the perfectly mixed drink all over the floor — that is audio distortion. It usually shows up first in the mid range around 400–800Hz, where most frequency clashes happen, then in the bass, which is often less noticeable but definitely loses power as the system limits or chokes.

Treat your input channel gain like a glass of fine wine: leave a fair amount of room for the wine to breathe, perhaps boosting mids for a swirl around the rim to lift the aroma.

IMPORTANT! The master meter on DJM series mixers is post-mix, not pre.

In short: for the best possible output, keep your input RMS gain at 0dB so you don't overdrive the mix bus engine.

2. Talk to the Engineer Before Your Set

Talk to the engineer before your set and reset the mixer to 0dB; the system engineer will sort out any volume disparity. It's common for the previous act to finish on a climax, get excited and leave the meters reading hot. The worst thing you can do is start your set with 0% headroom. Stay calm and ask your engineer — they will handle whatever you need, such as more foldback.

3. Be Aware of Your Space

Avoid playing a wide dynamic track before a limited, more mono-mixed one. You can't hear it from the DJ position, but the energy shift is very obvious out front when the sides disappear — it can go from magical to hard box sounding in no time.

4. Move the Sweet Spot by Adjusting Key

The sweet spot is largely where the root bass note frequency physically lands. Pitch up and the sweet spot comes closer; pitch down and it moves further back. Measured from the front of the subs: 80Hz = 4.28M or 8.56M, and 95Hz = 3.6M or 7.2M. For further calculations, click here.

5. Manage Audio Fatigue

Drop your mix volume by 2dB during a breakdown and give the crowd a minute or two of rest before returning to unity on the next drop or moment you want to emphasise. Repeat this 3–4 times an hour to keep the audience's ears and molecules happy and healthy.

Frequently Asked Questions

What is gain structure and why is it the first thing to learn?
Gain structure is how level is managed from the input channels through the mix bus to the system. This article calls it the number one thing to learn before performing on a large scale stage, because overdriving the mix bus engine is what causes the distortion described in the cup analogy.
What is the difference between peak gain and RMS gain?
Peak gain is the flickering peaks above the meat of the audio — the highest voltage the waveform will ever reach. RMS gain is the average dB value of that meat. This article refers to RMS gain.
Where should my input channel gain sit?
For the best possible output, keep your input RMS gain at 0dB so you don't overdrive the mix bus engine. In the input meter legend, 250ml represents 0dB RMS (green) and 275ml represents +24dB RMS (double red).
Why does the master meter on a DJM series read post-mix?
The article flags as IMPORTANT that the master meter on DJM series mixers is post-mix, not pre. That's why the advice is to reset the mixer to 0dB and talk to the engineer before your set rather than starting with 0% headroom.
How do 2dB and 3dB changes relate to watts and perceived volume?
As noted in the article: a 2dB increase/decrease is twice/half the watts, and a 3dB increase/decrease is twice/half perceived volume.
How can I manage audio fatigue across a set?
Drop your mix volume by 2dB in a breakdown, give the crowd a minute or two of rest, then return to unity on the next drop or emphasised moment — repeated 3–4 times an hour.

Contact

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Copyright 2019

Gain structure is the foundation of a clean, powerful set on any large scale rig. Keep your input RMS gain at 0dB, reset the mixer with the engineer before you start, and give the crowd room to breathe during breakdowns. These small habits protect the mix bus and keep the system sounding its best from the first track to the last.