When moving from your own studio to a new venue to DJ, you will find that your carefully crafted equalisation sounds a lot different than at home. Different types of speaker systems tend to emphasise music in different ways and the specific acuoustics of the space also effects the sound to a great deal. It is therefore important to try to do an extensive sound check in every new location and adjust your equipment accordingly. This can be done by ear, but it is usually difficult for a DJ to get a clear picture of the acoustics of the whole space, even if he can manage to make the necessary arrangements for the DJ placement.
A more systematical way to do this is to measure the acoustics of the space, trying to cover the entire dance floor. From those measurements it is possible to set the equalisation of the space specifically to a flat responce curve, equalising out any differences and oddities in the frequency transmission in the space in a uniform way. When the venue has been equalised in a satisfactory manner, one can procede with equalising individual songs as is ones custom, without having the take into account the specifics of the space in every instance.
Example venue equalisation
There are many different programs, plugins that can handle venue equalisation, as well as special equipment. What one generally needs is a suitable program and a calibrated omni-directional microphone. What I have found suits my situation best is a plugin from MathAudio called Room EQ, coupled with an UMIK–1 omni-directional USB measurement microphone by a 15 m extended cord. With this I am able to take measurements from most spaces to balance out the situation in every venue.
To use the plugin we connect it to the microphone input via Audio Hijack with the output set to the speaker system of the space. We then click on «Room Measurement» to start measuring. It is good to take between 10 and 15 separate measurements all around the dancefloor. When we have enough measurements the software genereates the frequency curve for the space and speakers. In the example above, we can see that the bass is overemphasised quite a bit, with the curve becoming more or less balanced with maximum fluctioations around 3 dB in the midrange and treble regions. When we have the measurement curve we adjust the level to the right of tha topmost image so that the leveling line goes beneath the fluctuations. When we have done this the plugin equals out the disparancies, creating a balanced frequency response in the room on average. Of course the sound will be different around the room, but if the speakers are reasonably well set up, most of the dancefloor should sound as good as it possibly can.