Tuning Frequencies

Recently I've been playing a few gigs recently at local studio space Frequencies.TV and I've noticed they had a lot of standing waves and acoustic anomalies in the live space. I approached the owner and asked if I might be able to have a crack at tuning the space.

(Frequencies.tv, 2017)

To undertake this venture I approached Mastering Engineer Stephane Elmosnino who has a new book coming out in February for some assistance with this project. He was kind enough to share a chapter of his new book with me and I went about researching and implementing my learning.

The software I used for this project is RoomEQ Wizard. This is a free room analysis software that I highly recommend anyone download for calibrating their audio world. Click on the picture to download.

The microphone I used was Sonarworks XREF20. This calibrated microphone is designed for this purpose.

(SonarWorks, 2017)

The Room

To begin with the space had to remain functional an the essential layout had to stay as close to the way it was in the beginning. It's a 9.35m x 8.3m room with the main speakers situated in a row 1.7m from the back wall.

This meant I had to change a few things firstly I angled the main speakers towards the centre of the dance floor to reduce direct first reflections and create a sweet spot in the middle of the dance floor. Next I used a sub tone generator to determine the best spot in the row. While standing in the sweet spot I moved the sub along the row until the best place was found.

These small changes made the most difference in the overall sound from the whole experience.

Setup

The next step was to place the microphone in the sweet spot at ear level and calibrate my sound card.

Using REW I calibrate the sound card by looping the output signal back into the input. This allows the software to calculate the frequency response of my sound card and generate a custom EQ for insure accurate measurements from the microphone.

Testing

Next it came to testing using my calibrated system I began running the signal tests for the main speakers first left main, then right main and finally both together.

Here is my screenshot of both speakers before.

I notice bumps at 14.9Hz, 30.1Hz, 59.1Hzn and 100Hz.

I noticed a very similar pattern with the DJ monitor speakers when I tested them.

When I Ran all 5 speakers together the trend was confirmed .

There were some minor phase issues that turned out to be EQ settings on the back of the speakers. To keep this post short I adjusted all speakers to give a flat response and the photos above are from these settings.

Tuning

Armed with this new information I went to the task of calibrating the space using EQ. After some research I found the frequency response of all the speakers in the room and use EQ on the interface to achieve the desired result.

Interface

Main Speakers EQ settings.

Notice the small cuts made around trouble frequencies and the large roll off in the lows which allows the sub to carry all the bass frequencies and control resonant frequencies in the room.

Sub EQ

Brick walling the entire upper frequency range and removing 20Hz and below as well as a small cut around 60Hz. This was the master stroke with these settings the room began to sing.

Here is my after graph.

You'll notice a much smoother graph with no massive low frequency bumps and I can tell you the room sounds a whole lot better. In fact the owner of Frequencies told me he has never heard the bass sound so musical it's always been a thud. I believe I achieved a fantastic result that not only removed mud from the live space but also has allowed them to turn their system up louder without annoying the neighbours with compounding bass frequencies.

This is far from perfect as the room needs more bass traps but the improvement is huge and I look forward to working with the team at Frequencies.tv in the future.

If i had my time again I would have liked to run tests on the room before I started moving speakers to achieve a more dramatic graphical representation.

Thanks Steph for your help and guidance.

To book Frequencies TV for click here.

References

Frequencies.tv. (2017). Banner Image. Retrieved from http://www.frequencies.tv/

SonarWorks. (2017). XREF20. Retrieved from https://www.sonarworks.com/reference/microphone