Advanced Bass Trapping

About two years ago, I’ve posted an article entitled “Room Acoustics – Ghetto Style”. It later became part of my bestselling mixing book YOUR MIX SUCKS, and has since been receiving very good feedback from many people who finally wanted to make their first step in treating their room.

The “Ghetto Style”-Treatment is simple, effective and doesn’t cost much, and while – in the context of mixing advice – we could leave it at that, I don’t want to hold back on a slightly more complex construction for those that are prepared to put a little more effort in.

The following construction is a whole level up from just stacking Rockwool, and is – depending on the space you have available – very close to perfection when it comes to bass trapping.

Anything below 200 Hz is very difficult to control. These frequencies have a lot of energy and most of this low-end energy ends up in the corners of your room.

Installing the so-called “Waveguides”.

The low frequencies – let’s call them “bass-waves” here for convenience – will be forced to reflect between these massive (12 – 18mm thick) MDF-panels, which literally “traps” them in the corner by losing their energy through the many reflections they’re forced into by the “waveguides”.

The MDF-panels need to reach from floor to ceiling, but they don’t necessarily have to touch the floor/ceiling – a small gap due to mounting brackets etc. is totally fine. The longer the MDF-panels reach into the room (measured from the corner), the better.
Leave a small gap (10 – 20 cm) in the corner, so the “bass-waves” can reflect back and loose even more energy.

As a first step, we are marking the positions of the MDF-panels:
• the panel in the middle points to the speaker
• the other panels fan out 12 degrees from the middle one

After we finish the construction of the MDF-panels, we fill the gaps with glaswool. This will reduce the energy of the “bass-waves” further. The reason for using glas wool instead of rock wool is its lower density – rock wool is already too dense and would reflect some of the very low frequency. But what we really want is the “bass-waves” to pass through the entire trap – bounce back and forth between the MDF-panels while being slowed down using the glas wool.

The density we seek in the glas wool is 15kg / m3. The following formula will help you to find the correct material in your DIY market/warehouse. In Europe you’ll definitely find it at OBI, Bauhaus, etc.

In the picture below we were almost done filling the gaps between the wave guides with glas wool.
The glas wool panels are quite solid and could easily be stacked on top of each other, vertically.

The final step is purely for cosmetics, using the same technique we’ve used for the ceiling cloud – we’re building a very simple timber frame covered with fireproof molton cloth.

Please do NOT include a layer of rockwool behind the frame, that would reflect some of the low frequencies that can only be tamed using our bass trap construction.

Here’s a picture made before fitting the frames – they are fairly light, but of course need to be properly secured!

If you found this post helpful, check out my bestselling book which will guide you through the entire mix methodology from DAW preparation to mix delivery, the eBook YOUR MIX SUCKS.