Why I heart tube traps, and you should too.
If you’re already fortunate enough that you enjoy what you do for a living, you can consider yourself even more fortunate whenever you discover something that makes your job easier and better at the same time. In my world this distinction belongs to the venerable Tube Trap.
I learned about ASC‘s TubeTraps back in the early 90s, when they had only been around for a handful of years. At the time, my attention was starting to turn toward acoustics and I felt that improving the acoustic performance of the studio might be the missing link in my stagnating recording style.
We had already improved the studio in several measurable ways, with equipment upgrades and a modified console, but my recordings didn’t seem to make a jump forward that was proportionate to the cost. The more I read about the benefits of an acoustically well-treated space, the more it seemed like the way to go.
I remember reading some brochures about Tube Traps (this was the pre-internet era when product information came on paper, by mail) and all of the explanations made sense. Plus, there was technical data to support just how effective these devices were, and the client testimonials seemed to be speaking to me directly as happy users recounted their difficulties with the very same acoustical problems that I had been encountering.
I was certain that buying some of these things would help reduce the acoustical issues in the studio. There was only one problem: They were not cheap.
I ran a small room at the time, Rosewood Studio in El Paso, TX, and we had a somewhat limited budget for further upgrades. And the fact that these upgrades wouldn’t be as shiny or showy as a new EQ or compressor made it even harder to justify that this would be money well spent.
Did I honestly believe that Tube Traps could make as big a difference? And if they could, was it worth spending that much money for something that I would notice but prospective clients might not? The expense did not seem warranted, so we waited.
Fast forward to several years later and suddenly the internet had become a viable place to do research and I found a website that described how to make DIY Tube Traps for a fraction of the cost of the originals made by ASC.
While the performance was not quite the same as the ASC version, they were similar enough that it seemed worth the effort and money to build some and see how it went.
The actual Tube Traps that are built by ASC are of the highest quality in terms of manufacturing and performance, and the company is constantly improving the design and experimenting with materials to offer something extraordinary to their customers.
While I certainly don’t want to imply that what you can build yourself is the same as what you can get from inventor Art Noxon and his crew at ASC, I’ve tried the DIY approach for myself and have been blown away by the performance compared to the cost.
I have shared this recipe with other friends and colleagues in the recording business many times over the years so why not do it again? I found the plans for DIY tube traps at Teres Audio, a small company run by the Brady family of Broomfield, CO, who must have found themselves in the same boat as I, but with more smarts and more handy disposition.
The plans are simple with just 7 steps, and a small number of materials: Some compressed fiberglass pipe wrap, some particle board, some 2-3mm plastic wrap, some fabric and some adhesives, along with a dose of patience and some elbow grease.
The short version is that your compressed fiberglass pipe wrap does most of the job all by itself. The rest is mostly finishing: You cut yourself some round caps out of particle board to cap the top and bottom of the fiberglass tube, and use some fabric wrap to cover it up and make it look pretty.
By first adding some plastic wrap to one side—which reflects the high frequencies— you can create custom tube traps with a live side/dead side setup for even more flexibility. Earlier versions of the build (like mine) only used the kraft paper facing for the high frequency reflection side, but the plastic works much better and is more similar in performance to the real ASC Tube Traps.
Some variations on these plans take this design even further by adding a few tall strips of rigid fiberglass insulation inside, or bulkhead discs that break up the cylinder into smaller compartments. Either method increases the absorption further still.
Following the instructions from this website, we built 16 tubes for Rosewood Studio in two different diameters—14” and 16” if I remember correctly. They were relatively easy to build and ended up looking pretty good too (though not quite like the real deal.) Certainly good enough that I could leave them in the live room and not be embarrassed by our handiwork at all.
The first time I used our DIY tube traps, I was shocked! I placed them around the drum kit and the improvement in the sound of the room—and the drum track—was enormous. They were exactly what I had been looking for, even though I didn’t know that I had been looking for them. They were arranged something like this:
To appreciate how they could have so much impact, it helps to understand how tube traps work in the first place.
A tube trap is both a diffuser and a sound absorber. The cylindrical shape makes it a very good diffuser across a range of frequencies, but it also absorbs sound waves as they enter and pass through the tube, so it effectively removes some of the sound energy from the room. They also do a good job of removing excessive low frequency energy, which is never easy.
This type of tube trap has a “bright” side and a “dark” side, with respect to their diffusion. The bright side has a thin limp-mass membrane (plastic wrap) across half of the tube that diffuses high frequencies, while the dark side skips this layer, absorbing the high frequencies instead of scattering them back into the room.
This feature allows you to change the sound of the space inside and outside of a tube trap array: If you want more life and presence, then you aim the bright or “live” side toward the source. If you want more high frequency control, then you aim the dark, absorptive side toward the source.
When I record drums, I tend to prefer the live side facing inwards, toward the kit.
I am always surprised at how much more lively and exciting the drum kit is when positioned inside the Tube Trap array like this.
Plus, the additional absorption of the bass and mid frequencies makes the kit sound cleaner, clearer, and tighter.
This also has the effect of making the close mics and OHs sound more “close” and acoustically neutral, while leaving the liveliness of the room mics relatively untouched—or even slightly enhanced. It’s a similar effect to using baffles or gobos, but without the unwelcome boundary effects of placing a large flat piece of wood and fiberglass right next to the kit.