How TubeTraps Work


Ever wonder How TubeTraps Work? TubeTrap Inventor Art Noxon shares some bass trap history with us.

TubeTrap History: A Short History

What would come to be the iconic bass trap was invented about 25 years ago in 1983 by me, a young acoustic engineer/physicist/speaker builder named Art Noxon. It turns out that I had also unknowingly invented in my basement an improved version of the “functional bass trap” which was something developed in the RCA labs in the 1940’s and revealed to the public in 1950 by the chief engineer Harry Olsen in his classic technical book, Acoustical Engineering.

Found in this book are untold numbers of RCA audio/acoustic lab secrets. Still, it took another 30 years and a patent search before I discovered the functional bass trap and the great book where it was disclosed. Frankly, I was relieved to discover my work fell right in line with and was a natural extension of earlier work in this same area. Even the same peak efficiency of 140% reported by Harry Olsen for his functional bass trap is a standard measurement of the TubeTrap product line.

The first hand made commercial TubeTrap was discovered by Rob Sample, a HiFi rep who passed through town every month or two. The TubeTrap had been gathering dust in two corners of a dealer demo room, behind a set of Magnipans, helping to reduce the strength of the back wave that would otherwise bounce out of the corner and right back towards where it came from, the huge Maggi diaphragm, where it pushed the diaphragm around, distorting the sound.

This TubeTrap was even covered in Maggi white fabric, purchased from the Maggi factory. The store staff pulled the trap out and put it back in while Rob listened.

The next day I got a call from Jon Dahlquist in New York, accent and all. I didn’t know who he was yet but he certainly asked wonderfully technical questions, it was such a relief to talk to another engineer about this device. Jon built the Dahlquist loud speaker and Rob Sample, his NW rep, had called him about what he had witnessed. After a little visiting Jon ordered a set of TubeTraps, I built and sent them. Never thought about money, I was happy that someone wanted to check them out.

A week later he called back and loved what they did for the bass but wanted less treble absorption. I couldn’t believe anyone could hear that well. Still, I asked what the crossover frequency should be and he paused, as if he was a chef, imaging how much seasoning to put in, and then told me.

I made the acoustic crossover to his spec and slipped it into the front of each trap as soon as they arrived and shipped them back the next day. He loved it and invited me to help him set up his demo room at the summer CES in Chicago where he was unveiling for the first time a time-aligned loudspeaker, the DQ-20. I didn’t know what CES was but I agreed to go. And within hours of setting up the demo room there, I was signed by Noel Lee and became the next new product exclusively distributed by Monster Cable.

Noel was an electrical engineer/marketeer who had realized that the electronic interconnects in the audio chain needed to be cleaned up. He had recently signed Bruce Brisson (now MIT) to clean up cable interconnects and now he signed me to help him clean up the acoustic interconnect. Despite the Monster marketing machine, big ads, dealer training and stocking inventories, the pipeline was filled, primed and ready to go but no one came, nothing happened. Monster never released their second PO and eventually TubeTraps (CSP-1s back then) were dropped from the Monster Line Card.

Now, with no hope of outside sales, a completely rebuilt factory full of production materials, I became a traveling TubeTrap salesman, knocking on recording studios doors, not much different from a vacuum cleaner salesman. But they loved them and I paid my bills, including the expensive international 1-800-ASC-TUBE phone bill. I’m glad I did because one day, with absolute no warning, the phone starting ringing off the hook, TubeTrap orders came in from HiFi shops all over the world.

What happened was that J P Moncrieff had finally published his long awaited review of TubeTraps in his IAR, International Audio Review newsletter. Noel Lee had given him a few traps to review. JP followed directions, put a set in the corners behind the speakers and all was good. And then JP asked for a few more, and later a few more and on and on this went for nearly a year before the review came out. JP had even interviewed me but it had been so long, I forgot all about it. What started out to be a review of one pair of TubeTraps in each of the front two corners of the room ended with him reviewing his own TubeTrap invention: The walls of his large listening room were lined with double stack TubeTraps on 3 foot centers, all around the room. And then the reflection panel of each trap was tweeked within an accuracy of “¼ inch”, which no one believed was possible, at that time. Despite this, the TubeTrap became a must have HiFi upgrade, an overnight success story that took 1 ½ years to happen. I will always be indebted to Rob Sample, Jon Dahlquist, Noel Lee and JP Moncrieff for applying their personal vision, imagination and power to the coming out party for the TubeTrap and what it stands for.

There was no such thing as “room treatment” back then except for treble range Sonex foam panels. But this new class of room treatment was nothing like daubing up a little treble splash in the room. This was a new listening room upgrade system, starting with a few traps in the corners, and evolving through different stages which end with floor to ceiling stacks on 3’ centers around the perimeter of the listening room. In its least form, a pair of traps in the corner, the speakers began to behave themselves. And in its ultimate manifestation the listening room was transformed into a magical palace of sound and ambience, imaging and sound stage, a fantasy listening room, a magically transformed listening room which evolved over time into the classic 2C3D reference listening room.


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