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Get That HiFi Sound…with That Built-In Look

Published On: February 19, 2021Tags: , , , , ,

To You, Room Sound is Always Important!

If you did not value the sound quality in your listening or studio room, you would not be receiving this email. But just because you love great sound, it doesn’t mean you want your living room to look like a recording studio, and maybe your studio workflow prohibits the installation of 20-odd TubeTraps and StudioTraps.

This hair salon has a wonderful, natural sound…with no acoustic products on the floor or wall!

Guess what? You can fix your room sound while consuming a minimum of real estate and potentially enhancing the room decor. Corner-mounted Fractional TubeTraps and PanelTraps to the rescue!

If you like charts and data, and love invisible acoustics, this week is for you.

This hair salon has a wonderful, natural sound…with no acoustic products on the floor or wall!

OK, What About those Built-in Acoustics?

You may or may not know that some “TubeTraps” are not round, nor are they Tubes!

Well, to be fair, the original, authentic, archetypal TubeTrap is still a cylinder and contains all the elements of room acoustic control that we hold dear. But the application of an RC-time constant lumped parameter acoustic bass trap can be-and has been-applied to many shapes, sizes, and geometries. This week we will start to look at some non-cylindrical versions of the classic ASC corner loaded pressure-zone bass trap.

Our main focus: QuarterRound TubeTrap (QRTT). Stay tuned for more in the coming weeks!

What is a QuarterRound TubeTrap?

Similar to the classic cylindrical TubeTrap, a QRTT utilizes a flow-resistive membrane surrounding a capacitive air volume to increase efficiency of low frequency sound absorption. Just like it is with its tubular brethren, a larger internal volume permits operation to lower frequencies. And just like the classic TubeTraps, each QRTT contains a built-in treble range polycylindrical diffuser. The icing on the cake: because its shape is that of a quarter-cylinder, each one only takes up one quarter the space of the full-round model, despite operating across the same frequency range!

Shown below is a cross-section of a HalfRound TubeTrap, which is similar to full-round and QRTT, but instead is shaped like a…you guessed it, half -cylinder.

Wait–Where is the Data?

Waaaay back, late in the last millennium, ASC ran a test to measure the effectiveness of its latest iteration of the RC-time constant bass trap—yes, it was a 16″ model QRTT. The room layout is shown below, using the original lab notes.

Ahh, the good old days, the ’80s, when you could buy a gallon of milk for $2.19. Wait, it’s still only about $2.60. How about: the good old days, when you could fully treat the acoustics in a listening room for less than a pair of interconnect cables today.

The room-under-test (RUT) had QRTTs installed along all the vertical corners and HalfRound TubeTraps installed flat on the ceiling along each wall. Tests were run in the same room when empty for baseline comparison. Partial room dimensions are shown below.

This is a pretty decent room size. Maybe a little on the small side, but the surfaces were highly reflective so the decay time was long and the sound quality was bad—when empty. Let’s look at what change after adding built-in acoustics!

Techron by Crown: Cutting Edge TEF Analysis System, ca. 1985.

Most of you will remember the days when Apple IIe and Commodore 64 ruled. Then there were the subsequent rapid chip and electronics advancements that put a Pentium in every home by the dawn of the 21st century, and by 2020, more computing power in the palms of our hands than was used to land astronauts on the moon. But in 1985, an all-in-one calibrated audio analysis system utilizing Time Delay Spectrometry was pretty amazing. Who are we kidding, that is cool even today!

Here, the first image shows the reverberation time of the bare room and the second shows the room with QRTT corner treatment.

Observe how quickly the room sound decays after installing the QRTTs. The RT60 has been cut by over 60 percent between 35 and 550 Hz! And this is with zero panels on the wall, with corner treatment protruding a mere 8 inches into the room. Talk about reducing the mud and boom!

And below we see the cumulative spectral decay (waterfall, for short) of the empty room followed by the treated room.

On these plots, the frequency scale runs left-to-right and the time scale protrudes outward from the screen. Observe how, across the entire test bandwidth, the bare room decay profiles smash up against the end of the time range at about 1/2 second, whereas the treated room has become almost silent by this same time. This tells us the invisible QRTTs in the corners are really doing a lot!

OK, I’m sold. Where and how do I get these?

Because of varying room dimensions, each order of QRTTs is built custom for your unique situation. Custom lengths can be made up to 8 feet long! Factors such as baseboards, crown moulding, picture rails, and architectural soffits can require further customization. Therefore, QRTTs are not available for online purchase at our e-commerce store. We prefer to help guide your choice of diameter and length to help assure the acoustic and aesthetic results you are looking for. We want to turn that frown upside down!

Is the QRTT the most economical acoustic solution for your room? No, custom work of this type commands a premium above that of our classic full-round TubeTraps. But how can you put a price on domestic tranquility when the goal includes immersive and realistic sound reproduction? Settle for nothing less than the best acoustics available—that also look the best!

Knock away that muddy sludge and enjoy some Sister Sledge!

Clean up the Mud and Muffle the Boom

By installing a sufficient number of QRTTs in your room to cover the vertical corners and upper wall/ceiling corners, you will achieve an optimal degree of bass control. Impeccable accuracy, increased tightness, and loss of boomy muddy bass will be your reward.

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