My dedicated audio room build - QuadDiffusor's Big Dig

[QuadDiffuser]

Preliminary REW waterfall results.

The deep trough right below 150Hz can be ignored, as it’s the crossover between the omni-360 speaker and the subwoofer, where no source energy was injected.

Gratified to confirm smooth spectral and temporal decay from 200Hz onwards. Peaks and troughs in the deep bass region are expected to be flattened through steel plate bass traps, deep/large QRDs, and many PSI Audio AVAA C20s and C214s.

 

[QuadDiffuser]

57 pieces of VPR (steel plate + foam) bass traps are finally starting to being mounted on the gypsum fiberboard walls!

Here's a close-up of the isolation mounting bracket, originally flat/straight but now custom bent at an optimum distance, to squeeze the melamine foam against the wall, yet hold the 1.5mm steel plate firmly and safely while maximizing the steel plates' freedom to vibrate in response to airborne bass energy.



The left sidewall is covered by VPR bass traps with 1.5mm steel plates in two different sizes (1.0m x 1.2m and 1.0m x 1.5m), designed to resonate to slightly different bass frequencies and broadening its effectiveness. Design details are in the link below:

My dedicated audio room build - QuadDiffusor's Big Dig

Left wall: 7 pcs. 1.5mm thick, 1.0m x 1.5m 4 pcs. 1.5mm thick, 1.2m x 1.5m

www.whatsbestforum.com

 

[microstrip]

57 pieces of VPR (steel plate + foam) bass traps are finally being mounted on the gypsum fiberboard walls!

Here's a close-up of the isolation mounting bracket, bent at an optimum distance to squeeze the melamine foam against the wall, yet hold the 1.5mm steel plate firmly and safely while maximizing the steel plates' freedom to vibrate in response to airborne bass energy.

View attachment 158946

The left sidewall is covered by VPR bass traps with 1.5mm steel plates in two different sizes (1.0m x 1.2m and 1.0m x 1.5m), designed to resonate to slightly different bass frequencies and broadening its effectiveness. Design details are in the link below:

My dedicated audio room build - QuadDiffusor's Big Dig

Left wall: 7 pcs. 1.5mm thick, 1.0m x 1.5m 4 pcs. 1.5mm thick, 1.2m x 1.5m

www.whatsbestforum.com

View attachment 158947


View attachment 158948

Excellent work. For those interested in such work the mounting devices are from a spanish manufacturer - SENOR. I have used them before - they are not cheap, but they are top quality - see their catalogs at https://senor.es/en/

 

[QuadDiffuser]

More photos of VPRs going up (while I’m traveling overseas in the US).

The left and front walls:


The front and right walls:

 

[gleeds]

QD, wow!

Jumping in to follow your heroic project. Damon and I look forward to visiting you when it's done!

 

[QuadDiffuser]

Gary and Damon,
You’re both welcome any time!
Eagerly looking forward to making my VSA Ultra.nines shine, with your help.

 

[QuadDiffuser]

Still abroad, but receiving photos showing progress with the ongoing VPR bass trap installation.

 

[MarkusBarkus]

...looking like a NASA project lately! So groovy, QD.

 

[Kingrex]

I'm still freaked out by how much absorption is in the room.
I wonder how close a result would come from a swarm of subs?

 

[QuadDiffuser]

It’s really not that difficult to understand. Bass signals create gigantic pressure waves which are extremely difficult to tame, due to their sheer power engulfing and overwhelming just everything in their way.

Actually, my room is relatively small in the eyes of deep bass notes; the longest dimension of my listening room can only “fit” a full 37Hz wave whose length is 30.4ft.

Every time bass frequencies strike a solid boundary perpendicularly, it “flips” 180 degrees out of phase and wreaks havoc with the purity of original wave. Multiply this corruption through exponentially higher combinations and permutations of other boundary effects, and bass response becomes highly erratic and location-dependent.

The best solution to achieving smooth and uniform bass response (not just at the listening position but throughout the room) is to have the bass *NOT* bounce between the boundaries, but to just have it disappear, by having it leave the room through the proverbial “black hole” or open window. But this is unfortunately impossible to achieve in my basement.

VPRs can help provide relief from ever-bouncing and ever-phase-flipping bass pressure, as they attenuate 3-4dB of bass in a narrow bandwidth corresponding to the metal plate’s dampened resonance modes. It’s important to broaden the range of bass frequency absorption peaks as I have, by installing six types of VPRs which differ in size and metal plate thickness.

The VPRs will progressively attenuate bass pressure with each back-and-forth strike of the bass waves. They’re also effective for axial, tangential and oblique bass pressure deflections alike.

Next, two bass-cancellation subwoofers which are each tightly phase-coupled to the two primary loudspeakers via high-voltage input signals tapped from the loudspeaker’s bass binding posts (ie. Von Schweikert Audio’s system for using subwoofers to cancel room nodes) would likely be the best solution.

Thirdly, by adding active bass-cancellation devices like the PSI Audio’s AVAA products should help take care of the remaining residual bass pressure anomalies.

Removing unnecessary bass pressure through the combination of passive VPR bass traps and two types of active bass cancellation devices should be superior to randomly placing infinite numbers of subwoofers in the room to ADD uncontrollable bass energy, don’t you think?

 

[pjwd]

It’s really not that difficult to understand. Bass signals create pressure waves which are extremely difficult to tame in a small room with solid walls, such as mine. Yes, my room is relatively small - the maximum dimension of my listening room can only “fit” a full 37Hz wave whose length is 30.4ft.

Every time the bass frequencies strikes a solid boundary perpendicularly, the wave “flips” 180 degrees out of phase, and wreaks havoc with the direct wave launch of the original signal. Multiply this through exponentially higher combinations and permutations of other boundary effects, and the outcome will be bass response which would be highly erratic and highly location-dependent.

The best solution to achieving smooth and uniform bass response (not just at the listening position but throughout the room) is to have the bass *NOT* bounce between the boundaries, but to just have it disappear, by “leaving” the room through an open window. But this is mostly impossible to achieve in a basement.

VPRs can help achieve some relief from ever-bouncing and ever-phase-flipping bass pressure, as they will at best only attenuate 3-4dB of bass in a narrow bandwidth corresponding to the metal plate’s dampened resonance modes. The key is to have the bass pressure progressively reduced with each back-and-forth strike of the VPRs.

Next, two bass-cancellation subwoofers which are each tightly phase-coupled to the two primary loudspeakers via high-voltage input signals tapped from the loudspeaker’s bass binding posts (ie. Von Schweikert Audio’s subwoofers) would likely be the best pressure cancellation solution.

Thirdly, by adding active bass-cancellation devices like the PSI Audio’s AVAA products should help take care of the remaining residual bass pressure anomalies.

The combination of passive VPR bass traps, and two types of active bass cancellation devices should be superior to randomly placing infinite numbers of subwoofers in the room, don’t you think?

Totally agree with the above ... it is best to optimise the passive approach and then refine with active if needed. I can't remember if you posted decay times in the bare room but I bet it would be a few seconds at lf
A before and after plot would be interesting.

 

[QuadDiffuser]

Hmm… any photos I try to upload, WBF says “photo is too large”. 3.2MB is too large? I’ll wait to upload pics on my posts until the bug is eradicated.

 

[pjwd]

It's been a very slow month waiting for the wood QRDs to arrive from Indonesia, and in the meantime, optimizing the already installed metal plate bass absorbers by trimming the mounting tabs into mere "finger pinches" to maximize their excitation nodes, and hence absorption capabilities.

BTW, hmm… any photos I try to upload, WBF says “photo is too large”. 3.2MB is too large? I’ll wait until the bug is eradicated.

QD are you running some measurements when each stage is complete .. it would be super interesting

 

[QuadDiffuser]

My dedicated audio room build - QuadDiffusor's Big Dig

Left wall: 7 pcs. 1.5mm thick, 1.0m x 1.5m 4 pcs. 1.5mm thick, 1.2m x 1.5m

www.whatsbestforum.com

My dedicated audio room build - QuadDiffusor's Big Dig

Preliminary REW waterfall results. The deep trough right below 150Hz can be ignored, as it’s the crossover between the omni-360 speaker and the subwoofer, where no source energy was injected. Gratified to confirm smooth spectral and temporal decay from 200Hz onwards. Peaks and troughs in the...

www.whatsbestforum.com

PJWD,
Initial tests from 5 weeks ago (see links above) of the empty room, done PRIOR to the VPR installation.

The next tests will be within a month, after the ventilation system is completed.

As is, the room is already sounding amazing: zero RFI, zero environmental subsonic rumble thanks to the floating isolated floors and six layers of wall treatments, eery silence with ambient noise at below 19dBA (not super accurate though, via Decibel X on iOS)… but spoken words are highly articulate, lively and natural without any reverberation.

With the QRDs in place, I’m expecting the perceived ceiling and wall boundary distances to dissolve/expand 40-50% further than the actual measured W, L, and H. That equates to more than double the room volume, without the typical problems associated with overly large rooms.

 

[lars66]

Still abroad, but receiving photos showing progress with the ongoing VPR bass trap installation.

View attachment 159465

I am a big supporter of the acoustic treatment of the space/room. This project seems extremely interesting. It's impressive. I'm very curious to see what it will look like when it's finished. I wish you a lot of luck and success.

 

[wil]

Hmm… any photos I try to upload, WBF says “photo is too large”. 3.2MB is too large? I’ll wait to upload pics on my posts until the bug is eradicated.

3 mb is excessively large for a forum post.

 

[wil]

Yes the next test will be within a month, after the ventilation system is completed.

As is, the room is already sounding amazing: zero RFI, zero environmental subsonic rumble thanks to the floating isolated floors and six layers of wall treatments, eery silence with ambient noise at below 19dBA… but spoken words are highly articulate, lively and natural without any reverberation.

With the QRDs in place, I’m expecting the perceived ceiling and wall boundary distances to dissolve/expand 40-50% further than the actual measured W, L, and H. That probably equates to double the room volume, without the typical problems associated with overly large rooms.

What are you using to measure rfi? Is the room below ground level?

 

[QuadDiffuser]

Uploading a 3.0MB size jpeg should be normal in today's world of modern smart phones, no? Thought that uploads will be automatically compressed / down-rez'd to 200-300kb by the WBF forum "engine". Maybe I've inadvertently tripped past the 3.0MB limit, by upgrading to the iPhone 17 ProMax.

 

[QuadDiffuser]

It's been a very slow month waiting for the wood QRDs to arrive from Indonesia. In the meantime, the metal plate bass absorbers' performance has been optimized by trimming the mounting tabs into mere "finger pinches" to maximize the plates' excitation nodes, thus their bass absorption capabilities.

The R wall; the lattice of steel bars on the ceiling will be holding 49 pcs. of solid mahogany Skyline diffusers totaling ~2,000 kgs



The rear wall; note the intake vent structure, running horizontally across the encased protruding pool structure



A close-up view of the shortened/truncated mounting tabs; note that two screws are used instead of four/six screws


Front R corner bass traps; instead of the metal plate "free floating" and flapping loosely in their diagonal corner supports, a solid plywood backboard has been added to allow the vibrational energy to dissipate more efficiently

 

[gleeds]

Us audiophiles are a special breed, persistently pursuing perfection despite diminishing returns, to reach the asymptotic limits of whatever constraints life imposes on us. Rarely do we have the chance to bust through and quantum-leap into a higher orbit, as we typically run out of energy, resources, and especially, time. During the past 40+ years as an audiophile, this hobby has brought me immense enjoyment and knowledge, always returning far more than the cost... few pursuits are as compelling as this one!

During my search for a new home to move into, the ideal space for a dedicated listening room was a Top Three on my criteria list. When the occasion would present itself, my wife will reveal to our friends the reason our search had dragged on for over a year - my obsession with finding the space for the audio room. How amusing it was when the occasional audiophile acquaintance we'd meet would be in rabid agreement with me.

The long search finally concluded last fall, when we found our dream “home“, a piece of land on which a very old 50+ house stood. Yay, an opportunity to design and rebuild a new home, which of course, must have a dedicated listening room!

I'd like to share my home-building, or more accurately, my dedicated audio room build, with my fellow WBF denizens. The "Big Dig" alludes to the basement in which the audio room will be built, and to fellow-WBF member Hugh, who started a forum thread describing his journey of digging deeply to build his very own dedicated listening room in a ground-breaking and heroic way. Collectively the experience and knowledge of everyone on WBF far exceeds whatever I've had the luck to acquire. Together, I'm hoping that this project will be a satisfying and worthy accomplishment on par with successfully reaching a magnificently higher orbit.

QD

It's been a very slow month waiting for the wood QRDs to arrive from Indonesia. In the meantime, the metal plate bass absorbers' performance has been optimized by trimming the mounting tabs into mere "finger pinches" to maximize the plates' excitation nodes, thus their bass absorption capabilities.

The R wall; the lattice of steel bars on the ceiling will be holding 49 pcs. of solid mahogany Skyline diffusers totaling ~2,000 kgs
View attachment 160930


The rear wall; note the intake vent structure, running horizontally across the encased protruding pool structure
View attachment 160931


A close-up view of the shortened/truncated mounting tabs; note that two screws are used instead of four/six screws
View attachment 160932

Front R corner bass traps; instead of the metal plate "free floating" and flapping loosely in their diagonal supports, a solid plywood backboard has been added to allow the vibrational energy to dissipate more efficiently
View attachment 160933

Keep sharing progress, QD. The project exudes passion, and your patience and hard work to build your dream home and dream listening room.