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[Bill Mueller]

http://www.deltahdesign.com/form.html

I believe I might understand what they are doing, but I wonder if anyone else has any ideas?

Thanks!

Bill

[franman]

I'm sorry but I'm not sure what you're asking specifically?? Are you asking if anyone has an opinion about this design firm?? Are you asking if we have an opinion about their approach (specifically the Taoism??)... Or are you asking if anybody likes what they see... I took a quick look, but.....

FM

[Bill Mueller]

franman wrote on Wed, 27 January 2010 22:11

I'm sorry but I'm not sure what you're asking specifically?? Are you asking if anyone has an opinion about this design firm?? Are you asking if we have an opinion about their approach (specifically the Taoism??)... Or are you asking if anybody likes what they see... I took a quick look, but..... FM

Fran,

I'm sorry, I made an assumption that the ZR acoustics from Delta H Design might have been discussed on this forum already.

The claims as I understand them are a near anechoic environment using typical construction techniques, in rectangular dimensions, with sheet rock and stud construction, common insulation and standard depth walls.

I have an idea how they might do it, but I was curious what you or others on the forum thought. Don't know anything about the Taoism.

Here is a recent article on the subject.

http://proaudioreview.com/article/18802

Bill

[franman]

Huh.. well the article reveals nothing and seems to make it all sound like 'black magic'... so... that's usually not the best recommendation. I prefer some actual repeatable science.. but I know the clients they refer to, and these guys have ears for sure... so... I don't really have any valid opinion.

If you know what he's doing (or think you do) please feel free to expand...

FM

[Bill Mueller]

franman wrote on Sun, 31 January 2010 23:43

Huh.. well the article reveals nothing and seems to make it all sound like 'black magic'... so... that's usually not the best recommendation. I prefer some actual repeatable science.. but I know the clients they refer to, and these guys have ears for sure... so... I don't really have any valid opinion. If you know what he's doing (or think you do) please feel free to expand... FM

Fran,

Thanks for taking a look. I posted this on Whatever Works, but clearly, I am wildly speculating. Just thinking inside the box.

Quote:

I really don't know anything more than anybody else who has not signed the NDA, but here is my personal speculation. Hsu talks about "classic" techniques, which to me means Helmholtz. He also talks about using wood studs, sheet rock, fiberglass and typical wall depths. With only a couple of inches available for absorption, what I believe he has developed is a computer model for drilling a pattern of holes in his interior walls to create a custom filter (various helmoholtz traps) out of the entire room surface. Here is how it would go within the program. I measure a given rectangular space, and from those measurements derive the resonant frequencies. Then I place my speakers (within the program) at the front of the space (or even better flush mounted in the front wall) and calculate the primary points of interference along each surface. The program then creates a pattern of holes that I can drill in the surface, to create tuned traps along the surface to match the resonance encountered at each point. The fewer the holes, the lower the frequency of the trap. Imagine the image of individual air particles (portrayed by holes in the walls) being compressed and rarefied along the plane of every surface. Like big rolling waves of dots. He then covers the bass trapping holes with a super hf absorptive covering, (one inch compressed glass for instance) and then covers that with fabric. Instant customized broadband acoustic trapping. Now this all might sound great until we examine the depths necessary to achieve efficiency in a Helmholtz absorber (depth of neck) and we will see (I'm sure) the we would need more than a couple of inches of fiberglass to achieve enough absorption at fundamental frequencies. So there is still something else going on IMO inside the walls. Maybe large suspended resonant panels within the walls. I forgot to mention that they say the wall structure does very little to ISOLATE the room from the outside. This really supports my wild speculation that they have compromised the isolation properties of the walls to create the absorption properties.

Best regards,

Bill

[0dbfs]

The low frequency energy has to go somewhere.

How would one approach designing an acoustic frequency specific "Check-Valve"?

[franman]

Bill,

It's a reasonable set of assumtions for a system that might work. I agree that the neck of the helmholtz being limited by typical drywall construction is a factor. Also, with the question of where does all the LF go... I think it just goes 'out' of the room. The entire room is a relief valve below some point (below 100-200 Hz somewhere??)..

So, this is a fun experiment if you can build studios that don't require any LF isolation. I rarely get these gigs!!???

FM

[Bill Mueller]

franman wrote on Mon, 01 February 2010 19:04

Bill, It's a reasonable set of assumtions for a system that might work. I agree that the neck of the helmholtz being limited by typical drywall construction is a factor. Also, with the question of where does all the LF go... I think it just goes 'out' of the room. The entire room is a relief valve below some point (below 100-200 Hz somewhere??).. So, this is a fun experiment if you can build studios that don't require any LF isolation. I rarely get these gigs!!??? FM

Fran,

Wow, I'm flattered that you think my wild speculation has any merit at all!

And yes, we were recently discussing "loose" control rooms over at WW. My observation has been that bass buildup and Westlake type bass trapping accompanied "tight" rooms that were necessitated by the need to isolate the studio/control rooms due to rock recording levels. Earlier rooms, especially in the US would have been lighter construction and would have appeared to be quite broadly "trapped" by the loose seams and panel action when viewed from within. Just as you describe, the entire room as a bass relief valve.

Best regards,

Bill

[0dbfs]

Pro's/Con's?

If your holes in each side of the drywall are spaced such that you have maximum separation (for instance vertically separated on each side by a number of feet or horizontally separated by a number of inches.. Like ten inches or so) and you stuff the stud cavities/chambers with compressed rockwool or fiberglass, you can still have numerous feet or inches of RW3 attenuation between the holes/wall-leaves...

In essence, you have can tune numerous chambers (8 or so along a ten foot wall) of about 14"x8'(or whatever the width/height is between framing plates and studs) filled with dense RW3 at the most important pressure points in the room (tuned like Bill explained with the holes at the pressure points and separated by as much space as possible on each side of the wall in order to maximize the RW3,730, or even R13). Use multiple layers of dryall for mass, seal each chamber/stud-drywall point with silicone caulk, cover the interior of the room with RW3 or 703 and place diffusion (or refectors) at up to ten ray-traced reflection points to direct HF away from the listening positions.

Typical structural isolation still applies.

Use the "ZR" walls between rooms/spaces with less of an isolation requirement. ie; Between CR and lobby or lounge.

Continue to use traditional non-perforated walls between areas with more critical isolation requirements (or maybe ZR walls would still be ok?). ie; Between CR and live room.

Here is a floor plan from The Invisible Studios (http://www.theinvisiblestudios.com/studio-tour/) website that uses the ZR system:



Best,
j

[Bill Mueller]

0dbfs wrote on Tue, 02 February 2010 09:38

Pro's/Con's? If your holes in each side of the drywall are spaced such that you have maximum separation (for instance vertically separated on each side by a number of feet or horizontally separated by a number of inches.. Like ten inches or so) and you stuff the stud cavities/chambers with compressed rockwool or fiberglass, you can still have numerous feet or inches of RW3 attenuation between the holes/wall-leaves... In essence, you have can tune numerous chambers (8 or so along a ten foot wall) of about 14"x8'(or whatever the width/height is between framing plates and studs) filled with dense RW3 at the most important pressure points in the room (tuned like Bill explained with the holes at the pressure points and separated by as much space as possible on each side of the wall in order to maximize the RW3,730, or even R13). Use multiple layers of dryall for mass, seal each chamber/stud-drywall point with silicone caulk, cover the interior of the room with RW3 or 703 and place diffusion (or refectors) at up to ten ray-traced reflection points to direct HF away from the listening positions. Typical structural isolation still applies. Use the "ZR" walls between rooms/spaces with less of an isolation requirement. ie; Between CR and lobby or lounge. Continue to use traditional non-perforated walls between areas with more critical isolation requirements (or maybe ZR walls would still be ok?). ie; Between CR and live room. Here is a floor plan from The Invisible Studios (http://www.theinvisiblestudios.com/studio-tour/) website that uses the ZR system: Best, j

Jonathan,

That was pretty much exactly were I was going. I would just add some hallways between those rooms for additional isolation.

Bill

[0dbfs]

Bill,

Thanks! I just wanted to add some details to what you had already explained and get to a better point of personal understanding.

I've got to build some control room walls soon which have a hall and lounge space on either side of the CR (and an adjacent vocal booth) so I might try this out to even out the LF response of the room. The front and back walls are exterior/fixed though and I need to keep as much space as possible. I might consider losing 5 or six inches on each the front/back as well to provide an exit path for the LF using this method to address the modes related to that dimension. I wasn't going to do anything special with these walls (like double drywall, RW3 in the cavities, etc. Except interior treatments) in this room but this potentially sounds like a reasonable and inexpensive method to even out room mode issues.

My biggest concern at this point is how to prevent (rather minimize) LF from coming into the room from the surrounding spaces. It might not be much of an issue in this case because the building is stand-alone, set back, and physically isolated by distance. Plus it would get in anyway via normal structure coupling.

Best,
j

[Bill Mueller]

0dbfs wrote on Wed, 03 February 2010 07:08

Bill, Thanks! I just wanted to add some details to what you had already explained and get to a better point of personal understanding. I've got to build some control room walls soon which have a hall and lounge space on either side of the CR (and an adjacent vocal booth) so I might try this out to even out the LF response of the room. The front and back walls are exterior/fixed though and I need to keep as much space as possible. I might consider losing 5 or six inches on each the front/back as well to provide an exit path for the LF using this method to address the modes related to that dimension. I wasn't going to do anything special with these walls (like double drywall, RW3 in the cavities, etc. Except interior treatments) in this room but this potentially sounds like a reasonable and inexpensive method to even out room mode issues. My biggest concern at this point is how to prevent (rather minimize) LF from coming into the room from the surrounding spaces. It might not be much of an issue in this case because the building is stand-alone, set back, and physically isolated by distance. Plus it would get in anyway via normal structure coupling. Best, j

Hey Jonathan,

Two things.

First, I am wildly speculating on the feasibility of drilling holes in walls to create a series of Helmholtz absorbers coincident with standing waves in a rectangular room. As Fran said, it might work, but no guarantees. There are a LOT of variables to work out. Also, you will need a program to create the patterns IMO, although I guess it could be done with a tape measure and sharpie. It hurts my brain to think about it though.

Having a program calculate a 3D environment and then either project the dots on the wall or print out hundreds of sheets of paper (or large drafting sheets) that could be pasted on the wall and drilled through would be so much easier to implement. (I subcontract for NASA so these kind of engineering challenges seem reasonably doable.) But it's a long way from speculating about it to actually implementing it.

Second, regarding the low freq isolation. You have a lot better consultants here than me! If it were my project, I would do the typical things of cutting and sealing the slab, (if possible), floating the floor and building the most rigid wall structure I could afford (money and space).

The only thing I might add, and I have done this before with a bit of success, is to build bass traps on the HALLWAY side of the walls. I did this once by mounting sealed and damped masonite panels on the walls of a hallway between rooms. By attempting to absorb the bottom BEFORE it entered the room, I was able to use the space in the halls to reduce the trapping needed in the rooms. I covered these panels with large colorful graphics and it looked pretty good. Of course this won't really help much right next to an exterior wall, so back to Mass, isolation and insulation.

Bill