Any thoughts on this for room treatment?

[Sonnie]

You can build me some too Quenton!

 

[OJ Bartley]

Those ramp diffusers look very interesting. I'm pretty sure I've run across something very similar before in the various communities of DIY treatments, but they are definitely not common. If they really are effective as close as 1' away, they would be ideal for my rear wall, something like in their image below.

I'm a big fan of diffusion, especially on the rear wall. Combinations of both on the front wall.

I particularly like the Leanfusor. They can be constructed in either 2X4 or 2X2 ft panels & hung next to each other. The number dictated by room width (5 or 7 panels).

Tonto, this is what I'm leaning toward at the moment too. Let us know how they work out... and please do a build thread!

 

[Sonnie]

And Tonto... build them in pairs my friend... I need a few myself.

 

[Tonto]

Hey Sonnie, I would think you would need 7 of the 2X4 panels for your rear wall. I can envision 1 placed horizontally behind your center & a free standing one behind each of your mains. I would expect that to add another layer to improve your SSI. It's pretty good now...so it will be interesting to see some measurements.

I'm completely swamped right now sawing lumber to build a barn. I have a good month of work with the logs I have on the ground now (that's with 1.5 days/week to dedicate to the sawmill)! Once I have it finished I will start the build thread.

If I can get them done by the speaker evaluation, maybe we can work something out.

And I'm not even sure I can get them done by then, but I will try.

 

[Sonnie]

After Wayne worked so feverishly to get my front stage sounding fabulous with the smooth panel reflections, I don't think I would do anything with them on the front, but on the back it would be nice to work some into the mix somehow.

 

[Tonto]

I know what you mean, but I would still try them, whether it makes a difference or not, wont know without trying. I do know you have enough room for them & the physics are good.

I'd mount 7 of them, centered on the back wall with a French cleat. Once I get my shop set up for the build, it should go relatively fast. I'll make jigs for each cut, there are just so many cuts! Each panel has 7 wells to configure. Lots of cuts! The outside cuts I can do with my table saw. The others with a dado blade...those will be the time consuming ones. We'll see how it goes, time wise!

It's nice to adjust the depth of each panel, maybe you and Wayne can figure out what is best for your size room and let me know. I think you have enough room to make them thicker to compensate for the periodicity (profiled modulation). See this ariticle:

http://arqen.com/wp-content/docs/diffusers/Diffuser-A1LF-Fab-Drawings-Arqen.pdf

 

[AudiocRaver]

I really like the idea for your rear wall, Sonnie. I am starting to think in more detailed terns about my new studio/HT build and what I will need there. I will need something like that as well. Probably do a custom design of some sort.

 

[Tonto]

Wow, I just realized the link above doesn't show the finished diffusor, just the base plate. Here is the finished product. All those surfaces is what makes it preform!

http://arqen.com/

 

[NBPK402]

Wow, I just realized the link above doesn't show the finished diffusor, just the base plate. Here is the finished product. All those surfaces is what makes it preform!

http://arqen.com/

That is one thing I like about the slanted one...less work to make if it works as they say it does. The Argen one is more work to make, and I am not sure it works as well or better than other types. I made a couple of the conventional ones that were similar to the slanted ones but not slanted, and they were not difficult to make. You just had to cut the pieces, and then cut the slots and assemble. A little time consuming, but they worked great. Buying them pretty assembled is expensive if you are trying to tune a room completely with them, but if you have the time you can save a lot by doing the math, and making them yourself. You can save money even if you have someone cut all the pieces for you like I did years ago.

 

[Allen Rumbaugh]

I think those are a gimmick. The depth of a diffuser is determined by the target frequency variable in the Shroeder defined quadratic residue equation. If you reduce the depth of a diffuser, you are raising the target frequency which will limit the bandwidth. The high frequency cut off is determined by the channel width, so as you reduce the depth it would act like a high pass shelving equalizer taking away the midrange and bass as you reduce the depth. I do not see that as a benefit.

 

[Matthew J Poes]

I think those are a gimmick. The depth of a diffuser is determined by the target frequency variable in the Shroeder defined quadratic residue equation. If you reduce the depth of a diffuser, you are raising the target frequency which will limit the bandwidth. The high frequency cut off is determined by the channel width, so as you reduce the depth it would act like a high pass shelving equalizer taking away the midrange and bass as you reduce the depth. I do not see that as a benefit.

The Arqen diffuser is no gimmick. The designer not only thoroughly modeled the design but built and tested them for his PhD dissertation project. It's been thoroughly peer reviewed. He isn't the inventor of the stepped diffuser, that was developes by one of the Principles at RPG and also built and tested at a University in England. It diffusses down into a lower frequency than expected for its depth. If you sign up and read the full article he explains the process and why it's true. The modeling software they use has been well vetted as accurate.

The ramp diffussers on the other hand have no sound science behind them. They took a QRD design and slanted it so it has a continuously changing depth, but the depth change is linear in a specific direction. Someone needs to model that in a proper program or have it tested using appropriate methods. I'm highly skeptical of the ramp diffussers.

There are a lot of diffussers developed by people who don't know what they are doing. A number of them were modeled and a few tested and in nearly all cases found to be sub-optimal.

http://www.realacoustixllc.com/blog-3/
Check out this blog for some nice information on diffussion. Outside of Peter D'Antonio he is one of the most knowledgeable people concerning diffussion. He codeveloped the new standard for measuring diffussion in the United States.

 

[Allen Rumbaugh]

I was talking about these:

I just found this, and I find it an interesting design. What do you think?

http://www.xix-acoustics.com/2011/09/04/why-does-the-acoustic-ramp™-work-better/

#1Negatron, May 21, 2017
Last edited: May 21, 2017

 

[Allen Rumbaugh]

I was talking about these:

I just found this, and I find it an interesting design. What do you think?

http://www.xix-acoustics.com/2011/09/04/why-does-the-acoustic-ramp™-work-better/

#1Negatron, May 21, 2017
Last edited: May 21, 2017

Now those are a gimmick!

 

[Matthew J Poes]

I was talking about these:

I just found this, and I find it an interesting design. What do you think?

http://www.xix-acoustics.com/2011/09/04/why-does-the-acoustic-ramp™-work-better/

#1Negatron, May 21, 2017
Last edited: May 21, 2017

I yes I think those are a gimmick as well. I think there is often a fundamental misunderstanding of how diffusion works and as such a lot of designers play fast and lose with the design. I think somethign this radically different needs to be modeled for its behavior to be understood. I suspect it’s ramp shape limits the low frequency diffusion that is possible.

 

[Allen Rumbaugh]

I yes I think those are a gimmick as well. I think there is often a fundamental misunderstanding of how diffusion works and as such a lot of designers play fast and lose with the design. I think somethign this radically different needs to be modeled for its behavior to be understood. I suspect it’s ramp shape limits the low frequency diffusion that is possible.

Amen to that! I have made lots of diffusers using Shroeder's equations, and while I don't have the measurements that some people insist on having, I do have empirical evidence that trained ears provide. In every case, the larger (higher prime) deeper (lower target frequency) sounded better across the entire range, with the unbelievable bonus of focussing the bass range better than bass traps!

 

[Matthew J Poes]

Amen to that! I have made lots of diffusers using Shroeder's equations, and while I don't have the measurements that some people insist on having, I do have empirical evidence that trained ears provide. In every case, the larger (higher prime) deeper (lower target frequency) sounded better across the entire range, with the unbelievable bonus of focussing the bass range better than bass traps!

Until such time that reliable and acceptable methods of measuring diffussion can be had, I am ok with not having measurements. Diffussion is something that can be simulated adequately, and if you rely on proven methods like the QRD I don't think it's a problem.

Where we run afoul in acoustics is when people take a 1D QRD and remove the fins (for example). The fins are part of how a QRD works. Another example are 2D "skyline" Qrd's with angles edges. If you model that I find it ok, but to just randomly throw in some angles isn't right. In a few models that were tested doing that added significant high frequency absorption because the reflected waves were getting caught in nearby deaper wells were air alone was sufficient to dissipate them.

I'm really excited about the new standard for diffussion measurement but worry it's too restrictive. It penalizes diffusion if there is associated absorption. While I understand why, it also means that absorption aided MLS diffussers measure as having only very high frequency diffussion. It also causes 3D well diffussers that use complex well shapes to have lower diffussion than the model and concept suggests. I am not smart enough to make a cogent argument against this but I am convinced that MLS Absorption is diffussion based on Schroeders work there.

 

[Allen Rumbaugh]

Until such time that reliable and acceptable methods of measuring diffussion can be had, I am ok with not having measurements. Diffussion is something that can be simulated adequately, and if you rely on proven methods like the QRD I don't think it's a problem.

Where we run afoul in acoustics is when people take a 1D QRD and remove the fins (for example). The fins are part of how a QRD works. Another example are 2D "skyline" Qrd's with angles edges. If you model that I find it ok, but to just randomly throw in some angles isn't right. In a few models that were tested doing that added significant high frequency absorption because the reflected waves were getting caught in nearby deaper wells were air alone was sufficient to dissipate them.

I'm really excited about the new standard for diffussion measurement but worry it's too restrictive. It penalizes diffusion if there is associated absorption. While I understand why, it also means that absorption aided MLS diffussers measure as having only very high frequency diffussion. It also causes 3D well diffussers that use complex well shapes to have lower diffussion than the model and concept suggests. I am not smart enough to make a cogent argument against this but I am convinced that MLS Absorption is diffussion based on Schroeders work there.

"The Arqen diffuser is no gimmick. The designer not only thoroughly modeled the design but built and tested them for his PhD dissertation project. It's been thoroughly peer reviewed. He isn't the inventor of the stepped diffuser, that was developes by one of the Principles at RPG and also built and tested at a University in England. It diffusses down into a lower frequency than expected for its depth. If you sign up and read the full article he explains the process and why it's true. The modeling software they use has been well vetted as accurate. "
I have found the fins to be unnecessary in my research, I have heard RPG's that were large and had them and came away unimpressed. I notice that the Arqen diffusers you are fond of use no fins. What gives? Opinions I have read deem them unnecessary in large high prime diffusers that are used alone. They seem to think that small diffusers placed close together need them, however I never use a group of small ones together, so I will leave that research to others. I have found that the bigger they are, the better they work, so that is what I generally recommend.

 

[Matthew J Poes]

"The Arqen diffuser is no gimmick. The designer not only thoroughly modeled the design but built and tested them for his PhD dissertation project. It's been thoroughly peer reviewed. He isn't the inventor of the stepped diffuser, that was developes by one of the Principles at RPG and also built and tested at a University in England. It diffusses down into a lower frequency than expected for its depth. If you sign up and read the full article he explains the process and why it's true. The modeling software they use has been well vetted as accurate. "
I have found the fins to be unnecessary in my research, I have heard RPG's that were large and had them and came away unimpressed. I notice that the Arqen diffusers you are fond of use no fins. What gives? Opinions I have read deem them unnecessary in large high prime diffusers that are used alone. They seem to think that small diffusers placed close together need them, however I never use a group of small ones together, so I will leave that research to others. I have found that the bigger they are, the better they work, so that is what I generally recommend.

Sorry Allen I wasnt being clear. I don't think fins are required. Just that they need tonne accounted for. Most diffuser design software allows either.

The Arqen is a different kind of diffuser. It's a step diffuser, not a QRD. There are some research articles on these. They aren't great on their own in singles. A QRD or PRD would work better. They are mostly useful in large arrays where their frequency range can be extended. The Author on Arqen shows data for the different configurations.

I'll be honest I am not all that experienced with diffusers. I worked under a studio designer who used them, which gave me a chance to hear a studio with and without them a few times. I helped a musician friend setup in a large studio with among the largest PRD diffusers I've ever seen in my life. In my own home I have those MLS diffussers and at one time had some styrene QRD diffusers. I eventually tossed them and have wanted to build some wood ones of different designs to try. I mostly have book knowledge on diffusers.