It's pretty mind bending to me that we live in an age where we can all sit in our chairs and benefit in near real time from the knowledge and expertise from experts in a nascent area of research. Thank you for sharing this information.
@@mourlyvold64 born at the onset of the 80's and have enjoyed watching the evolution of technology. I just wish Facebook and like platforms hadn't destroyed people's social skills. LOL ironic isn't it?
@@xil.sanctified I fully agree, young man. Though, since I know teenagers fed up with facebook and the like, I'm still somewhat hopefull. Greetings from the Netherlands.
So good to see that your research and testing is slowly cracking the code, and you've got the documentation and test results to prove it. 3 years of perseverance and hard work pays off. Well done indeed Richard. My hats off to you. Really looking forward to the next diffusion chapter.
Has any research been undertaken, investigating textile composite fiber blends (dare I say it), for example two layered composite fiber with a concentration of carbon on the forward dimension with wool woven on the reverse side. Published data shows significant bass absorption to 40hz in low freq. and significant rejection of high mid, high and transient frequencies?
Went through this in 2004 with our two low frequency diaphragmatic FRP products. Wish we had spoken before you ran a bunch of tests. However, you guys learned more by running those tests and will be able to present to ASTM. This back pressure you experienced because of the conduit- could it be adiabatic related? Typically adiabatic behavior is thought to lie above 1kHz. I'll bet the modes lower in Q once you introduce effective diffusers into the chamber. It will be interesting to see what happens. Great work!
We're talking about the tests done at Nwaa Labs which need no additional diffusion. Both Ron and Richard were describing the resonance effects of trapped air behind the units being tested.
@@JHBrandtI recently watched a video where you suggested that the only way you would get the benefits of frequency absorption at a lower frequency of a given panel thickness by leaving an air gap of equal thickness of the panel, was to enclose the panels in a box. Do you still feel this way?
@@HalcyonGuitars It's NOT a feeling. LOL! We have done the tests and confirmed this as true. Equal thickness, however, may not be the case. An enclosed airspace of up to a few inches will be compressed with the pressure wavefront and increase absorption. This does not operate the same way as fiber absorption does. This is something that will require further testing to quantify.
19:52 Im confused. This whole talk is about how to properly test diaphragmatic absorbers or install them? I'm sorry but why would we care how to test them. We just want to utilize them correctly. He says you get edge effect by placing them too close together. Isn't that a good thing? Doesn't that make them more effective?
We talk about this because it does affect how you place them in a room. They will affect each other if placed too close together. So, flat on the wall, not in the corners, and no closer to another than 1 meter.
At first it looks like a nice presentation with graphs which is rare. At the second look not very much. Firstly you don't have Schroeder frequency at 41 Hz in your lab but rather at least at 282 Hz. To reach 41 Hz Schoerder you would have to have 0,12 s RT60 with 210 Sabins in the room. Therefore there would be no diffuse field, nor could you measure adding 20 more Sabins into the room accurately. The ISO norm states for 281m3 you can have 8,15 Sabins in an emty room at maximum. So the basics are wrong. The vast differences when reasonators placed in different positions furthermore support the basics beeing wrong. Not sure how customer relevant tilting the panels is, when nobody uses it this way. Measurements shown are not valid for other rooms, since the effect will be very different according to room size and placement. Graphs should not be called Sabins at all. There can be a discussion of how to measure it and I support it and will gladly contribute to it. But this seeems to be presented as a breakthrough which is not. Only the placement is optimised for highest absorption on graph not real world usage. I have actually seen this type of measurements done many times by other companies, as a over the line marketing. Once you step out of the rules you have to be very carefull how you define things. I do not think this is transferable to other rooms. So you will not be able to do accurate calculations with this measurements. Please take this note as a constructive criticism, I know it is sensitive and difficult topic. I am beeing honest here as an engineer to an engineer.
Martin, You have a point about the Schroeder Frequency. The other things you mentioned are just wrong. I work with many people who do laboratory testing, design labs, sit on standards committees, etc. You don't. We're doing science AND we're working in an area where no one has gone before. Ron and others are working on presentations to describe what was learned at the laboratory to present to the standards committees. In this video, Richard is discussing what he learned during the process. It may take years for standards to catch up and acknowledge the verifiable and repeatable data. It IS a breakthrough. And you haven't seen this done anywhere before because there are no laboratories capable of testing this low. Watch the video again. Listen and learn.
@@JHBrandt there is a diference when somebody presents the results as measurement irregularities trying to decompose the result into particulate factors influencing the measurement. This aproach is the right way to show and tell about the results. This is the way Ron Sauro does it. In this presentation Richard Lenz makes basically the argument, that this one measurement with tilted panels and lots of space behind and inbetween the panels gives higher absorption, therefore it is right. This is backwards. It only shows the maximum edge effect. With the tilting and large space behing panels it is impossible to state the sample area (which is not front face area in this case). Therefore impossible to calculate Sabins accurately. A lot of manufacturers use this kind of measurement to prop up the graphs. Usually not even bothering to state the measurement conditions (as this is omited in later graphs of the presentation). Which means it is worth nothing. When you want to make such a large changes to ISO normalized mounting condition (which are very particulate about sealing all the joints, sides and back of panels with borders and tape to the room) you have to check for validity of it first. Here are the mounting conditions ignored and used for numbers maximalisaion instead. Ron Sauro's aproach is the right way - checking the placement with dummy panels made of full chunks of steel - checking for edge effect - trying to discern the individual contributions of different physical effects to the total absorption measured - checking for spacing patterns influence. This one piece by Richard Lenz is based on circular definition - change everything so the measurement gives higher numbers - therefore it is the right way to measure. This is fundamentally wrong aprocach - you don't know what gives the higher numbers and how (unknown surface area (back side absorption efect unknown), side asorption, tilting, spacing, corner placement). If you chose to present the results and to discuss about it what does it - it could be fruitful in LF edge effect description. There is a long way before you can call any of this a real measurement.
@@martinvitvar3101 that's not what was being done. You misunderstood. Ron and I have already gone over all of this. It was Ron's idea to place them like that. There is no sealed tube behind the tested diaphragmatic traps this way. Why don't you take this up with the standards committee - Both Ron and Richard are on the committee. ☺
Martin, I just saw your post and found it.... interesting. John is right, all this testing was done in Ron Sauro's NWAA labs. Where you fall short in your analysis is to say that the placement is not "real world". Point in fact, it is the attempt to use ASTM C423 standards that is not real world for testing frequencies under 125Hz. Bass traps are nearly always used in modal zones of rooms, primarily corners and walls. Reverberation chambers, under C423 or ISO354, are designed to be used with the test samples in the diffuse zone of the lab, which, in the case of C423, is .75 meters from the walls. Diaphragmatic bass traps are not used in diffuse zones, period. They are designed to control modal frequencies. For this reason, we chose to put them in the spaces where the modal frequencies exist. That should make sense to anyone that understands the behavior of modes. Ron's lab is qualified down to 20Hz, so we were well within the boundaries of the models tested. For the record, if we had the capability of testing these flat to the walls, we would have. However, NWAA's lab has a 3/4" conduit around the entire perimeter, which prevented this. Tilting the units was the only way to get rid of the back pressure caused by the 3/4" space behind them, which, as I indicated, caused a nasty 50Hz spike that was not part of the actual performance. I have been on the ASTM E33 committee for over 10 years. I sit on the C423 committee as well. I would argue that this testing may be the most consistent and accurate use of a reverberation chamber. It does not rely on whether or not the lab has a really "diffuse" field, inasmuch as this is a a sticky point in a lot of labs. This is why round robin tests can have a lot a varibles, among other reasons. This test method does not rely on the diffuse field, and therefore the empty room/full room offset is much more likely to be accurate. I could site more examples, but after 3 years of experimentation, both good and bad, I can attest to the efficacy of this methodology. We will be presenting it at our next ASTM meeting as an addendum to the standard.
@@richardlenz9007 You have mentioned your lab at Real Acoustics and shown visualisation of modal field for it. It is not mentioned the measurement was done at NWAA - this is confusing. NWAA lab size is 12,65 m by 11,28 m by 6,1 m. It think at this point the measurement provided proves the lab is not diffuse field down to 25 Hz. What the diffuse field actually is or how to asses it is another part of story I am not going here for the sake of length. Diapragmatic absorbers are quite nonlinear. Meaning horizontal vs vertical position makes a big difference both in frequency and efficiency. So I am not suprised it is much more efficient when used standing up. That is also my concern when used in tilted mode - band and efficiency will be different when vertically mounted as usuall. I would hope by now you and Ron would subtract the edge effect. There are to many unresolved issues here - tilted angle, spacing, not sure how we can continue calling this reverb chamber measurement using standard diffuse field method. Using absorption formula for volume of the room seems wrong when not all of the room participates the same. At least it would be useull to prove, that the different number of LF devices has the same average effect. I suspect not, meaning it is another hole in the story. I suspect more devices will have disproportionally less effect, because of the modal field. This is a lot of work and money to do and standardize, I wish you well at your journey.
