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Primare Knob

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  1. Primare Knob

    Room bass measurements

    If you EQ the peak, it would output less pressure/power, which would influence the ringing as well. In my concrete and brick room it shows very little effect. How much effect does it have in the decay time with your room?
  2. Primare Knob

    Room bass measurements

    When you don't use subs I would start with moving the listen position in good pressure zone. Away from 1/2 and 1/4 room dimensions. The best pressure zones to sit in can be found at 0.2, 0.32, 0.45, 0.55, 0.68, 0.8 x room dimensions. If you sit at 0.45 room width you will need to setup your speakers asymmetrical, which isn't bad for the bass response but your stereo image can suffer. Try to find out which things are related to room modes and which to near room boundaries. The first one can be helped by EQ to generate a smoother response, the other cannot. EQ won't help, dealing with ringing, which is mostly the domain of acoustic treatment.
  3. Primare Knob

    Noob's adventure into accoustics

    I should get my hands on some books. I got the general idea that on Gearslutz, not many are following the design principle of the VPR. My understanding so far is that you need a free "floating"/vibrating plate and a foam with a rigid backing that can work as a spring. The function of the frame to me seems more related to a way of hanging the unit, although it does seem to help extending the broadband effectiveness due to edge diffraction. Which kind of idea are you playing with when it comes to diffusion. There seems to be some designs with a foam mounted on the front of the plate, but not sure if you mount a BAD type panel onto that, that it might start to act as a (second) leaf. It will be nice if the two can be combined successfully within a 100mm unit depth.
  4. Primare Knob

    Noob's adventure into accoustics

    I'd be very interesting in your progress with this. So far, reading about them on Gearslutz, no-one really has been able to make a proper one with good (and tested) results. I thought that the minimum dimensions of these units need to be at least 1m by 1.5m.
  5. https://www.gearslutz.com/board/studio-building-acoustics/630460-panel-helmholtz-resonators-studio.html?s=fd142976fdf788bd70c6a7880b4afb9d Have a read through this thread and you will get a good idea about the best approach in tuning the helmholz resonator. Not sure why this guy uses so many ports compared to a single port solution. Probably has to do with the limited available sizes in PVC tubing.
  6. Primare Knob

    Noob's adventure into accoustics

    It has been a whiles since my last post, and a lot has happened in the mean time. I have had an acoustical consult and done a few THX courses as well in the mean time. Most of the time I have spend on the planing, budgeting and designing the acoustical treatment as it is going to be large scale. The major plan is to build an acoustical front wall 500mm out from the existing front wall and turn this into a large bass trap. Hang up an AT screen and use the area behind the screen for acoustic treatment as well. (nearly all front wall first reflection points end up on screen). I am currently looking for different products to use as porous absorbers. Polymax is one candidate, simply because of the known flow resistance, but the price of it is putting me off. I am currently trying to find out the flow resistance data of the Greenstuff AAB products as these are much cheaper in price. I have been doing a lot of reading/research into helmholz resonators and panel resonators, as the limit of the Polymax porous material isn’t going to solve all my nodal problems. But the potential shear size of these units and their effect on the rooms volume, and their effect on the effeciency (air gap) of the porous traps, has put things on hold. Theoretical, when using a low flow resistance of 3000 over 500mm I could theoretical effectively reach into the 35Hz region. But as I found out reading a bit more, these models/calculators don’t necessarily produce a predictable outcome. In other words, I just been going around in circles, that every time I found an answer, something else pops up and put a dent into it. The consensus on Gearslutz seems to be (also by Ethan Winner) that in small rooms it is better to work with porous absorption. The biggest issue with online research about this subject seems to be, that everyone who seems to know a good deal about the subject, keeps his cards close to his chest. If this is due to, competition, the amount of time and energy invested needed to grasp the subject, or simply due to many variables effecting the outcome I don’t know. Once the front wall trap has been made I will need to put in reflection panels to balance the room. I am looking at a MLS hole sequence like the RPG BAD pattern. Ideally I would need to come up with a custom sequence as I need custom sizes to fit around the screen. I have calculate the % of wholes for the RPG BAD (25%), Artnovion(21%) and Vicoutic (30%) patterns, as this will be useful to balance the absorbtion rastio of max 25% total surfarce area, between front and back wall. Does anyone know how to create/program your own MLS sequence? As I believe there are some people on the forum who have done this and can help with the CNC production of the panels. The second trap will be the ceiling trap with bulk heads along the length of the room. I am planing of using a MLS sequence I found generated on Gearslutz with 18mm thick mdf as reflection slats, to balance the reflection/absorbtion area to +/-40% wich comes down to less than 25% between (timber) floor and ceiling, which allows for the placement of a fabric sofa in the room. I have made the slats out of 5 different heights (11, 18, 30, 42, 66mm) mostly for ecstatic reasons. Obviously everything is theoretical, and most likely is going to need adjustments in real life. I am still toying with the idea of building a riser as this could potential hide a subwoofer for clean looks and will rise the seating area in a better pressure zone. (0.2, 0.32, 0.45, 0.55, 0.68, 0.8 x room dimension) As I have access to advanced 3D modeling software I have build and rigged the room in 3D so that it can visualize, room nodes areas based upon dimensions, best out of the box pressure area’s, early reflection points based upon listen position and speaker placement. One thing that I need to test before starting this build is the influence of the acoustic wall on my speakers. With the wall in place, the speakers will be sitting 55cm from the acoustic wall, which doesn’t sound to pleasing to me if you consider the advise of min distance of 100cm on the Martin Logan forum. Having some BAD panels to play with would be nice. I might have to simplify my setup as well in the end, as I might have to much equipment to access in a tight space.
  7. Primare Knob

    Polymax Absorb XHD 100mm batts

    I am researching poly bats at the moment and I am being put of by the price for Polymax. Does anyone know what the gass flow resistance is for Autexx Greenstuff AAB ? It comes in different densities and is much more affordable. Looking at the posted video, the way to cut this seems to be with a heated knife. You can buy these of Ebay and seem to be designed to clean cut Polyester and Styrofoam. The guy in the video is using a solder iron.
  8. I am walking down this rabbit whole for a while now as well, and every time I think I have found an answer, I stumble upon reasons that contradict this. The biggest problem with taming low frequencies in small rooms is the large size needed for the trap, and the small size of the room. The trap itself becomes part of the room, and build from stiff and rigid materials introduces the risk of new and changed modes. I believe that for diaphragmatic absorbers the minimum dimension of the trap (width or height) is 1/10 of the target frequency wavelength, usually multiplied by 1,5 for the other dimension. This has to do with efficiency, but it is not clear to me how much they are talking about. BBC papers have showed that smaller sizes can work, but their lesser efficiency needs more units to tackle a problem, claiming more real estate again. BBC units are all about a standard and interchangeable size unit though. You should also ask yourself how much of a problem the 30Hz room node is in real live. As I understand it for music, it doesn't get activated much. This is something that I am trying to clarify for myself as well, regarding movies. Edit: Have a look at the porous acoustic modeling/calculators. It is not impossible to get a theoretical efficiency of 0,5 at 30Hz with porous absorption, if you use a combination of different flow resistance products. Low flow resistance product used in bulk can be effective. Edit: have a look at Helmholz resonators as well, as they require similar volume as diaphragmatic absorbers but are easier to tune when you use a longer tube length that you can adjust to tune the frequency.
  9. Hi, I am looking into buying an 100" 16:9 AT screen as part of my acoustic upgrade program. I am thinking about buying a 4K qualified AT screen, so that I will be ready for 4K if I decide to go down that path. I assume that a 4K weave isn't going to cause any problems with moire or any other artifacts, but it never hurts to ask. Viewing distance is about 3meters.
  10. Primare Knob

    Absorption or diffusion panels behind ESLs?

    I would experiment with placing absorbent panels on the left wall, and the wall opposite from your right speaker in an attempt to compensate for the asymmetrical room.
  11. Primare Knob

    Absorption or diffusion panels behind ESLs?

    Having some Martin Logan's myself I did find the following. The speakers like to be placed wide apart. The back wall has more impact than the side walls. They work best in a symmetrical setup and room 3 ft from the back wall is a minimum, the closer to the wall, I would look into absorption first, the further from the wall I would start with diffusion. The ML formula for listen position compared to speaker width placement is a rather important one. Speaker width distance x 1.25 as a minimum. I would Honor this and compromise on back wall distance than the other way around. Tow in, and vertical angle alignment can also help improve things, as they aren't completely uniform over the whole panel area. They aren't difficult speakers to get a good result, they are more tricky to produce a great sound, where the room and shape will start to play a big role.
  12. Primare Knob

    WTB: 100" Acoustic Transparent Screen

    Thanks Peter, I'll take that into consideration. I might also try to order the screen from the same manufacture as my current screen so it will fit the frame without a hassle.
  13. Primare Knob

    WTB: 100" Acoustic Transparent Screen

    Thanks for your reply. After reading your AT post and see which problems you have I don't think this is going to work for me, as I will be sitting close to 3m while using a 1080 projector, and have a rather reflective center speaker.
  14. Item: 100 inch Acoustic Transparent Projection Screen. Price: Negotiable Location: Melbourne Region Hi, I am searching for an AT projection screen, preferably in a 100" 16:9 size. Larger sizes might be possible, but is gonna make things difficult for me. Cheers.
  15. WTB: 100 inch Acoustic Transparent Projection Screen. Price: Negotiable Location: Melbourne Region Hi, I am searching for an AT projection screen, preferably in a 100" 16:9 size. Larger sizes might be possible, but is gonna make things difficult for me. Cheers.