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Primare Knob

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  1. Noob's adventure into accoustics

    After putting the sub at ear height at the listen position and placing the mic at different positions it doesn't look like it is going to be better than placing them halfway. It produces the flattest response from 20-40Hz and smallest null/dip between 40-70Hz. Theoretically that null should mostly disappear when racing the speakers up, but the measured results are telling a different story. I have become rather interested in this VPR type acoustic trap since it seems to have a broadband behavior and is also very good in taming decay times. https://www.gearslutz.com/board/studio-building-acoustics/667929-my-experiment-metal-panel-absorber.html?s=5dfd1dfd745d261f103486db4ddcaca5 On top of that, it is rather easy to build. Glue a metal sheet onto an acoustic foam. I still have many pages to read through from that forum topic.
  2. LF Sub vs Full Range

    It definitely looks like a crossover glitch. As my latest measurements show the proper behaviour.
  3. LF Sub vs Full Range

    That I don't know yet, as the settings are all the same. 80Hz in the PrePro.
  4. LF Sub vs Full Range

    The sub The subwoofer roll of might have something to do with placement. As positioning them halfway the length of the room (green line) produces a different roll off.
  5. Noob's adventure into accoustics

    I have played around with the subwoofer placement and placed them half way the length off the room along the wall (green line) which produces a better response. Wether if this is a bennifit or not I don’t know yet, as the ¼ along the front placement (blue line) produces a more identical ouptut compared with my front speakers, which I can’t really move a round a lot to improve their LF response. So I can tune acoustics for them and the subs in a similar way I also mocked up some absorption pannels that I placed in the front corners of the room (red line). They do their work between 100Hz – 200Hz, but I get the idea that they are more effectieve on the Tangential room nodes, but perhaps these are inprovements in the SBIR nodes. Edit: When placing the subs halfway the room, it will control the modal length nodes around 35Hz and 70Hz. If I do a good job on the ceiling acoustics I can control the modal nodes around 70Hz and 140Hz. Then there will be left the width nodal node which I can't figure out which sub placement can deal with these using the simulator. The dip in the graph from 50Hz - 60Hz has to do with the Axial width node at 50Hz, which doesn't seem to have a large effect, and the tangential Length/Width node around 62Hz, which seems to have a much larger effect. This could potential being fixed by raising the gain of the subs to lift the dip to about 85dB en EQ all the peaks down. The next room width nodal node is around 100Hz which might not be an big issue when perhaps using an aggressive cross over setting. What would your thoughts be on this? I also discovered that my ceiling height might be closer to 245cm reading the graph which puts it almost exactly at 1/2 the room length. The theoretical response curve would look something like this
  6. Noob's adventure into accoustics

    After reading a bit more on GearSlutz " to use pressure based absorbers and regardless of type used; they need to be placed at a surface related to the modal/SBIR –related problem that your trying to fix. " This suggest that treating the ceiling isn't going to improve my biggest problems, as those a likely to be room width and length modal nodes. The question that arises is the need and the how, to make a distinction between modal nodes and SBIR
  7. Noob's adventure into accoustics

    You guys have made a strong case for the ceiling that I truely considering it. I am thinking about a combination of limp traps and absorber with a diffuse pattern of slabs. I hope to be able to DIY this, but it will depend on material costs as well. The cost of those slabs could quickly become rather expensive.
  8. Noob's adventure into accoustics

    I thought by reading a BBC document which uses hardboard instead of Vinyl, that filling it up with absorption drops the peak but widens the bandwidth.
  9. Noob's adventure into accoustics

    It would be a good reason for buying another tool.
  10. Keith_W system

    Just as a train of thought. You are using high efficiency horn speakers, which could potentially blow up minor imperfections, where the noise floor isn't low enough. Could it be bad channel seperation on the Nadac? Have you tried swapping channels? My first thought is that it might have to do with the interface. Do you use the AES output from PC into the RME? The Ethernet connection for the Nadac should actually be as good as it gets, as it would be galvanized isolated from each other. My second thought was, if it could be related to difference in the power consumption between programs on the PC. But if changing to PCM doesn't make a difference than perhaps not. Maybe there is a difference between JRiver and HQ Player in which package it delivers the data. Funny thing is, dat my DAC seems to perform better when I deliver the 24 bit data in a 32 bit wrapper. But this should effect the whole performance and not an isolated incident. If the troubled frequency is around 2000Hz maybe you could use this as a starting point for finding a technical reason for something that could be a possible cause. Maybe have a chat [email protected] as he seems to have a good grip on the PC - DAC interface. I think he posted a few times that the only thing you need to keep your PC out of your DAC is a large buffer and independent power supply. (Something along those lines)
  11. LF Sub vs Full Range

    It is in line with the specs, but I was wondering if the "better" roll off after 30Hz compared to the subs could be DSP based, as that is what the speaker uses. It does seem that way. But it is rather well out of line with the specs. ( -3dB 19Hz DIN ) Yes. Less LF output when crossing over speaker to sub at 80Hz setting. I know you do.
  12. Keith_W system

    Besides the technical issue regarding the PC, do you have any "musical" issues with your setup? It sounds to me that you have overcome most technically issues, or have found a solution yet to be implemented, but it also sounds your search is far from over at the same time.
  13. Noob's adventure into accoustics

    I honestly like the look of those 2D panels. The 1D version could potentially be used for the ceiling trap. Is there a pattern behind the chaos?
  14. Noob's adventure into accoustics

    What kind of effect can one expect from such a ceiling trap? The 1/4 wavelength rule suggest it is not going to be very effective below 200Hz.
  15. LF Sub vs Full Range

    Hi, I have started taking measurement to find out my room problems (other topic) but ended up with these graphs. REW, -20dBU 85dB SPL at listen position. Reading these graphs, my subwoofers (Paradigm UltraCube 12, -3dB 19Hz DIN) have a rather steeper fall off than my main speakers (Martin Logan Montis -3dB 29Hz). Cross over settings for the sub is 80Hz in PrePro and speaker setting is large which bypasses this setting for L and R Could this potential be due to the DSP that is used for the LF 10" driver? And what should I think about my subwoofers. There is plenty of gain left to pump them off, but that won't change the roll off. The other things is, when I set my speaker settings to small in the PrePro and start crossing over (L and) R to the subs (A+B) the LF output drops, compared to their individual measurements. Could this be due to timing or phase differences? My plan is to use the subwoofers only for LFE in Movies, and use the Martin Logan's as full range in Music