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Everything posted by 3ll3d00d

  1. came across this paper recently which goes into this area in some more detail -> http://koti.kapsi.fi/jahonen/Audio/Papers/AES_PortPaper.pdf
  2. the filters are applied to input channels (e.g. LFE) not output channels (e.g. subwoofer). The JRiver sub channel simply refers to channel 4 which means the LFE input channel if the PEQ block is before bass management and the subwoofer output channel if the PEQ block is after bass management. This means you need to place a PEQ block before bass management and apply these filters there.
  3. this works well -> http://andyc.diy-audio-engineering.org/mso/html/ v nice piece of software
  4. it's rather hard to read a graph with loads of lines, different scales and no legend are you sure about that point about usable data being found under the window limit? I've never heard anyone say such a thing. The frequency resolution is defined by the window length after all.
  5. I wouldn't trust the data from a 4ms window here, at least certainly not for the 350Hz and below part and the 600Hz might be questionable as well.
  6. there were some polars linked from http://www.audioheritage.org/vbulletin/showthread.php?33972-JBL-Master-Reference-Monitor&p=381408&viewfull=1#post381408which seem to come from http://www.soundandrecording.musikmachen.de/Magazine/SOUND-RECORDING/2014/12/JBL-M2-Master-Reference-Monitor-Testbericht
  7. no baffle step compensation as the woofer is loaded by the floor so I knew that that would add something but I found it hard to get a reliable reading on exactly what it would add. My best guess is that it would add more than baffle step under 150-200Hz hence I decided to ignore it and rely on EQ to compensate instead. I know what you mean re letting it sink in over time. Personally I find back to back A/B a bit of a fruitless exercise, I find that something either sounds wrong pretty immediately or an itch develops over the course of a few weeks. If either happens then it's a signal to drill into what is going on, if not then I leave things alone. This tends to lead to bursts of activity followed by long periods of stasis (with respect to the configuration), last time was after the subs changed ... took ~3months to dial in them in but then that configuration was then left unaltered til now (~18months later).
  8. I mean anechoic flat, there is the usual mess caused in room though I haven't had time to measure except to quickly verify levels. I thought I'd live with it as is for a bit and then get into EQ'ing to give me a better handle on how it actually sounds in itself. What are the diffusers made out of btw? also why place some above the speaker, I didn't catch what the rationale was there.
  9. btw I have just got my speakers up and running, atm I'm running them flat as I haven't had time to do any sort of in room measurements. I was slightly surprised to find that I don't find them forward/bright at all. What this says about the room and/or my hearing is TBD
  10. have you considered that this is what your eyes are telling you? I don't recall the details off hand but IIRC the chapter on localisation in https://auditoryneuroscience.com/topics/book-previewwent into some detail on how the visual system influences this.
  11. I haven't looked at other platforms tbh, not many have the ability to set something that low down.
  12. go to Driver Arrangement (Ctrl+D) and change the dropdown to Offset Driver OD there's a good summary of the options here -> http://www.hometheatershack.com/forums/diy-subwoofers-general-discussion/36532-hornresp-dum-hmm-everyone.html I don't think this is comprehensive for all the options hornresp has today but I found it useful for understanding what the different params in hornresp correspond to in different arrangements
  13. The drivers facing each other version sounds like the way a PPSL is modelled. AIUI this is generally described as an OD so S1-S2 forming the rear of the slot and S2-S3 the front of it. This means you'd set S1-3 to some constant value according to the area of the slot and set the lengths accordingly, set to a sealed back chamber and use Vrc/Lrc as usual to define the size of it.
  14. I have been thinking about this in the last day or two, both with respect to port positioning (relative to the body) and how many ports to use. The downside of a ported box for nearfield is the box is bigger so you can fit fewer boxes in a given seating area. The upside is they have much greater PVL so you need fewer of them to achieve a given level of TR or you can run them at a lower level (to avoid negative audible impact from the NF). Most NF subs appear to be simple sealed designs (often using an HT18 or a cheap car sub like the infinity 1260) and the 12 inch designs are commonly used in multiples, 2 per seat seems pretty common so you're looking at a bank of 8 subs spread out behind the seats. This sort of output seems to be enough to deliver plenty of TR across those seats. Therefore I've been thinking that running multiple ports (3-4 for the rear chamber, 2 for the front chamber) is a good idea so as to spread the output out across the area. I could also then more at chest height as people seem to report that this is more effective for a (lower) mid bass tune I thought this might also let me play with the tune of the box a little bit (though whether that is practically useful remains to be seen). The other thing I've considered is a 4th order bandpass box which comes out quite a bit smaller & still provides significant PVL through most of the range. It seems, on paper, one could use this design quite effectively if using multiple subs NF to get both the low end and the upper end.
  15. Try https://i.imgsafe.org/3ce614b15e.png
  16. for completeness, a high Q ULF LS has some ripple in jriver. It equates to a minimum corner frequency of ~8Hz for completely predictable behaviour. I'm not sure if this is to be expected or not, probably irrelevant anyway but I thought I'd mention it (can't attach a pic due to space issues, not sure if http://yabb.jriver.com/interact/index.php?action=dlattach;topic=106708.0;attach=22139;imageis visible either)
  17. Ok so practically speaking we are back to rules of thumb (aka experience) as it doesn't seem amenable to modelling without being a fluid dynamics expert.
  18. as subject really, I might be blind but I haven't found good info on this so far. I am aware of rules of thumb like "keep it under x% of speed of sound" but this seems distinct from whether a particular port will compress or not. if the answer is "yes, if you use akabak" then any example would be appreciated as I've never used it but have been planning to try it out context is I'm planning on building a dual reflex bandpass sub to test out this PVL hypothesis, design details in http://www.avsforum.com/forum/155-diy-speakers-subs/2539913-ported-nf-uxl-18-build.html#post46292769in case anyone is interested
  19. I modelled it beforehand but the best fit was only found after I had actual data, see http://www.avsforum.com/forum/155-diy-speakers-subs/1881217-close-mic-measurement-anomaly-what.htmlfor details In retrospect, and this is perhaps not surprising, the loading is extremely sensitive to the nature (size, lossiness) of the slot. If you really want to eke out every last cc of your enclosure then build a test box of the appropriate size & measure it.
  20. the next build of MC22 allows S<=5 (which equates to Q~=1.73), there might be some instability in the output if the corner frequency is set to 5Hz but it seems ok above this (not sure if measurement issue on my part)
  21. I would think he's using an appropriate FIR filter to deal with that, at least that's how I handle it
  22. I would have thought the local environment is a major contributing factor here. I can't realistically use all of the capability I have in the house because I live in a densely populated city, have neighbours who I respect (and who haven't minded on the occasions when it does get somewhat feisty in here!) and have ears I don't want to damage further (tinnitus which I would assume is derived from years of standing too close to PA speakers in clubs). Normal viewing levels for me are ~ -10 (bass has a ~4-5dB rise by the bottom end), -5 probably about as loud as it ever goes for normal film viewing). No idea what that equates to on the scale referenced in the original post.
  23. I get the reason why you want to push the XO lower, it's a good reason for sure. I'm just saying it might be a risky strategy and that dynamically compressing the content to deal with it is not, IMV, a good trade off. I'm not saying what you're doing won't work btw or that it's an inherently bad idea, testing (using your ears) is the best and quickest way to verify. FWIW I have found there are a few tracks from Adele 21 to be perfect for stress testing this aspect of a crossover, she can really belt it out and her voice has a broad range (which you can see if you watch a live spectrum analyser alongside listening).
  24. I don't understand why you'd want to design something that requires you to deliberately introduce distortion in a critical part of the frequency range, it seems completely contrary to some of your goals too. At what distance will you listening btw? FWIW I made a speaker recently for which the 1st iteration of the crossover pushed the tweeter too low, I found this introduced a harshness/roughness that was really obvious with certain content even at lower levels. It was quite unpleasant, almost unlistenable in fact, but only on that specific content. I didn't think I'd even pushed it that far beyond and the measurements didn't look bad but it was still rough (this was roughly an LR6 at 1500Hz vs an LR4 at 1900Hz). Different speaker obviously so ymmv.
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