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  1. Today
  2. Fix for image links

    Strong work. JSS
  3. Big thanks to SME for fixing the images

    Terrific, thanks!!! JSS
  4. Yesterday
  5. I have confidence
  6. Thanks Kyle! Actually, he jumped the gun a bit here and declared victory while the update was still running. NOW it's all done. Edit: Total count of posts updated: 169!
  7. Fix for image links

  8. SME worked very hard yesterday and today to write a custom python script which used the invision rest API to iterate each post, find issues, and fix broken <a> tags which had the url assigned to the incorrect parent tag. Invision was unable to perform the bulk fix, so we had to create a custom solution to get it done. If anyone finds anything else wrong with links or images please let me know, but as of now, the broken thumbnails should all be fixed!
  9. Last week
  10. Fix for image links

    So the final word here is there is no provided too to do a mass fix. I don't have access to their db to do a mass conversion. What I'm going to attempt to do is learn the REST api (I tried to get it working but there is a problem with the headers right now so I have a support ticket for that. I will query all POST, parse them for broken HTML, change the text to correct HTML, then perform POST requests to edit each one. I'll need to do dry runs first then small tests then probably batch everything and while being careful. none of this is very easy so it might take some time... which is also limited since I'm trying to launched db 2.0 If anyone wants to help with this and knows web , rest and html requests, then I'm happy to delegate
  11. Bulding the Room2 listening room

    Posted this eminent solution on FB. It is basically useless for its intended purpose, but some will find it cool to use the phone to calibrate the stereo. Some phones will work, some will not. There are no speccs available, so you just need to try a phone and see what happens. If you have my horns, you can place the phone in the horn mouth, and see if you get a reasonably flat graph down to below 20hz - if you don't, the phone is useless.
  12. Bulding the Room2 listening room

    @SME, I only tested with a HTC, and that one looks good below around 1-2K, and down to at least 10hz. I have observed the SPL meter apps are popular, and they look nice and advanced, but I have always had my doubts regarding accuracy of those. Even a decent measurement mic needs to be calibrated, so what can you expect from a very cheap mic inside a mobile.. Dynamic range should be a concern for spl meter app, but for pink noise freq response can be assumed that the level is kept fairly low. I noticed there was not much correlation above around 5-8k, but below say 1k the response matched REW very well. Those spectrum apps must be set up properly, to show a graph with stable and correct response. This complicates the use. If I write my own app, it can be tailored specifically for this purpose, no settings or tweaking needed. If many phones have significant deviation from flat below 1K, that is actually a show-stopper for any app for speaker calibration. There is a point here were total complexity and cost becomes higher than the simplest REW + mic system - which actually works.
  13. Bulding the Room2 listening room

    A big caveat here is that the response of phone mics is a big unknown. I have a Google Pixel XL, and I recently installed an SPL meter / analyzer app. I figured it'd be helpful for a quick SPL measurement while playing music, without having to get up and go get my SPL meter. The app is pretty comprehensive and allows selection of Z-weighting for flat response, in the app at least. Unfortunately, the mic on my phone seems to have much diminished response in the sub range and also has poor dynamic range. IIRC, it taps out in the 80s dB, which is pretty much useless for measuring music that's loud enough to be fun. The sub response on the phone seems to be bad enough that it'd be useless for doing sub measurements. I wonder if they high pass it on purpose to improve speech clarity and reduce unwanted clipping? Oh well.
  14. Bulding the Room2 listening room

    How can you set up a bass-system if you have no measurement rig. Believe it or not, most people actually does not have acoustic measurement equipment. Here is how: 1. Download and install a spectrum analyzer app on mobile. 2. Download the <don't remember the name> full frequency range spectrum pink noise file from my web site. 3. Play the file on repeat and monitor what happens to the sound using the spectrum app. What can be fixed using this approach: - Setting level for bass system. - Adjust delay for main speakers. - Add custom parametric filters for horrible and obvious resonances. Very far from REW or similar, but compared to going totally blind this can fix integration and calibration to a level where many will be happy with the results.
  15. Questions about othorn,keystone, Xoc1 th18, DSL118 and others

    What type of design did you use the 18ipal and 21ipal in, bass reflex?
  16. Questions about othorn,keystone, Xoc1 th18, DSL118 and others

    I didn't test it after all , because I changed the 18"s with 21"s to use them in my own designs. I don't want to use that design anymore, it's better to use my own The difference though is huge, the efficiency and thermal stability are way higher than those of the SW115. I'll use the 18 IPal in one of my other designs and after that I'll use the 18Sound where normal drivers are needed. And the 21" Ipal is so powerful compared to anything else, the sound is so much better!
  17. Earlier
  18. Bulding the Room2 listening room

    Just to continue, in between measuring the V110 in detail.. Frequency response is useful, as a tool - when used right. Tonal balance, potential resonances, getting the relative levels correct. It is also good for presenting a nice, smooth graph, after some heavy smoothing. Impulse is nice to look at, I use step response for bass. But it doesn't tell much about the sound. There is little correlation between perceived sound and the shape of the curve. Decay is important. Here the peaks that shows in freq can be analyzed, if they are resonances those will stand out as ridges, easy to see. Waterfall is great for show-off. Spectrogram is the other important graph. It shows how the sound start and stop, and reveals problematic reflections and decay.
  19. Bulding the Room2 listening room

    @SME, more knowledge often reveals that things are more complicated than you once believed, and you realize you don't have a simple answer anymore. Frequency response is always the first we look at, and its destroys the day as we see it is not completely smooth, there are obvious flaws that needs to be corrected. As we learn more, gain more knowledge and experience, we realize this is just one visualization of what goes on, and reading a frequency response graph to actually get useful information out of it is not that easy. It is a steady-state visualization, and most of the signals we want to reproduce are transient in nature. Right now I am working on bass-systems. Trying to find universally applicable methods and rules to set up the subwoofers. Does not help with a very good subwoofer, if it is not set up and calibrated properly. And in most practical cases, room acoustics efficiently destroys the possibility to achieve perfect sound in a simple and predictable way. Measurements are accurate and very useful as a tool to compare before and after when doing changes on the system. But to be able to say exactly how it sounds, by merely looking at the measurements, that is not easy. When I observe something about the sound, I try to find a way to objectively measure and quantify what I hear. Then perhaps i can be better at predicting how it sounds, and find ways to improve faults. The first thing, though, is to verify what I think I hear - not as easy as one might believe. Often it is necessary to rig experiments.
  20. Bulding the Room2 listening room

    I agree that there should be no advantage to SBA/DBA solutions, provided that "you can manage to somehow get rid of the cancellation reflections", or otherwise remove the effects of the room using another method. In both cases, one achieves very smooth (near-anechoic) bass frequency response (when viewed without using smoothing) across a wide region of space. I don't have an SBA/DBA, but I do have DSP-optimized filters to achieve the above near-anechoic ideal. This condition is maintained up to about 65-70 Hz, above which I have multiple issues preventing me from maintaining an completely smooth response. This is probably an issue in most other types of near-anechoic sub systems, including SBA/DBA also. To be honest, I wasn't expecting to have to go back and shape the broad response by ear the first time, and I was even more surprised when I had to shape the broad response *in a different way* after I re-did it with new crossovers. More recently, I did an EQ overhaul of my mains speakers above 160-200 Hz only, and I had to re-do the broad shape of the subs *again*. These weren't minor changes either. Whereas before, boosting below 40 Hz even 0.25 dB caused the bass to go to mud, with the latest config, I was able to boost the low end by several dB without loss of intelligibility. So at this point, I'm not convinced that any particular way is better than another. If anything, my work with mid and high frequencies has convinced me that some early reflections are better than none, provided that the speaker is well-behaved. The main reason so many pros are convinced that early reflections are bad is because they are experienced with using monitors with poor off-axis response, and the elimination of early reflections prevents that nasty off-axis sound from corrupting the better on-axis sound. With good speaker design, that's no longer an issue. It does lead me to wonder if maybe early reflections are good for bass too, to a point. It appears to be well established that modal resonances have negative perceptual consequences, but do early reflections have as much impact as we think they do? We practically hear through early reflections for mids and highs. We may also do so for bass, but it probably depends on how much reflected sound energy there is in total and how well it is distributed in time. At lower frequencies, there is definitely a propensity for the sound field to become quite structured within the room, even if discrete modes are not obvious. This is a substantial open problem that I plan to devote more time to in the future. I would strongly caution anyone not to read too deeply into frequency response data. Because we hear pitch (frequency) and level, it is easy to assume that a frequency response (FR) plot tells us how different pitches will be emphasized, relative to one another. However, this is far from the truth. An FR plot with smoothing is largely meaningless because the smoothing discards most of the information that's relevant to perception in the first place. An FR plot without smoothing and with phase data does contain that information, but it is a terrible visualization of that information. Time-frequency plots like waterfalls and spectrograms are kind of a step in the right direction, but it is hard to glean quantitative information from them and the information within them is still not weighted very close to how perception weighs the information. All of this makes sense if you imagine what it would take to analyze an IR to determine the true spectrum of a source within the room. One must deal with a variety of acoustic interference effects and possible obstructions in the path of the direct sound. It takes some very clever processing in order to accomplish this with the accuracy that our ears and brain do. As can be seen, I'm rather short on good advice here. I am less confident in what I know about bass reproduction than I ever have been, having tried a variety of strategies and having failed, in the sense of not achieving any consistency. And that's just in one room. And this is yet another reason why I am very skeptical of the relevance of particle velocity, independently from pressure. Why? Because there's so much we don't understand about how pressure response affects perception. Unless or until one constructs an experimental apparatus in which velocity response can be varied while keeping pressure response *exactly the same*, no one has proven anything with regard to the relevance of velocity response. In practice, this kind of test is extremely difficult to do. Almost anything that changes velocity response will change pressure response in some way. "Close" does not cut it here.
  21. Bulding the Room2 listening room

    @maxmercy, I have never heard one with drivers mounted across the whole wall. There are practical problems with SBA/DBA solutions - obviously. And - I may be scolded for saying this - I am not convinced they add so much more than a more conventional system can do, when properly set up and calibrated, and you can manage to somehow get rid of the cancellation reflections. From the experiments when I first found that velocity has significant impact for low bass perception - especially in the 20 - 50hz range - I also had a set-up with very much of that powerful wall-of-sound feel, and part of this has to do with getting more velocity than you get in the steady-state free-field condition. Similar to what you can achieve with near-field subs. A DBA done right will get predictable and very good results. Other solutions often end up with one part of the freq range having some special and very good performance, but then there are faults in other places. The trick is to achieve that special part, but at the same time be able to fix the bad parts.
  22. Bulding the Room2 listening room

    Good to know. Have you every heard an SBA/DBA? JSS
  23. Bulding the Room2 listening room

    @maxmercy, yes, now, that is the question to ask. Fact is, I did not notice any huge difference. Even the 1x is as good as should be expected, and the 2x and 4x does not really have that much more, though they sound a little bit more tight and immediate, 2x a little better, and 4x even a little more. But I can not say there was a difference large enough in tactile experience to really differentiate the systems. The 1x hold up with bass-heavy music up to +3dB, enough for some tactile feel. But the larger ones can do much louder, and THAT makes a huge difference. ULF below 20-25hz is similar, as long as kept within limits. I still have 2x V110, so I can test some more, perhaps find a way to measure and get objective information.
  24. Bulding the Room2 listening room

    Kvalsvoll, With all 4 configurations, (1,2,4), for equal SPL with each, which configuration had the greatest perceived impact? JSS
  25. Bulding the Room2 listening room

    This is the tricky part. If the solution is to just eq to flat, it would be easy. But it isn't. Especially in the bass range, velocity and intensity matters. And you have to measure at different locations, at least cover different locations in height where the listener is located. Decay is important. Resonances will affect perceived tonal balance.
  26. Bulding the Room2 listening room

    Of course the boundaries of a real room are not perfectly rigid. They are lossy, especially at certain mechanical resonance frequencies. Your room is also open at the rear. However the side-walls, floor, and ceiling are rigid enough that the sound field between those dimensions is qualitatively similar to what I described. Pressure still peaks at the boundaries where velocity drops to almost zero, and there are likely dips at certain frequencies . My point is that the effect of multiple subs on your velocity measurements is entirely consistent with this perspective. I don't know what you mean by "intensity pressure". If you mean merely pressure, then we are in agreement that pressure is the most important characteristic for transmission of vibration from the air into the body of the listener. The proposition that the motion of clothing depends on velocity is interesting, but I suspect the situation is more complicated than that. It may have more to do with pressure gradients, which may coincide with areas of high velocity as it does for standing wave sound-fields, but high velocity and high pressure gradients don't always present together. It would be interesting to do some experiments with subs outdoors to see if clothing movement perception is affected by source distance, while pressure is kept constant. In the far-field of a monopole radiator, pressure and velocity both drop with 1/R, but the pressure gradient drops with 1/R^2. Thus, if what I suggest above is true, we'd expect less clothing motion at greater distances, even after compensating for SPL. To your point that frequency response and phase are very important, I totally agree, but I would say it's a lot more complicated than most people think. And of course, the sub range is only one part of the picture. The rest of the speaker response also impacts perception a lot, and 100-500 Hz is particularly important for tactile sensation. Unfortunately, this range is often harmed by speaker placement problems, but there may be ways to fix this with EQ. This is work in progress for me, but I can say with confidence that a perfectly flat or smooth in-room response is not optimal unless the room is completely dead. And if the room is completely dead, then you have another problem.
  27. Bulding the Room2 listening room

    Velocity measurements now available: Sideways velocity (90 degrees): Green is 1x configuration. Vertical (h): Red is 4X. Normal to front wall (0 degrees): Frequency response has a huge, narrow dip around 60-70hz. This must be caused by reflection from the back wall corners. This dip becomes progressively more deep and narrow as the sound field from the source gets closer to plane wave.
  28. Bulding the Room2 listening room

    @SME, inside a room the situation is complex, because boundaries are not rigid, there are windows, and sometimes openings, such as in Room2. These velocity measurements are only another tool to try to get more information, to get a better understanding of what is going on. Sound intensity and sound field properties affect perception of sound, we know that now. But velocity alone is only one part of this, and especially for higher bass frequencies - where chest slam occurs - it looks like intensity pressure is more important, due to the acoustic impedance properties of our body. To feel the sound moving your clothes, you need velocity. Also, frequency response and phase behavior have huge significance for perception, both what we hear and tactile. Just finished testing the V110 in the Moderate Cinema, to find out if it is suitable for movies. It is. But compared to the original T138 horn, it drops off a little below 20hz, above 15hz the V110 has more output, and should sound cleaner and more defined because there are no resonances left around the crossover, where the T138 no longer performs well in the time domain. I didn't bother doing a proper calibration, did not even use the default dsp settings, but the freq response looked reasonably similar to the T138, so I just left it like that. And does it sound better? Is it better to have this vertically large sound source? Does the effort put into the advanced design pay off in better sound quality? It does sound different, but not necessarily better. I suspect my lazy calibration approach comes to play here. The sub bass is experienced as similar, the level drop in the 10-15hz range does not seem to have much significance. The airplane-flyover-scene from Hanna sounds similar, Oblivion works fine, the storm in Kon-Tiki moves the whole house. Mid-bass is stronger and more powerful. Nice punch, and there is capacity available to turn it up, bass-heavy music at +6dB works fine, and then you add another +6dB on the bass system for that visceral feeling. Transients with large bandwidth lacks some of the precision and sudden impact. I blame this on my lazy calibration. Example - the cannons in Hunger Games. All in all, my conclusion is that the V110 works for movies. Same powerful bass transients with impact, like you are hit by a small shock-wave. Now I will look at the measurements to see if it is possible to see something there that corresponds with what I think I hear.
  29. Questions about othorn,keystone, Xoc1 th18, DSL118 and others

    Did you end up comparing the 18ipal to the 18SW115? I have 2 TH18's with the 18SW115 (4 ohm) powered by a Crown Itech 6000 and am very happy with the output and sound quality!
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