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Kvalsvoll last won the day on February 28

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  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 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.
  11. Bulding the Room2 listening room

    @maxmercy There is not much correlation between velocity and spl. For the 1x config the spl looks like it follows the sideways velocity to some degree in the range where the 1x config partly fills in the cancellation dip. Velocity in 0 direction (normal to front wall) has a small dip where the cancellation occurs, but this dip in velocity does not follow the spl exactly. Especially in the 4x config the velocity is present where the spl drops off to 0. This shows that velocity and spl must be out of phase here. Just measured 3 V110 units. They are reasonably consistent, and matches the design sim quite well. Nearfield measurements at different locations in the horn mouth, and inside the horn path. I don't have any useful outdoor measurements, tried to measure the first one while moving it from the workshop, but with temp below freezing and windy conditions this was hopeless. It is also difficult to measure properly, due to the size of the radiating horn mouth - it is too long for 1m measurements, and the outdoor space is not large enough for good measurements at longer distances, may have to go up to around 4m to get correct results on the V110. Nice to see the smooth response across this wide frequency range, the rather complex internal construction with 4 damping chambers actually works.
  12. Bulding the Room2 listening room

    Yes, with 4x the measurements show that most of the velocity is head-on, as in a plane wave. It is also interesting to observe that the magnitude in the 0-direction (head-on, normal to the front wall plane) is the SAME for all configurations - it does not increase when sideways and up-down velocity decreases.
  13. Bulding the Room2 listening room

    Front wall has been like this since the room was built, it is 20cm Rockwool A with some slats, designed to work from around 100hz and up, which it does. There is a correlation, yes, but in this room, for this set-up, the frequency response is very similar for all those configurations. This is because the huge cancellation problem is a LENGTH reflection, it must come from the corners on the back wall. I did not believe that was the case, as there is a very large opening on the back wall, but those measurements show that a more plane wavefront from the front actually causes the cancellation dip at 60hz to be larger.
  14. Bulding the Room2 listening room

    3.35m wide, around 4.6m length - before adding the 20cm front wall absorption. So this is a small and quite narrow room. It doesn't feel cramped, there are openings on back wall and right wall, and having all walls white i suppose helps. But sound doesn't care about wall color, especially the width is challenging - little room for treatment to fix it, and since it is narrow, the side wall reflections hardly do anything good. Turned out quite nice, sounds reasonably good, but this small space requires treatment to work for high quality sound reproduction. Mind that quite many will find themselves in a quite small room, or constricted to a smaller part of a larger living room, for the music and sound. It is often better to use the longer wall as front wall - turn it 90 degrees - in a small room of such proportions. Then you would sit close to the back wall, which causes its problems, but also the advantage of not having to deal with back wall reflection in the bass range. There are some pictures earlier in this thread, showing the acoustic treatment with absorption and hard back with poly diffusors.
  15. Bulding the Room2 listening room

    @maxmercy, 4 units stacked (2 units stacked) near corners on front wall, so you get these systems: 1x: FL 2x: FL FR 4x: 2xFL 2xFR Let's see if it is possible to get a picture: I managed to take a full set of measurements before taking down the system. And they show that the systems have different sound field properties - but which one is better.. The 1x is all over the place, the 2x removes sideways velocity, the 4x removes both sideways and up-down. Yes, the 4x is better, but at any sane volume, it is hard to justify the double cost compared to 2 units. In a different room, or larger room, the situation may be very different. The 1x holds up surprisingly well, but it does not have enough capacity for that wall-of-sound feel that the 2x and 4x certainly has.