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Kvalsvoll

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Everything posted by Kvalsvoll

  1. Kvalsvoll

    X-curve compensation re-EQ

    Speaker tuning with radiation pattern, on-axis response, power response and then add in room acoustics - which will be more or less an unknown parameter for a speaker designer. This is difficult and complex, and has huge impact on perceived sound - in contrast to amplifiers, dac's, all the nonsense products. I also believe that this field has not yet been fully discovered, there is still more to learn and find out. Experiments focusing on how perception of sound relates to the technical parameters are key factors for improvement. Horn speakers sound different from trad-hifi partly due to fundamental differences in radiation pattern. It is impossible to make them sound equal, because tonal balance depends on what sound is being reproduced. If you tune for flat and equal steady-state, the transients will sound different because decay profiles are different.
  2. Kvalsvoll

    X-curve compensation re-EQ

    @SME, you are aware that loudspeaker manufacturers tune their speakers ("voicing") according to power response and estimated typical room acoustic properties, and have done so for decades? If you look at on-axis measurements of typical hifi-speakers, they often have a response that deviates considerably from flat - look up some of the well regarded speakers on stereophile. This is because the radiation pattern changes with frequency, and by adjusting the response the "sound" can be changed into more balanced and neutral, but the measured charts seemingly show a "defect" speaker. Since most speakers have a pattern omni at low f and then narrowing towards higher f, they will radiate more power at lower frequencies. This causes some problems if you design a speaker with radically different pattern - a speaker with flat fr and flat power will sound different from these typical once, and since music is mastered for use with the typical speaker and room, it is necessary to alter the reposne of the flat speaker into something that gives a perceived tonal balance more similar to those typical ones.
  3. Kvalsvoll

    Bulding the Room2 listening room

    Compact Horn, basically a rear loaded horn with resonance chamber for extended usable range.
  4. Kvalsvoll

    Bulding the Room2 listening room

    I have posted about the new Room2 in the bass punch threshold thread, and announced that I would start a thread on the building of this room. I plan to present a complete article describing what the acoustic improvements do for the sound, from start to finish, and I also have measurements form all stages of the build process. Here is how the room looked initially, after removing subwoofers and audiophile mains, and some furniture, including the table, which will be replaced: Preview of the process:
  5. Kvalsvoll

    Bulding the Room2 listening room

    Testing midbass horns in Room2. Calibration is complicated, and benefits in this system and room are questionable. This is just to ensure they work, and to learn how to set up and calibrate the system, so that the customer can receive some useful guidelines. Usable range around 45hz up to 200-300hz, but for cf above 150hz you should absolutely use stereo processing, so for a typical av-processor system with bass-management it can be used up to 150hz. Capacity around 120dB+, depends on how much power you have.
  6. Kvalsvoll

    The Bass EQ for Movies Thread

    Would it not be great if you could bring back the lost bass in you favourite movies? Well, perhaps you can. By applying equalization customized for each movie during playback, it is possible to dig out some of the low bass lost due to filtering and processing in the studio. Why Bass EQ How to Bass EQ How to recognize good candidates for Bass EQ and what to fix How to submit Movies with Bass EQ Movies improving with Bass EQ This is the list of movies that can be improved by applying Bass EQ: A Space Odyssey Alien Aliens Alien3 Avatar Avengers Avengers: Age of Ultron Battleship Bølgen (The Wave) Ender's Game Eyes Wide Shut Full Metal Jacket Godzilla Gravity Guardians of the Galaxy Iron Man Iron Man 2 Iron Man 3 Man of Steel Oblivion Pacific Rim Scott Pilgrim vs the World Shining Star Wars: The Force Awakens Super 8 The Matrix The Matrix Reloaded Thor Thor: The Dark World Transformers Transformers:Revenge of the Fallen Transformers:Dark of the Moon Transformers:Age of Extinction coming soon: Master & Commander BluRay Tron:Legacy Batman Begins The Dark Knight Fight Club Star Wars: The Phantom Menace Star Wars: Attack of the Clones Saving Private Ryan Wreck-It Ralph Top Gun Alien Resurrection The No Hope Movies Some movies can not be improved: The Hobbit: An Unexpected Journey Update sep 16 2014: Changed Bass EQ implementation and description method, updated movie entries. Update jan 11 2015: Filter parameters for early entries updated to match new MiniDSP implementation.
  7. Kvalsvoll

    The Bass EQ for Movies Thread

    Huge improvement (Star Wars - The Last Jedi). It already sounds quite good as-is, due to nice dynamics and the fact that levels are not pushed beyond clipping. But Bass-EQ improves this in a dramatic way. And you can increase mv a bit, I tried +3dB now, and that still works very well. Effects now have full frequency range, and anyone who experiences this difference will not need any abx-blind-testing to hear and FEEL this improvement. This is not about shaking the house more, it is about lifting the experience with improved sound quality. Mid-bass level is quite moderate, so a little lift from 50hz and up may give more impact on transients. This is exactly what sound quality is about - excitement without fatigue.
  8. Kvalsvoll

    The Bass EQ for Movies Thread

    Huge gain on the LCR+Surronds here in your BEQ, also more gain on the lfe than I would assume, but now I have not seen the spectrums, an the result looks fine to me. Just listened briefly to some scenes, and I wonder if just some boost below 20hz will do most of what is needed here. Also agree with your BEQ in that there is no need to reduce any mid-bass bump.
  9. Kvalsvoll

    Bulding the Room2 listening room

    @maxmercy, I use a modified 10" driver, it is an old discontinued seas. 10" is a good size - good area for sensitivity, not too large so it does not change the sound field it is supposed to measure. The 3x has less velocity in the important 30-40hz range, and a little less above up to around 120hz. Changing eq or delay on the BL back unit changes velocity response. The 3x sounds better because it fills in a dip in the response around 60hz, phase is same, spectrogram is a little better. The loss in velocity 30-40hz is noticeable. The increased v at ulf is more noticeable, because low freq noise stands out and becomes annoying - too much is not good. Further experiments can be to move the high-pass on the BL up in frequency, this will change the phase and perhaps make the velocity smoother - less ulf, fill in the dip 30-40hz.
  10. Kvalsvoll

    Bulding the Room2 listening room

    Sound field properties are important for how low frequencies are perceived. Sound field properties are the relations between pressure, particle velocity and intensity. Both level and phase of velocity relative to pressure can change significantly inside a small room when properties of the bass system are changed - position of sound sources, delay, eq settings. In Room2 I experiment with different bass system configurations, to find methods for setup that are repeatable and consistent. I experience differences even if the measured frequency response is the same. Some of those differences are caused by time-related issues like phase and decay. But some effects, notably at lower frequencies, are caused by differences in sound field properties. The system I test now is a FL FR + BL config - one additional unit located at the back of the room. In this setup there is and increase in velocity and sound power around and below 20hz, which causes more movement in the floor than desired, on many music recordings there is simply way too much ulf. I noticed this instantly, before doing sound field measurements - too much ulf. And indeed it looks like the BL back unit changes the sound field from 20hz and down, there is more velocity in the vertical direction. The way to fix it is to adjust the frequency response - reduce the level around 20hz. It gets much better, but still not perceived as neutral - there is too much ulf, and noise and unintentional ulf sounds become distracting. Also further up in frequency, there seems to be a clear correlation between velocity level and perceived bass quality - smooth is more neutral, more velocity is better and sounds more powerful and natural. Simply more fun. Above the 40-50hz range the situation changes, velocity is still important, but will be more of a measure of sound directivity. In the upper bass range phase and timing and frequency response is the important properties to focus on, as the velocity and intensity more or less follows due to the sound waves being smaller compared to room dimensions and distance to sound sources.
  11. Kvalsvoll

    Bulding the Room2 listening room

    Acoustic noise - fan noise. Signal noise is rarely a problem with power amplifiers. Plate amp is a no-go, requires cabinet building. They also tend to be more expensive. Crown could work, I see they have the xli 2500 with regulated fan. Or if we could find a used K2.
  12. Kvalsvoll

    Bulding the Room2 listening room

    Looking for a reasonably priced power amp for midbass use - 2 channels, around 500-1000W/8 ohms/channel, NOISE-FREE. Something like the inuke 3000, without the noise. I have a design for some very powerful and compact midbass horns, and now I found a customer for them, so if we can find a suitable amplifier they will be built and tested. My SA-700 can be used, but it is kind of overkill, and quite expensive. Any tips for such an amplifier? And no fan-mods or similar tweaking, it must work out-of-the-box.
  13. Unfortunately the de-clip does not work. Clipping is usually caused by lower frequency transients, and when the signal clips, a very noticeable duration of higher frequency content is lost, and this can not be accurately restored. Some more advanced plugins may have algorithms that try to restore by estimating what should be there, by looking at previous and after signal content, but it will not be possible to restore the content completely. For the lfe channel a declip can work better, but it requires gain adjustment to make room for the recovered transients, so the overall level will be reduced, and there is no gain in transient impact before gain is restored by increasing gain later in the chain. Clipping is annoying and destructive for sound quality because of the harmonics that are introduced. For lfe, the lfe signal will always be filtered somewhere later, so the destructive effect is not so severe. And a clipped transient will add up to 3dB headroom, you can see this by low-pass filtering a clipped signal, the result will look like a de-clipped signal and it will have a higher peak amplitude.
  14. Kvalsvoll

    Othorn - HT capable?

    Let me see if I got it right: You found a suitable horn (lilmike's F20?), a suitable driver for this horn (pro driver), the size is not an issue, you have cabinet builder ready to make them for you, and you have a friend willing to assist in calibration & setup. Build it. If you go for anything else, you will regret because you will always wonder how those horn would sound. Integration of these horns will be no more problematic than the sub you already have, the worst case scenario is that you achieve a similar result. It can be solved. But first - build the horns. No need to go deep into all potential problems up front. Now I am looking forward to read about how this turned out, how it sounds.
  15. Kvalsvoll

    Othorn - HT capable?

    The typical consumer subwoofer will never deliver a sound character similar to what you experience with your horns. But that does not make it useless, it fills in the deep bass below where the horns roll off, and for a lot of music most of the bass is reproduced from the horns. From what you write it looks like you have identified this difference in sound, and now start to wonder if it is possible to achieve a sound more similar to the horns at lower frequencies. And it is possible. But of course the lower bass will by nature sound different and give a different experience compared to the upper bass range, where most of the attack and kick is. One way to achieve this is to build something yourself, use a pro driver with limited excursion and high BL, place it in a ported cabinet that is too large and ported too low.
  16. Kvalsvoll

    Othorn - HT capable?

    If you plan to cross at 60-80hz, the alternative suggested by @Ricci could be a good alternative - a ported box. Use a pro driver, port it very low, choose a smaller driver for smaller cabinet size. For very low frequencies the size of the radiating surface does not matter so much, so the ported would give you much of the benefits of a horn, in a smaller cabinet, and much easier to build.
  17. Kvalsvoll

    Othorn - HT capable?

    I can not help you with the Othorn, but when I read "apartment" I am curious to learn how your neighbors cope, of course it is possible you only listen at moderate levels, but most people with capable systems tend to actually use it.. And those horns look great, by the way.
  18. Kvalsvoll

    Bulding the Room2 listening room

    And you need some method to measure it, doesn't need to be accurate or calibrated, just to be able to compare.
  19. Kvalsvoll

    Bulding the Room2 listening room

    I really should find something new for another article to post, so we can continue to go far-too-deep into something else, don't think we disagree enough to continue this one much more now.. I have one, most of the text is ready, there are pictures and measurements, perhaps tomorrow. I think @Ricci's post sums it up quite nice - mostly, not an issue, but, depends - some subwoofers, placements, floor and building issues, can cause problems. I still see your example here as surprising, even when considering that those subwoofers will create much more force than the very different V110. To give a substantial difference in tactile feel, there must be a very significant difference in vibration level. And this can be measured. It should show up on the frequency response, and can be measured with a mobile accelerometer app. It is actually possible to partially replicate this experiment; you could run only one driver active and short the other one - it won't be the same as single driver as the dead driver will still move a little, but should be enough to show a difference in vibration level form the subwoofer. With 2 drivers it should be dead, with one there will be motion. And just when writing this, I read another difference - from PORTED to sealed. That can also be a factor in tactile feel experience, but is it really that huge.. Maybe I should repeat the measurements comparing sealed and ported/horn. Difficult to seal off the horn output in a V110, and there may actually be too little output left even for a measurement only.
  20. Kvalsvoll

    Bulding the Room2 listening room

    I can assure you the floor is not more stable and firm and damped than any other typical house. It is a very old house, so the walls are heavy, but the floor does not seem to be more rigid than in typical newer houses. It gives a nice and pleasant tactile effect, from around 20hz and down towards 10-12hz. The problem you mention SME, about resonating and vibrating coupling between any loudspeaker and the floor certainly can cause audible problems, but it is also easy to fix, even those isopod products should work well for that. I consider this to be something that should be designed in to the speaker/subwoofer, so that the customer does not find the need to buy additional products to fix rattling and noises. When you have something capable of decent output full-range, clean, then all kinds of rattles and noises suddenly appear, often from outside the room you are listening in. On the processor in Room2 there is a small strip of tape attached to the acrylic display cover - it rattles. The spotlight assembly in the ceiling in The Moderate Cinema rattled, then there are the structural noises from the house, which can not be fixed so easily. The measurements were done with only one V110. Really no reason to complicate things by trying to decouple several subwoofer units.
  21. Kvalsvoll

    Bulding the Room2 listening room

    After looking into specifications - which I could not find, because there are none - for the product you mention, I now looked into a different product, where I was informed that the resonance frequency was 5hz. I could not find any information on the product's web site to verify this claim. I could not find any relevant technical information. So I stand corrected about the specifications for those products, and the description reads like snake-oil to me. If the spring is too hard, it will place the resonance right in the active working range of the subwoofer, and potentially make things worse. It also need to decouple in all directions - pivot, fore-aft, up-down, rotational. It is easy to verify if it can work. If the spring is compressed less than several inches/cm, it is too stiff. If you measure the deflection of the spring, the resonance frequency can be calculated, provided the spring is linear. A foam pad is not linear. If you make one large foam platform , sufficiently thick and soft to provide a low resonance, it would still be too stiff on the fore-aft direction, because the supported area is too large. A platform with springs in the corners could work. The foam blocks I used are only suitable for experiments, the subwoofer is not stable on top. But the most important observation here is that it makes no difference, even if the decoupling is made so that it significantly reduces mechanical coupling down to frequencies below working range. The floor in the room used for measuring this is what I consider quite normal for a wooden floor. But the subwoofer is placed close to walls, close to a corner. And in that location, the floor is much more rigid than in the center of the room, because the beams supporting the floorboards are supported only at the ends where the floor meets the walls. The subwoofer vibrates, it moves, and it is transmitting those vibrations to the surface it sits on. It just that the level is too low to be significant, compared to the effect from the acoustic sound pressure in the room, which acts on the whole surface of all walls and ceiling and floor. And the reports from people who tried this, says the same - no sound reduction for the neighbor. The V110 is different from the usual sealed box subwoofer with long-excursion, heavy-moving-mass driver. The moving mechanical mass is 118g - very low compared to the usual around 500g or more. But the driving force is similar or higher. And it is quite tall, creates a large momentum. The main force from the surroundings acting on the cabinet will be the acoustic load on the port exit, and this load is far less than the typical 500g mechanical mass. The 118g cone assembly does not move much, due to the acoustic loading, so even comparing the moving mass to a different subwoofer is not relevant. Still, this subwoofer certainly moves and vibrates. The older ancestor T138 in the media room is more lightweight, they move and have to be pushed back into location occasionally. A dual-opposite design is one solution to remove low frequency vibration, that actually works. But the floor still vibrates.
  22. Kvalsvoll

    Bulding the Room2 listening room

    Focusing on only one part makes it easier to follow: The decoupling I used works. I knew before I did the measurements, actually I did the measurements because I had a readily available decoupling solution that works TECHNICALLY. However, this solution is not suitable for ordinary use due to looks and the fact that the subwoofer floats on top and is very unstable. I had the blocks because i use them to handle the subwoofers when moving them around. Transfer of vibrations are determined by only 2 parameters - resonance frequency and damping. If the resonance frequency is low enough, and the damping is not too high, it works. The problem with foam is that the spring stiffness increases in a nonlinear fashion when compressed. If the foam is too soft and too low, it will compress and give a resonance frequency that is too high. The product you link to here (spec-sheet) can not work, because there is only 1 inch foam to act as the spring. this product may very well work to remove vibrations at higher frequencies, but it will not decouple at very low frequencies. If I had used a similar product or solution, it would be correct to assume that the measurements are not valid becuase the subwoofer is in fact not decoupled at low frequencies.
  23. Kvalsvoll

    Bulding the Room2 listening room

    The measurements and the article explains how this works, and why it is so. It is explained and verified by measurements that vibrations and movement in the floor is caused by acoustic energy in the room, and that any directly induced vibration by mechanical transfer from the subwoofer to the floor is not significant. The decoupling requires no advanced science, anything that gives a resonance frequency below around 5hz will work. The foam I used is very suitable for this purpose. Commercially available isolation platforms have specifications for resonance frequency. Obviously the platform must be dimensioned to match the weight and surface area of the subwoofer. The flaw here is not the claimed function of the product - it will isolate the subwoofer mechanically from the floor. The flaw is the assumption that this will give less vibration in the floor, which it does not, because it is not the mechanical vibration of the subwoofer that causes the floor to move. I may - or may not - do an English language translation of the article. Fixed it, here it is: https://www.kvalsvoll.com/blog/2018/03/29/myth-or-fact-vibration-damping-platforms-for-loudspeakers/
  24. Kvalsvoll

    Bulding the Room2 listening room

    Another audio-myth busted: Vibration damping platforms for loudspeakers. Place your subwoofers on an isolation platform, and reduce vibration and noise emitted though floor to keep your neighbor happy. But this does not work. Because it is the acoustic energy in the room that excites walls and floor to create vibration, it is not due to the subwoofer jumping up and down. Actually, most subwoofers remain quite stable, even at excessive loudness levels, and they do not transfer much motion down to the floor. We know that - either from experience or simply because we have some basic understanding of acoustics and physics involved. I decided to measure this, to verify whether it works, or is it one more example where basic theoretical principles and engineering trumps the marketing department. The article is up on the web-site in the blog section, but only in Norwegian language. I will post some links to measurement results, and make some comments here. One V110 was measured, both spl at listening position, and floor vibration, for 2 cases - original solid base, and blocks of foam creating a completely decoupled and dangerously unstable base. Results reveal that there is no reduction in vibration level with the decoupling - as expected. There is also no significant change in frequency or time domain at the listening position. SPL difference at lp: Vibration difference at floor below lp: We see that the vibration response did change, but not enough to be noticeable, and at very low frequencies there is no change at all. The decay plots also show very little difference. However, at higher frequencies, above 100Hz, there may be a difference, depends on the loudspeaker and the floor. A good isolator can have a positive effect on vibration and decay higher up in frequency, and thus impact sound quality. But on the V110 the effect is so small it is very unlikely to make any audible difference. On a different floor, such as concrete in a basement, the situation will be very different, with no movement at all at very low frequencies.
  25. Kvalsvoll

    The Bass EQ for Movies Thread

    I liked it, simple and no-nonsense story. With spaceships and decent sound quality with BEQ, and some nice actors, what more can you wish for. Favorite scene is where the girl is serving the king his lunch, and suddenly realizes that she is the meal..
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