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Kvalsvoll last won the day on February 28

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About Kvalsvoll

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  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. 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.
  6. 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.
  7. 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.
  8. 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.
  9. 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/
  10. 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.
  11. 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..
  12. The Bass EQ for Movies Thread

    I did a simpler approach on this one, and found huge improvements. Did you find any ulf at all in LCR? I remember they dropped off very high.
  13. 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.
  14. 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.
  15. 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.