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StabMe

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  1. StabMe
    Ok, some measurements at the LP to assess the effect of room treatments: Reverberation (Topt): Clarity (C80): ETC Curve (%FS): So reverberation time is almost where it should be from about 200hz and onwards and a tab better in the lower frequencies as well. Clarity has improved indeed: the dialogue is much easier to understand in movies. The amount of detail in music is also much greater. As for the ETC - this is the first time I am trying to work with this kind of graph. I can see that spikes between 1.5ms and later are seriously reduced. Those between 0 and 1.5ms are not as reduced as the others. But the 'before' measurement also had some treatments near the edge of the horn (1" thick instead of 2" plus a gap that is used now). Is there 'an acceptable level' of ratio between the spike at 0ms and early reflections? Am i near that ideal ratio? To my ears, the difference is huge. Bass is much easier to comprehend but still a bit boomy. What should i do now? Currently all the traps are placed in the first part of the room. I still have place to add a pair or 200x60cm traps in the second part. Then, a bit later I will buy a huge rack for books and stuff which will also be placed in the end of the room. Will that suffice?
  2. StabMe
    Ok, here is how it currently looks: I was afraid that putting absorption will decrease the subjective width of the soundstage and decrease the liveliness. But the soundstage now feels even more wider, highs are even more pronounced which will have to be dealt with the housecurve (speakers are EQed flat 1m on axis currently) and the amount of detail that has emerged after those treatments is kind of spooky - can't think of any other word. I moved the speakers into the room away from corners about 30cm in AND installed traps across the corner - maybe this is the reason low end is kind of lacking. I do not have a lot of experience listening to high quality setups. This is probably the closest I have ever approached to a "quality setup", but I haven't heard a system that is so crisp, detailed, so loud and images as great as this. Will get back with the measurements later today.
  3. StabMe
    This weekend I will be installing absorbers - 10 huge 2x0,6 meters and 4 smaller 1x0,6 meters. Thickness of the material is 10cm and there is an additional air gap of 5cm. I will be also placing 6 Leanfusers on the back wall and one leanfuser on each side near the listening position. Here is how the whole setup will look like: Ceiling diffuser is not shown. Listening position is 4.7 meters from the front wall. Horn mouth is about 1 meter from the corner now, because i am going to place bass trap across the corner to tame some resonances. Angled sides of the speaker are now about 20cm from the walls because of that too (they were right at the walls before. Looking at the picture and on those traps, I have a few worries: - I moved the speaker a bit away from corners - will it reduce the loading significantly? - absorbers are 15cm deep (6") - can it negatively affect the sound by creating surfaces for unwanted reflections? - As can be seen on the front wall, it is almost fully treated, but is there enough treatment near the edges of the horn that is closer to the side walls? - Does it look like I am overtreating the room? I would only be glad to keep everything as it was, but i still have 1000-1200ms reverberation so this seems like the only way to tame it. Thanks!
  4. StabMe
    Yeah, a bit less bad Unfortunately, I am locked into these dimensions. At the end of the room we have a big window and there is a door just in the beginning of the room. So, dividing the space is out of question. Maybe when I move to another house...
  5. StabMe
    Actually, i already can hear HUGE improvement. Speech in movies is much easier to comprehend. Imaging is much better and i can hear a lot more detail. Currently I have those diffusers on the ceiling and Leanfusers on the backwal simply standing on the floor. Can't wait to have my absorbers installed - this will improve the sound even further. I am afraid that I won't be able to tame resonance on very low frequencies - below 100Hz. Maybe some active absorption on the back wall with subwoofers a-la double bass array...
  6. StabMe
    No, it is ~40X20 Ft.
  7. StabMe
    It is painted rectangular steel tube. I should have filled them with sand, actually. But since the weight of the speakers is really huge (I expect about 60-70 kilos each), that should damp vibration. Thanks! Already hear huge difference in how much easier it is to listen and comprehend dialogues in movies.
  8. StabMe
    I used XPS at 35 kg/m3 density. Diffuser geometry was calculated in QRDude. I bought XPS insulation and used a local workshop with CNC hot wire. Then diffusers were painted. I used foam glue when attaching those to the ceiling. Hope that the material is dense enough to reflect sound at frequencies it is supposed to work. And i am not terribly against some absorption if it happens as well, especially at lower frequencies.
  9. StabMe
    Hey! Did you document build process here on the forum? Wasn't able to find a thread.
  10. StabMe
    First step in room treatment complete - installed ceiling duffusers. It is an area of 3 by 3 meters. Half of it (13 pieces) is filled with 2D diffusers (600Hz-2200Hz diffusion) and the rest (12 pieces) are 1D diffusers which should work between 2200-6800Hz. Hope, that mixing 1D and 2D diffusion is not a big deal. The reason i decided to go this way is cost savings. Building 2D diffusors with 23 wells to necessary to cover the whole bandwidth would cost a lot more for me than to build half as much 7 well 2D diffusers and the rest 1D diffusers. Next up are bas traps and back wall diffusers. Oh and a carpet.
  11. StabMe
    Ron, did you have a chance to measure your RT60?
  12. StabMe
    When I am listening at high levels, I usually feel the floor vibrating. Looking at the waterfall graphs, I see very long decay times on some frequencies. So I figured what if it is the floor that is ringing having its own resonances? Here is an overlay of full range signal (before correction) and an RTA signal of me hitting the floor with my heel. Purple is full range sweep, red is floor: Waterfall of the full signal: With a bit more smoothing: Full signal was measured at 1m distance from the speaker while floor hits were produced at LP. May I conclude that those long decays are produced by floor (18cm concrete) and there is nothing I can do about it? OTOH, could it still be modes that get activated by me beating the floor? I looked closely on the waterfall graphs and room simulation and find that a lot of peaks correlate.
  13. StabMe
    Agree on matching absorption coefficients vs. frequency of material with RT values. I was thinking about using OC705 (which is of double density) for the corner straddled traps and whether increasing the density of the material may somehow improve performance in the bass-midbass region. Don't get the mechanism of this kind of trap completely, so still have questions I have some confusion WRT placing a trap behind the corner horn. From what i understand, corners are used as extensions for the horns. But when we place a trap behind, don't we negate the purpose? I know this is probably a silly question, just want to understand what's happening more clearly.
  14. StabMe
    Any potential benefit in obtaining higher density material like OC 705 (6 pcf, 96km/m3)? Would this picture be a good visualization of correct placement? Currently have a panel 2x4 panel with 2" fiberglass standing near each of the side edge of the horn. It does indeed improve phantom center. I've read Corner Horn FAQ over at DIYAudio and I can see that you advice in favor of using absorption and against diffusion at least near on the front wall and side walls near the horn edges. Would you advise against using diffusors in the rest of the room if the goal is to deal with large reverberation time? I will probably be placing diffusors on the ceiling and back wall and was also going to place them on the side walls at listening position. But now I am thinking if it is better to use absorption at the sides of listening position. I can place 3 2x4 panels at this location: Room size is It is 10m x 6m. Or 32.8 by 19.6 feet. Currently have a TV with desk, horns, sofa and that's about it.
  15. StabMe
    I am sure you meant 1 s, but yes - i have a lot of work to do. Will report back when i apply some treatments and measure the result. But the RT is too big at this moment. That was a very good advice, actually. A raised bass bin volume so that its levels matched the level of compression driver at x-over frequency. After that i attenuated the 200-500 band so that its level also matches CD at x-over. It required -17db cut at about 300Hz with Q equal to 1. Took measurement at 1M distance: Then ran APL correction to about 180hz and upwards to achieve this on both channels: This is at 1/6 oct smoothing so one can see the difference. APL takes its own measurement, I used REW to see what's happening pre-post. This very flat response is exactly the same mic position as was used in APL software. Then i took some measurements at listening position and only dealt with 20-200Hz region. This is what i was able to achieve: Sorry for the picture from the screen from my laptop - forgot to save the REW file. Overall - very good imaging, very deep bass. Reverberation ruins the detail, though. Singing, acoustic versions of some of favourite songs, strings (Richters version of Vivaldi's 4 Seasons, for example) - all sound good and excessive reverberation add some interesting taste to it, but listening to music with many layers of intricate detail doesn't sound good. Need. More. Room. Treatment. Chris, can you please tell me what is the thickness and density of the material used in the bass traps you placed behind your speakers? Since I'll be adding some treatment, why not build the traps as well And by the way - you recommend treating sidewalls near the edges of the horns - what thickness and density would you recommend in these traps?
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