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Post by tommy81norway on Dec 15, 2017 19:03:43 GMT
Hi guys, I’m new to this forum and I’m looking for some advice about acoustics. I have been a Audioholic for years, but it’s now the last couple of years I’ve realy understood what a difference room acoustics makes. So, to my inquiry. The sweet spot in my room seems to be about 1,2 meters from the back wall. This is the spot where I experience the sound to be most detailed and “correct”(in my opinion). If I move 30cm backwards the sound gets a good 3D effect, where sound comes from behind and from the sides, I think this is very cool in a 2 channel system😎. The trade off is that I loose some detail, like for instance effects panning between speakers that is clearly audible in the sweet spot, will not be as clear anymore, and panning may disappear. Is this a common problem? Wrong speaker setup many? Looking forward to hearing some suggestions😊 Best regards Tommy S. Norway
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Post by tommy81norway on Dec 15, 2017 22:37:13 GMT
Solved👍 I played around with speaker placement for a couple of hours. I found that aming the speakers a little more towards the sweet spot did the trick. I read somewhere that if you want a wide soundstage the speakers should have less toe in, so I probably overdid it at the time. I hope this information can help other people too. Play around with your speaker placement, there is nothing to loose I used masking tape to preserve their original possessions...just in case. Tommy
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Post by Hexspa on Dec 16, 2017 5:14:59 GMT
Solved👍 I played around with speaker placement for a couple of hours. I found that aming the speakers a little more towards the sweet spot did the trick. I read somewhere that if you want a wide soundstage the speakers should have less toe in, so I probably overdid it at the time. I hope this information can help other people too. Play around with your speaker placement, there is nothing to loose I used masking tape to preserve their original possessions...just in case. Tommy Hey Tommy. Let me toss you a few ideas. People tend to like envelopment. The minority of people seem to prefer a dead room even if it is the cheapest, most convenient, and easiest way to obtain a good standard. Liveness comes from reflections but there are several types of reflections. What you don't want is strong and flat reflections. Instead, you want many smaller spatially and temporally diffuse reflections. You achieve that with diffusers. Where I'm going with this is that, though you might like the 3D sound your current reflections are offering, it may be that the type of reflection is also negating the benefits which you seem to experience as a loss of detail, imaging, and unwanted coloration. So I leave you with two tasks: 1. consider the types of reflections you are actually experiencing and investigate whether diffusion could help you achieve a better result and 2. take an acoustic measurement of your "sweet spot" to determine whether it is actually the sweetest spot and for what reasons. I think these two activities will help. Thanks.
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Post by tommy81norway on Dec 16, 2017 7:00:28 GMT
Hi, thanks for your good advice. I will take some measurements later today. I was thinking about adding some diffusion, but my room is small, and I have read that diffusers needs space/ distance to work. The 2 diffusers that I have are currently standing in front of my windows, this helped a lot in the upper frequency range. I confirmed this with measurements. Do you think I could benefit from using diffusers if the distance is less then 2 meters? Here is a measurement taken in October. Tommy Attachments:
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Post by Deleted on Dec 16, 2017 9:16:08 GMT
Hard to see much of detail in that picture. Also even real diffused field needs space, i still think diffuser is better then bare wall. I have diffusion in my room and its a small room. You can look for pictures, i have posted several of them.
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Post by Ethan Winer on Dec 16, 2017 18:26:47 GMT
Tommy is getting good advice, but I can address one other point brought up earlier: Speakers should always be angled (toed in) to point at the prime listening position. That's where the response is flattest. It also reduces the amount of treble hitting the side walls, though absorbers are needed there anyway. Since high frequencies fall off on the sides, that reduces cob filtering at high frequencies where it's most noticeable. This article shows a simulation of how comb filtering is reduced when less HF content reaches the side walls: Early Reflections
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Post by Hexspa on Dec 17, 2017 6:36:42 GMT
Hi, thanks for your good advice. I will take some measurements later today. I was thinking about adding some diffusion, but my room is small, and I have read that diffusers needs space/ distance to work. The 2 diffusers that I have are currently standing in front of my windows, this helped a lot in the upper frequency range. I confirmed this with measurements. Do you think I could benefit from using diffusers if the distance is less then 2 meters? Here is a measurement taken in October. Tommy So, I should probably double check but iirc Ethan's rule-of-thumb for diffusion is 1' listening distance per inch of diffuser depth. I think there are some other guidelines which I can't remember. 2m is about 6', right? And if a diffuser needs to be half wavelength for lower limit of effectiveness then you can diffuse down to 1130Hz with a 6' diffuser. Then, there's an additional effect down one octave. You should be able to effect down to 565Hz with a 6" diffuser. Again there may be different specs and I may be totally wrong. If I'm right, or close, you can make a huge impact in your case. I have no first-hand experience with diffusion so maybe wait for further corrections before proceeding. Where I can offer advice is with your SPL graph. Your target is +-10dB or better but the resolution of your graph is too low. While it looks like you have met that target between 25 and 200Hz I can't be sure and you didn't say whether you applied smoothing. To produce a better SPL graph, set the resolution to 5-10dB and make two images: one 300Hz and under unsmoothed and one full-spectrum with up to 1/3 octave smoothing. Also, a screenshot may be better than a photograph. Additionally, you may want to investigate your waterfall and decay measurements. They're just two clicks away. Your basic target there is 20dB decay within 150ms (though you can definitely do more if so inclined) from about 40Hz and up. Thanks
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Post by tommy81norway on Dec 17, 2017 16:47:32 GMT
Thanks for replying to my post, I really appreciate your time and advice guys. The unclear image is a clean measurement from 0hz to 10khz, no smoothing applied. I was supposed to make a measurement yesterday, but did not get around to it. Here is is a new measurement 1/3 smoothing, full range. I hope the fotos are ok.
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Post by tommy81norway on Dec 17, 2017 17:38:45 GMT
This is a measurement from 0hz to 300hz, with no smoothing.
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Post by Hexspa on Dec 19, 2017 9:02:47 GMT
Hey your decay looks good. Those look like big images. Ethan asks that they be less than 100kB. Your bass SPL should look something like this: And decay is best like this, I've found: If you choose to show just the longest two decay intervals and color them in, I find you get a cleaner result. Looks like you have a slight bump at 80Hz. That's about 12-14' so any dimension that, double that or half that will contribute. Back to your op, diffusion can help but you might want to get your spl sorted. Then again, your decay looks very good so your call. Thanks.
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Post by tommy81norway on Dec 19, 2017 13:22:15 GMT
Thanks👍 So where should I focus on placing diffusers? I also have two more corner traps in the making 😊 I was thinking that I could fit two more in the front, on top of the floor standing traps. I also want to space out my wall absorbers, but don’t know by how much. Maby 5cm?
Tommy
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Post by Hexspa on Dec 19, 2017 13:56:27 GMT
Thanks👍 So where should I focus on placing diffusers? I also have two more corner traps in the making 😊 I was thinking that I could fit two more in the front, on top of the floor standing traps. I also want to space out my wall absorbers, but don’t know by how much. Maby 5cm? Tommy Your diffusers should go at first reflection points. That includes where normal RFZ panels go. The problem with diffusion is the well depth. Shallow diffusers don't work to a low frequency. It's for this reason Real Traps makes a abfussive product. There is a new technology known as a metasurface diffuser but it's not commercially available. If it was, you could theoretically diffuse the whole room with a much thinner product. Long story short, place your diffusers on the rear wall and anywhere else you have space. Some designs require a multi-instance array so be aware of that. There is a design concept which places absorbers at ear-level while placing diffusion higher on the wall. It just comes down to what you want to accomplish within your limits. I just reviewed your pics and that rear wall, if you intend for people to sit there, needs to remain absorptive. You can place diffusers above where you art is. I think your main consideration is art vs diffusion Spacing absorbers is a compromise between low mids and lower extension. Usually, 1-4x the thickness of the absorber is recommended. Another alternative you can consider is using FRK facing on your existing non-RFZ absorption points. This will increase upper range reflection while enhancing lower absorption. I don't know what kind of effect placing a diffuser in front of an absorber will have. Seems like that's the idea solution but I don't know how to implement it. Again, find the 6', 12' or 24' (or is it 7', 14' and 28') dimension(s) that are contributing to your peak at 80Hz. If you happen to have a dimension at odd multiples of 6-7' (like 21', for instance) then you can possibly reduce absorption there thus increasing energy which will reduce your peak due to a nullifying effect. Glad I can help.
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Post by tommy81norway on Dec 19, 2017 16:26:07 GMT
Thanks 👍 Then I will work on diffusers, the art is not important 😊I will post the results when I’m done 👍 I use a calibrated Umic-1 for measuring.
Best regards Tommy
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