novi
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Post by novi on Dec 24, 2016 19:54:58 GMT
Hi Ethan, There are so many conflicting opinions on speaker placement and treatment. Regarding speaker boundary interference, Dennis Foley says to keep your speakers a minimum of 4 feet from the closest walls. Can you please comment on this? Here's his video on the subject. www.youtube.com/watch?v=P6N3uXxdYFsCheers
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Post by Hexspa on Dec 24, 2016 22:53:00 GMT
I watched that video too.
Here's my take on it:
One option will be the better one; near or far.
It's up to you to measure to find out which.
That A.F. guy is somewhat totalitarian - either you have a room with 14' minimum dimensions or you don't.
In contrast, I think Ethan (and hence myself) are more flexible - work with what you got.
Of course, ideal is ideal but,
you don't have ideal. So work with what you have.
-m
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novi
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Post by novi on Dec 24, 2016 23:57:27 GMT
Thanks M, I was experimenting earlier and it seems that against the wall I have far too much bass throttling the mids and highs; my speakers are rear ported Tapco S8's. The sweet spot (so far) in my nearly cube shaped room is with them about one foot away from the front wall. I'm right at the beginning stages and haven't applied any treatment yet except some quarter inch Auralex foam that I had laying around behind the speakers. The plan currently is to build a bunch of 5'' thick absorbers with rockwool to dampen reflections and hopefully tame the bass a little. (No spare cash for proper traps right now.) Anyway - life story over, sorry if you were dropping off while reading that!
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Post by Hexspa on Dec 26, 2016 0:59:52 GMT
Thanks M, I was experimenting earlier and it seems that against the wall I have far too much bass throttling the mids and highs; my speakers are rear ported Tapco S8's. The sweet spot (so far) in my nearly cube shaped room is with them about one foot away from the front wall. I'm right at the beginning stages and haven't applied any treatment yet except some quarter inch Auralex foam that I had laying around behind the speakers. The plan currently is to build a bunch of 5'' thick absorbers with rockwool to dampen reflections and hopefully tame the bass a little. (No spare cash for proper traps right now.) Anyway - life story over, sorry if you were dropping off while reading that! Hey, Novi. Does bass "throttle" mids and highs? I'm not sure if it does. Subjective placement assessment is good but the best way to orient your room is with the assistance of a linear response omni condenser and something like room eq wizard. Can't wait to see your panels! -m
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Post by Ethan Winer on Dec 26, 2016 16:56:47 GMT
Dennis Foley says to keep your speakers a minimum of 4 feet from the closest walls. Thanks for the link. As I mentioned on YouTube: I just posted a comment at that video. I'll try to be kind, but Dennis is a sort of laughing stock among acoustic professionals. I've seen several of his videos and they are full of misinformation. The guy is truly clueless, so please don't follow his advice. If you want to find the best place for your speakers, do that by measuring the response with software like REW as you experiment. The good news is as you add bass traps all of these problems are reduced, including response changes versus position. Then you asked for more specifics, and I'm glad to oblige. It's true that sound becomes softer with distance due to the inverse square law, so you'd think that being four feet away from a boundary gives half the SBIR interference when only two feet away. But that's only for sound outdoors away from reflecting surfaces. My home studio is 33 feet from front to back, and my speakers are less than a foot from the front wall. Even with the rear wall 33 feet away, for a round trip distance of 66 feet, the peaks and nulls in my room are not that different than those in a smaller room. Plus, in a typical bedroom size home studio, it's not even possible to put the speakers four feet away from every boundary! More important, the farther you put a speaker from the walls (and floor and ceiling), the lower in frequencies the SBIR peaks and nulls begin. So that makes them more difficult to treat. At one foot away the lowest problem frequency is 283 Hz, but at four feet it's 70 Hz. An SBIR null at 283 Hz is very easy to tame! But a null at 70 Hz requires much thicker bass trapping. Indeed, this is why the main speakers in a million dollar control room are built directly into the wall. That's as close as you can get. Not to pick on Dennis too much, but he really is a fountain of misinformation. Just a few other observations from this and one of his other videos: This video is about SBIR but he mistakenly calls it SBIE. Then he claims that loudspeakers have such a small amount of distortion it's inaudible, which of course is ridiculous. Then he shows even more confusion by claiming that amplifiers amplify loudspeaker distortion. Say what? Then he says putting a speaker against the wall is the worst place, when in fact it's often the best place. If Dennis had spent even half an hour experimenting and measuring with SBIR he'd realize he's completely wrong. So that's one video. I just watched this other video, and I feel confident saying that pretty much every single statement he makes is just wrong: www.youtube.com/watch?v=WdlriyxsvPc
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novi
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Post by novi on Dec 26, 2016 18:15:31 GMT
Thanks Ethan, I don't see your comment, maybe it got removed? All of that is good to know as I have what I thought was a very difficult room to treat and not having everything set up miles away from the wall is a big help (considering it is also my bedroom and I can't afford that much space!) Also that if at one ft all I have to deal with is 283 Hz then I'm sure that can be helped a lot by simple rockwool insulation which I've read at 4 inches can absorb 100% of 125 Hz - Happy days.
On a sad note, I've wasted hours of my life taking notes from his videos. Thanks for the calrity Ethan, now I can finally get on with treating my room.
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novi
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Post by novi on Dec 26, 2016 18:20:50 GMT
Does bass "throttle" mids and highs? I'm not sure if it does. Subjective placement assessment is good but the best way to orient your room is with the assistance of a linear response omni condenser and something like room eq wizard. Can't wait to see your panels! -m Hi M, I'm sure it doesn't but the effect is of the bass overwhelming much of the soundstage I'm used to hearing in the mids and high's of the song I am using to test my speaker placement; It sounds muddy and over compressed basically. I'll try and wrap my head around R.E.W and get a more accurate idea of what is going on in my room and I'll post up a photo when it's done. Cheers! Save
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Post by Hexspa on Dec 26, 2016 23:26:09 GMT
Read Ethan's articles and my free stuff.
YouTube has a good tutorials on REW.
Also, go one step at a time and ask questions the same way.
It's really not that hard. Just the beginning is confusing.
-m
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novi
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Post by novi on Dec 28, 2016 14:36:02 GMT
Thanks M
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Post by Ethan Winer on Dec 28, 2016 20:10:48 GMT
I don't see your comment, maybe it got removed? I see it, but this has happened to me before, that I post a comment and I'm the only one YouTube shows it to. I must have a reputation. (kidding) Here's what I posted: About 90 percent of the information in this video is simply wrong. Plus, it's SBIR, not SBIE, where R= Response. Dennis, if you would simply measure the response with one speaker at various distances you'd see your 4-foot suggestion is just silly.
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Post by ellenoir on Feb 10, 2017 16:24:22 GMT
Hi Ethan, I'm Arif a newcomer in here , saying hallo from jakarta Indonesia. I'm glad to see your own forum. I already made membrane traps for low, mid and high frequency. Still not finished yet, but I still dont understand how to manage Speaker Boundaries Interference especially at 70Hz. I can't even put my speaker close to rear wall, because my enclossure has rear port and when i try to put speaker close to wall behind speaker, mid and high instrument became unclear, I think because of wood panel behind and beside the speaker. very poor kickdrums in my room. I calculate my room size, speaker placement, seat position with REW, and the result is like my rta. drop 15db at 75hz. Already think to try any option like hemholtz, very thick absorber, but still can't decide is that enough? please help me Ethan. thank you
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Post by Hexspa on Feb 11, 2017 15:35:12 GMT
75Hz null is probably due to a 4', 12', 20' or 28' dimension somewhere (actually a little less from those exact dimensions).
Since 4' is 1/4 wavelength of 70Hz then that is the proper distance from any boundary to treat that frequency.
However you don't need to do that. Gapping four 4" rigid panels 16" has worked for me; my cloud handles my ceiling peak mode at 70Hz.
Basically you need to find the dimension of your room which correlates closely to the first posted lengths and treat that surface with broadband absorption.
I know nothing about pressure absorbers other than they're typically not recommended for small rooms.
Thanks,
-m
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Post by ellenoir on Feb 13, 2017 15:27:00 GMT
75Hz null is probably due to a 4', 12', 20' or 28' dimension somewhere (actually a little less from those exact dimensions). Since 4' is 1/4 wavelength of 70Hz then that is the proper distance from any boundary to treat that frequency. However you don't need to do that. Gapping four 4" rigid panels 16" has worked for me; my cloud handles my ceiling peak mode at 70Hz. Basically you need to find the dimension of your room which correlates closely to the first posted lengths and treat that surface with broadband absorption. I know nothing about pressure absorbers other than they're typically not recommended for small rooms. Thanks, -m -Yes Hexspa, my room has 12' length. If I made absorber with air space behind , I thought my room will be narrow. But its nice to try gapping four 4' rigid panel behind speakers. thank you.
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Post by Ethan Winer on Feb 13, 2017 17:20:46 GMT
SBIR is why I suggest road band bass trapping rather than tuned absorbers. My recent article explains more about this: Bass Trap Myths
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Post by Hexspa on Feb 13, 2017 18:59:11 GMT
75Hz null is probably due to a 4', 12', 20' or 28' dimension somewhere (actually a little less from those exact dimensions). Since 4' is 1/4 wavelength of 70Hz then that is the proper distance from any boundary to treat that frequency. However you don't need to do that. Gapping four 4" rigid panels 16" has worked for me; my cloud handles my ceiling peak mode at 70Hz. Basically you need to find the dimension of your room which correlates closely to the first posted lengths and treat that surface with broadband absorption. I know nothing about pressure absorbers other than they're typically not recommended for small rooms. Thanks, -m -Yes Hexspa, my room has 12' length. If I made absorber with air space behind , I thought my room will be narrow. But its nice to try gapping four 4' rigid panel behind speakers. thank you. Behind speakers could be good. I presume that prioritizing for treating your rear wall is better; speakers fire forward mostly. Treating both parallel surfaces is best considering that an axial mode is a standing wave almost like a card pressed and bending between your palms. I have my fore and aft walls treated extensively. -m
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