|
|
Post by ansat on Oct 12, 2012 16:53:58 GMT -5
Absorbtion absorbs sound energy and converts to heat (very little). Thanks, ansat So once you've tamed the room somewhat with absorption, you then direct reflection to where you want/need it?(sounds kinda Bose-ish  ) jk I was under the impression that all/most reflection was undesirable; wrong? g Diffusion breaks waves up at frequencies. Think of diffusion as a eq and absorbtion as a high pass filter. You can target areas with diffusion. Absorbtion works on all frequencies. The effectivness decreases the lower the freq. As far as sound, diffusion would help tame frequencies without deadening the sound. You start with absorbtion to get the room close to where you want it and follow with diffusion to fine tune (if needed at all). No, It acts as a notch filter. it will break up the wave. The energy is still left in the room but the idea is to scatter most of that energy. You would use the absorbtion and diffusion to tame the room. |
|
|
|
Post by ansat on Oct 12, 2012 17:02:25 GMT -5
Easy anology. Think of sound as a jet of water. Spraying a wall off angle will just redirect most of the water in one area. Spray a pile of clothes at the same angle and most of that water will be absorbed. Spray a rigid object with many angles and surfaces then water goes all over the place (be diffused).
|
|
|
|
Post by Jean Genie on Oct 12, 2012 17:25:07 GMT -5
Well put. Thank you.
|
|
jamrock
Emo VIPs 
Courtesy Costs Nothing. Give Generously!
Posts: 4,750
|
Post by jamrock on Oct 12, 2012 17:47:08 GMT -5
How do you decide where to place the panels. Isn't there supposed to be some type of room measurement conducted to decide where they are supposed to be placed. And an after measurement to see how effective they are? I'm just asking because I really don't know  |
|
|
|
Post by jlafrenz on Oct 12, 2012 17:56:41 GMT -5
How do you decide where to place the panels. Isn't there supposed to be some type of room measurement conducted to decide where they are supposed to be placed. And an after measurement to see how effective they are? I'm just asking because I really don't know There are a few different methods for placement. One very common one is to sit in your listening position and have another person move a mirror along the walls. Where ever you see your speakers in the mirror, put a panel there. As far as measurements, you are talking frequency measurements right? Assuming you are, you can use REW as a free software with some other equipment and graph your room. There are also CD's that will allow you to do this manually. Depending on what frequencies you are trying to tame (based on your graph) will help you select the proper material and thickness. Combining these two will give you a good start on your room. There are some mathematical calculations you can use to figure out placement. I would visit realtraps.com to view some of these. |
|
|
|
Post by ansat on Oct 12, 2012 18:23:33 GMT -5
How do you decide where to place the panels. Isn't there supposed to be some type of room measurement conducted to decide where they are supposed to be placed. And an after measurement to see how effective they are? I'm just asking because I really don't know Well you can take a measurement with a mic to look at what your rt20, 30, 60 would be. before and after would give visual proof to your ears. But its parts of the sound you are trying to tame and can be done by ear. Say your low end in lingering in the room and the bass is really boomy. Putting traps in the corners is the most bang for the buck. If you have a echo in the mids and highs then absorbtion on the sidewalls is the best place to start. To find these points the mirror trick is the easiest method. (have someone move a mirror at listening level at the wall and move it across the room. Anywhere you see a speaker is a reflection point. 1 ft = 1.13 ms of time delay. If the speaker is 10 feet from you then you have the delay it takes the sound to get to you as well as the reflection point. The reflection off my rear wall is 24 feet. that would be a difference of 15.82 ms it takes that sound to get to my ears. And that is hitting my ears at roughly 4.5db less then the original signal hit my ears. The brain does a good job of putting everything of everything up to 37 ft together by averaging the sound but the brain would think it heard the sound at a slightly different location thus creating localization issues. The goal is to knock those early reflections down to inaudible ranges before they become a problem. My example above in my room would NOT mess with much at all in the first reflection but on the second and third reflection this would turn to a echo that we can hear. It is just easiest to kill the freq early. Tony |
|
|
|
Post by Jean Genie on Oct 12, 2012 19:08:04 GMT -5
So is absorption effective on 3rd & 4th reflections or would diffusion be a better solution.
BTW, ansat and jlafrenz, thank you again for the info. & expertise.
This is one of the most informative threads I've seen in the lounge, I'm sure it's beneficial to many.
g
|
|
|
|
Post by The Mad Norseman on Oct 12, 2012 19:16:32 GMT -5
Teach me something here. Are acoustic panels best placed behind the speakers? Considering there are 4 walls in a room plus the ceiling where the panels could be put is there an order of placement if you couldn't get all the panels you needed at one time? This book explains all in general terms - that EVEN I can understand! Its full of great (and cheap) ways to improve your sound, a lot of very practical suggestions as well - highly recommended! Attachments:
|
|
|
|
Post by spurriersucks on Oct 12, 2012 19:22:57 GMT -5
The 3 you got so far will definitely help, but you will really notice a difference with the thicker/bass trap ones installed into your room also. And don't forget a couple on the side walls and/or the ceiling if feasible! I read that with the omni polar design of the Mirage speakers that if the speakers were 4' or so away from the side walls or rear walls that panels were not needed but if closer then they would recommend them. They are far enough away from the sides but I can't really get them any farther away from the rear wall, 14". My next purchase will be corner bass traps and 2 more bass traps to put on the walls under the surrounds. Thoughts? |
|
|
|
Post by spurriersucks on Oct 12, 2012 19:24:29 GMT -5
Another suggestion (after looking at your photos again) is you'd probably benefit from some carpet right in front of your floorstanders - negate that first reflection off the hard wood floor. I see you've got a throw rug further into the room, but more absorption right in front of those speakers would also cut down on those 'echoing' sounds you're reporting. Getting rid of those "first reflections" (whether off of the floor or sidewalls) will work wonders by themselves! I plan on pulling the rug up some soon. I've been wanting to do this for a year or so but have not done it yet. |
|
|
|
Post by spurriersucks on Oct 12, 2012 19:26:05 GMT -5
When I look at those pictures I see a ton of absorbion. The carpet and furnature should be doing a lot more then it is. Try getting those speakers off the hardwood. Use pillows or dense foam to see if decoupling could do you some good. sent from my phone. sorry for the short response. Tony Not sure I can get the ife to go along with having taller speakers. These about didn't make it as is. Thanks for the helpful info in the thread. |
|
|
|
Post by ansat on Oct 12, 2012 19:47:03 GMT -5
So is absorption effective on 3rd & 4th reflections or would diffusion be a better solution. BTW, ansat and jlafrenz, thank you again for the info. & expertise. This is one of the most informative threads I've seen in the lounge, I'm sure it's beneficial to many. g if you knock out the first you dont need to worry about the 2nd and 3rd. Most rooms dont need diffusion. Most are so alive that there is no room on the walls for the monsterous panels to give a very small notch of the frequency. Unless you are chasing a problem that is very specific you shouldn't even be looking at diffusion. If you need to to address a 2nd and 3rd I would still look at absorption. So when does one look to diffusion. 1. Say that the roon sounds really good except at around 1k hz you are getting a measurable poor rt20 (time it takes the sound to decrease 20db). You would want to a panel designed to diffuse that area to bring just that ranges reflected freq down to where you want it. 2. Say your rooms rt20 is in check for the lows and highs. But your mids are out of the norm. You might not want to add absorption as it could over deaden the room even thouh you have a problem across a broad frequency. You would use a series of diffusion to keep the room in check. Now to add another layer of complication to this. Most speakers are relativly flat when measured outside a room. The room is creating the peaks and nulls to the sound. There really isn't a danger in cutting the level of the frequency. The danger is adding gain. So .. say your issue is that you have a big dip 5k hz. Room treatments can be used to increase that frequency. When sound waves intersect they can cancel or combine. Limiting the reflections will help keep the speakers natural response true. So if the room isn't bad is there a still a benefit for room treatments. Especially with modern room correction. My answer is yes. Most corrections made are designed to overpower the nulls and cut the peaks. I dont have trouble with cutting peaks. But I am not a fan of adding any gain at all. I have seen gain increases of 6db added to fill the voids. Further limiting your headroom. Tired of typing, sent from my phone. sorry for the long response. Tony |
|
|
|
Post by ansat on Oct 12, 2012 19:48:47 GMT -5
Teach me something here. Are acoustic panels best placed behind the speakers? Considering there are 4 walls in a room plus the ceiling where the panels could be put is there an order of placement if you couldn't get all the panels you needed at one time? This book explains all in general terms - that EVEN I can understand! Its full of great (and cheap) ways to improve your sound, a lot of very practical suggestions as well - highly recommended! Imo The dvds are cheaper and more effective. But I own both. sent from my phone. sorry for the short response. Tony |
|
|
|
Post by jlafrenz on Oct 12, 2012 20:50:45 GMT -5
So is absorption effective on 3rd & 4th reflections or would diffusion be a better solution. BTW, ansat and jlafrenz, thank you again for the info. & expertise. This is one of the most informative threads I've seen in the lounge, I'm sure it's beneficial to many. g There is some debate on absorption vs. diffusion. It depends on your application, what you are trying to achieve, and as with anything audio a bit of personal preference. I would start with your 1st refection points and go from there. Remember that first reflection points include those on your ceiling an floor. Ceiling is tough, but can be done. I don't currently have any on my ceilings as I don't want to have to repair the finish, but I have in previous residences. |
|
|
|
Post by The Mad Norseman on Oct 12, 2012 21:25:38 GMT -5
jlafrenz typed:
"I would start with your 1st refection points and go from there. Remember that first reflection points include those on your ceiling an floor".
Very true - but don't forget about the side wall surfaces nearest your front speakers too!
Especially if a side wall is close, those first reflections also need to be tamed...a mirror and a flashlight will tell you where to place the acoustic panel for each, but you'll need a helper while you sit in the sweet spot!
|
|
|
|
Post by jlafrenz on Oct 12, 2012 21:37:01 GMT -5
jlafrenz typed: "I would start with your 1st refection points and go from there. Remember that first reflection points include those on your ceiling an floor". Very true - but don't forget about the side wall surfaces nearest your front speakers too! Especially if a side wall is close, those first reflections also need to be tamed...a mirror and a flashlight will tell you where to place the acoustic panel for each, but you'll need a helper while you sit in the sweet spot! I probably should have worded that better. What I was meaning to say was that in addition to the side walls, ceilings and floors have 1st reflection points too. Thanks for catching that and pointing it out to clear up any confusion for those following.  |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Oct 12, 2012 22:35:34 GMT -5
There are a few different methods for placement. One very common one is to sit in your listening position and have another person move a mirror along the walls. Where ever you see your speakers in the mirror, put a panel there.
Not sure if this system of placement is universal for all speaker designs? Seems like tweeter design could vary this quite a bit. For example, the high frequency dispersion throw of a Klipsch speaker say with its "throated" horn design it quite different than a Emotiva X-Ref front loaded tweeter design. Using Ansat's water nozzle analogy, it seems like the water would be long throw on the Klipsch vs a wide spray pattern for the X-ref. Therefore, if the "side panels" are also for the high frequencies it seems like there would have to be some placement deviation of the side panel to allow for this or the mirror method could miss the mark for the high frequencies. Am I over analyzing here?
|
|
|
|
Post by The Mad Norseman on Oct 13, 2012 11:21:46 GMT -5
jlafrenz typed: "I would start with your 1st refection points and go from there. Remember that first reflection points include those on your ceiling an floor". Very true - but don't forget about the side wall surfaces nearest your front speakers too! Especially if a side wall is close, those first reflections also need to be tamed...a mirror and a flashlight will tell you where to place the acoustic panel for each, but you'll need a helper while you sit in the sweet spot! I probably should have worded that better. What I was meaning to say was that in addition to the side walls, ceilings and floors have 1st reflection points too. Thanks for catching that and pointing it out to clear up any confusion for those following. Right. I figured you knew that, and meant to include sidewall 1st reflections too, but just to clarify for the OP... |
|
|
|
Post by jlafrenz on Oct 13, 2012 12:23:20 GMT -5
There are a few different methods for placement. One very common one is to sit in your listening position and have another person move a mirror along the walls. Where ever you see your speakers in the mirror, put a panel there. Not sure if this system of placement is universal for all speaker designs? Seems like tweeter design could vary this quite a bit. For example, the high frequency dispersion throw of a Klipsch speaker say with its "throated" horn design it quite different than a Emotiva X-Ref front loaded tweeter design. Using Ansat's water nozzle analogy, it seems like the water would be long throw on the Klipsch vs a wide spray pattern for the X-ref. Therefore, if the "side panels" are also for the high frequencies it seems like there would have to be some placement deviation of the side panel to allow for this or the mirror method could miss the mark for the high frequencies. Am I over analyzing here? Typical panels are 2ft wide so once you find the spot where you can see the tweeter you have roughly a foot on each side of that spot that is covered. |
|
|
|
Post by spurriersucks on Oct 13, 2012 20:29:36 GMT -5
Panels are up. Except for the center.  |
|
) jk
