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    Room Acoustics

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    bluemeanies

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    Room Acoustics

    Post by bluemeanies on Tue Mar 14, 2017 2:23 pm

    Thought I would post this since I have been thinking about a difussor in my system. First let me say they are not cheap, but I think they are just as important as sound absorbers.
    I have not noticed any discussion about acoustics on this forum and I just thought I had to open my BIG MOUTH to see if I get any feedback.
    Would be interested in hearing what other people do for acoustics in their dedicated or undedicated room.
    Below is a link I found about making a difussor from concrete cylinder forms. Cheap to make and they look pretty good for home-grown.


    https://www.lifewire.com/make-your-own-audio-diffuser-3134903
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    Peter W.

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    Re: Room Acoustics

    Post by Peter W. on Tue Mar 14, 2017 4:03 pm

    I have been playing around in the audio hobby for over 40 years now, using pretty much every type and style of "consumer" speaker from the likes of Accoustat, AR, ADS, Dynaco, Magnepan, EPI, Infinity, and more. Bookshelf, floor-standing, funny-shaped, planar, and more. Including AR LSTs, 9s and Holographics. I have never found a room that could not be tamed simply with proper placement of the speakers.

    What I have found, repeatedly, is that when the speakers are placed *without* reference to the room - in other words with the intention of achieving some sort of 'sweet spot' or theoretical placement - THAT is when such heroic measures as are described in the article become necessary.
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    corndog71

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    Re: Room Acoustics

    Post by corndog71 on Tue Mar 14, 2017 5:44 pm

    I use and recommend ATS acoustics. They have a nice room calculator that works well even with my rough estimates. It was good with a few but placing the last two pieces really made a huge difference in my room.



    Last edited by corndog71 on Wed Mar 15, 2017 10:30 pm; edited 1 time in total

    GP49

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    Re: Room Acoustics

    Post by GP49 on Tue Mar 14, 2017 7:09 pm

    Peter W. wrote:What I have found, repeatedly, is that when the speakers are placed *without* reference to the room - in other words with the intention of achieving some sort of 'sweet spot' or theoretical placement - THAT is when such heroic measures as are described in the article become necessary.

    The real disaster is when a "decorator" decides where your speakers should be..."Let's put one of them up on top of that bookshelf and the other one in the alcove next to the fireplace."

    The way to avoid that problem is to fire them when you get that first inkling.
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    LeGrace

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    Re: Room Acoustics

    Post by LeGrace on Tue Mar 14, 2017 7:21 pm

    Was that taken with a fisheye lens? Interesting looking units either side of the center console. Subs of some form?
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    corndog71

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    Re: Room Acoustics

    Post by corndog71 on Tue Mar 14, 2017 7:41 pm

    LeGrace wrote:Was that taken with a fisheye lens? Interesting looking units either side of the center console. Subs of some form?

    Panoramic shot from my iPhone.

    They are indeed subwoofers.  Designed in collaboration by GR Research and Rythmik Audio.  Each pair of 12" open baffle subs is driven by a 370 watt servo-controlled amp.  They can reach down under 20Hz and do bass like no other subs I've heard.  I had the cabinets cut for me but I glued and painted them.


    Last edited by corndog71 on Wed Mar 15, 2017 1:40 pm; edited 1 time in total
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    sKiZo

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    Re: Room Acoustics

    Post by sKiZo on Tue Mar 14, 2017 9:46 pm

    Little bit of this, little bit of that ...

    Took some readings on the room some time back using REW (Room EQ Wizard) using a calibrated microphone and laptop to see what the big issues were. Addressed those with basic room treatments (a full wall of insulated fiberglass curtains at the front of the room, sound baffles for an archway behind the comfy chair, a couple smallish traps in the corners, and carpets on the ceiling to kill some hard reflections at the primary bounce spots ...

    (carpets on the ceiling?)



    (Yup ... carpets on the ceiling ... don't forget to wipe your feet!)

    Once that was done, yet another set of sweeps with REW to pinpoint what was left. This was mostly handled with some basic "big lump" EQ courtesy of a McIntosh MQ104 "environmental equalizer", followed up by yet another sweep. The results of that last test were overlaid with a custom "room curve" to compensate for my environment and listening taste, and exported to the "convolution kernel" in jRiver Media Center. That gives me next best thing to perfect room response.

    Only took 30 some odd years (some odder than others) to get it right ...
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    Kentley

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    Re: Room Acoustics

    Post by Kentley on Wed Mar 15, 2017 1:23 am

    At the risk of repeating myself (something I do, yes, to excess) I have a unique opinion about how to approach your listening space.
    For me, the danger is a room that might add too much to the quite various ears (producers, engineers, masterers) who have taken pains to provide what they consider a finished listening experience to as wide an audience as possible. Which means that our task is very different from a live-venue architect. In other words, NEUTRAL is our goal.
    No matter what you have to work with, it is likely flawed. The task is to minimize the mistakes.
    Which means a combination of absorption and diffusion. Each of which is liable to decrease the actual SPLs . So Rules One and Two - More Power than you think you need, and Bigger Speakers. These will be cut down to size by as much modding of the room as the situation will allow (read: wives and lovers).
    Your ears are the best guides. They are also your worst enemies. Only your grey matter can sort out the contradiction.

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    tubes4hifi
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    Re: Room Acoustics

    Post by tubes4hifi on Wed Mar 15, 2017 12:59 pm

    Corndog,
    way to go!!  congrats!   and nice subwoofers (and the speakers too).
    BlueMeanies - no thoughts posted on room acoustics???   guess you haven't seen this past I made last year . . .
    http://dynacotubeaudio.forumotion.com/t2634-your-listening-room-is-a-system-component?highlight=room
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    bluemeanies

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    Re: Room Acoustics

    Post by bluemeanies on Wed Mar 15, 2017 4:23 pm

    I just read your thread...thank you.
    I am happy with the sound of my 2channel. Acoustics or lack there of. I personally have spent a few hundred dollars for acoustics to tame my room which is dedicated. To describe it I will say it is a room within a room. The orginal garage was all cider block and brick walls. The room I built ( with a little help from my friend) has a drywall ceiling on metal tracks, my room walls are floating on rubber u-shaped forms. The walls and ceiling are insulated with mineral fiber and sheet-block all surrounded with 7.5" thick walls and soundproof doors.
    Overkill?...you decide, but I enjoy both movies and 2channel regularly in my hide-away.
    My posting was as yours to help those diy'ers.
    The price of the difussors are a cost factor of fifty dollars or less if I decide to make them. If I do not like what I hear I have did not break the bank.
    At this point I am still weighing out whether to go back to just two output tubes in my m125's. My speakers are pretty efficient.
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    Ernstmach

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    Re: Room Acoustics

    Post by Ernstmach on Thu Mar 16, 2017 8:46 pm

    I couldn't agree more about acoustic treatment for your room.

    recently renovated my listening room. Acoustic treatment with the help/advice from Brian Pape of GIK.

    My dedicated room is 12X18X9 in a stand alone building. Treatments include absorption at first reflection point, ceiling. Bass traps front and rear corners and diffusion in different positions.
    Incredible what this has done to improve sound in this room. Still tweaking but pretty close at this point.
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    sKiZo

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    Re: Room Acoustics

    Post by sKiZo on Thu Mar 16, 2017 10:01 pm

    ... and it's not like fine tuning a room has to be all that expensive either. Lots of DIY options, long as you know where to start. That's where something like REW comes in real handy, as playing it by ear just ain't gonna cut it, as there's just too many variables.

    I remember the bad old days, having a whole crew in the house setting up a van full of expensive equipment required to tune a room ... here's my setup ...



    ... and it's actually gotten simpler since I got that stuff. Now, instead of a mixer and breakout box, most laptops have decent enough built in audio to do the job, and a USB mike eliminates the need for the mixer. Not shown is my BSR SPL meter, but nowadays, there's phone apps for that.
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    bluemeanies

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    Re: Room Acoustics

    Post by bluemeanies on Fri Mar 17, 2017 9:27 am

    Ernstmach wrote:I couldn't agree more about acoustic treatment for your room.

    recently renovated my listening room. Acoustic treatment with the help/advice from Brian Pape of GIK.

    My dedicated room is 12X18X9 in a stand alone building. Treatments include absorption at first reflection point, ceiling. Bass traps front and rear corners and diffusion in different positions.
    Incredible what this has done to improve sound in this room. Still tweaking but pretty close at this point.


    I was in contact with Brain Pape at GIK. Very helpful with a quick response. I sent him a diagram of my 25'L 8'-10'5"W & 6'3"-6'10"ceilings and his response with what I need and the placement of the acoustics was very helpful.
    Unfortunately the cost factor was a bit high.
    Retired...I need some additional cash flow and save.
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    Ernstmach

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    Re: Room Acoustics

    Post by Ernstmach on Fri Mar 17, 2017 9:35 am

    "Retired...I need some additional cash flow and save."

    I'm right there with you. I made most of mine. It was a great project and really paid off. Costs were much better too.
    Still working on bass trapping though.
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    LeGrace

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    Re: Room Acoustics

    Post by LeGrace on Fri Mar 17, 2017 10:56 am

    The bass ports on my Tannoy floor-standers are rear firing. To try and get the most from my system I have tried several fundamentally different in room placements. The best so far being 1/3 the distance from opposing walls; following a ratio recommend by Cardas folks. This put them 8 feet off the wall behind them, so ample breathing room for the ports. Sounded very good.

    But then there's an additional, even more important consideration, the infamous WAF. After a couple months of constant complaining about how I had ruined the room to the point she didn't want to step into it anymore I threw in the towel and moved them back to either side of my components console. Speaker wires are all nicely out of sight again! Furniture placement making sense again! Harmony is restored!

    Anyway now that they are close to a wall again (14" gap) should I be installing bass traps in behind given the rear port layout? I also think I should probably be doing something with the walls directly opposite. Is a bass trap fundamentally different from an absorptive panel? I'd like to look at making something myself. I was thinking rectangular wooden frame with fabric stretched across the front and fibrous insulation fill. That way I can customize size to suit along with color scheme to match the room. SO has approved the plan as long as I don't go crazy. Any thoughts/advice appreciated.
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    Peter W.

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    Re: Room Acoustics

    Post by Peter W. on Fri Mar 17, 2017 11:44 am

    Please note the interpolations.

    Heresy Warning!


    LeGrace wrote:The bass ports on my Tannoy floor-standers are rear firing. To try and get the most from my system I have tried several fundamentally different in room placements. The best so far being 1/3 the distance from opposing walls; following a ratio recommend by Cardas folks. This put them 8 feet off the wall behind them, so ample breathing room for the ports. Sounded very good.

    There are two schools of thought on rear-firing bass ports.

    a) The ports are naturally 180 degrees out of phase with the speakers. Air gets 'sucked in' when the woofer cone moves out, and pushed out when it moves in. So, 'breathing is important to obviate any cancellation waves.
    b) If the ports are close to a wall, that phasing is cancelled by the reflection from the wall (there is a formula for the correct distance).

    I think that both schools have validity - you may as well use b) to satisfy the WAF requirement.


    But then there's an additional, even more important consideration, the infamous WAF. After a couple months of constant complaining about how I had ruined the room to the point she didn't want to step into it anymore I threw in the towel and moved them back to either side of my components console. Speaker wires are all nicely out of sight again! Furniture placement making sense again! Harmony is restored!  

    Repeat after me: Symmetrical Speaker Placement IS BAD. Symmetrical Speaker Placement IS BAD. Make that your mantra when positioning them in a room. I am not suggesting that they should not be on either side of your component, just that they NOT be placed symmetrically within the room. More on why later.

    Anyway now that they are close to a wall again (14" gap) should I be installing bass traps in behind given the rear port layout? I also think I should probably be doing something with the walls directly opposite.

    You should not need any of this unless you are locked into symmetry and other issues. No more than simple placement should be enough to tone down excess bass and/or enhance higher frequencies. If you are locked into symmetry, then you will need to make some choices to either enhance or reduce bass.

    Is a bass trap fundamentally different from an absorptive panel? I'd like to look at making something myself. I was thinking rectangular wooden frame with fabric stretched across the front and fibrous insulation fill. That way I can customize size to suit along with color scheme to match the room.

    It is a matter of degree. Bass traps can often be a combination of absorptive material and shaped surfaces to 'tune' bass. An absorptive panel is only that.  

    SO has approved the plan as long as I don't go crazy.  Any thoughts/advice appreciated.

    Just for giggles, try this:  On the LONG wall of the room place speaker A 1/3 the length of the wall from the corner. Place it no more than six (6) inches from the wall.  This is your anchor speaker. Starting at 1/3 the distance from the other corner on the same wall, gradually move Speaker B closer to A. Listen for the best sound-stage and most pleasing sound you can get in *this* way. One single variable - the position of Speaker B.  When you have this down, and your SO approves of the sound as well. Then in very small increments, start moving the speakers away from the wall, 1/2" at a time - but no more than (rule-of-thumb for ported speakers) 1.5 x the woofer diameter from the wall.

    What is likely going to happen in a moderately "live" room is that your speakers will wind up at about 8 - 10 x woofer diameters apart, with A being at the 1/3 point of that wall. And they will wind up about 1 woofer diameter from the wall. No BS with so-called "sweet spots", but a pretty dam**d good sound stage and a comfortably large listening area. And, as the speakers are placed asymmetrically, there are no cancellation waves and interference waves - the effects of which are the primary causes for physical room conditioning in the first place.

    End Heresy.
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    sKiZo

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    Re: Room Acoustics

    Post by sKiZo on Fri Mar 17, 2017 1:34 pm

    Doesn't take long to find out that any professional help ... be ready to add some zeroes to the end of the estimate.

    If cost is prohibitive, that still doesn't rule out DIY treatments and digital EQ ... you can build some nice bass traps and dampers for dirt (literally, if you want to do the sand box thing for your speakers) and a basic digital EQ solution might set you back a couple hundred. The end result can be night and day ...
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    LeGrace

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    Re: Room Acoustics

    Post by LeGrace on Fri Mar 17, 2017 2:26 pm

    I've been thinking about one these.
    Driverack

    Combines active crossover with parametric EQ functions. I would have to go into my speakers and bypass the built in crossovers. But in my case the rear ports are advantageous in that I can run wires through them without anything showing. Only question, am I ready for this much control . affraid
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    Peter W.

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    Re: Room Acoustics

    Post by Peter W. on Fri Mar 17, 2017 2:32 pm

    OK, first, thinking is good. Always. Often when I get that urge to think about equipment of this nature and utility, to paraphrase Mr. Twain, I lie down until it goes away. Sometimes I get a lot of rest!

    Heroic measures such as that are seldom necessary with reasonably careful placement. Try that if the SO permits.
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    LeGrace

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    Re: Room Acoustics

    Post by LeGrace on Fri Mar 17, 2017 3:02 pm

    What appeals about this approach is the huge improvement I noticed after running the DSP processing that came built in with my AVR. (ref Marantz SR7008, powers a 5.1 movie setup in another room) I installed the microphone, it beeped a bunch of times, and wow did the sound ever improve afterwards. This unit does the same, but offers way more fine tuning options.
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    sKiZo

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    Re: Room Acoustics

    Post by sKiZo on Fri Mar 17, 2017 4:17 pm

    I've heard good things about the dbx PA series ...

    You can get an original PA for maybe half the price of the PA2. Pretty much the same features, only they've cleaned up the menus and navigation a lot on the newer ones making them easier to use. I understand the PA+ also allows several levels of accuracy, each requiring a bit more work on your part. Not sure if that's an improvement or not.

    I don't like work
    And work don't like me
    And we stay away from each other
    That's the way it ought to be


    (Lyrics are a little tribute to James Cotton, who just passed ...) Neutral
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    Ernstmach

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    Re: Room Acoustics

    Post by Ernstmach on Fri Mar 17, 2017 4:58 pm

    (Lyrics are a little tribute to James Cotton, who just passed ...)

    Nice! Thanks for that.
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    sKiZo

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    Re: Room Acoustics

    Post by sKiZo on Sat Mar 18, 2017 4:46 pm

    One of the greats ... was just listening to High Compression ... Cool

    81 years young ... ain't doin' too bad at all!



    Some of the folk he worked with over the years ... reads like a who's who of blues ... yall may recognize a few of the names ...

    Gregg Allman
    William "Billy Boy" Arnold
    Elvin Bishop
    Mike Bloomfield
    Joe Bonamassa
    Paul Butterfield
    Grateful Dead
    Pat Hare
    Howlin' Wolf
    Janis Joplin
    B.B. King
    Freddie King
    Alexis Korner
    Steve Miller
    Charlie Musselwhite
    Quicksilver Messenger Service
    Keith Richards
    Todd Rundgren
    Santana
    Willie "Big Eyes" Smith
    Otis Spann
    Taj Mahal
    Big Mama Thornton
    Jimmie Vaughan
    Joe Louis Walker
    Muddy Waters
    Sonny Boy Williamson
    Johnny Winter

    Oh. Sorry for the hijack ... we now return control of your television set ... pirat
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    Kentley

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    Re: Room Acoustics

    Post by Kentley on Sun Mar 19, 2017 2:40 am

    There's another factor in determining system/room interaction which I rarely hear mentioned. It is your personal SPL Preference. If you are in the habit of Big Listening - i.e. LOUD - your room will undoubtedly be more of an issue. This, I believe, is partially physics and partially psychology. The brain changes the way it hears when forced to focus on quiet sounds. When loud, there is less direct sound perception, and more peripheral.
    You can test this easily. When your speakers are pumping, your ears will hear the room more, good or bad.
    I've long maintained that an intuitive grasp of the conditions present during mixing and mastering at the studio level helps us maximize our listening experience. If that should seem obtuse, it is.
    In short, when considering room treatment, consider listening habits. And if your primary sources are recorded in a real space (Classical and some live acoustic and jazz) you will need an essentially different approach. Yea, Team!

    P.S. Though if you go the acoustic route, you are more likely to solve the problems of your room for all sources than the other way around.
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    bluemeanies

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    Re: Room Acoustics

    Post by bluemeanies on Sun Mar 19, 2017 8:36 am

    Kentley wrote:There's another factor in determining system/room interaction which I rarely hear mentioned. It is your personal SPL Preference. If you are in the habit of Big Listening - i.e. LOUD - your room will undoubtedly be more of an issue. This, I believe, is partially physics and partially psychology. The brain changes the way it hears when forced to focus on quiet sounds. When loud, there is less direct sound perception, and more peripheral.
    You can test this easily. When your speakers are pumping, your ears will hear the room more, good or bad.
    I've long maintained that an intuitive grasp of the conditions present during mixing and mastering at the studio level helps us maximize our listening experience. If that should seem obtuse, it is.
    In short, when considering room treatment, consider listening habits. And if your primary sources are recorded in a real space (Classical and some live acoustic and jazz) you will need an essentially different approach. Yea, Team!

    P.S. Though if you go the acoustic route, you are more likely to solve the problems of your room for all sources than the other way around.


    Good observation Kently.
    My room is relatively small in cubic feet.
    I do not BLAST (as I call it now) my music. I am enjoying low volumes especially with jazz, blues and classical. I still do the R&B, R&R just not as much. One of the best groups (IMO) played on my system is Pink Floyd. Second choice would be The Beatles, along with Neil Young. The list can go on and on.
    I am really into jazz. My new hero is Bruce Forman Trio. He sounds great on my system and for blues I am starting to settle in with James Cotton, one hell of a harmonica player.

    Good input Kently,
    Blue

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