it's easy to over damp a room for hi-fi..we generally like the reverb of our rooms...but control rooms don't want the room involved...they of course aren't listening for enjoyment.
So this is the challenge...the panel sellers don't really understand hi-fi goals so they will tell you to kill your sidewall first reflections and also to put a cloud on your ceiling to kill that first ceiling reflection...all those spatial cues we love they correctly see as colorations.
Floyd Toole discovered during the Harmon studies that people generally don't like the first reflection absorbed for music...but the dogma to kill first reflection points persists and is repeated in every corner on the internet. ;-)
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@mijostyn, I expect you intended "It is . . ." when you said, "If is extremely hard to over dampen a room."
But I guess it is not impossible. Several years ago I had a friend who was a reviewer for one online audio magazine. Being serious about the task he hired a then well-known acoustics company to advise him on room treatments. That resulted in installation of a large number of Tube Traps plus several panel absorbers, along with an array of diffusers suspended from the ceiling. At first he was pleased but after a few weeks became dissatisfied that so much dynamics and "life" seemed to be missing.
At his invitation another friend and myself came over to help. One by one we eliminated most of the tube traps while he listened to a couple of reference recordings. After about six traps had been removed he found the sense of dynamics and aliveness he'd been missing. So he sold the excess traps.
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Based on my extensive experience with speaker placement in various sized rooms over the years, I've found that speakers, in almost every case, sounded better farther out into the room. Just go to any High End Audio Show, and in 99.9% of the exhibitors rooms, you'll find that these experts always place their speakers out into the room several to many feet from the front wall. Placing the speakers out into the room helps to create greater depth of field within the soundstage, which creates spaciousness, and that lovely layering and airy effect that we all search for in our own rooms.
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A long time ago I noticed a big improvement moving my speakers so the backs of them (which has ports for the bass) are 3 feet from the wall behind them. It was surprising because I didn't move them out all that much. Maybe 6 inches. I have a credenza between them that is about 2-1/2 feet high which probably increased the improvement a lot since the speakers are now an inch or two in front of the credenza.
FYI- the sound also improved a lot when putting my speakers (KEF R500s) on top of multilayered Symposium acoustics stealth platforms. Supposedly it cleans up the vibrations inside the cabinet while also isolating it from vibrations from my suspended floor. All I know is it sounds clearer and more focused.
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@mijostyn: Just for the record, I much prefer an "over"-damped room to an "under"-damped one. My current one is on the over-damped side, and I have found diffusion to keep all the output of my dipoles audible, whereas I believe damping (please, not dampening 😉) would absorb the high frequencies too much. But then I use dipole planars, which produce very little output to their sides, and therefore very little sidewall reflections. The loudspeaker/room is an integrated system, you can't separate the two.
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That is the wrong way to look at it lanx. Sounds that reach your ear after 10 ms are perceived as an echo. Less than 10 ms and they are perceived as one with the direct sound.
I'm not sure where you received that information from. The reference to a 5 ms time interval was made by Haas (1951), who stated that a single reflection arriving within 5 to 35 ms can be up to 10 dB louder than the direct sound without being perceived as a secondary auditory event (echo). The shortest possible interval is 5 ms. You can find this information in the following reference. Should you need more details, let me know.
Haas, Helmut, The influence of a single echo on the audibility of speech, J. Audio Eng. Soc., Vol. 20, Issue 2, pp. 146-159, March 1972 (English translation by Dr. Ingr. K.P.R. Ehrenberg of Haas’ original German paper published in Acustica 1, pp. 49-58, 1951).
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@paulrandall
I stated, I thought clearing, that the reference is the face of the driver, not anywhere else.
@invalid
It makes not difference whether or not you are direct driving ribbon speakers although you have to be careful. The tweeters have VERY low impedance, < 1 ohm and can burn up some amps. All planer dipoles benefit from subwoofers. It is not a mater of speed. Speed has nothing to do with it. Lack of spurious resonance's, time and phase coherence along with the right crossover point have a lot to do with it.
@lanx0003
That is the wrong way to look at it lanx. Sounds that reach your ear after 10 ms are perceived as an echo. Less than 10 ms and they are perceived as one with the direct sound. That does not mean these sounds are not distorting what you are hearing, they are in a big way. They are sound that was not present on the recording and as such are distortion. They change frequency response (amplitude) and screw up phase affecting the image.
@bdp24
If is extremely hard to over dampen a room. Most system/rooms that I have auditioned are under dampened. What people think is dull and lifeless is generally much more accurate, they are just use to sizzling hot with echoes and have a hard time reorienting themselves. Turn the volume up, way up to 95 dB. If the sound wants to cut your throat you are underdamped.
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Read the question? That’s no fun. Kinda like reading the directions first.
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@dsper Wrote:
Five feet from the front wall
Just what does "X" feet from the front wall mean? Is this from the front of the speaker or the back of the speaker?
The front baffle of the speaker. 😎
Mike
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OMG, does no one on here actually read the OP’s question? I have long wondered the same thing; When a reviewer says they placed the speakers 2 feet from the wall, are they talking front or back of the speakers? Almost no one on here seems to actually know the answer to this question.
These threads start out about the OP but then the OP becomes non-relevant IMO.
Reviewers typically reference the back or side wall of the speaker when communicating distance....speaker designers normally mean the acoustic center of the driver for a measurement.
One challenge with going out 5 feet is that you are pushing down the frequency at which SBIR occurs in a box speaker. A SBIR dip at 50hz would take massive bass "traps" to bring up the dip...or multiple subs calibrated with DSP timings.
If the speaker is 2 feet from the front wall, the SBIR dip may be around 100hz, which can be treated with bass traps behind the speakers...a 5 inch thick trap from GIK with a 5 inch air gap will give you almost 10 inches of depth, which should do well from around 90hz and up.
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For the best playback clarity, it’s advisable to position your speakers at least 3 feet away from the nearest wall, measured from the tweeters. This spacing minimizes sound reflections, which can otherwise be perceived as part of the direct sound and adversely impact listening experience. Human hearing tends to distinguish reflected sounds less than 5 milliseconds apart as part of the direct sound. With the speed of sound measured at approximately 1100 feet per second at sea level, the minimum spacing required for reflected sound to be longer than 5 milliseconds is calculated as (1100 x 0.005) / 2, resulting in 2.8 feet, which is rounded up to 3 feet.
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OMG, does no one on here actually read the OP's question? I have long wondered the same thing; When a reviewer says they placed the speakers 2 feet from the wall, are they talking front or back of the speakers? Almost no one on here seems to actually know the answer to this question.
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@mijostyn
Good information. My data came from a "good source" 30+ years ago, Lots of charts and graphs and beautiful illustrations. I was unmarried at the time and didn't have to "sell" someone on the concept of putting hand-built, 6'-4" tall, Alpine white (line source) speakers in the Living Room. Now my wife just accepts them as part of me being me.
Thanks for the technlogy refresh. Good to know I'm still trainable.
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Hmmm… maybe that’s why it sounds good now😵💫
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@marco1: Reminds me of my stoner days, laying on the floor with the left and right speakers on either side of my head, like giant earphones.
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My speakers are 5ft off the ceiling looking at them while sitting on the floor with my back to the front wall. They sound fine that way.
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@waytoomuchstuff
No. With a point source the volume drops at the cube of the distance. With a line source it drops at the square of the distance. Volume drop off is an order of magnitude less. As for height that depends on the frequency. For a driver to act as a line source it has to be taller than the longest wavelength it is to reproduce with one very cool exception. Low C has a wavelength of 56 feet. A little hard to get a 56 foot tall speaker into most houses. BUT, if the ends of the line source butte up against barriers like the floor and the ceiling, the line source becomes infinitely long as if the floor and ceiling were mirrors. This is the rational behind 8 and 9 foot tall speakers. In the case of ESLs it turns a modest gentleman into Axel Rose. Add a line source subwoofer array and bring on the concert! Line Source systems have a very different presentation. Everything is larger, front row vs rear of the hall. The image is more stable and the overall sound more comfortable as in less prone to sibilance and distortion at high volumes. Many people prefer Point source systems but usually not because of the sound, more likely the size of the speakers. I had a new friend over who is a Bricasti dealer. He listens to Franco Serblin speakers, very fine Italian point source speaker. His first comment was, "I'm not use to this! There is so much bass!" The system runs flat down to 100 hz then rises at 3 dB/oct down to 20 Hz. The treble falls off from 2000 Hz at 1 dB/oct. This is very standard target curve for most rooms. Dirac live usually starts with this curve. Most systems do not project much under 60 Hz. The frequency response specs are taken at one meter.
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On the "front wall" being in front of the listener vs behind the speakers:
People (listeners) are aware of their position in time and space and can contemplate their position relative to objects in their environment. Speakers are not aware of anything, so they should be disqualified from having an opinion about what's in front, back, to the side, below, on top, or inside of them. They just do what they are told to do via electrical impulses controlled by the listener. So, I vote for the listener, and defining walls relative to the listener.
@mijostyn
"Because loss of volume with distance is much less severe with line sources"
My understanding this subject is something like this: sound attenuates 6db as distance doubles. With a line source (array) the height of the array pushes the phenomenon back relative to the height of the array. So, if the array is 8', the attenuation process is pushed out 8' before it begins the process of attenuation. Correct?
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Well with my Clarisys Minutes (Planars, Ribbons), I have found 5 feet from the front wall with some diffusors behind them to be ideal. No absorbers nearby. I do however have acoustical tile over the drywall ceiling and carpeting on the floor.
The distance between them also matters. Too far apart and you lose the center image and some treble. In my 17W X 25L x 8H foot room I have found about 8.5 feet from the center panels to be about right.
ozzy
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I should add,
Listening distance- distance from centerline of the tweeter to the listener’s ear.
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Stop for a moment thinking about yourself. Think of the speakers. Then you understand it’s the back wall.
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Some standardized definitions can avoid confusion and errors. I use these::
Front wall- wall in front of the seated listener.
Back wall- wall behind the seated listener
Speaker distance apart- distance between centerlines of the tweeters (this works even for speakers like Magnepan)
Use the center point of the tweeter at the baffle surface to define measurements from the front wall and side walls. Speakers come in different shapes and sizes and the drivers are not always in the same vertical plane, ie many speakers place the tweeters a bit farther from the listener. So use the tweeter position as the reference point. It does not make much sense however, to compare positions of different speaker models since their cabinets and designs such as ported, sealed, driver size, etc determine the best placement. But these measurements are useful for someone trying to decide on the best type of speaker for their particular room.
Toe-in can be defined as an angle but that requires some geometric type calculations. I have defined it for myself as rise over run or distance change from one front corner of the speaker to the other front corner. But I found the most accurate way to set toe in is to use a laser.
I use a laser measuring device to dial in the speaker toe in. Place the measuring tool on top of the speaker and square it and center it to the front baffle. I do this by using a block of wood. Align the block of wood to the side of the speaker and then place the laser measuring tool against the block of wood. ( I made the width of this block of wood to place the laser tool at the speaker tweeter centerline). I extend a tape measure across my listening position and then activate the laser. The laser spot shines on the back of my listening position and I can now position the toe-in precisely using the scale of the tape measure. Repeat for the other speaker.
Does this sound over the top? C’mon, most of us here embrace this level of intensity. How could I listen without anxiety otherwise?
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...toe & tilt is meaningless with omnis, BTB...
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"Front wall" =s' "Stage wall".....staging wall?
We are 'staging' speakers, after all....
...even if they end up an afront...to take an affront of.... ;)
...had to go there....😏
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also check toe and tilt....very important with my speakers
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@invalid: I believe you meant to direct your last post to @mijostyn, not me.
I somehow never managed to hear any Apogees, perhaps because there weren't many dealers on the West Coast. My dipole planar exposure is limited to Quad, Infinity, Dayton Wright, Magnepan, RTR, Beveridge, Acoustat, Martin Logan, SoundLabs, and Eminent Technology.
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@bdp24 I take it you were not direct driving the Divas, it's a whole different animal if you are using an active crossover and directly driving the speaker. I don't like using subwoofers with the apogees, I've never heard a subwoofer that has the speed of the apogees.
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@ditusa
Yes, a good horn can have almost the same frequency response way off axis then they will fall off dramatically which is an advantage as it limits room interaction. But, that is not the problem. Horns are point source drivers and like any point source driver the volume level drops off rapidly with distance. The center image shifts like any other point source driver and you can still lose the far speaker far off axis.
With a line source array I can stand 3 feet away and right in front of one speaker and still hear the other.
@invalid ,
I had Apogee Divas for 6 years. It does not matter how far off the wall you are. If it is a hard wall behind the speakers sound deadening will always improve image specificity. The farther away from the wall you are the more of the wall you have to cover. Closer to the wall, like 3 feet and you only have to do right behind the speaker. This only control frequencies over 250 Hz. At three feet you will attenuate 185 Hz which will take some of the snap away from the sound. If you move it farther away you will attenuate lower frequencies. At 8 feet you are looking a 16 foot wavelength 180 degrees out of phase and that would attenuate 70 Hz. Unless you are using subwoofers (which I highly suggest with those speakers) you are missing a lot of bass. It is a compromise any way you look at it unless you want to move them to the front lawn.
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@bdp24 I have apogee duetta 2 speakers and my room is on the live side, but my speakers are just over 82" from the wall and sound great without any damping. I think it depends if you have them far enough from the wall behind the speaker you may not need absorption .
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Regarding the wall behind dipole planars: One of the hardcore Maggie owners on the Planar Speaker Asylum completely damps the wall behind his very-modified Tympani T-IVa’s (he also braces the panels to the walls), other owners prefer diffusers.
Both absorption and diffusion can work; when choosing between the two, one consideration is the acoustic properties of your entire room. If you have a very lively room, absorption is probably the way to go; if it’s on the dead side, perhaps diffusion. Too much absorption in a dead room can lead to lifeless sound.
My room is definitely on the dead/warm side, so I went with diffusion. I have stacked Vicoustic Multifuser DC3’s behind my planars, and have found them to work great. Diffusers don’t absorb high frequencies, they scatter them randomly, keeping the inherent sound of the room intact. The scattered reflections don’t head straight back to the planar (or listener), so it’s back wave doesn’t compromise the sound coming from it’s front side. But that back wave does enhance spaciousness and depth, not a bad thing imo.
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5’ from the front wall in a 10’ deep room.....?
Just a random concept to be or not to.... ;)
A Hall effect....
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To call the wall behind the loudspeakers the rear wall makes no sense. Sure, that wall is behind the speakers, but so what? The wall the listener is facing is the front wall, the one behind the listened the rear wall. Period.
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Why don't we just say the wall behind the speaker?
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@markalarsen
That would be a mistake. When seated at your listening position the front wall is in front of you and the rear or back wall is the one in back of you.
@ditusa
There is much more to imaging than lateral position, there is image size, location in depth in the sound field and the third dimension which is the sense that the instrument is a 3 dimensional object in space. Early reflections will disturb all of them even if lateral location is not affected. As far as stability of the image is concerned, especially with point source speakers, The image is extremally fragile when out of the listening position even by a few inches. 30 degrees or more off axis you can even lose the far speaker completely. Because lose of volume with distance is much less severe with line sources they create a more stable image and you never lose the far speaker of axis. The image is still perfect only at the listening position. This is why Line Arrays are used exclusively at large concerts. We were at the Arctic Monkeys concert at Red Rocks last night and even the subwoofers were linear arrays just outside of the main Linear Arrays.
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@tweak1 Wrote:
Many are confused by FRONT wall; it's the wall BEHIND the speakers.
I agree!
Precedence effect:
Below is a quote from my speakers tech manual:
''2. Stereo imaging will be improved The frequency response of the new monitor design is quite uniform, even at angles sufficiently off axis both horizontally and vertically to be unlikely listener positions. However, this results in more uniform room reflections which contributes to a stable virtual source that does not change with frequency [Queen [13]). In addition, increased toe-in can be used with no degradation of the direct sound field, rf enough toe-in is used for the axes of the systems to cross somewhat in front of the listener, then the level precedence effect can partially offset the time precedence effect (Haas [14]). This contributes to a more stable stereo image as the listener's position varies along the length of the control board.''
Mike
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I agree with you but often see reference to the wall behind the speakers as the back wall.
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Many are confused by FRONT wall; it's the wall BEHIND the speakers. In my room which is 35ft long there is no BACK wall reinforcement, which throws a monkey wrench into positioning. My speakers are dipole at ~ 4.5ft from the front wall. Moving them back from 5ft helped fill in the upper midrange/lower treble
hth
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@mijostyn
I agree ! Better to be over absorbed than under.
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When you see a measurement like "X feet from the front wall" in the context of speaker placement, it typically means the distance from the front of the speaker cabinet to the front wall of the room. In other words, it's the space between the front of the speaker and the wall that's directly in front of it.
This measurement is important because it can have a significant impact on the sound quality and imaging of your speakers. The distance between the front wall and the speaker can affect the interaction of the sound waves coming from the speakers with the room's acoustics. The ideal distance can vary depending on the specific speaker model, the room size, and your personal preferences for sound.
To set up your speakers effectively, you may need to experiment with speaker placement, including the distance from the front wall, to find the position that delivers the best sound quality and imaging for your listening environment. Adjusting this distance can help you achieve optimal bass response, minimize potential reflections, and enhance the overall listening experience.
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I found that my apogee duetta 2 sound best 82" from the wall, there is no bass problem as long as you have proper amplification.
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@pryso
I have been using dipoles exclusively since 1979, I currently use 8 foot Sound Labs ESL and they are between 2 and 2.5 feet(towed in) from the front wall. The wall behind a dipole should always be heavily deadened. I use 4" thick acoustic foam tile, but that is all you have to do with them other than use subwoofers below 100 Hz. Dipoles have a lot of trouble with the longer wavelengths.
I hate to disagree with Bell Labs, but that is a purely subjective evaluation. Any sound within 100 ms of the direct sound is sound that was not in the recording and by definition is distortion. After 100 ms it is an echo or a different sound altogether. Dipoles are 180 degrees different than other types of loudspeakers because the sound that comes off the back is 180 degrees out of phase with the front wave which means that at three feet from the wall 185 Hz is attenuated. At 5 feet 100 Hz is attenuated which is not good for bass. It is a lot more complicated than this as again other frequencies are reinforced. I keep my speakers closer to the wall because higher frequencies are easier to manage with acoustic absorption. Below 200 Hz there is not much you can do other than digital room control.
The issue that causes such varied opinions is that some distortions sound good to some people. They can add warmth and ambience to a recording. Being the stubborn purist that I am I only want to hear what is on the recording. It seems to me that like @rauliruegas I find that systems that are devoid of most distortions sound better.
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Based on my reading I agree with bdp24 regarding the 5' minimal placement, at least for dipoles.
Bell Labs research determined the 10 ms minimal delay between direct and reflected sound for best clarity. That applies to side wall reflections as well (less so with dipoles due to directivity), which is why there are so many recommendations for identifying the primary side wall reflection points and applying diffusion or absorption panels there.
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@bdp24
Thanks, my question was the simple one of do I need to explain what x feet from the front wall means.
Regarding speaker placement, I always try to get the best bass relative to where room logistics force the listening chair to be.
I agree that measurements are at best a generalization as I have never had a "perfect" room. There's always walls of different dimensions or an opening on one wall that isn't mirrored on the other side of the room.
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The distance from the front wall is going to effect the mid and upper bass/lower midrange. If the face of the woofer is three feet from the front wall, the distance to the wall and back is 6 feet, that is the wavelength of about 185 Hz. Thus 185 Hz and the frequencies around it are going to be reinforced. As you move the speaker closer to the front wall the reinforced frequency increases, as you move away the reinforced frequency decreases. At five feet it is about 100 Hz. Other frequencies are attenuated. None of this is good. Sound absorption on the front and side walls is very important but it is only effective above 200 Hz at best. If you could set up the speakers 10 feet from the front wall you could reinforce 55 Hx. 28 feet would reinforce 20 Hz. All this is impossible in residential situations.
All the above is the reason that digital room control is so important particularly in the bass.
Any other changes in sounds quality with speaker positioning depend on the timing of reflections which depends entirely on the room. These reflections effect fine detail and imaging. If reflected sound can travel 100 feet before reaching your ear you hear an echo. Thus the more sound absorption you use anywhere in a room the more you are going to decrease the likelihood you will hear an echo, which IMHO is a good thing as the echo was not in the recording. Some people actually like echoes as they add a false sense of spaciousness. All the echoes of the venue where the recording occurred are on the record. Studio recordings frequently have echo added to them to create dimension. Live recordings generally do not need it.
Sorry for preaching.
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@dsper
When I measure, it’s from the front of the speakers to the front wall and when I do toe in, it’s in relation to the front wall as well. So I have two systems. The first has the front of the speakers four feet from the wall and no toe in and the other has the speakers 42” from the front walls and about 10° toe in.
All the best.
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At least for my Apogee ribbon dipoles the sweet spot seems to be 4’ off the back wall, but always experiment with your speakers in the listening space. There are too many unique factors in any listening space.
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desper,
for box speakers. For bipolars I have no idea as the back wave is out of phase. I will have to think about the math on it.
Macg19,
good to hear it worked out. those distances are based on wave lengths and the speed of sound. What ever the distance is from the wall times 4 it will cancel at that frequency. So 5’ is 1/4th of 20’ and that works out to 57hz (57hz has a 20’ wave peak to peak) right at where kick drums get their weight. Keep in mind it is the center point of the bass so if you have rear ports that center point is the sum of the port and driver… at least at the port tuning point.
I use active crossovers so my speakers are highpassed so it it a bit more complicated as both sub and speaker distances matters. Those pictures of my system the speaker is 43” from the speaker face and 24” for the subs when using an 80hz crossover. I am using a 60hz now and have them out 4.8’ to accommodate that (I should update picture I guess).
the room clutter might hurt a bit. The screen between my speakers is “acoustically transparent” screen from Screen Innovations. It is said to drop 6db starting at 2khz though audioholics measured it at closer to 10db. Regardless I have A/Bed it up and down and it is really hard to tell a difference. The JBLs are very directional at 2k so it might be moot. My real issue is the low ceiling which causes problems at 40hz. I turned my whole ceiling into a bass trap (cost $3k and about a month of work), I also have 9 bass traps in the room. It helped but still not great without room correction which I try to avoid these days. I am +/- 6db now… sounds ok.
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@james633
You will want to be no more than 39” or more than 7’ for smooth bass due to 1/4th wave rear wall cancelation.
I found this to be true for my Harbeth 40.3XDs, although I read somewhere 24" from the rear of the speaker so 39" from the front is a coincidence. The furthest I could get the front baffles from the rear wall was about 5ft - bass response was poor. 39" tightened up the bass nicely. I don't have side walls to content with.
You have a lot going on behind your speakers - which may be detrimental.
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