on wall or corner loudspeakers

I was building a music enjoyment room and it works well. The dimensions are around 4.5x6.1x3.2m and the room is constructed out of concrete, so quite quiet (even with an outdoor music venue close by) but to get control of reverb the largest surfaces are designed for sound absorption: the floor has a damped layer and the entire ceiling has microperforated sound panels with a layer of cotton insulation above it. Also most of the back wall is a bookshelf to act as a sound diffusor. So I am quite content with the acoustics of this room.

One restriction is the placement of my loudspeaker as there is a room opening to the hallway around 1m from the right corner so the distance of the speakers to the front wall is reduced in contrast to my previous listening rooms. Almost all speakers are designed to have enough distance from the wall in order to reduce the back wave and other early reflections to interfere with the primary sound or at least get enough time difference between the acoustic events.

On wall mounted speakers have no back radiation and that fact is used for a lot of monitoring or mastering rooms but not much for domestic listening. Obviously wall hang speakers require different parameters which may be too restrictive for commercial manufactures (with a few exceptions) but for DIY it should be more an opportunity than a restriction. I am thinking of a wedge shaped loudspeaker (25-30º) either close or direct at the corners. My present speaker design is vented but as on wall close to the corner room gain should be much more significant at 1/2 to 1/4 space so a closed box design may be better.

Playing with REW (which is restricted to .3m as a minimal distance to the the front wall) a distance of around .6m to side walls should work. One issue I try to find out are early reflections from the side walls (obviously no issue with front wall) with would reach the listening position between 1m and 1.8m from the corner so no issue at the hallway side (opening there) but on the left side. Would that be a significant issue? I was thinking one could design some sound baffles at the side of the loudspeakers even have a small gap between loud speakers and the side walls with some sound absorber stuffed behind. Maybe only beneficial for secondary reflected low frequencies but not too much early reflections. So I'm thinking of wedge shaped speakers direct in the corners (the easier design but no way to adjust the distance to side walls later) or just similar but smaller wedges close to the corners with or without some corner sound treatment.
 
Would that be a significant issue? I was thinking one could design some sound baffles at the side of the loudspeakers even have a small gap between loud speakers and the side walls with some sound absorber stuffed behind. Maybe only beneficial for secondary reflected low frequencies but not too much early reflections. So I'm thinking of wedge shaped speakers direct in the corners (the easier design but no way to adjust the distance to side walls later) or just similar but smaller wedges close to the corners with or without some corner sound treatment.

Hi,

little story, been in similar situation having issues with sound but not quite sure what they are and why, and what to do about it. All kinds of advice online but it's hard to relate to; how do I know if something is significant or not, am I hearing problem with speakers or with the room, how do I reliably hear change with positioning, what actually is envelopment and how does my room sound actually? The problem is with listening skill.

Try this:
find size of stereo triangle where you get a "studio near field" sound. This is likely quite small, could be 1m - 3m, start with stereo triangle whose size is about 2m. Put on some mono white / pink noise, same mono signal to both channels to make as strong stereo phantom center as possible. Now, walk on the center line between speakers always staying equidistant from both speakers, but so that distance from you to both speakers change as you move closer or further to speakers. Start from far away, moving closer to speakers and concentrate on listening the size / sharpness of the phantom center. Eyes closed if it helps. If you don't hear it, try adjusting toe-in, size of the triangle and try again. On my setup, there is quite distinct transition from big hazy blob of phantom center to quite pin point and small and quite sharp sounding phantom center, and it happens literally with one step. On / off kind of effect, not much sliding with it, when I'm close enough something just snaps in the brain and the image is now localized sharply.*

Ok, now that you have the perception of the transition and know where it happens, you now know there is two perspectives on stereo image you can change at will: Hearing the transition you are then sure when you are listening "studio near field" or "far field" sound. That is when you are closer than the transition the local room effect to perception is somehow suppressed, while "far field" sound is when you are beyond the transition where local room (early reflections) seems to have quite strong effect to the sound you hear. Knowing where the transition is allows you to root your perception in a way that you are now sure what you are listening to, and be able to change perspective at will. Basically, you'd use the the transition as a tool to hear how the room affects the stereo perception, now you are able to hear how early reflections sound like and how speaker positioning changes them and the sound!

Here is how I use it:
I'll sit about at the transition, so I can just lean forward to suppress local room sound, and lean back to get the washed sound. The washed sound changes much less with speaker positioning than the close sound because it's more of an average of all sound in the room. However, it's possible to hear quite small changes with the close sound, concentrate listening how envelopment and direct sound is affected when you adjust toe-in, find a balance between the two. You might find out the speaker directivity does not allow to get good envelopment and direct sound at the same time and you need to do something about it. Listen if the stereo image width natural or too wide or too narrow, does hole appear in the middle, is there some frequency band that seems to localize weirdly inside the head or in height or what ever, to tune the positioning and toe-in. These kinds of things are quite readily audible when just leaning forward or back, and comparing the two and reasoning about the sound.

Why it's important? People discuss quite a lot about stereo image, but without talking about differences between far or close listening or which context they are while talking about details, which makes the whole thing very confusing in a way. In general I found it very hard to relate words to sound I perceive in my place with my setup, and the other way around, before I knew how to relate text to perception! For example, left/right asymmetry you are worrying about is likely much more important with the "far sound" which is heavily affected by early reflections, and asymmetry would make the whole "image" bit weird sounding. On the other hand on the close sound the asymmetry affects envelopment but not so much the direct sound, the sound and space baked to the recording. Now that you know the transition and can utilize it as tool to listen how the asymmetry affects sound, you now know when you should hear envelopment and can now quite reliably listen to effects of additional gobos you plan to try. On "near field" the direct sound is not heavily affected by the asymmetry but the envelopment is, while on the "far field" the whole image depend on the symmetry.

You might find out you like the "near field" or the "far field" sound better, or both depending on recording, and can then adjust everything based on that and utilize the other perspective to evaluate. Your speakers and the room might effect which one you like, also your own preference. What ever it is you know them both now, and how to change between them, and after some listening with the transition you learn what you hear and what to listen to, hopefully :)

Have fun!

ps. I'd be very delighted if you try it and report if you found it useful advice, or not, thanks! or perhaps you already knew all about it?:)

*) I'm not sure what it is, but David Griesinger studies are closest I've been able to relate to. Being "near field" means brain is able to lock in to the direct sound, is able to separate direct sound and room sound to their own neural streams and you can listen them both separately. These would be direct sound and envelopment. If you are further away, the separation does not happen in such way, but what you perceive is one neural stream, sound heavily influenced by local room, a blob of sound.
 
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You may want to get some inspiration and/or design ideas from this on-wall speaker:
index.php


@bbutterfield explained the ideas behind it here: https://www.diyaudio.com/community/...raight-cbt-with-passive-xos-and-no-eq.330031/
 
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Speaker doesn't have to be flat or wedge or anything particular to work with wall or a corner, various bandwidths could have different strategy to mate with the wall and so on :) But yeah, perhaps some wedge would work, perhaps multiple solutions could work.

I failed to write on my previous post, that what ever speakers you end up with, it is impossible to know whether speakers work best at the corners or further away and with what toe-in, before listening and arriving to a good sounding positioning, and possibly an idea what the directivity should be if current one has something that doesn't seem to work. If you just make a wall speaker and stick them on the wall or on a corner, but don't factor in how directivity and toe-in and room acoustics affect stereo sound in your room, it is just by luck if it comes out alright or not. Basically, your sound changes, but doesn't necessarily get any better or worse, it would be different but you wouldn't know if it got worse or better if you don't know how to listen about it.

Point is, it doesn't matter where the speakers are in a way, or what the speakers are, as long as the sound is good, right? the speakers and positioning must be determined by listening what sounds good assuming you are looking for good sound first and foremost. If you want to be sure to get better sound you must listen how speakers work with the room, and where they should be located at and what their directivity should be in order to sound just the way you want it to, or think works best for what ever it is you are seeking from the sound. You'd be sure the setups sounds as good as you are able to listen and reason with it. It is very likely going to sound better than what you have now. Not just different, but better to you because you know what it should sound like and what it actually sounds like. You could use material online, make measurements, inspiration from speakers others have built, taking advice, anything, it is all very helpful information to aid listening, but you must know what you are hearing and how it relates to the material you are looking at with your eyes.

Building optimal speaker for some situation requires you knowing what the situation is and what is optimal for it, which means listening skill. You could build and rotate 10 speakers with ten years never thinking about listening skill and learn gradually but the best one is always as good as you can evaluate by listening. Thus, writing a listening guide hopefully helping cut down the 10 years to less. Of course one could utilize some person/company do it for you, but still it would help if you knew what you wanna. Hope it helps :)

ps. why not flip the room around, put speakers where the bookshelves are and vice versa?
 
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Thanks for the replies. My present speakers were originally optimized in a larger room with a lot of space behind them. They are a 2 way design with a bending wave driver developed by me (originally I used Manger MSW but found that one can make better bending wave drivers but that Is different story) and 11 inch woofers. The bending wave drivers have a a very wide frequency range and I use a crossover point around 250Hz. These drivers have very wide dispersion so there sound good at in the entire room except close to the side walls. The reason I have the speakers on the wall next to the entrance to the hallway is that I have my desk in front of the bookshelf and that would impede a lot the traffic into the room.
The toe in of these speakers is not supercritical as they have such wide dispersion over their frequency range. So I could vary the angle to some degree to modify early reflections. At least something to explore but main issue with on wall corner speakers is difficult to change the final built.

P.S.: Manger makes an on wall version: https://mangeraudio.com/en/systems/product/w1-en but with my previous experience with their driver is that the lowest octave is better not used
 
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Hi Monteverdi,
yeah alright, interpreting your posts I think it would be fine option to put speakers on the corners, go for it!
You don't have to toe them in if you feel that even the high frequency coverage is wide enough. If you have found out some particular listening angle works best, then you might want to consider having that pointing at your listening position. There is term listening window, which is usually +/-30deg from main listening axis, consider the angling the speakers so that most of your time in the room is spent within the listening window. If you don't find these important then I'd just put the corner wedge so that on-axis was 45 deg from either wall just to have it nice and symmetric.

I guess you have prepared to build new boxes, and not sure if you are going to use the same drivers, but prepare yourself to make some adjustment at least to low frequency response, corner placement will boost lows quite dramatically.

You could just tuck your current speakers to the corners and test how it plays out and what to expect. I would listen if the frequency balance is still nice, or does it need adjustment. Also listen if lyrics are still intelligible, corners are quite far apart and there might be a "hole" in the middle, less intelligible sound. But, you'll find it out fast just by trying corner placement.

Have fun!:)
 
Now that sounds interesting!!
Would you share some details?
I am planning to have another thread about that design but as I have spent most of my time the last years renovating my "new" house I have interrupted my other hobbies. I am presently trying to improve the magnet structure and make a new suite of measurements but eventually I would like to share that
 
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