Diffusers for your room
DJN, it is a little unclear to me where you want to place the diffusers. Do you want to cover your door with them, is that why you want to make a door out of them?
I will make some comments based on your room and speakers. I see that you use horns for your midrange and something like Heils for treble. Keep in mind that these diffusers start to work around 500 hz (they work a little bit at a lower frequency, but not at a high level until around 1000 hz). Thus, with horn speakers, which are directional, the best place for diffusers is on the back wall to keep the sound bouncing off the back wall to be reflected directly back at you. The sidewalls and ceiling are secondary since the speakers likely keep the midrange and lower treble away from the walls and ceiling. It is a little ironic, but the next best place for diffusers, after the back wall, would be the floor, since that is the other place where your speakers would interact with the boundaries of your room more directly. It would be challenging to have diffusers on the floor though.
Treble might be a different matter depending on their dispersion as the side walls and ceiling would likely figure more into it.
The front wall behind the speakers are impacted by omnidirectional speakers, which you don't have. That said, even if a wall does not receive direct sound, these boundaries may still benefit from diffusion.
You have a bookshelf on your back wall which already would act as an ad hoc diffuser. You may want to change how you arrange items in the bookshelf to make it function for effectively as a diffuser.
Depending on your room construction and room dimensions, bass traps may be the most important feature to add to your room since bass nodes are usually the highest priority issue to focus on.
These are just my thoughts based on what I have read, and I am not in any way, shape or form an expert on acoustics.
Retsel
DJN, it is a little unclear to me where you want to place the diffusers. Do you want to cover your door with them, is that why you want to make a door out of them?
I will make some comments based on your room and speakers. I see that you use horns for your midrange and something like Heils for treble. Keep in mind that these diffusers start to work around 500 hz (they work a little bit at a lower frequency, but not at a high level until around 1000 hz). Thus, with horn speakers, which are directional, the best place for diffusers is on the back wall to keep the sound bouncing off the back wall to be reflected directly back at you. The sidewalls and ceiling are secondary since the speakers likely keep the midrange and lower treble away from the walls and ceiling. It is a little ironic, but the next best place for diffusers, after the back wall, would be the floor, since that is the other place where your speakers would interact with the boundaries of your room more directly. It would be challenging to have diffusers on the floor though.
Treble might be a different matter depending on their dispersion as the side walls and ceiling would likely figure more into it.
The front wall behind the speakers are impacted by omnidirectional speakers, which you don't have. That said, even if a wall does not receive direct sound, these boundaries may still benefit from diffusion.
You have a bookshelf on your back wall which already would act as an ad hoc diffuser. You may want to change how you arrange items in the bookshelf to make it function for effectively as a diffuser.
Depending on your room construction and room dimensions, bass traps may be the most important feature to add to your room since bass nodes are usually the highest priority issue to focus on.
These are just my thoughts based on what I have read, and I am not in any way, shape or form an expert on acoustics.
Retsel
Covering the IKEA with diffusors will work but you might must do something against rattling effects.
Same holds true for the middle that you've mentioned. Basically if using two diffusors as in your case would mean to repeat the sequence which is a bit less than optimal.
It would be better to use the old RPG idea with a an asymmetrical sequence used for the construction and to mount the second diffusor after turning it around counterclockwise for 180 degrees .
As Retsel already pointed out, due to the assumed high directivity of your speakers a diffusor in front of the audio rack will be of minor importance although the LEDE idea (that you might have in mind) would ask for damping material in front of the rack.
Thanks Retsel. My plan is to build two of the diffusers and use them as doors for the shelving unit in the back of the room. They will be the two diffusers will be as wide as the shelving unit and hinged on the shelving unit so if I want an LP I would open the diffuser doors to get at them.
I'm building super chunk bass traps for the front two corners now and just finished absorbers for the first reflection points on the walls and ceiling.
The bass traps surrounding the shelves are from my old house and I will redo them to fill the entire space around the shelves.
I'm building super chunk bass traps for the front two corners now and just finished absorbers for the first reflection points on the walls and ceiling.
The bass traps surrounding the shelves are from my old house and I will redo them to fill the entire space around the shelves.
good point --- I will put foam around the inside of the diffuser door to stop the rattling.
If I cut the meeting point of the two door down by half it will just make the normal low segment where they come together..... will that work?
I wouldn't put the second diffusor oriented 90 degrees, as that one would only diffuse sounds toward ceiling and floor where they will be more likely to get absorbed than keep the room lively. But the second diffusor should do better if mounted so it is offset by one or two riser heights (a few inches or so) to break up the repeating sequence as seen from the chair.
(disclaimer: I'm also no acoustics expert, just have done reading and some diffusor modelling, building and placement)
(disclaimer: I'm also no acoustics expert, just have done reading and some diffusor modelling, building and placement)
Hi Scott, see my post #159 above
I have 'played around' with styrene panels a bit with excellent results - I haven't tried foamboard (available here in Oz in 3, 5, 10 & 20mm thickness) as too expensive - currently I'm playing with 'foam-concrete' (added foam beads) that's used as window lintels, etc - quite 'messy' but showing some promise.
"djn" - that Ikea wall cupboard looks to be a bit over 5ft tall/wide, maybe 65" - the OP design is a bit over 34" wide so you could fit 2 of the units across the front of the cupboard rather neatly with the join in the centre.
Unfortunately, the timber construction is rather heavy and doubt that the Ikea structure would be strong enough to hold it, even with wheels on the bottom.
If you were to make it out of "foam-core" as Scott suggested, it'd certainly be a lot lighter and a rather neat finish - not sure of the cost as 'foam-core' over here in Oz is quite expensive and comes in 3, 5, 10 & 20mm thickness.
If you wouldn't mind some 'diy', you could apply a veneer surface to a styrene foam build that you could cut yourself with a 'hot-wire' knife, etc and ….
I have 'played around' with styrene panels a bit with excellent results - I haven't tried foamboard (available here in Oz in 3, 5, 10 & 20mm thickness) as too expensive - currently I'm playing with 'foam-concrete' (added foam beads) that's used as window lintels, etc - quite 'messy' but showing some promise.
"djn" - that Ikea wall cupboard looks to be a bit over 5ft tall/wide, maybe 65" - the OP design is a bit over 34" wide so you could fit 2 of the units across the front of the cupboard rather neatly with the join in the centre.
Unfortunately, the timber construction is rather heavy and doubt that the Ikea structure would be strong enough to hold it, even with wheels on the bottom.
If you were to make it out of "foam-core" as Scott suggested, it'd certainly be a lot lighter and a rather neat finish - not sure of the cost as 'foam-core' over here in Oz is quite expensive and comes in 3, 5, 10 & 20mm thickness.
If you wouldn't mind some 'diy', you could apply a veneer surface to a styrene foam build that you could cut yourself with a 'hot-wire' knife, etc and ….
No problem! Maybe support all the weight on a couple sets of wheels …
As you'll find, the listening chair needs to be a couple feet in front of the diffusers nd also, something to keep in mind that your bass drivers may still benefit from some side wall absorbent panels too
Plus, maybe play around with some diffusers behind those Heil drivers as it's a bit of a waste to lose that rear radiating extra treble energy that increases the 'sense of space' in your room.
Looks like you'll need some of those absorbers (front wall and ceiling corners) to maintain the bass note clarity - might try adding some reflective foils/light ply/etc to reduce some of the mids (as per the "8th Nerve" articles)
As you'll find, the listening chair needs to be a couple feet in front of the diffusers nd also, something to keep in mind that your bass drivers may still benefit from some side wall absorbent panels too
Plus, maybe play around with some diffusers behind those Heil drivers as it's a bit of a waste to lose that rear radiating extra treble energy that increases the 'sense of space' in your room.
Looks like you'll need some of those absorbers (front wall and ceiling corners) to maintain the bass note clarity - might try adding some reflective foils/light ply/etc to reduce some of the mids (as per the "8th Nerve" articles)
I did not figure out at first that you wanted to make doors for your Ikea cabinet...
As Jamesshillj stated, we have been warned by acoustic engineers that diffusers create a poor soundstage if you sit too close to them. For this style of diffuser (sound diffusion down to 500 hz), Tim Perry, the original designer of this style of diffuser, recommends 10 feet of distance between listener's position and a diffuser of this capability. He backs off that somewhat and says that 5 foot minimum should be the absolute minimum distance. But I don't have any knowledge or experience of the drawbacks of sitting closer than some minimum distance.
If you build these and it seems that the soundstage is worse, you can move them to your front wall and place absorption just behind the listening position.
For my room, I am planning on about 5 feet of distance between my listening position and the diffusers on the back wall. I will see how that works out.
It seems that you are planning on a lot of good acoustic features for your audio room.
Retsel
As Jamesshillj stated, we have been warned by acoustic engineers that diffusers create a poor soundstage if you sit too close to them. For this style of diffuser (sound diffusion down to 500 hz), Tim Perry, the original designer of this style of diffuser, recommends 10 feet of distance between listener's position and a diffuser of this capability. He backs off that somewhat and says that 5 foot minimum should be the absolute minimum distance. But I don't have any knowledge or experience of the drawbacks of sitting closer than some minimum distance.
If you build these and it seems that the soundstage is worse, you can move them to your front wall and place absorption just behind the listening position.
For my room, I am planning on about 5 feet of distance between my listening position and the diffusers on the back wall. I will see how that works out.
It seems that you are planning on a lot of good acoustic features for your audio room.
Retsel
Thanks
I like the idea of veneer, or even a thin ply, over polystyrene foam, I would have thought that should work quite well?
I built my system for a much larger room years ago. My new room is quite a bit smaller and I'm not sure I have 5 feet from the diffuser but I'll still build it and see. I like the idea of putting the diffuser in front if it doesn't work out in back of the room. thanks Retsel.
Yeah Scott, I thought the veneer would be a nice touch but turned out to be a real PIA to glue to the styrene - you could tell that it was a slightly different sound to the bare styrene so I persevered with the strips of 3mm ply (hard to get clean edges) and this was easier as I pinned them on with those automotive plastic plugs (and glue!) after sealing both sides - the slats from the venetian blinds (both timber and plastic) was the best and easiest to apply.
I found some quite thick film plastic sheet (thermo-setting plastic) and I'll give this a try too - might have to cut the width down to 600mm wide to manage the 'sticking' and hard corners of the styrene.
I asked about the 'plastic dipping' that's used on hand tools but it seems it's a soft surface, and not cheap.
I asked one of the plastic companies in China about a 'blow-mould' of thick stiff plastic (stronger than the 'skyline' ones) but a minimum of a thousand order and filling the back with expanding foam isn't a 'life ambition'!
The paint people suggested adding rice flour (?) to an exterior paint as a thickener - must try that too.
These are with the original 'leanfusers' as per the website (not this timber version) and I assemble 5 or 7 modules (2100/2940mm wide) and 1200mm high, usually mounted about 300/400 above the floor.
I had the styrene company cut some of the fractal versions (the B2 units) at the same time and apart from a right pest to paint, they actually seem to produce a 'more detailed' and 'airy' sound - the thin fins on the surface absorb a lot of paint, using an 'airless' Wagner spray-gun to better seal the surface (like fence palings).
I love the sound benefits of these simple things!
I found some quite thick film plastic sheet (thermo-setting plastic) and I'll give this a try too - might have to cut the width down to 600mm wide to manage the 'sticking' and hard corners of the styrene.
I asked about the 'plastic dipping' that's used on hand tools but it seems it's a soft surface, and not cheap.
I asked one of the plastic companies in China about a 'blow-mould' of thick stiff plastic (stronger than the 'skyline' ones) but a minimum of a thousand order and filling the back with expanding foam isn't a 'life ambition'!
The paint people suggested adding rice flour (?) to an exterior paint as a thickener - must try that too.
These are with the original 'leanfusers' as per the website (not this timber version) and I assemble 5 or 7 modules (2100/2940mm wide) and 1200mm high, usually mounted about 300/400 above the floor.
I had the styrene company cut some of the fractal versions (the B2 units) at the same time and apart from a right pest to paint, they actually seem to produce a 'more detailed' and 'airy' sound - the thin fins on the surface absorb a lot of paint, using an 'airless' Wagner spray-gun to better seal the surface (like fence palings).
I love the sound benefits of these simple things!
Looking at your pics, I obviously misinterpreted the room, as I thought the green walls were already covered with damping material and fabric, therefore my remark to LEDE.
I'm not sure, why Bwaslo thought about 90 degree orientation because I mentioned 180 degrees (if using the RPG idea of an asymmetrical design for this purpose).
If cutting the middle on each side is sufficient is hard to say, from a theoretical point of view serie repetition makes the diffusion/scattering less optimal, otoh using diffusors in small rooms always means to accept some compromises and only practical evaluation by listening will allow for finding the best realization for your liking.
Finding real data from well documented listening tests on this kind of acoustical room treatment is IME extremely difficult, as usually only conclusions are reported, if any controlled listening tests were even done.
But what is the problem with the distance from a diffusor? If the distance is too small, can it do more harm than the already existent reflection?
IMO it depends on the kind of already existent reflection and the type of diffusor used. When compared to the reflection from a uniform wall, the wall reflection is uniform over the frequency range, while a broadband diffusor with reflective surface elements might lead to nonuniform reflections (means onyl some frequencies are directly reflected to your ears while others are more diffracted which will be perceived as anomaly).
Best usage would be under far field conditions with a distance >3m (see literature by Cox and D'Antonio), reported german listening tests results suggest that the minimum distance should be 1 m (~3,x feet ? ) to provide a minimum time gap between the direct sound and the first reflection from the back of 6 ms .
And it would lead to the recommendation to better use a diffuser construction with thin dividers between the wells.
In your case the current situation is a bit different as it is not an uniform wall behind your listening chair and you're already getting kind of diffracted/diffused sound. Depending on the lower bandwidth limit that you want to use for the diffuser which would add another 25-30 cm depth to the IKEA it could be a violation of the "1m rule" .
Retsel already mentioned that it could be an idea to use the IKEA with inserts like a diffusor, it seems that the three upper rows are above the chair back so would be a good start to implement the diffusor elements.
If it is of interest I'll post some examples for such arrangements, variations from RPG to get better diffusion at higher frequencies and some general literature.
I haven't yet tried it myself, but from the same german publication it was reported that for tryouts diffuser models realized in cardboard were quite effective. So it would be a good idea to use these cheap versions for trying what works under the specific conditions before starting with the rigid/heavy realizations.
My daughter and I had a great time building the Depot Diffusers out of foam board this weekend. I kick myself for not taking pictures because we only listened for about 2 hours before we had to take them down so she could bring back the foam board to school today.
My main concern was how they would sound if I could only be 4 feet in front of them. I was extremly surprised at how much deeper the room sounded. I could hear any issues with being so close it was all just good. So as soon as my contract picks up again, I'll build the real thing as doors on my Ikea unit.
Pictures to follow.
My main concern was how they would sound if I could only be 4 feet in front of them. I was extremly surprised at how much deeper the room sounded. I could hear any issues with being so close it was all just good. So as soon as my contract picks up again, I'll build the real thing as doors on my Ikea unit.
Pictures to follow.