I do know Bill Waslo had succes with ambiance speakers behind his horn/synergy setup, so that makes me believe it should work too. Only testing something like that yourself could provide a definitive answer, I suppose.
My question would be, are there strong ceiling reflections present to work with? I mean an OB with equal distance from front and back of the speaker could still cancel out in that direction? (create a null there, or lessen the effect of energy hitting that ceiling)
My question would be, are there strong ceiling reflections present to work with? I mean an OB with equal distance from front and back of the speaker could still cancel out in that direction? (create a null there, or lessen the effect of energy hitting that ceiling)
Having some nice late reflections from the front and back of the room should be pretty nice.
I do. Have a nice - 10db reflection from. One of the speakers, i suppose my room's L shape is creating all kinds of mismatched responses between the speakers
Would having the reflections come from one speaker only cause a problem? E.g the ceiling reflection redirected to the front wall only from one speaker
I do. Have a nice - 10db reflection from. One of the speakers, i suppose my room's L shape is creating all kinds of mismatched responses between the speakers
Would having the reflections come from one speaker only cause a problem? E.g the ceiling reflection redirected to the front wall only from one speaker
For a reflector (or ”Haas Kicker”) you need to think about the wave length you wish to influence. For full reflection its width and height needs to be the same as the wave length or larger. 200 Hz = 1,7 m. It starts to have ”some influence” from about 1/3 wavelength in size (if I remember correctly). If you wish to re-direct the sound wave it needs to be angled and the depth behind the front at one end versus the wall behind needs to be quite substantial to re-direct it. If you have it, say 17 cm angled out from the wall behind, the sound wave will not be influenced. That would be only 1/10 wave length for 200 Hz. -The angled reflector would not be ”seen” by the sound wave and the reflector would just be a part of the flat wall behind it. 200 Hz is just too low a frequency to influence with diffusers and reflectors in a normal sized rectangular room. Somewhere around 600-4000 Hz is where I would spend my efforts with acoustical fixes like diffusers and reflectors of ”acceptable size”.
For improved envelopment and the ”spaciousness” of a large room, it would be advantageous if a reflected sound wave from left front speakers ends up at your right ear entering sideways from your right hand side wall. Ideally around 20 ms later than the direct sound, within some 15-30 ms is OK depending on room size. It should be fairly strong too, stronger than any other early reflections which would tell your brain that you have a small room.
To accomplish that is not really hard, more quite tedious work with measuments between every little change of position and angle. It can be impossible too, -depending on room size and practical reasons. I used a laser pointer fixed on top of the front speaker + 3 mirrors to get the exact right angle. For each measurent at LP a small piece of numbered tape was fixed on the sidewall. To fixate the angle of the reflector a small WESA TV mount was used, as it can be angled both sideways and up-down. (Similar to mine: https://www.amazon.com/Mount-World-...keywords=TV+wesa+mount&qid=1605741696&sr=8-41 ) If the bouncing sound wave travels a long distance, very small adjustments are needed. A change of about 10 mm or so (3/8") can be enough to change REW measuments a lot.
Some 6 year old pictures of the laser pointer, angled Haas Kickers, dark picture of reflection ending up sideways at left ear from right front speaker after 3 reflection points and it strength from REW measurement after about 28 ms. The Haas Kickers has now been replaced by some DIY volumetric diffusers, as well as the front speakers.
Edit: Will post the pictures later, internet is slooooow right now.
For improved envelopment and the ”spaciousness” of a large room, it would be advantageous if a reflected sound wave from left front speakers ends up at your right ear entering sideways from your right hand side wall. Ideally around 20 ms later than the direct sound, within some 15-30 ms is OK depending on room size. It should be fairly strong too, stronger than any other early reflections which would tell your brain that you have a small room.
To accomplish that is not really hard, more quite tedious work with measuments between every little change of position and angle. It can be impossible too, -depending on room size and practical reasons. I used a laser pointer fixed on top of the front speaker + 3 mirrors to get the exact right angle. For each measurent at LP a small piece of numbered tape was fixed on the sidewall. To fixate the angle of the reflector a small WESA TV mount was used, as it can be angled both sideways and up-down. (Similar to mine: https://www.amazon.com/Mount-World-...keywords=TV+wesa+mount&qid=1605741696&sr=8-41 ) If the bouncing sound wave travels a long distance, very small adjustments are needed. A change of about 10 mm or so (3/8") can be enough to change REW measuments a lot.
Some 6 year old pictures of the laser pointer, angled Haas Kickers, dark picture of reflection ending up sideways at left ear from right front speaker after 3 reflection points and it strength from REW measurement after about 28 ms. The Haas Kickers has now been replaced by some DIY volumetric diffusers, as well as the front speakers.
Edit: Will post the pictures later, internet is slooooow right now.
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Very helpful, thank you for taking the time and sharing you knowledge.
Getting the left speakers wave redirecting to come from the right side is not possible in my room i'm afraid,
What allen said might be a good idea though, what about deadening the ceiling and front wall, redirecting the side wall energy to the back diffused wall? Which is 3.5 meters behind me, and should give me a nice 20 ms ITSG, not sure how strong the first diffused reflection will be, should have a series of reflections around - 15 db or so.
So basically aim for an anechoic path from 0 till 20 ms(around - 25db or better)
Have diffused energy from the back wall at around 20 ms.
Is there any problem with the diffused energy coming from the back only?
Is - 15 db or so of reflections good enough for the effect to work?
Do both speakers have to have the same ITSG? No so easy to do in my L shaped room.
Would having diffusers on the wall behind the speakers be beneficial somehow if i don't redirect strong reflections at it? (i like the way the diffusers are looking there so if they won't cause a problem and possibly help I d prefer leaving them there
Thanks again guys
Getting the left speakers wave redirecting to come from the right side is not possible in my room i'm afraid,
What allen said might be a good idea though, what about deadening the ceiling and front wall, redirecting the side wall energy to the back diffused wall? Which is 3.5 meters behind me, and should give me a nice 20 ms ITSG, not sure how strong the first diffused reflection will be, should have a series of reflections around - 15 db or so.
So basically aim for an anechoic path from 0 till 20 ms(around - 25db or better)
Have diffused energy from the back wall at around 20 ms.
Is there any problem with the diffused energy coming from the back only?
Is - 15 db or so of reflections good enough for the effect to work?
Do both speakers have to have the same ITSG? No so easy to do in my L shaped room.
Would having diffusers on the wall behind the speakers be beneficial somehow if i don't redirect strong reflections at it? (i like the way the diffusers are looking there so if they won't cause a problem and possibly help I d prefer leaving them there
Thanks again guys
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Hey allen, why would you eliminate the ceiling and front wall reflections first, i wonder?
Is it cause they're close to the LP and would mess the the anechoic path before the ITSG?
They come at you from the front, just like the direct sound, and with a short delay time. Prime listening fatigue potential. I like to put heavy drapes behind the speakers with more absorption under them in the usual positions. (If you have speakers with good directivity to begin with then the benefit is reduced.)
The ceiling is distracting and the content there tends to be susceptible to crossover lobing, so potentially not a good tonal match. Still coming from in front, and at a short time delay, but the height itself is also off-putting IMO.
The ceiling is distracting and the content there tends to be susceptible to crossover lobing, so potentially not a good tonal match. Still coming from in front, and at a short time delay, but the height itself is also off-putting IMO.
would you still use drapes and absorption behind them if you have no major reflections coming from there? judging by the ETC i mean
If you manage to have a delay of 20 ms coming from the front wall, would you use it or kill it?
i suppose heavy drapes can be replaced with rockwool ?
by under them you mean under the speakers as in to take care of the floor reflection? or under the drapes? and why is that?
my ceiling is 3.5 meters high, i miscalculated before, apparently i have no loud reflections coming from there, should i use some absorption there or just leave it be?
thanks allen!
If you manage to have a delay of 20 ms coming from the front wall, would you use it or kill it?
i suppose heavy drapes can be replaced with rockwool ?
by under them you mean under the speakers as in to take care of the floor reflection? or under the drapes? and why is that?
my ceiling is 3.5 meters high, i miscalculated before, apparently i have no loud reflections coming from there, should i use some absorption there or just leave it be?
thanks allen!
With regard to 20ms, anything that I can get to go behind me can stay and be considered reverberation. The front reflections are a different matter.
I should have said 'behind', just to extend lower in frequency of effectiveness.
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