I think the Gearslutz rebranded to Gearspace some time ago 
https://gearspace.com/board/studio-building-acoustics/
Also John Sayers forum https://www.johnlsayers.com/phpBB2/index.php
These both are more for studio / home studio forums but the physics of acoustics is the same as for us mere listeners
https://gearspace.com/board/studio-building-acoustics/Also John Sayers forum https://www.johnlsayers.com/phpBB2/index.php
These both are more for studio / home studio forums but the physics of acoustics is the same as for us mere listeners
hello krivium
i have a lot to ask but i will try to make it short.
i have some very annoying bass overhang in my room that peaks at about 50 and 60hz. i have built 12 tower traps with size 0,43x0,43x1,2m placed in room corners, from floor to ceiling and 4 traps placed at mid points on the short walls with little success. many years ago i built some large tube traps and i recall they where very good, but in a weak moment i said yes to my wife to let all these go in the trash bin! now when in need i thought i could not go wrong by building tower traps instead, they work identically but it is much easier to get hands on sheets of ridgid fiber glass then tubes.
the peak at 50hz is due to the front and back wall distance, when i listen in the middle of the room i get a nice suck out and all sounds fine, but further back where i have my chair it sounds very bass heavy on some tracks. i had hope that those tower traps would do something to target this but it does not seems so, it seems that the soundwaves of interest just passes by mostly unaltered
my homebuilt tower traps does not seems to function as i hoped for, maybe these traps just works as plain friction absorbers and as such they are way to small, they should have been twice as large for that.
and also, the corner placement of the tower traps does also seems to be wrong, to get rid of the overblown bass i think i need to have the absorption at front or back wall, or both.
the question here is; when i simulate my room in rew and ad absorption value of 0.5 to both front wall and back wall i get rid most of the bass peaks of concern, will this work in reality? can i put half the absorber thickness on one wall and the other half of the absorber thicknes on opposing wall and they will be effective down to a frequency that matches their combined thickness/depth?
to absorb 50hz with a friction absorber i need an absorber thickness that is around 86cm, but can i put 43cm absorber to one wall and another 43cm of absorber to opposing wall for the same effect?
then we have panel absorbers, more to come...
i have a lot to ask but i will try to make it short.
i have some very annoying bass overhang in my room that peaks at about 50 and 60hz. i have built 12 tower traps with size 0,43x0,43x1,2m placed in room corners, from floor to ceiling and 4 traps placed at mid points on the short walls with little success. many years ago i built some large tube traps and i recall they where very good, but in a weak moment i said yes to my wife to let all these go in the trash bin! now when in need i thought i could not go wrong by building tower traps instead, they work identically but it is much easier to get hands on sheets of ridgid fiber glass then tubes.
the peak at 50hz is due to the front and back wall distance, when i listen in the middle of the room i get a nice suck out and all sounds fine, but further back where i have my chair it sounds very bass heavy on some tracks. i had hope that those tower traps would do something to target this but it does not seems so, it seems that the soundwaves of interest just passes by mostly unaltered
my homebuilt tower traps does not seems to function as i hoped for, maybe these traps just works as plain friction absorbers and as such they are way to small, they should have been twice as large for that.
and also, the corner placement of the tower traps does also seems to be wrong, to get rid of the overblown bass i think i need to have the absorption at front or back wall, or both.
the question here is; when i simulate my room in rew and ad absorption value of 0.5 to both front wall and back wall i get rid most of the bass peaks of concern, will this work in reality? can i put half the absorber thickness on one wall and the other half of the absorber thicknes on opposing wall and they will be effective down to a frequency that matches their combined thickness/depth?
to absorb 50hz with a friction absorber i need an absorber thickness that is around 86cm, but can i put 43cm absorber to one wall and another 43cm of absorber to opposing wall for the same effect?
then we have panel absorbers, more to come...
tower trap and tube trap are said to work as friction absorbers in pressure zones. normally friction absorbers do not work in pressure zones, but tube traps and tower traps is said to work as pressure difference devices, when put in a pressure zones their will be a pressure difference within the absorber vs outside the absorber, this pressure difference will generate an airflow throu the absorber wall since nature wants to even out the pressure difference, and by friction of this airflow absorb the soundwave. to enhance this pressure difference asc has started to fill their traps with loose filling to cool down the air within the absorber, exactly what we do with our subwoofer boxes to virtually increase the internal volume of the box, this is called isotherming.
but this has not worked for me, when using this calculator to simulate my traps i get very poor results
http://www.acousticmodelling.com/multi.php
i have changed some of my traps accordingly but still have not got the results i want, my traps just seems to be way to small
so i have started to doubt asc traps, i find their products very cool and i really like the idea of having movable absorbers, but do they really work as they claim? some of their own measurements do looks a bit "fishy" and not as great as they claim...
but this has not worked for me, when using this calculator to simulate my traps i get very poor results
http://www.acousticmodelling.com/multi.php
i have changed some of my traps accordingly but still have not got the results i want, my traps just seems to be way to small
so i have started to doubt asc traps, i find their products very cool and i really like the idea of having movable absorbers, but do they really work as they claim? some of their own measurements do looks a bit "fishy" and not as great as they claim...
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Thing is, that most homes are not always easy to cover with all sorts of acoustic material. Further, a good speaker with well controlled and smooth anechoic measuring response, will play pretty good in most rooms, as long as the room does not ring like a bell or empty bathroom.
As I understand it, home cinemas are a bit different, since they can be in darker, non living and more dedicated spaces, where surround sound typically makes the sound come from all around in a way, that does not mix well with reflections like in a normal living space.
I would say, that a room that is as a minimum, comfortable to have a conversation in - would also mostly be a good listening room for music.
I agree with Allen. Multisub approach is the answer imho.
The issue with small rooms ( and most of our domestic rooms are from an acoustic pov) is the ratio of acoustics treatments needed/room's volume is not good for something other than a dedicated auditorium.
I'm not saying it's not usefull, i just say for it to be able to 'solve' the issues you face you need a LOT of them and so availlable space within the room is really impacted.
This is especially true when porous absorbers are used. Depending on their type the location can be critical to efficiency too, which is another obstacle for domestic room.
Other acoustic approach could be used like VPR panels which are diy-able. Member Audiothings here have done lot of experiments wiyth them and had impressive results implementing T.Hidley's 'zero/non environnment' principle using them in smaller room than required initially by Hidley ( they use up to 1m or more space dedicated to 'hangers' -wide band absorbers- on each side walls, rear wall and ceiling making for huge rooms for domestic standards).
Audiothings's VPR ( he use some porous absorbers in front on them too) have a total depth around 15/30cm (including porous absorber iirc).
Some of his works are documented at gearslutz/gearspace with great acousticians ( P.Newell's son and T Jouanjouan) impressed by measured results and saying it.
All this to say VPR are effective for reasonable bulk, ime not so critical regarding location and what i would study at first.
But i would do it as a second step, first and foremost multisub.
The issue with small rooms ( and most of our domestic rooms are from an acoustic pov) is the ratio of acoustics treatments needed/room's volume is not good for something other than a dedicated auditorium.
I'm not saying it's not usefull, i just say for it to be able to 'solve' the issues you face you need a LOT of them and so availlable space within the room is really impacted.
This is especially true when porous absorbers are used. Depending on their type the location can be critical to efficiency too, which is another obstacle for domestic room.
Other acoustic approach could be used like VPR panels which are diy-able. Member Audiothings here have done lot of experiments wiyth them and had impressive results implementing T.Hidley's 'zero/non environnment' principle using them in smaller room than required initially by Hidley ( they use up to 1m or more space dedicated to 'hangers' -wide band absorbers- on each side walls, rear wall and ceiling making for huge rooms for domestic standards).
Audiothings's VPR ( he use some porous absorbers in front on them too) have a total depth around 15/30cm (including porous absorber iirc).
Some of his works are documented at gearslutz/gearspace with great acousticians ( P.Newell's son and T Jouanjouan) impressed by measured results and saying it.
All this to say VPR are effective for reasonable bulk, ime not so critical regarding location and what i would study at first.
But i would do it as a second step, first and foremost multisub.
@celef all rooms have strong distributions of cancellation and reinforcement at low frequencies that come from room geometry. Your room dimensions don't look particularly troublesome at a glance, there aren't strong mathematical relationships between dimensions that would lead to coincident reinforcement. You can't just throw absorbers at this problem and expect to solve it in my opinion. Sound does not bounce around at these frequencies, the room is modal. Try and imagine 3D pressure maps filling the space that change with frequency. Those peaks and nulls in the pressure distribution don't change unless you hit them with mathematical precision. Forgive me but you are so much more likely to succeed if you don't excite the worst of them in the first place. Get the placement right. The most important step in setting up any system is to place the speakers and the listening position at points where the interaction with room does least damage. Start with placement always, direct your efforts there and you can get much better results at zero cost.