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04-28-2017, 11:38 PM
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#1
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Human being with feelings
Join Date: Dec 2013
Location: Trondheim, Norway
Posts: 376
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Acoustic treatment question
I have a small room 305x288x240cm (LxWxH) which I use for mastering purposes. I have done a lot of experimentation with acoustic treatment and loudspeaker and listening position. Things start to sound ok, but I still have one major issue. Since both the speakers and ears are placed almost in the middle between the ceiling and floor, the 72Hz ceiling to floor room mode causes cancellation at the listening position. These frequencies sound a bit to weak, thin and hollow. I have so far no acoustic absorbers in the ceiling and wonder what is the most efficient placement to solve (or reduce) this problem? I know they have to be thick to have effect on this low frequencies, but should I place absorbers above the speakers, above the listening position or generally add ceiling-wall bass traps? Unfortunately it is not an alternative to change speaker or listening position.
Thanks in advance for help!
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04-28-2017, 11:53 PM
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#2
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Human being with feelings
Join Date: Aug 2007
Location: Near Cambridge UK and Near Questembert, France
Posts: 22,754
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Have you read up on limp membrane tuned traps? Might be a good solution in your case.
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Ici on parles Franglais
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04-29-2017, 01:04 AM
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#3
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Human being with feelings
Join Date: Dec 2013
Location: Trondheim, Norway
Posts: 376
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Quote:
Originally Posted by ivansc
Have you read up on limp membrane tuned traps? Might be a good solution in your case.
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Thank you for your reply! I have not read up on limp membrane tuned traps, I will check this out! Basically I have followed the advices on this webpage as far as possible and within reasonable costs.
http://arqen.com/acoustics-101/room-...ker-placement/
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04-29-2017, 01:40 AM
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#4
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Human being with feelings
Join Date: Mar 2009
Location: Dartmouth, Nova Scotia
Posts: 11,184
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That is a very small room.
About the best you can do is put as much absorption over as much surface area as possible.
If you are using traps, don't forget to leave an air gap between the trap and the wall or ceiling -- space a 1" trap 1" away, space a 2" trap 2" away, etc.
For a room this small you are going to need lots of thick trapping to get anywhere close to decent bass performance.
Of course, the unfortunate downside is that with, say, 4" traps spaced 4" of the wall, you lose 8" per wall so your width would be reduced by both walls, 16" = 40 cm !!
To be honest, I would NEVER attempt to master in a room that small.
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04-29-2017, 02:48 AM
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#5
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Human being with feelings
Join Date: Aug 2007
Location: Near Cambridge UK and Near Questembert, France
Posts: 22,754
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European accommodation tends to be way smaller tan the Northern American Continent's equivalents. I could fit two normal UK houses into my nothing-special home in Nashville.
Even the garage was bigger in terms of square footage than my current house!
Hence the suggestion of a tuned membrane for his specific mix position problem.
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Ici on parles Franglais
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04-29-2017, 02:53 AM
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#6
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Human being with feelings
Join Date: Nov 2013
Location: IKEA
Posts: 2,778
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Invite 5 sumo wrestlers to watch you mix, problem solved.
Wh0t?
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Last edited by SmajjL; 04-29-2017 at 08:41 AM.
Reason: Well done SmajjL.. :)
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04-29-2017, 04:15 AM
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#7
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Human being with feelings
Join Date: Aug 2015
Posts: 2,969
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Definitely worth trying a panel / membrane absorber / resonator on the ceiling. A stiff (plywood?) panel may be suitable. Calculators here: http://www.mh-audio.nl/acalculators.asp
I'm starting to fit out a basement with more floor area but a little less height than your room and I'm expecting to have to do something like that. I'm not tall, so it (and I) should fit.
You can do quite a bit of good with only 10cm depth. And some luck.
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04-29-2017, 05:44 AM
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#8
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Human being with feelings
Join Date: Dec 2013
Location: Trondheim, Norway
Posts: 376
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Quote:
Originally Posted by Geoff Waddington
That is a very small room.
About the best you can do is put as much absorption over as much surface area as possible.
If you are using traps, don't forget to leave an air gap between the trap and the wall or ceiling -- space a 1" trap 1" away, space a 2" trap 2" away, etc.
For a room this small you are going to need lots of thick trapping to get anywhere close to decent bass performance.
Of course, the unfortunate downside is that with, say, 4" traps spaced 4" of the wall, you lose 8" per wall so your width would be reduced by both walls, 16" = 40 cm !!
To be honest, I would NEVER attempt to master in a room that small.
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Thank you for your reply! A very small room is far from ideal for mastering but I have to relate to the reality. I think the frequency response is ok now except for the 72Hz ceiling to floor cancellation.
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04-29-2017, 05:49 AM
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#9
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Human being with feelings
Join Date: Dec 2013
Location: Trondheim, Norway
Posts: 376
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Quote:
Originally Posted by jrk
Definitely worth trying a panel / membrane absorber / resonator on the ceiling. A stiff (plywood?) panel may be suitable. Calculators here: http://www.mh-audio.nl/acalculators.asp
I'm starting to fit out a basement with more floor area but a little less height than your room and I'm expecting to have to do something like that. I'm not tall, so it (and I) should fit.
You can do quite a bit of good with only 10cm depth. And some luck.
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Thank you for your reply! Yes, I think I should do something like this. But where in the ceiling do you think it is most efficient to place panels/membranes? I do not plan to mount several panels and wonder if I should start mounting them over the speakers or over the listening position?
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04-29-2017, 06:26 AM
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#10
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Human being with feelings
Join Date: Aug 2015
Posts: 2,969
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I'd concentrate on the area above the listening position. A resonant panel is fairly simple and cheap to build. It's just a box that you fix to the ceiling. So it's probably a good idea to knock up a prototype and measure it in situ - stick a contact mic onto it. If you need to tweak it to nail the frequency you're after, it should only involve a bit of light woodwork. And then you can knock up another one to your refined design - or as many as you need. I'm expecting to need at least two panels 60x240 cm. Since you're not after broadband absorption I'd be inclined to damp it quite lightly - maybe put a little loudspeaker wadding in there rather than stuffing it with rockwool.
... checks calculator - a 6mm ply panel (ca. 3kg/m2) might need a depth of up to 23cm for 72Hz Would that be too much for you? Thicker (heavier) panels are less compliant / bendy and probably less effective. An alternative might be what they call "mass loaded vinyl" (back to ivansc suggestion - limp membrane - but on a ceiling?)
... and another thing, sorry :-)
How you mount the panel to the "enclosure" is probably a bit of a "gotcha" - if it's rigidly fixed then you're counting on the flex in the panel - if it's on some kind of resilient mount then this is probably less important. You can get permanently flexible sealant/ adhesives for acoustic purposes - I'd try that, with a 12mm ply panel. Less than 12cm depth required. Don't sue me if it doesn't work.
Last edited by jrk; 04-29-2017 at 07:21 AM.
Reason: afterthought
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04-29-2017, 07:53 AM
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#11
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Human being with feelings
Join Date: Dec 2013
Location: Trondheim, Norway
Posts: 376
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Quote:
Originally Posted by jrk
I'd concentrate on the area above the listening position. A resonant panel is fairly simple and cheap to build. It's just a box that you fix to the ceiling. So it's probably a good idea to knock up a prototype and measure it in situ - stick a contact mic onto it. If you need to tweak it to nail the frequency you're after, it should only involve a bit of light woodwork. And then you can knock up another one to your refined design - or as many as you need. I'm expecting to need at least two panels 60x240 cm. Since you're not after broadband absorption I'd be inclined to damp it quite lightly - maybe put a little loudspeaker wadding in there rather than stuffing it with rockwool.
... checks calculator - a 6mm ply panel (ca. 3kg/m2) might need a depth of up to 23cm for 72Hz Would that be too much for you? Thicker (heavier) panels are less compliant / bendy and probably less effective. An alternative might be what they call "mass loaded vinyl" (back to ivansc suggestion - limp membrane - but on a ceiling?)
... and another thing, sorry :-)
How you mount the panel to the "enclosure" is probably a bit of a "gotcha" - if it's rigidly fixed then you're counting on the flex in the panel - if it's on some kind of resilient mount then this is probably less important. You can get permanently flexible sealant/ adhesives for acoustic purposes - I'd try that, with a 12mm ply panel. Less than 12cm depth required. Don't sue me if it doesn't work.
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Thank you for a lot of interesting information! I meant that the 72Hz frequency issue is something I need to solve, but it is only an advantage if other resonance frequencies are dampened as well. I also have a boost at 144Hz, but I have tamed it with a correction eq.
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04-29-2017, 09:51 AM
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#12
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Human being with feelings
Join Date: Aug 2015
Posts: 2,969
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Quote:
Originally Posted by osflaa
I also have a boost at 144Hz,
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Ha! Yes, if you're sitting in a hole at xHz it's a good chance you have a peak at 2x. Isn't maths fun?
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04-29-2017, 01:32 PM
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#13
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Human being with feelings
Join Date: Aug 2007
Location: Near Cambridge UK and Near Questembert, France
Posts: 22,754
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Quote:
Originally Posted by osflaa
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Might be worth having a look at both Sound on Sound mag archives and Ethan Winer's site for their take on tuned membrane traps. When you have such a specific problem, this is often the best bang for the buck.
Also, if you have a peak at 130-ish and a hole ant half that wavelength, chances are the membrane trap will help with both.
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Ici on parles Franglais
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04-29-2017, 11:23 PM
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#14
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Human being with feelings
Join Date: Jul 2010
Location: Denmark
Posts: 465
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I mix in a room of almost identical dimensions to yours. It is heavily treated with absorbers on walls, in corners and hanging from the ceiling from this one:
http://gikacoustics.co.uk/
Their prices are reasonable, but I did find some sloppy work here and there which I had to hide from vision.
Still I am not sure if my room is good enough for mixing. But it is what I have. I supplement with reference music and checking with headphones with software correction and room/speaker emulations to compensate.
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04-30-2017, 01:22 AM
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#15
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Human being with feelings
Join Date: Dec 2011
Location: Norway
Posts: 100
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Use 9 minutes on this one:
https://www.youtube.com/watch?v=0bt6Zex-fk0
"Too small rooms produce large acoustic issues. See where your room size and volume fits into our chart and follow Sam Small through his too small room fix."
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04-30-2017, 02:51 AM
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#16
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Human being with feelings
Join Date: Dec 2013
Location: Trondheim, Norway
Posts: 376
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Quote:
Originally Posted by tombuur
I supplement with reference music and checking with headphones with software correction and room/speaker emulations to compensate.
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Thank you for your reply! In my opinion the most important thing is to know the sound of my system very well and how it translates to other systems. I always test mixes/masters on my hifi-stereo and headphones (I use Toneboosters Morphit to emulate different brands). Also, I use analyzing tools a lot and reference tracks. But I find it a bit exhausting to mix/master without fully trust what I hear :-)
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04-30-2017, 02:55 AM
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#17
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Human being with feelings
Join Date: Dec 2013
Location: Trondheim, Norway
Posts: 376
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Quote:
Originally Posted by sveinpetter
Use 9 minutes on this one:
https://www.youtube.com/watch?v=0bt6Zex-fk0
"Too small rooms produce large acoustic issues. See where your room size and volume fits into our chart and follow Sam Small through his too small room fix."
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Thank you for your reply! I watched the video and was a bit surprised that he mounted a lot of relatively thin wall tiles before he thought of using bass traps. But he apparently achieved the results he wanted.
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04-30-2017, 05:07 AM
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#18
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Human being with feelings
Join Date: Jul 2010
Location: Denmark
Posts: 465
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Quote:
Originally Posted by osflaa
Thank you for your reply! I watched the video and was a bit surprised that he mounted a lot of relatively thin wall tiles before he thought of using bass traps. But he apparently achieved the results he wanted.
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It would have been nice to see some frequency curves of his room after acoustic treatment. That he managed to mix some song to the satisfaction of the mastering engineer is kind of second line evidence.
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04-30-2017, 05:33 AM
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#19
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Human being with feelings
Join Date: Mar 2009
Location: Dartmouth, Nova Scotia
Posts: 11,184
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Quote:
Originally Posted by tombuur
It would have been nice to see some frequency curves of his room after acoustic treatment. That he managed to mix some song to the satisfaction of the mastering engineer is kind of second line evidence.
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Yeah, that video didn't ring true at all, researched it a bit, you might want to see what some of the more respected names out there (Ethan, Glen, Rod) have to say about this bunch, buyer beware !
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To install you need the CSI Software and Support Files
For installation instructions and documentation see the Wiki
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04-30-2017, 07:01 AM
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#20
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Human being with feelings
Join Date: Jun 2015
Posts: 8,696
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Is it a bedroom?
If so it could be made to be a decent room for mastering in the nearfield, especially if it has a lot of clutter to break up the sound and a bed to absorb bass. The more clutter the better. Mass for absorption, mess for diffraction.
Use the width of the room instead of the length. Listen in the nearfield.
Use quality headphones to more accurately assess the bass, along with the nearfield speakers.
Top quality headphones like HD800 will give you more accurate insight into the real bass balance in your recordings than most speakers in well optimized domestic rooms of any size anyway, what is missing is the visceral chest thump we all enjoy (so you want the speakers/room to be optimal for your budget).
A combination of quality cans and nearfields comparison is a good compromise. HD600 is a nice option too on a tighter budget; you can find good used examples of both if needs be too.
Last edited by Softsynth; 04-30-2017 at 08:14 AM.
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05-01-2017, 01:30 AM
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#21
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Human being with feelings
Join Date: Dec 2013
Location: Trondheim, Norway
Posts: 376
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Quote:
Originally Posted by Softsynth
Is it a bedroom?
If so it could be made to be a decent room for mastering in the nearfield, especially if it has a lot of clutter to break up the sound and a bed to absorb bass. The more clutter the better. Mass for absorption, mess for diffraction.
Use the width of the room instead of the length. Listen in the nearfield.
Use quality headphones to more accurately assess the bass, along with the nearfield speakers.
Top quality headphones like HD800 will give you more accurate insight into the real bass balance in your recordings than most speakers in well optimized domestic rooms of any size anyway, what is missing is the visceral chest thump we all enjoy (so you want the speakers/room to be optimal for your budget).
A combination of quality cans and nearfields comparison is a good compromise. HD600 is a nice option too on a tighter budget; you can find good used examples of both if needs be too.
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Thank you for your reply! This is not a bedroom, but a room dedicated to mixing/mastering. I used nearfield monitoring and checked the bass using spectrum analyzer and headphones earlier, but this time I hope to achieve ok bass response using speakers. However, a check using good quality headphones is a good idea. I have used AKG K271 and Sennheiser HD380 and think both have a very unbalanced frequency response. Unfortunately the price of HD800 exceeds my budget, however HD600 is within range. I have compared the frequency balance of HD800 and HD600 using emulation in Toneboosters Morphit. I assume this only gives a rough idea, but it seems like their frequency balance in the bass area is about the same. So I will consider buying these.
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05-01-2017, 09:31 PM
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#22
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Human being with feelings
Join Date: Jul 2010
Location: Denmark
Posts: 465
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I have Morphit which is fine too. I have also tried other software emulating everyting from car stereo to tv speakers. However, I generally find they sound more like a recording through a microphone in those places rather than the experience I get when actually listening with my own ears in the same situation.
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05-01-2017, 11:37 PM
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#23
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Human being with feelings
Join Date: May 2010
Location: Norway
Posts: 7,318
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Quote:
Originally Posted by osflaa
Since both the speakers and ears are placed almost in the middle between the ceiling and floor, the 72Hz ceiling to floor room mode causes cancellation at the listening position.
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Why not move speakers up/down, and tilt them?
Will of course not fix the problem, but maybe help a little.
Then, a Helmholtz resonator maybe?
https://www.google.no/search?q=hemho...oltz+resonator
or maybe that's the same as above suggestion.
Anyway, this is advanced room-tuning, and you typically should consult a professional.
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05-02-2017, 01:40 AM
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#24
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Human being with feelings
Join Date: Dec 2013
Location: Trondheim, Norway
Posts: 376
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Quote:
Originally Posted by G-Sun
Why not move speakers up/down, and tilt them?
Will of course not fix the problem, but maybe help a little.
Then, a Helmholtz resonator maybe?
https://www.google.no/search?q=hemho...oltz+resonator
or maybe that's the same as above suggestion.
Anyway, this is advanced room-tuning, and you typically should consult a professional.
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Thank you for your reply! Yes, it should be a good idea to move the speakers up and tilt them. I have not testet it yet because I would need to buy new speaker stands, however I have turned the speakers upside down so they are at least not 100% in the middle between ceiling and floor. Helmholtz resonator is possibly a little too advanced for me at this stage, however it is very interesting and may be something I will consider in other rooms in the future.
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