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Please help this miserable square room dweller
Old 4 weeks ago
  #1
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Please help this miserable square room dweller

I didn't want to post another thread related to this problem since there are so many but I just can't find a solution to a specific issue i have.

Long story short this is the only room i can use, building or throwing down walls or other extremely permanent stuff is not an option since i'll just be moving eventually. I'm an audio engineering student and moved recently, covid has me trapped in a square room and i need to mix and master stuff for my thesis project. It's a 4.68m x 4.68m square by 2.79m tall (15.35 x 15.35 ft by 9.15 ft tall) (blueprint in attachments)

I know it will never be fixed and I know i must use a lot of broadband absorption to get the closest with solving the problem.
My goal here is not to make a perfect studio room but just to have a decent room to outlive university, to have a decent reference while mixing and hopefully even mastering and if i make my room nice for audio production for the remaining time i live here that's a great plus too.

About placement: I used the cardas recommendation for ISBR handling in square rooms
http://www.cardas.com/room_setup_hor...and_square.php

I also set my mixing triangle using the 39% Y axis listening position suggested by a lot of people and i set my triangle 1.2 meters or 4 ft long on each side.

I chose my front wall as the one with the window because i saw that being recommended, although it's a sealed window and has only a small vent to let air in on the bottom, it does have a dense vinyl curtain and i plan on getting an acoustic or at least heavy one.

I sometimes let the doors open and i think it helps with mode buildups is that a good idea? my bathroom is made of granite/quartzesque materials (can't remember the exact name)

My main issue here is that I ordered a pair of Yamaha HS8, so i'm planning on having two reference monitors (i'd be fine with just the yamas but in an ideal world i'd use both pairs). If I place the yamahas on stands to solve the decoupling issue (which I discovered is a whole different rabbit hole ) and i place them where my monitors are right now, (which is the best possible place, i think) i'll have to move my desk away from the front wall and i'll be sitting in the center of a square room. What should I do? what is worse, to be sitting on the center or to have SBIR buildups? I thought maybe I could sit 39% away from the rear wall, but isn't sitting too far away from the monitors a bad idea because of the overall problematic room? i would be making it interact more with my perception. Should I not use stands then? I'm open to arranging my room and furniture any possible way, i just want to get the best acoustic performance i can with my room limitations.

I read the yamahas' manual and it says the recommended distance by yamaha is at least 1.5 meters away from each wall, which would put me sitting very near to the center of the wall too.

So what about setting them directly against the wall? that would put them against a window tho...




Also, a separate question regarding modes: i know a square room is the worst thing you can have, is it even worth it using EQ wizard and mode analysis or should i just blindly attack the boundaries with bass traps?

My overall strategy is to also make a RFZ with panels using broadband absorbent materials in walls and ceiling to at the same time reduce the boundaries on which the low end reflects, basically covering a lot of surface to stop mid/high frequency from reflecting and low frequencies from building up.

I'm thinking on using semi permanent solutions: what do you guys recommend for corners? what is more efficient: 4-6 inch thick floor to ceiling rockwool panels or filling the whole corner with a triangular array of rockwool? What size should the triangle be? what size should the panels be if instead that should be the way to go?

and btw is there a way to diffuse while also preventing modes from building up in the rear wall?

I know I have a lot of questions but any answer is greatly appreciated, acoustics was my least favorite assignment at school and now karma has got back to me , it looks like i didn't learn it well enough

BTW i've made all sorts of math predictions: RT60, room mode analysis etc etc that i can provide if needed, i'm fully open to actually measuring the room when the speakers arrive, i just don't know if it's of any use with a square room
Attached Thumbnails
Please help this miserable square room dweller-captura-de-pantalla-2020-06-02-la-s-23.43.46.jpg  
Old 4 weeks ago
  #2
Quote:
Originally Posted by Sonic Vitriol View Post

I know it will never be fixed and I know i must use a lot of broadband absorption to get the closest with solving the problem.
This is already part of your problem.

No broadband solution can compensate for bad mode distribution in a square space. The peaks and nulls will be so pronounced that even trapping the entire space will still have problems remaining.



Quote:
Originally Posted by Sonic Vitriol View Post
My goal here is not to make a perfect studio room but just to have a decent room to outlive university, to have a decent reference while mixing and hopefully even mastering and if i make my room nice for audio production for the remaining time i live here that's a great plus too.
While you state your goal is not to make a "perfect studio room" you still need certain criteria to be met in order to have a space where you can judge a reference for mixing and mastering.

It sounds like relying more on a pair of headphones that you trust will be your best bet. And then take things outside and listen on different systems to see how its translating.
Old 4 weeks ago
  #3
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Quote:
Originally Posted by thethrillfactor View Post

The peaks and nulls will be so pronounced that even trapping the entire space will still have problems remaining.
First of all, thanks for answering.

I know that, i'm just trying to do my best to try to overcome my limitations, I mean, it must be better than nothing.


Quote:
Originally Posted by thethrillfactor View Post

you still need certain criteria to be met in order to have a space where you can judge a reference for mixing and mastering.
My criteria is to attack early reflections to avoid comb filtering and help stereo image, to use diffusion in the rear wall, reduce the RT of the room and control some low end, to reduce the extreme modes in this room so that they are not as pronounced as they are, combine treatment with optimal placement and get the best i can out of it. I really don't know how you could quantify the parameter of improvement? maybe i'd like to improve its frequency response related to the triangle mix position at least by a factor of 50%?

I've done work in horrible rooms or without gear, i'm used to compensating and learning my system. Yes, I don't have a very specific criteria, but that is because I know there is no ultimate solution and because I'm not an expert in the field of acoustics, but I am fully aware of the idea that there is no way to get a completely reliable result in my case, which I'm okay with.

I'm looking at it from a harm reduction perspective: trying to get the most I can, even though I am aware that ultimately, some day I will have to build or find another room, that is one of the reasons i'm thinking about using semipermanent solutions.

Quote:
Originally Posted by thethrillfactor View Post

It sounds like relying more on a pair of headphones that you trust will be your best bet. And then take things outside and listen on different systems to see how its translating.
Yes, I will use that heavily for mixing reference, but i don't want to rely solely on headphones, in past experiences, i've done better mixing in another small and square room (a friend's place that I ended up learning to compensate for in my head) than with my old trusted SN HD280 pro, I love them, they are great references and I use them a lot, but I want to use monitors as well, even if i cant trust them completely, because i can't trust headphones completely as well, I know i'll have to check lots of references. I still want to make the most out of this room because this situation is what I have and there's no other way around.

Thank you for your advise, I was actually planning on doing that, using multiple references including headphones, but I don't think that approach is mutually exclusive with treating this room, I really do want to have at least a reasonable amount of certainty while doing critcal listening inside here. I don't think things are black or white, that either I need to make this a completely balanced room or i can't treat it at all.

I can understand if you do not wish to help me but making me have to justify or explain my motivations behind acoustic treatment does not really help. I'm sorry if me asking for this is an inconvenience or a nuisance.

In the end even if it was impossible to mix inside here, i still live here and i enjoy different types of media in this room, I'd like to improve the acoustic properties of it and I'd be infinitely grateful if you were willing to help to improve it even by 10%. Even that tiny improvement is worth it to me as I spend 90% of the time inside of this square space.

Have a great day.
Old 4 weeks ago
  #4
Quote:
Originally Posted by Sonic Vitriol View Post
BTW i've made all sorts of math predictions: RT60, room mode analysis etc etc that i can provide if needed, i'm fully open to actually measuring the room when the speakers arrive, i just don't know if it's of any use with a square room
Sure, you have a decent-sized room, why not?

PS: I think as soon as you improve your impulse response and reduce the decay times, mixing will get much easier.
Old 4 weeks ago
  #5
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Quote:
Originally Posted by johannburkard View Post
Sure, you have a decent-sized room, why not?

PS: I think as soon as you improve your impulse response and reduce the decay times, mixing will get much easier.
Alright, i'll do it then! Are measurements more important than theory regarding placement? (like in my original question, for example)

Also, before I measure: I've read in several places speakers should be separated by 1.2 meteres from the floor, is that a rule or should i place them a certain height depending on my ceiling? (maybe 39% to get them out of modes, or for destructive SBIR for example) im going to build sand filled stands, so idk what height they should be, I think the highest ear listening position I can get to in the chair I have is around 1.5 meters, my room height is 2.79m, that would mean 39% is around 1m from the floor or 1m from the ceiling (1.79 from the floor) those don't seem really possible solutions for my room and don't fit the 1.2m criteria
Old 4 weeks ago
  #6
Quote:
Originally Posted by Sonic Vitriol View Post
Are measurements more important than theory regarding placement? (like in my original question, for example)
I would say measurements are a certain representation of how sound behaves but who am I?

Also, I was hoping you wouldn't get back to your OP because I didn't feel like answering War & Peace.

Quote:
Originally Posted by Sonic Vitriol View Post
Also, before I measure: I've read in several places speakers should be separated by 1.2 meteres from the floor, is that a rule or should i place them a certain height depending on my ceiling?
You want the acoustic axis at the same height as your ears. If the manufacturer of your speakers doesn't publish that, use the height of tweeters. Your head moves...

Quote:
Originally Posted by Sonic Vitriol View Post
i'll have to move my desk away from the front wall and i'll be sitting in the center of a square room.
That's not a good idea because half the modes have a null in the middle of the room.

Quote:
Originally Posted by Sonic Vitriol View Post
What should I do?
Get an omni measurement microphone, REW and start measuring.

Quote:
Originally Posted by Sonic Vitriol View Post
what is worse, to be sitting on the center or to have SBIR buildups?
I would say unless you're sitting in a grass field, you can always have interferences.

Quote:
Originally Posted by Sonic Vitriol View Post
i just want to get the best acoustic performance i can with my room limitations.
I would put the speakers against the front wall and use as small a desk or workpad as possible.

Treatment: Front wall floor to ceiling to where you're sitting, ceiling, rear wall.

Quote:
Originally Posted by Sonic Vitriol View Post
btw is there a way to diffuse while also preventing modes from building up in the rear wall?
I wouldn't worry about diffusion initially.
Old 4 weeks ago
  #7
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Thanks a lot for your help, johannburkard. I'm so sorry, I was feeling very Tolstoian the other day I just had too many questions
I'll try to be more short and direct from now on


Quote:
Originally Posted by johannburkard View Post
You want the acoustic axis at the same height as your ears. If the manufacturer of your speakers doesn't publish that, use the height of tweeters. Your head moves...
But how high should my ears be? Is that not too important?

Thanks again



EDIT: NVM i found a thread regarding this after changing my search terms as "listening position"

height of the listening position.
Old 4 weeks ago
  #8
Quote:
Originally Posted by Sonic Vitriol View Post
But how high should my ears be? Is that not too important?
People like chairs so we don't have much choice there, I guess.
Old 4 weeks ago
  #9
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Quote:
Originally Posted by johannburkard View Post
People like chairs so we don't have much choice there, I guess.
i have a sliding chair so i thought i'd measure it out the way i have it set and yup, 1.20m from floor to ears, lol, i thought there was another reason about that


I measured my room, I'll attach the measurement files and screenshots for frequency response comparison and waterfall graphs.

Unfortunately i do not own a measurement microphone, the only omni directional mic own is an AKG P 420, this is its freq response:
http://recordinghacks.com/graphs2.php/0908

Bad news is that it has a drop from 50-100HZ of 6dB, is there a way to compensate for this in REW?

im thinking maybe i could eq a low pass in my DAW and route it to REW with soundflower but im afraid about latency, and about doing calibration right. I hope this measurements work

"Front wall" has my speakers 4 inches away from the front wall (i measured with open vs closed window and it didnt really change anything)

Front wall 39% Is the same placement setting but my "listening position" is at 39% of the room

"39%" Is the cardas square room recommendation and me sitting at the 39% Y position


I made this interpretations from the waterfall graph, please tell me if I'm wrong:

1.- 4 inches against the wall i have approx 20dB Modes in 30, 60, 90 and 128 Hz a bit of build up especially in lower frequencies

2.- In that same position but listening further away i have less drastic constructive sums, 10dB approx at 35, 93, 138 and 180.
5dB approx at 62, 66 and 200
BUT theres a very destructive sum at Hz that is just horrendous, could it be the mic freq response?
this one has a lot of frequency build ups

3.- Setting everything in the Cardas position and listening position at 39% of Y axis i have a more even response and less lasting energy resonation but still a massive drop at 50Hz, maybe I can use this position and a resonator? or maybe it is bigger because of my mic... hmmm... IDK because there are massive peaks too...
Peaks at 35, massive 85dB peak at 60
massive valleys at 50 and 75, the 75 valley worries me because that kinda makes the resonator idea feel like it would be more complex


What should I do?

BTW, johannburkard, Im already looking for a local rockwool dealer to make panels for your original suggestion, thanks a lot
Attached Thumbnails
Please help this miserable square room dweller-front-wall-waterfall.jpg   Please help this miserable square room dweller-39-waterfall.jpg   Please help this miserable square room dweller-front-wall-39-pos-waterfall.jpg   Please help this miserable square room dweller-clarity.jpg   Please help this miserable square room dweller-39-vs-front.jpg  

Please help this miserable square room dweller-impulse-response.jpg  
Attached Files
File Type: mdat Measurements sonic vitriol.mdat (8.74 MB, 6 views)
Old 4 weeks ago
  #10
Quote:
Originally Posted by Sonic Vitriol View Post
i have a sliding chair so i thought i'd measure it out the way i have it set and yup, 1.20m from floor to ears, lol, i thought there was another reason about that


I measured my room, I'll attach the measurement files and screenshots for frequency response comparison and waterfall graphs.

Unfortunately i do not own a measurement microphone, the only omni directional mic own is an AKG P 420, this is its freq response:
http://recordinghacks.com/graphs2.php/0908

Bad news is that it has a drop from 50-100HZ of 6dB, is there a way to compensate for this in REW?

im thinking maybe i could eq a low pass in my DAW and route it to REW with soundflower but im afraid about latency, and about doing calibration right. I hope this measurements work

"Front wall" has my speakers 4 inches away from the front wall (i measured with open vs closed window and it didnt really change anything)

Front wall 39% Is the same placement setting but my "listening position" is at 39% of the room

"39%" Is the cardas square room recommendation and me sitting at the 39% Y position


I made this interpretations from the waterfall graph, please tell me if I'm wrong:

1.- 4 inches against the wall i have approx 20dB Modes in 30, 60, 90 and 128 Hz a bit of build up especially in lower frequencies

2.- In that same position but listening further away i have less drastic constructive sums, 10dB approx at 35, 93, 138 and 180.
5dB approx at 62, 66 and 200
BUT theres a very destructive sum at Hz that is just horrendous, could it be the mic freq response?
this one has a lot of frequency build ups

3.- Setting everything in the Cardas position and listening position at 39% of Y axis i have a more even response and less lasting energy resonation but still a massive drop at 50Hz, maybe I can use this position and a resonator? or maybe it is bigger because of my mic... hmmm... IDK because there are massive peaks too...
Peaks at 35, massive 85dB peak at 60
massive valleys at 50 and 75, the 75 valley worries me because that kinda makes the resonator idea feel like it would be more complex


What should I do?

BTW, johannburkard, Im already looking for a local rockwool dealer to make panels for your original suggestion, thanks a lot
Something was wrong with the measurements.

You have at times too much low end distortion and at times to much noise in measurements. Check the card or mic or speakers that they aren't distorting or noisy.

Also try to measure left and right separately.

Lastly set the freq range from 20hz-20,000khz and 1 sweep.
Old 4 weeks ago
  #11
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Quote:
Originally Posted by thethrillfactor View Post
Something was wrong with the measurements.

You have at times too much low end distortion and at times to much noise in measurements. Check the card or mic or speakers that they aren't distorting or noisy.

Also try to measure left and right separately.

Lastly set the freq range from 20hz-20,000khz and 1 sweep.
I used the check level function between measurements and tried to set it to -18dB FS, ill do the regular level calibration each time then because maybe there was something wrong

Does it matter where im positioned when i so the measurement?

Should i do just l and r separately next time then?

Thanks for your help, ill add some better done files tomorrow
Old 4 weeks ago
  #12
Quote:
Originally Posted by Sonic Vitriol View Post
Should i do just l and r separately next time then?
Yes.

BTW: Your graphs, summarized: The room needs treatment.
Old 4 weeks ago
  #13
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Quote:
Originally Posted by johannburkard View Post
BTW: Your graphs, summarized: The room needs treatment.

Yeah... I'll get more informed on using REW and be very methodical to get good measurements just for the sake of having that recorded, i'll post those updates later.

I think right now with my immediate budget I can build about 12 (maybe even more) broadband rockwool panels (2ft x 4ft x 4in) , considering 8 corner panel traps (ill try to go 6in on them) a medium sized RFZ array and front or rear wall treatment. I plan on upgrading once I know whats the best way to go (what if i need helmholtz, membrane or other more expensive treatment and I already made 30 rockwool panels ).

This will probably take me around a week considering corona but I hope if I work like a mule it takes less

Ill post updates and measurements again when it's done, hopefully my course of action will be clearer then

thanks for helping me out guys



By the way for any people unexperienced with REW reading this looking for help: I realized i have a little bit of noise from my monitors because I am using unbalanced TS cables, I figured that may be contributing to some distortion and errors while measuring. I don't have my soldering iron with me so i'll have to order a pair of amazon TRS balanced cables.
Old 4 weeks ago
  #14
Quote:
Originally Posted by Sonic Vitriol View Post
Ill post updates and measurements again when it's done, hopefully my course of action will be clearer then
And pictures, to motivate others.
Old 4 weeks ago
  #15
Quote:
Originally Posted by Sonic Vitriol View Post
Yeah... I'll get more informed on using REW and be very methodical to get good measurements just for the sake of having that recorded, i'll post those updates later.

I think right now with my immediate budget I can build about 12 (maybe even more) broadband rockwool panels (2ft x 4ft x 4in) , considering 8 corner panel traps (ill try to go 6in on them) a medium sized RFZ array and front or rear wall treatment. I plan on upgrading once I know whats the best way to go (what if i need helmholtz, membrane or other more expensive treatment and I already made 30 rockwool panels ).

This will probably take me around a week considering corona but I hope if I work like a mule it takes less

Ill post updates and measurements again when it's done, hopefully my course of action will be clearer then

thanks for helping me out guys



By the way for any people unexperienced with REW reading this looking for help: I realized i have a little bit of noise from my monitors because I am using unbalanced TS cables, I figured that may be contributing to some distortion and errors while measuring. I don't have my soldering iron with me so i'll have to order a pair of amazon TRS balanced cables.
The distortion figures you are seeing in the low end have nothing to do with unbalanced cables. Also the noise figures spikes in the mid figures are not in every measurement.

Lastly to cut the decay down that show up as mountains in the waterfall, will need to be something more significant especially in the low end. You need something that targets the first order modes, 1-0-0, 0-1-0, and 0-0-1.

Before building a bunch of 2 x 4 traps that will soak up all the hi's and not tackle the issues in the low end, figure out first what can be realistically done for the 1st order modes. Then if you get that under some control you can attack the ETC and deal with the energy spikes with some broadband trapping.
Old 4 weeks ago
  #16
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Quote:
Originally Posted by thethrillfactor View Post
The distortion figures you are seeing in the low end have nothing to do with unbalanced cables. Also the noise figures spikes in the mid figures are not in every measurement.

Lastly to cut the decay down that show up as mountains in the waterfall, will need to be something more significant especially in the low end. You need something that targets the first order modes, 1-0-0, 0-1-0, and 0-0-1.

Before building a bunch of 2 x 4 traps that will soak up all the hi's and not tackle the issues in the low end, figure out first what can be realistically done for the 1st order modes. Then if you get that under some control you can attack the ETC and deal with the energy spikes with some broadband trapping.
Thank you, ill read more on the matter. Im guessing that would be along the lines of maybe helmholtz or some kind of tuned traps for the specific first order modes of the x and y axis. Placement would be completely out of my understanding but i suppose it would be near a hard boundary, be it in a corner or wall.
Anyway, I have some studying to do then. Thanks for correcting me, its some valuable info you are sharing.

Is there any way of predicting the most helpful (if any) monitor placement from the distorted measurements? Ill assume no and find what i did wrong and post updates anyway, but im completely lost regarding that.

Thanks again.
Old 4 weeks ago
  #17
Quote:
Originally Posted by Sonic Vitriol View Post
Thank you, ill read more on the matter. Im guessing that would be along the lines of maybe helmholtz or some kind of tuned traps for the specific first order modes of the x and y axis. Placement would be completely out of my understanding but i suppose it would be near a hard boundary, be it in a corner or wall.
Anyway, I have some studying to do then. Thanks for correcting me, its some valuable info you are sharing.

Is there any way of predicting the most helpful (if any) monitor placement from the distorted measurements? Ill assume no and find what i did wrong and post updates anyway, but im completely lost regarding that.

Thanks again.
REW has a room simulation tool and you can input all of your dimensions, listening position and speaker positions and you can move things around to see what kind of response you "might" get. I wrote "might" as it doesn't take into consideration if you have windows or doors or what materials your walls and ceiling is made of.

But it does give you an idea and I do use it theoretically to look at different positions before moving speakers which sometimes can be difficult if they are big and heavy.
Old 4 weeks ago
  #18
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Quote:
Originally Posted by thethrillfactor View Post
REW has a room simulation tool and you can input all of your dimensions, listening position and speaker positions and you can move things around to see what kind of response you "might" get. I wrote "might" as it doesn't take into consideration if you have windows or doors or what materials your walls and ceiling is made of.

But it does give you an idea and I do use it theoretically to look at different positions before moving speakers which sometimes can be difficult if they are big and heavy.
Thanks for this tip, after checking measurements, REW room simulation tool and this room calculator
https://amcoustics.com/tools/amroc?l...68&h=279&r60=1

it seems like my room fits the predictions: after seeing every calculation and measurement point to 36.3-36.6 HZ as the first order mode i checked and yes, that is the loudest point you get in that band and boy did it shake my room and furniture

I did a modal distribution map of both modes by ear because I realized one of my cables is probably desoldering or breaking from extensive use and is distorting fast transients (switched cables and the issue switched to the other monitor) but I will measure it with REW when i get them replaced

36Hz are completely null at the center, almost inaudible, and at that same x axis value (center or 0) it goes up a little and then dies completely again at the right boundary (theres a bathroom and a wardrobe room in that wall), it becomes a little bit dampened but not dead at the center of the left boundary. front right and rear right corners did not have such a big buildup (there's doors in both corners) the most extreme buildups are the left corners and the center of the front and back boundaries. The 39% rule seems to apply here as it evens up, though, hard to know how much by ear, it could help tho, so ill take it into account and try to measure it correctly next time.

My 1-1-0 mode is the null around 51-52 HZ, it dies pretty much everywhere except at the rear wall, left corners and the 39% listening position, right corners have some pressure too but not as much

I checked this site
http://www.mh-audio.nl/acoustics/CancellationFreq.html
Unfortunately to use SBIR in my advantage against 30Hz I would have to place the speakers or sit at about 3m from the front wall, which is not a good idea because of the rear wall

My next step is getting informed on what is a realistic way to trap that 36Hz mode, especially a cost effective, or even if its more expensive, a very effective one, i'd go for Helmholtz resonators but im still not sure about that since it looks like a DIY design can be not too effective, so im trying to find another solution, if there is not another one then I could make 3 DIY Helmholtz resonators and place one at the back and one at the two problematic corners, since from what ive seen most of them help with about 5-10dB in the best case scenarios, this being a square room makes me think it wont be one of those. The design also worries me, because i cant really find a good methodology online but ill keep searching

Here's two Arqen bass traps that might work but I don't know if they'll help all the way to 30Hz:

http://arqen.com/bass-traps-101/placement-guide/
Superchunk Bass trap and edge absorver (looks like a broadband trap to me), although I'm skeptical I'll continue to investigate

I found one recommended by a BBC study theres no data below around 35Hz and the absorption coefficient seems to go down below 40 cycles...

Haven't been able to find a real solution by now, might try to look for local acousticians and ask for the price of a Helmholtz or another resonator that has a narrow Q for most effectiveness since i don't think I can get that shipped because of its size but ill keep trying to find a solution I can build myself to lower costs since i figure something like that must be pretty expensive
Old 4 weeks ago
  #19
Quote:
Originally Posted by Sonic Vitriol View Post
Thanks for this tip, after checking measurements, REW room simulation tool and this room calculator
https://amcoustics.com/tools/amroc?l...68&h=279&r60=1

it seems like my room fits the predictions: after seeing every calculation and measurement point to 36.3-36.6 HZ as the first order mode i checked and yes, that is the loudest point you get in that band and boy did it shake my room and furniture

I did a modal distribution map of both modes by ear because I realized one of my cables is probably desoldering or breaking from extensive use and is distorting fast transients (switched cables and the issue switched to the other monitor) but I will measure it with REW when i get them replaced

36Hz are completely null at the center, almost inaudible, and at that same x axis value (center or 0) it goes up a little and then dies completely again at the right boundary (theres a bathroom and a wardrobe room in that wall), it becomes a little bit dampened but not dead at the center of the left boundary. front right and rear right corners did not have such a big buildup (there's doors in both corners) the most extreme buildups are the left corners and the center of the front and back boundaries. The 39% rule seems to apply here as it evens up, though, hard to know how much by ear, it could help tho, so ill take it into account and try to measure it correctly next time.

My 1-1-0 mode is the null around 51-52 HZ, it dies pretty much everywhere except at the rear wall, left corners and the 39% listening position, right corners have some pressure too but not as much

I checked this site
http://www.mh-audio.nl/acoustics/CancellationFreq.html
Unfortunately to use SBIR in my advantage against 30Hz I would have to place the speakers or sit at about 3m from the front wall, which is not a good idea because of the rear wall

My next step is getting informed on what is a realistic way to trap that 36Hz mode, especially a cost effective, or even if its more expensive, a very effective one, i'd go for Helmholtz resonators but im still not sure about that since it looks like a DIY design can be not too effective, so im trying to find another solution, if there is not another one then I could make 3 DIY Helmholtz resonators and place one at the back and one at the two problematic corners, since from what ive seen most of them help with about 5-10dB in the best case scenarios, this being a square room makes me think it wont be one of those. The design also worries me, because i cant really find a good methodology online but ill keep searching

Here's two Arqen bass traps that might work but I don't know if they'll help all the way to 30Hz:

http://arqen.com/bass-traps-101/placement-guide/
Superchunk Bass trap and edge absorver (looks like a broadband trap to me), although I'm skeptical I'll continue to investigate

I found one recommended by a BBC study theres no data below around 35Hz and the absorption coefficient seems to go down below 40 cycles...

Haven't been able to find a real solution by now, might try to look for local acousticians and ask for the price of a Helmholtz or another resonator that has a narrow Q for most effectiveness since i don't think I can get that shipped because of its size but ill keep trying to find a solution I can build myself to lower costs since i figure something like that must be pretty expensive
Your waterfall and spectogram are showing 37.6 hz, but the minimum phase is showing is 36.9hz & 37.3.

You need a membrane trap around these frequencies(front wall and backwall). You could also use EQ at the end to bring down the peak if needed.

The big nulls around 47-49hz is SBIR. This will be much more difficult to fix and finding the right positioning( speaker/listening) will be the challenge.
Old 4 weeks ago
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Would the limp mass resonator of "build it like the pros work" or what type of membrane trap do you recommend? would making the grid 1/8 inch instead of 1/4inch help?
Im thinking about combining it with rockwool tubes

and regarding the null, time to move everything around then, thanks

ill adjust my speaker's room control too, and try with it, ill also try with an eq

thank you very much, i'll try switching front and rear walls and different positions and then ill do my room design based on what i find, after I get closer to flatten the room, as much as it is possible, of course, Ill post an in depth guide of how i did it for anyone looking for treating square rooms in the future
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