Ran REW, now what?

Redid your waterfall plot. That does not look too bad to me.

https://photos.app.goo.gl/iaQgudkVz3NnFn9y2

I've scaled it to about 30 db below the max, and that is probably not loud enough to be heard.

Having said that, the worst issue - the hill that marches right up to all most 450ms is at ~ 60 Hz and by 120 Hz or so the ringing seems to be below 350 ms.

ciao
gr
How did you change the waterfall and is it something wrong I did.
 
The only thing that helped is loading the filters onto Dirac processor and then running rew. It then controlled a major amount of the dips and peaks.

Does that mean I need to use parametric eq to manage this besides traps and diffuser?

Positioning, treatment and correction are all useful tools. And correction is at the end of that sequence of steps/ actions. I would think that you will benefit from the first two steps (and I am assuming that you have not implemented #2, I could be wrong)

How did you test Dirac results with REW ?

How did you change the waterfall and is it something wrong I did.

I found a peak at about 100 db and scaled y to about 30 or 35 db below that, the other parameters are in the screen shot. I have to look at it to recollect.

ciao
gr
 
Positioning, treatment and correction are all useful tools. And correction is at the end of that sequence of steps/ actions. I would think that you will benefit from the first two steps (and I am assuming that you have not implemented #2, I could be wrong)

I came across this chart - Wavelength of frequency - http://www.jdbsound.com/art/frequency%20wave%20length%20chart%202013.pdf

W.r.t bass <= 250hz, due to thickness of the traps reqd to contain the respective wavelength seems impractical in a room.. So positioning & EQ correction look to be the only possible solution..I believe this is one of the reasons, why more than one sub is reqd to tame the peaks & dips..
 
How did you change the waterfall and is it something wrong I did.

https://photos.app.goo.gl/qhp4c4giZvPBGp7f1
The settings I used


https://photos.app.goo.gl/4LyrKtqlNcnUExLC2
The waterfall plot with a reworked x/y axis.

I think that your biggest problems are the hills that are matching forward and are relatively high - the ringing issues are the worst here.

Also calculated your room modes

https://amcoustics.com/tools/amroc?l=15&w=12&h=9&ft=true&r60=0.6

See the 3d room on the webpage. It has a panel called the bolt area and for your room "If the red cross lies within this area you have a good chance of more evenly distributed modes" it does.

There are also recommendations on absorption needed

ciao
gr
 
What would be the solution to address peak's ?


RPG Modex Plate - Acoustic Products

OR

SpringTrap Bass Trap

OR

Cumulus Tri-Corner Bass Trap | Primacoustic

OR

https://acousticalsolutions.com/product-category/ceiling-treatments/ceiling-clouds/

OR

https://community.roonlabs.com/t/a-guide-how-to-do-room-correction-and-use-it-in-roon/23800


AFAIK DSP is the only answer for pretty much everything below ~ 100 Hz. Glad to be corrected, if wrong

And I guess crossover and speaker correction, or dual subs or many others. There must be many other I have no clue about.

ciao
gr
 
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AFAIK DSP is the only answer for pretty much everything below ~ 100 Hz. Glad to be corrected, if wrong

ciao
gr

Not really sound_cycle:
this works till 50hz
http://www.gikacoustics.com/wp-content/uploads/2012/08/GIK-Tri-Trap-Corner-Bass-Trap-Datasheet.pdf
I have these which work till 80 hz
http://www.gikacoustics.com/wp-cont...ass-Trap-w-FlexRange-Technology-Datasheet.pdf
And when placed in a corner with an air gap behind them they absorb even lower than 80hz. I have measured their effect in my room.
Cheers,
Sid
 
AFAIK DSP is the only answer for pretty much everything below ~ 100 Hz.

And I guess crossover and speaker correction, or dual subs or many others. There must be many other I have no clue about.

Letz take the OP case as example.. Per the attached PDF (Wavelength/thickness to trap), a 91 inch trap is reqd for a 37Hz.. That is approx 7.5 feet thick.. I understand thickness, but unsure of what area [1' x 1' (or) 2' x 2'] should one target at and at what locations ?..

Not really sound_cycle:
this works till 50hz
http://www.gikacoustics.com/wp-content/uploads/2012/08/GIK-Tri-Trap-Corner-Bass-Trap-Datasheet.pdf
I have these which work till 80 hz
http://www.gikacoustics.com/wp-cont...ass-Trap-w-FlexRange-Technology-Datasheet.pdf
And when placed in a corner with an air gap behind them they absorb even lower than 80hz. I have measured their effect in my room.
Cheers,
Sid

These traps have imposing sizes..looks big & heavy..

Below 50Hz, is DSP the only solution?..
 
These are even heavier (15kgs) than the one's in previous links (7 Kgs)..

Few questions for clarity..

What is more important ?.. Surface area of these panels (or) thickness (or) both.. Bcoz the panels in the above link are 2' H x 2' W x 1' D..

I have no idea Elangoas. Just know that they work great.
Cheers,
Sid
 
Unfortunately, gik has closed its Indian dealer so we need to import which is difficult for bass traps

Sent from my ONE A2003 using Tapatalk

I think there are other suppliers in India. Google should be able to help.
Cheers,
Sid
 
The room dimension is 15'2"*11'10"*8'9"
Room modes (resonances) for a 15'2" dimension are multiples of 37Hz (37Hz, 74Hz, 112Hz, etc). Is the 15'2" dimension the width or the length?
Does that mean I need to use parametric eq to manage this besides traps and diffuser?
One single band of PEQ can bring down the 37Hz peak. But it is better to find out why you're getting a peak and see if it is possible to fix it using placement. Moving a subwoofer or your seating doesn't cost anything. So before spending more money, first fix whatever problems you can using placement.
 
I tried different placements, including pull the speakers by around 4 feet and still I find the 37hz hump. I kept my door open, still it comes. So I wonder is it something else, like the APC UPS which is kept outside the room, but is it possible thats the hum. My speakers I am quite sure dont go below 50hz (55 as per rating).

Unfortunately, there is no way I can run the speakers without the UPS, unless I find a way to short them.

Maybe I will try and keep the mic next to the ups and put my speaker volume to zero and check again.
 
I wonder is it something else, like the APC UPS which is kept outside the room, but is it possible thats the hum. My speakers I am quite sure dont go below 50hz (55 as per rating)

Ah! Like I thought.

Identifying the source is one issue, then.

What you could do for a simpler solution would be to control the lower end of the sweep tone REW plays for the measurement. Start from 55 Hz.

I have to look up the manual, but IIRC you can average sweeps or use longer ones or something to get rid of b/g noise. In my case it is the fridge that has a better bass extension than my speakers :rolleyes:

PS: have you tried the audiobeat method / pink noise in mono positioning. I found that works well for me. Then I would make the measurement at the centre of the listening position. Check distances to the speakers you want it to be the same, within an mm. The general recommendation is to have the mic pointing at the speakers, but I read somewhere that it is better to have it pointing upwards and that is what I follow (with the 90 deg cal file)

ciao
gr
 
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I tried different placements, including pull the speakers by around 4 feet and still I find the 37hz hump.
IF 37Hz is being reproduced by your sub, then moving the speakers isn't going to have any effect. As mentioned before, can you post measurements from a couple feet forward and rearward of your listening position? And unplug your speakers; measure just the sub.
 
Room modes (resonances) for a 15'2" dimension are multiples of 37Hz (37Hz, 74Hz, 112Hz, etc). Is the 15'2" dimension the width or the length? One single band of PEQ can bring down the 37Hz peak. But it is better to find out why you're getting a peak and see if it is possible to fix it using placement. Moving a subwoofer or your seating doesn't cost anything. So before spending more money, first fix whatever problems you can using placement.

15'2" is the length of the room.

If you see the post 3 of this thread, the multiple graphs posted are by using mono speakers (only left, only right), two channel (left+right), and with both channels plus sub. The 37db peak is there in all four. I can try the sub alone too and check if that helps.

Probably this wednesday being a holiday will dismantle my entire setup and check if there are other causes to this.
 
If you see the post 3 of this thread, the multiple graphs posted are by using mono speakers (only left, only right), two channel (left+right), and with both channels plus sub. The 37db peak is there in all four.
I'll ask for a third and last time: can you post measurements from a couple feet forward and rearward of your listening position?
 
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