sud98
Well-Known Member
How did you change the waterfall and is it something wrong I did.
Ran REW, now what?
- Thread starter sud98
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sound_cycle
Well-Known Member
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 ?
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
elangoas
Well-Known Member
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..
sound_cycle
Well-Known Member
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
elangoas
Well-Known Member
What would be the solution to address peak's ?
sound_cycle
Well-Known Member
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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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
elangoas
Well-Known Member
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 ?..
These traps have imposing sizes..looks big & heavy..
Below 50Hz, is DSP the only solution?..
These can be used to target below 50hz.
GIK Acoustics Scopus Tuned Membrane Bass Trap (T40)
Cheers,
Sid
elangoas
Well-Known Member
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..
sud98
Well-Known Member
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
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.
sud98
Well-Known Member
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.
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.
sound_cycle
Well-Known Member
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
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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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.
sud98
Well-Known Member
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.
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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