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Decent RT60 Time but Still Have Drowning Out Bass in Waterfall Plot.

Trdat

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I am a little confused how a significantly large space can still exhibit so much decay on the waterfall plot when the RT60 time is actually quit decent for such a large venue. Have I read the measurments wrong?

To put the issue in perspective the room is large 300m2 with a vaulted ceiling and is 17 metres back to front and 23 metres from one side to the other. I was under impression that bass waves would potentially drown out in larger spaces.

The only thing I can think of is that the overall RT60 is decent but the side walls(possibly front wall) are still bouncing bass waves back into the room causing ringing. Or possibly some noise in measurement?

Any insight would be helpful...
 
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Trdat

Trdat

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I don't think you can upload MDAT files, it didn't upload.

I attached the waterfall and RT60 of just the left side. Let me know if the controls are correct, I can change them if need be.
 

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abdo123

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I don't think you can upload MDAT files, it didn't upload.

I attached the waterfall and RT60 of just the left side. Let me know if the controls are correct, I can change them if need be.

decay time in seconds increment is not very usefull when the target should be in 200-400 milliseconds.
 
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Trdat

Trdat

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decay time in seconds increment is not very usefull when the target should be in 200-400 milliseconds.
Your refering to the settings?

What do I change and what to?
 

dasdoing

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adjust the lower level of the waterfall until you filter all the noise out. you want to see the modes clearly, like so (also 30-200Hz range):


ggg.jpg
 

dasdoing

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but I think you need to sweep louder. hard to see though.

a good way to have a clean water fall is to do a "quiet sweep", adjust the lower level so the noise waterfall disapears. than you sweep your speakers and all you see is speaker
 

Rick Sykora

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I don't think you can upload MDAT files, it didn't upload.

I attached the waterfall and RT60 of just the left side. Let me know if the controls are correct, I can change them if need be.

if you still want to share the mdat, try compressing it and then should upload.:cool:
 
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Trdat

Trdat

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decay time in seconds increment is not very usefull when the target should be in 200-400 milliseconds.
If I have understood you correctly your talking about a target for small room acoustics right? The venue is a large and just bellow 2sec is fairly good considering. But the funny thing is I have a similar problem with my small room so I want to rule out any problems in my measuring or if there is a theory or concept I have not yet fully got a grasp of in terms of RT60 and decay times.
 

abdo123

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If I have understood you correctly your talking about a target for small room acoustics right? The venue is a large and just bellow 2sec is fairly good considering. But the funny thing is I have a similar problem with my small room so I want to rule out any problems in my measuring or if there is a theory or concept I have not yet fully got a grasp of in terms of RT60 and decay times.
the most elaborant cathedrals in the world might have 3 to 6 seconds reverb time, but these venues are not really used to record or play stuff and the reverb does not come off as modal / tonal issues because of how gigantic the place is, the room modes would be in the 1-10Hz region.

I don't have much experience with large venues and indeed the target i shared is for home cinema / music in a residential space (room modes in the audible spectrum).
 
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Trdat

Trdat

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adjust the lower level of the waterfall until you filter all the noise out. you want to see the modes clearly, like so (also 30-200Hz range):

Does this look better?

1643475356536.jpeg
 
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Trdat

Trdat

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if you still want to share the mdat, try compressing it and then should upload.:cool:
I tried compressing it and it still says file to large(I will try again though). I presuming with a truncated file to 9.9 sec in REW the file might be very large.
 
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Trdat

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According to some other study I read 1.3 sec usually are the best sounding rooms but not much difference between 1.3 and 1.5. I suppose getting it down to around 1.5 would be a massive improvement. The hall has many helmontz type absorber cavities if I may call it that. With the ceiling itself having a 60cm gap between the plasterboard and the concrete above with many other places that have box type designs that might act like a absorber. Plus the back wall is mainly window allowing the bass to pretty much get out. The vaulted celing which rises to 9m in the middle so had a feeling the RT60 wasn't going to be that bad. I am just trying to get my head around the waterfall plot.
 

dasdoing

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I think it is mostly noise. modes wont go up and down like that. the meassurement needs to be significantly louder than the background noise.
on the other hand, I have no clue how waterfalls in big spaces are suppoused to look like

thinking it over again. since 1,5 seconds would be the xpected, you have to make the window and time range big enough acordingly
 
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Trdat

Trdat

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PA guys are the right people to ask for this room

Yeh will pop it up in the prosound forum. I didn't know there could be anomalies in the measurement regardless if it is from teh interpretation. I just wanted to see if I had missed a concept if and when the RT60 is decent but the waterfall plot is haywire but yeh a PA guy will get better understanding of what is going on.
 
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