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FR vs Waterfall chart for analyzing room measreuments
Old 7th September 2019
  #1
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FR vs Waterfall chart for analyzing room measreuments

In a sticky in this forum it said that the FR is less important but I want to know why and if this is the case?
I posted my measurement results in another post but in the meantime, just in case I don't have the good fortune of someone looking at them, I would like to learn to interpret them myself. So here I am adding 2 charts from my room measurements and have some very simple questions. I don't understand which I should pay attention to and why. The waterfall looks ok because there isn't a long decay time in the low end but the FR is all over the place. How can there be this disparity and how should I interpret this?



thanks
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-1.jpg   FR vs Waterfall chart for analyzing room measreuments-2.jpg  
Old 7th September 2019
  #2
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Quote:
Originally Posted by camomiletea View Post
In a sticky in this forum it said that the FR is less important but I want to know why and if this is the case?
I posted my measurement results in another post but in the meantime, just in case I don't have the good fortune of someone looking at them, I would like to learn to interpret them myself. So here I am adding 2 charts from my room measurements and have some very simple questions. I don't understand which I should pay attention to and why. The waterfall looks ok because there isn't a long decay time in the low end but the FR is all over the place. How can there be this disparity and how should I interpret this?



thanks
Is it one speaker or the two measured in the same time?
Old 7th September 2019
  #3
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Both but I measured very precisely the mid point between the two where my head is in listtening position.
Old 8th September 2019
  #4
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Quote:
Both but I measured very precisely the mid point between the two where my head is in listtening position.
You still need to measure them individually. There will be strong interaction of the two sources at the mix position in the high frequencies, with phase cancellation, the resultant comb filtering, and other effects, that will make it impossible to see what's really happening. Also, there's no way of comparing the differences between the two channels, if you don't measure both of them separately.


- Stuart -
Old 8th September 2019
  #5
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Quote:
Originally Posted by Soundman2020 View Post
You still need to measure them individually. There will be strong interaction of the two sources at the mix position in the high frequencies, with phase cancellation, the resultant comb filtering, and other effects, that will make it impossible to see what's really happening. Also, there's no way of comparing the differences between the two channels, if you don't measure both of them separately.


- Stuart -
Understood. Here are the measurements of all of them. Seperately. Since I have 2 sets of speakers, I did tests with both sets. I only generated waterfall graphs for my Yamaha speakers however.

Now that I have this data. What can i make of it? The SPL still bothers me but I read somewhere that even in professional rooms there can be varitions of 10db.

Waiting for your response, thanks Stuart.
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-krkl-r.jpg   FR vs Waterfall chart for analyzing room measreuments-krkleft.jpg   FR vs Waterfall chart for analyzing room measreuments-krkright.jpg   FR vs Waterfall chart for analyzing room measreuments-yamahal-r.jpg   FR vs Waterfall chart for analyzing room measreuments-yamahaleft.jpg  

FR vs Waterfall chart for analyzing room measreuments-yamahaleftwaterfall.jpg   FR vs Waterfall chart for analyzing room measreuments-yamaharight.jpg   FR vs Waterfall chart for analyzing room measreuments-yamaharightwaterfall.jpg  
Old 8th September 2019
  #6
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akebrake's Avatar
 

Corrupt measurement?

Quote:
Originally Posted by camomiletea View Post
Now that I have this data. What can i make of it? ...
For a start we have to find out if your measurements are valid.
Then we can go into detail. (The first one looks a bit strange IMHO)

Pls upload your mdat here

Best

Last edited by akebrake; 8th September 2019 at 09:28 AM.. Reason: typo
Old 8th September 2019
  #7
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Quote:
Originally Posted by akebrake View Post
For a start we have to find out if your measurements are valid.
The we can go into detail. (The first one looks a bit strange IMHO)

Pls upload yor mdat here

Best
Here is the MDAT file.

I will add that when I open to take measurements I get this warning message saying "SPL meter reading has not been calibrated"

Do I have to do this? In the GIK tutorial, there was nothing about this so I jsut ignored the message.
Attached Files
File Type: mdat Sunday08092019.mdat (10.66 MB, 12 views)
Old 8th September 2019
  #8
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akebrake's Avatar
 

Quote:
Originally Posted by camomiletea View Post
Here is the MDAT file.

I will add that when I open to take measurements I get this warning message saying "SPL meter reading has not been calibrated"

Do I have to do this?
You can ignore it. The warning appears because you have not inserted an "SPL value" into the "system"
E.g. REW don't know the sensitive of your microphone, how much preamp gain you have added or how loud you are playing.

So ALL (absolute) SPL/ dB values are wrong. (default)

Comparing levels are OK (relative levels)

Hope that helps

PS If you have an USB microphone (with Mic Cal and sensitivity included in the loaded text file) the shown dB/SPL values are shown more correctly.
Old 8th September 2019
  #9
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Quote:
Originally Posted by akebrake View Post
You can ignore it. The warning appears because you have not inserted an "SPL value" into the "system"
E.g. REW don't know the sensitive of your microphone, how much preamp gain you have added or how loud you are playing.

So ALL (absolute) SPL/ dB values are wrong. (default)

Comparing levels are OK (relative levels)

Hope that helps

PS If you have an USB microphone (with Mic Cal and sensitivity included in the loaded text file) the shown dB/SPL values are shown more correctly.
Oh ok . I dont have a usb microphone and I am using just an Oktava mk012 omni mic . Why did you say the measurements look strange?
Old 8th September 2019
  #10
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akebrake's Avatar
 

Room Info

Quote:
Originally Posted by camomiletea View Post
Why did you say the measurements look strange?
I'll look into that later to day 'cause I'm busy with other stuff.

Can you show us a sketch/ photo of your room/spkr setup?
Kind of walls, ceiling, floor openings windows etc.

Best
Old 8th September 2019
  #11
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Quote:
Originally Posted by akebrake View Post
I'll look into that later to day 'cause I'm busy with other stuff.

Can you show us a sketch/ photo of your room/spkr setup?
Kind of walls, ceiling, floor openings windows etc.

Best
Yeah sure, anything that can help. I did something quick in Adobe illustrator. It shows the room to scale and the yellow part is the low density absorption. The absorption is around 40cm all around (including ceiling) except for the corners which is a bit thicker. Then I have slats on the walls too, not everywhere though. For example 1st reflection points have no slats. The floor is laminate flooring. Oh and the ceiling heighr before treatment is 290 - 293cm.

The walls themselves behind the treatment are concrete except for the north and south wall which are drywall.

hope that helps. will check back in a bit and see if you need any other details.

thanks
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-room.jpg  
Old 9th September 2019
  #12
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Quote:
Originally Posted by akebrake View Post
I'll look into that later to day 'cause I'm busy with other stuff.

Can you show us a sketch/ photo of your room/spkr setup?
Kind of walls, ceiling, floor openings windows etc.

Best
Was the info I sent you good enough? Please let me know if there is something else you need.
Old 9th September 2019
  #13
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Quote:
Originally Posted by akebrake View Post
I'll look into that later to day 'cause I'm busy with other stuff.

Can you show us a sketch/ photo of your room/spkr setup?
Kind of walls, ceiling, floor openings windows etc.

Best
I have been studying as much as possible and from what I can tell, the waterfall graph is good because in the low end the bass notes dont take too long to decay. But I dont understand why there is so much discrepancy with the FR CHART. The 150 hz region especially seems louder than everything else. What can be causing this? Can it be fixed?
Old 9th September 2019
  #14
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Rule out errors

Quote:
Originally Posted by camomiletea View Post
Was the info I sent you good enough? Please let me know if there is something else you need.
The measurements shows fairly high distortion, strong early reflections, resonances and and lack of bass.

I want to find out what causes one or more of these problems. Is it:
1. Monitoring level? Too loud= Speaker distortion.
2. Placement of speakers?
3. Microphone problems?
4. Reflecting surfaces/objects close to speaker or mic? Shelf, Desk , computer monitor, chair, alt. speakers, mic stand/ clamp
5. Interfaceproblems? Sample rate differences. Soundcard settings?
6. Resonance of desk/ shelf /stands/ doors..

A photo of your setup might give a clue here and one can then try alternative test methods to rule out more of the possible causes.

Best
Old 9th September 2019
  #15
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Quote:
Originally Posted by akebrake View Post
The measurements shows fairly high distortion, strong early reflections, resonances and and lack of bass.

I want to find out what causes one or more of these problems. Is it:
1. Monitoring level? Too loud= Speaker distortion.
2. Placement of speakers?
3. Microphone problems?
4. Reflecting surfaces/objects close to speaker or mic? Shelf, Desk , computer monitor, chair, alt. speakers, mic stand/ clamp
5. Interfaceproblems? Sample rate differences. Soundcard settings?
6. Resonance of desk/ shelf /stands/ doors..

A photo of your setup might give a clue here and one can then try alternative test methods to rule out more of the possible causes.

Best
Ok well here is a photo of my studio space. Where do you see distortion in the measurement results?

Quote:
1. Monitoring level? Too loud= Speaker distortion.
I can try lower level and do new tests but the monitors weren't all that loud
Quote:
2. Placement of speakers?
Ok so I feel like asking you where they should be but I get the feeling you will tell me that you need to experiment with this? is this correct?
Quote:
3. Microphone problems?
I have two omni microphones. They are the stereo pair from Oktava so I can try either of them but it would be handy to know where you consider this "distortion"
Quote:
4. Reflecting surfaces/objects close to speaker or mic? Shelf, Desk , computer monitor, chair, alt. speakers, mic stand/ clamp
Could be my desk or the slats on the walls, those are the only things I can think of. I will try and remove the desk and see what comes up. It would be good if you can tell me what we are looking for in the measurement results so I can see if trying things makes a difference.
Quote:
5. Interfaceproblems? Sample rate differences. Soundcard settings?
My sample rate is 44.1khz on my focusrite interface.
Quote:
6. Resonance of desk/ shelf /stands/ doors..
the only thing that I think can cause a resonance inside the room are my acoustic guitars and hand percussion. Shall I take those out? Unless...hmmm, I wonder if the space between the two doors can cause resonance problems. I have double doors on both sides as you can see in the sketchup I did.

Otherwise, please let me know if you think I should do something specific to adress these issuse. Right now I am going to start with the table removal

Thanks!
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-20190908_123600.jpg  
Old 9th September 2019
  #16
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Maybe start with measuring with the speaker(s) against the front wall instead of a meter or so from the wall
Old 9th September 2019
  #17
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Ok so here are some new measurements.

1) I took out the KRKs to keep things more simple. I removed desk, all guitars, percussion and pretty much everything else.

I notice now a dip at 337Hz. This is just my guess but doesn't that frequency coincide with the distance between the two doors in some way (around 640cm). those are the only two adjacent hard surfaces in the room and although I put some light treatment on there to remove the flutter echo issues, it may still be a problem for that frequency range. just a guess so let me know what you think.
Attached Files
File Type: mdat Monday09092019am.mdat (5.32 MB, 6 views)
Old 9th September 2019
  #18
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Quote:
Originally Posted by bert stoltenborg View Post
Maybe start with measuring with the speaker(s) against the front wall instead of a meter or so from the wall
THanks for the tip. Interesting how the results change. There seems more bass now but a dip at around 130Hz

What do you think about the results? I guess I could play around all day moving speakers to try and get the best frequency response in the room. What do you think about that? I mean if the frequency response changes so drastically with the speakers closer to the back, there could be a million variations to try. We could be here a while
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-speakersclosertobackwall.jpg  
Attached Files
File Type: mdat Monday09092019am2.mdat (5.33 MB, 5 views)
Old 9th September 2019
  #19
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speakers even closer to back wall

This time I moved them back even further and when I did the right speaker, I noticed that these peaks and valleys are multiples of each other. 170hz, 340hz, 680hz etc etc. Is there something helpful here?
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-1-copy.jpg  
Old 9th September 2019
  #20
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Quote:
Originally Posted by camomiletea View Post
This time I moved them back even further and when I did the right speaker, I noticed that these peaks and valleys are multiples of each other. 170hz, 340hz, 680hz etc etc. Is there something helpful here?
The smooth must be in 1/24 dbo

Thr deep are little and showing without smoothing, there are not a big issue and due to the free standing use.

The level of high frequency is low?

Last edited by dinococcus; 9th September 2019 at 12:42 PM..
Old 9th September 2019
  #21
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Quote:
Originally Posted by dinococcus View Post
The smooth must be in 1/24 dbo

Thr deep are little and showing without smoothing, there are not a big issue and due to the free standing use.

The level of high frequency is low?
I have attached the same one with smoothing but I still see peaks and valleys of around 10 -12db so what difference does smoothing make?

2 more questions please:
1)What do you mean "there are not a big issue"?
2)what do you mean by "free standing use"?
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-3smoothed.jpg  
Old 9th September 2019
  #22
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Quote:
Originally Posted by camomiletea View Post
I have attached the same one with smoothing but I still see peaks and valleys of around 10 -12db so what difference does smoothing make?

2 more questions please:
1)What do you mean "there are not a big issue"?
2)what do you mean by "free standing use"?

1) easy to fix regarding the frequency when the source of the deeps will be find.

2)speakers on stand with a woofer far from the floor. Cause of sound cancelation.
Old 9th September 2019
  #23
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Quote:
Originally Posted by dinococcus View Post
1) easy to fix regarding the frequency when the source of the deeps will be find.
Ok could you give me a suggestion on how to treat this? My entire walls and ceiling are treated. So not sure what you mean.

Quote:
Originally Posted by dinococcus View Post
speakers on stand with a woofer far from the floor. Cause of sound cancelation.
Oh you are saying that because I dont have a subwoofer it will be easier to fix?
Old 9th September 2019
  #24
Gear Addict
 

Speakers should ideally be integrated in the wall.
At lower frequencies the speaker becomes omni directional and when the speaker is positioned in front of a wall youi get direct sound and delayed sound from the wall reflection causing problems.
Same goes for the reflection from the floor.
The floor reflection is according to some sources from a psycho acoustical point of view not as annoying as reflections from other room boundaries.

If you cannot flush mount the speaker you put it against the wall and put absorption around it.
Old 9th September 2019
  #25
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Quote:
Originally Posted by camomiletea View Post
Ok could you give me a suggestion on how to treat this? My entire walls and ceiling are treated. So not sure what you mean.


Oh you are saying that because I dont have a subwoofer it will be easier to fix?
The Woofer far from the floor is an issue so two sub in stereo could be a solution.
Old 9th September 2019
  #26
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Quote:
Originally Posted by bert stoltenborg View Post
Speakers should ideally be integrated in the wall.
At lower frequencies the speaker becomes omni directional and when the speaker is positioned in front of a wall youi get direct sound and delayed sound from the wall reflection causing problems.
Same goes for the reflection from the floor.
The floor reflection is according to some sources from a psycho acoustical point of view not as annoying as reflections from other room boundaries.

If you cannot flush mount the speaker you put it against the wall and put absorption around it.
Did you see the drawing above of my studio? I think you didn't see it because there you can see that all the walls are absorption. The speaker even up against the wall is not up against the wall because there is a layer of absorption behind it 40cm thick.
Old 9th September 2019
  #27
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Quote:
Originally Posted by dinococcus View Post
The Woofer far from the floor is an issue so two sub in stereo could be a solution.
I don't have subwoofers. Are you saying I need to get subwoofers to fix the problem
Old 9th September 2019
  #28
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Quote:
Originally Posted by camomiletea View Post
I don't have subwoofers. Are you saying I need to get subwoofers to fix the problem
No, for me this deep are not an issue. Your lake of high frequency is an issue.

See your curve with the psychoacoustic smoothing.
Old 9th September 2019
  #29
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Quote:
Originally Posted by dinococcus View Post
No, for me this deep are not an issue.
See your curve with the psychoacoustic smoothing.
See image with psychoacoustic smoothing. It definitely looks much smoother now but what about those "deeps" and "peaks" I circled in green? Won't those frequencies sound too soft or too loud when I am playing my guitar in the room or when I am mixing?

Ok so you say that the high frequency is the issue. did you see my treatment in the room? Can you suggest what additional treatment can help me with the high frequencies. Also, when you say high frequencies, do you mean from 7 - 8kz and up?
Attached Thumbnails
FR vs Waterfall chart for analyzing room measreuments-psychoacoustc.jpg  
Old 9th September 2019
  #30
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Quote:
Originally Posted by camomiletea View Post
See image with psychoacoustic smoothing. It definitely looks much smoother now but what about those "deeps" and "peaks" I circled in green? Won't those frequencies sound too soft or too loud when I am playing my guitar in the room or when I am mixing?

Ok so you say that the high frequency is the issue. did you see my treatment in the room? Can you suggest what additional treatment can help me with the high frequencies. Also, when you say high frequencies, do you mean from 7 - 8kz and up?
Do you hear the deep and the bump?

For the high frequency, it's not a question of treatment but
1) the mic not towards to the acoustical axis of the speakers
Or
2) the tweeter or the mic have an issue.
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