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Online Room mode calculator
Old 14th September 2011 | Show parent
  #31
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Ethan Winer's Avatar
 
🎧 15 years
Lightbulb

Quote:
Originally Posted by gouge ➑️
i'm looking for a way to calculate how much absorption/diffusion is required.
That's something else altogether. You can't have too much bass trapping, so that settles that part. heh

I think the general rule for absorption is between 20 and 40 percent of the surfaces. Everyone's taste is different. I'd start with bass traps and broadband absorption at all the reflection points. Then live with that for a few days or a week and see what else is needed.

--Ethan
Old 16th October 2011 | Show parent
  #32
Gear Head
 
🎧 10 years
Hello,

Has anyone come across a room mode calculator that allows more than length, width, & height for input? For instances, something that could calculate the modes for a diamond shaped room?
Old 16th October 2011 | Show parent
  #33
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ritelec's Avatar
 
🎧 10 years
Quote:
Originally Posted by daveyroberts ➑️
Hello,

Has anyone come across a room mode calculator that allows more than length, width, & height for input? For instances, something that could calculate the modes for a diamond shaped room?
I'm developing one for a room shaped as a sphere.

Not. heh

Read around that even your basic room calculators would not be exact (cubed rectangle) . Conditions are different for each room and it just gives a basis for a starting point.

Doubtful there's a diamond cubed calculator.
Old 16th October 2011 | Show parent
  #34
Gear Guru
 
1 Review written
🎧 15 years
Perfect

The calculators will be exactly right if the walls are extremely hard and flat and perpendicular. That would be never.
Many rooms have a layer of plasterboard on studding or insulation, with concrete behind. The room modes may end up between or you may end up with two very closely spaced ones. For A roofs, or rooms with stepped boundaries, I would calculate the low the mid and the high, or the short and long of the stepped.

You can get straight to the real numbers very easily using a Sine Wave Generator. REW has a great facility where frequency follows the cursor, nice and slow and smoothly. The SLM can be run simultaneously to show the peaks when you hit a mode. Great if you are deaf....

DD
Old 1st October 2012 | Show parent
  #35
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antstudio's Avatar
Found this old thread but I want to thank John for the excel room mode calculator. Very nice!

I currently have a room-within-a-room studio in my garage. It's 12'x8'x7' - very small and used as an all-in-one practice, recording and mixing room. With heavy treatment (superchunks on all corners, cloud and absorber/diffuser) per Ethan's guidance plus a little HW EQ and ARC2 on the monitoring chain I've been able to turn this room into something quite usable despite the small size.

I'm moving to a larger house and planning to build a larger 19'x15'x8' room and it's great to see with this tool that those dimensions should be a much better starting point for getting a good sound.

BTW, I ran the numbers for my smaller room through your tool and it confirmed all the problematic frequencies I've had to deal with, especially in the 100Hz zone.

..ant

Current Room (12'x8'x'7):

Online Room mode calculator-small-studio-analysis.png

Planned Room (19'x15'x8' minus framing):

Online Room mode calculator-mid-studio-analysis.png
Attached Images
File Type: png Mid Studio Analysis.png (27.3 KB, 3378 views) File Type: png Small Studio Analysis.png (33.6 KB, 3922 views)
Old 1st October 2012 | Show parent
  #36
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3 Reviews written
🎧 10 years
Quote:
Originally Posted by DanDan ➑️
I like it!
Old 1st November 2012
  #37
Gear Maniac
 
🎧 5 years
yea h its good to know where to place the bed when neighbours bought cheap 40$ Subwoofer and watching movies at 100% volume
Old 5th November 2012 | Show parent
  #38
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jhbrandt's Avatar
 
🎧 10 years
Ant,

You're welcome!

Make sure that you input the interior FINISHED dimensions of the hard surface walls, ie; gypsum board, block, whatever your walls are made of.

NOTE: if your construction is frame and gypsum board, you should dismiss any modes/LF reflections that are lower in frequency than (the square root of 2 times the resonant frequency of the wall partition) - You can find this information by downloading my ReflectionsBoundariesMass spreadsheet found on my publications page.

I'm happy that you found the mode calculator helpful.

Cheers,
John
Old 24th May 2013 | Show parent
  #39
Gear Head
 
🎧 5 years
Quote:
Thanks John, for making this tool - I find it very interesting and useful!
I do have a few questions, though:
- On the mode strength tab, I dont understand how exactly the interval is calculated, what no-support alerts means, and the background for the IDEAL interval 5.611807 note (why this exact number?).

Also, in general I'm slightly bewildered by something I read elsewhere; that "the modes are NEEDED, since they carry the sound out into the room", or smth along those lines. Hmm...
I realise some of this is already discussed here, but won't mind at all if you care to elaborate a little :-)


To everybody: Thanks for an excellent forum - it's almost hard to believe so many knowledgeable and experienced people gather here to share and discuss these topics for FREE.

Cheers;
Eivind
Old 24th May 2013 | Show parent
  #40
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jhbrandt's Avatar
 
🎧 10 years
Eivind,

Thank you. Yes, I see this time and time again.. it's good to see you found someone saying something correct on the internet.
- Always 'Question Everything'.

MODES ARE CRITICALLY NECESSARY. yes.

You want and need modal support, that's why there is a column indicating lack of support.
I picked the interval of 5.611807 because that is the average interval between music notes as a percentage of change. (Pay no attention to the man behind the curtain!)... I'm sure that I made it more complicated than it needs to be. haha! But it works out to show where you DON'T have notes on the piano keyboard supported - which means that those notes will be attenuated in level in that room.

If you get the modal distribution right first.. THAT is your foundation - Then you'll have a solid base on which to build your studio acoustics. Treating for acoustics is easy after the correct shell size and mass is done.

Cheers,
John
Old 24th May 2013 | Show parent
  #41
Gear Head
 
🎧 5 years
Quote:
Originally Posted by jhbrandt ➑️
Eivind,

Thank you. Yes, I see this time and time again.. it's good to see you found someone saying something correct on the internet.
- Always 'Question Everything'.

MODES ARE CRITICALLY NECESSARY. yes.
Yes, I saw this signature once: "on the internet, nobody knows you're a dog" ;-)


So, in the modal strength tab, all mode frequencies are listed in Column A. And a corresponding '1' in column D indicates that the mode does not support any note (by sufficient proximity) on the piano.

And '0' in column D and '1' in column E indicates not 'full' support, but quite close? So you'll never have '1' in both columns. Correct?


Cheers;
Eivind
Old 24th May 2013 | Show parent
  #42
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jhbrandt's Avatar
 
🎧 10 years
second tab, 'Mode Strength'

a. If you see a '1' in column D, you will need to look at the same row column A. - Check the 'f' listed in column A and find the piano note the corresponds (or close). Next look at the row above your column A 'f'. Find the closest piano note. Check to see if there are any other notes between these two frequencies. If you have a note between the 'mode' listed in column A, THAT note will be noticeably lower in level than the surrounding notes & could be a problem.

b. If you see a '1' in column E, you have modes that of too close for comfort below the Schroeder frequency. Above that frequency, it won't be a problem. So check the 'All Modes' tab and go down to N51. Below this frequency you don't want any '1s' in column E.

Good luck!

Cheers,
John

PS. on my room mode calculator, the Schroeder frequency listed is generated from the pre-determined RT-60.. so be sure to use enough trapping to actually HAVE the Schroeder frequency at that point.. understand?

Last edited by jhbrandt; 24th May 2013 at 02:44 PM.. Reason: PS.
Old 24th May 2013 | Show parent
  #43
Gear Head
 
🎧 5 years
Hi John!

Quote:
Originally Posted by jhbrandt ➑️
a. If you see a '1' in column D, you will need to look at the same row column A. - Check the 'f' listed in column A and find the piano note the corresponds (or close). Next look at the row above your column A 'f'. Find the closest piano note. Check to see if there are any other notes between these two frequencies. If you have a note between the 'mode' listed in column A, THAT note will be noticeably lower in level than the surrounding notes & could be a problem.
Perhaps it is a little complicated, but the point I get is that notes falling in between other notes who HAVE supporting modes in the room, will; being without support from the room, sound weaker.

Quote:
Originally Posted by jhbrandt ➑️
PS. on my room mode calculator, the Schroeder frequency listed is generated from the pre-determined RT-60.. so be sure to use enough trapping to actually HAVE the Schroeder frequency at that point.. understand?

I think you're talking about diffuse conditions or not...
In rooms of sufficient size, it will be important to have absorption distributed so that you dont end up with a "hot and cold" situation, where reflections in one plane die out MUCH faster than in another. Correct? For example, not only in the ceiling.


Do you have some pointers on mode calculations for rooms with tapered ceilings?


Thank you, I am enjoying your posts and learning a lot.
Cheers;
Eivind
Old 13th October 2016
  #44
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firubbi's Avatar
 
🎧 10 years
im running Ethan Winer's ModeCalc which looks nice. one thing i like to know.
* these room measurement is before i place some bass trap for side walls right?
* ModeCalc's minimum wanted volume is 2500 cubic feet. so what happen when our room is smaller then that like my studio is 20L/13w/9H and i make it 18-13-9 =2106 cubic feet.
*is it good to do a octagon shape room? how to calculate that?
thanks
Old 13th October 2016 | Show parent
  #45
Gear Guru
 
1 Review written
🎧 15 years
Fortune Telling

Best to ask the guy who wrote ModeCalc, which IMO is great fun.
As are they all, John's, bobgolds.com
Octagon would be pretty awful, almost as bad as circular.
Here is a circular library tower with a story intended for singing chanting.
It is absolutely unusable for music as it rings like a bell, one note.
RHA Architects: Glenstal Abbey Library
DD
Old 23rd February 2017 | Show parent
  #46
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Keith Moore's Avatar
 
🎧 10 years
Quote:
Originally Posted by jhbrandt ➑️
Hey John,

What is the "Critical Distance" measurement?
Old 24th February 2017 | Show parent
  #47
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jhbrandt's Avatar
 
🎧 10 years
Quote:
Originally Posted by Keith Moore ➑️
Hey John,

What is the "Critical Distance" measurement?
Critical Distance is basically that 'near-field' bubble they talk about in LEDE. In our BNE rooms, this is approximately the smallest dimension (either room width or room height)

We should try for the largest sphere of free field as possible.
Cheers,

John
Old 24th February 2017 | Show parent
  #48
Old 24th February 2017 | Show parent
  #49
Gear Guru
 
1 Review written
🎧 15 years
Direct Answer

In Acoustics, Critical Distance is the distance at which the sound pressure level of the direct sound D and the reverberant sound R are equal.
Typically our rooms are not really reverberant, so substitute the term Room Tone.

DD

Last edited by DanDan; 24th February 2017 at 07:09 PM..
Old 26th February 2017 | Show parent
  #50
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jhbrandt's Avatar
 
🎧 10 years
I was replying to a question about my Room mode calculator. Basically, everything you need is IN the calculator...

I try do my best to help the average musician understand what is being expressed or explained WITHOUT the use of mathematical formulas or technical explanations. I know that you guys know that I know what I'm talking about and I don't need to impress you.

I also know that, technically speaking, reverberation does not exist in a small room. However, we USE the term to define our acoustics. It is a very important parameter... Also I would NEVER use the term, Room Tone, because it infers that the room has a 'tone' - or SHOULD have a tone. I should not... ever. I prefer the word 'decay' as it more clearly expresses what is going on. I believe that it is important not to confuse... LOL! I know that I have confused people here before, so I try my best to correct that.

So, to recap; Use the data presented in my Room Mode Calculator to set a target RT60... This will result in the listed Critical Distance. Also note that a Critical Distance measurement is a radius; measured from the center (or observer) to the 'Dc', or " the distance at which the sound pressure level of the direct sound and the reverberant sound are equal".

All the best!
Cheers,
John
Old 26th February 2017 | Show parent
  #51
Gear Guru
 
1 Review written
🎧 15 years
Extinction

Jeez John, a Room should not have a tone? Have you ever heard drums in a non reflective room or outdoors.
I think Sonic Decay describes what MP3 has achieved.
Room Decay? Sounds like it needs a lick of paint.

DD
Old 28th February 2017 | Show parent
  #52
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jhbrandt's Avatar
 
🎧 10 years
Quote:
Originally Posted by DanDan ➑️
Jeez John, a Room should not have a tone? Have you ever heard drums in a non reflective room or outdoors.
I think Sonic Decay describes what MP3 has achieved.
Room Decay? Sounds like it needs a lick of paint.

DD
LOL!

A CONTROL ROOM should not (ever) have a tone. Actually, neither should a tracking room - (perhaps I should do a thread about this...) But I was only talking about a CONTROL ROOM. These are the types of rooms that need to be calculated and checked with a room mode calculator. - But you know that.. I know you're just giving me a hard time.

Yeah, room decay... or decadence. LOL

Cheers,
John
Old 28th February 2017
  #53
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ReDRuMx's Avatar
 
1 Review written
🎧 10 years
I apologize if this is off topic, but I am really struggling with the analysis of my room...

I see the term here "modal support", could this be the reason for my problems?

My (for now completely untreated) room shows the frequency response in attachment. Extreme lack of bass. Walls mostly stone and concrete. 8m*4m*5,3m. Ceiling lowered and angled a bit using wooden boards... The thread is this (link to the useful post - more measurements can be found earlier in the thread) - Studio renovation in Croatia - Help please :)

Again, I am really sorry for going off topic, but I would really appreciate it if someone could help me make sense of this weird LF response.
Attached Thumbnails
Online Room mode calculator-screen-shot-2017-02-27-20.54.59.jpg  
Old 1st March 2017 | Show parent
  #54
Gear Guru
 
1 Review written
🎧 15 years
Hard Time

I know you were referring to a CR, so I was joshing you of course. For dissing my Room TONE. Room tone is part of the sound of the recording instrument.
None at all is great for clarity, e.g. vocals, and the singer can have reverb in the cans. But a violin or drums get actual energy feedback from the room particularly at the lower end. For general or all purposes a neutral room tone, which is what I think you are really referring to in a LR, is obviously desireable. But some facilities have dedicated drum rooms with stone or rock walls.....
Tom Waits records here but often in the outbuildings, literally, Pig and Chicken Sheds.....
Never say never I say.


ReDRuMx, probably best to keep working on that anomaly over in that thread.
It does seem almost certain that there is something wrong with your REW process.
Over in the other thread I will post a FuzzMeasure sweep which you can play and record the room response outside of REW....


DD
Old 1st March 2017 | Show parent
  #55
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ReDRuMx's Avatar
 
1 Review written
🎧 10 years
Quote:
Originally Posted by DanDan ➑️

ReDRuMx, probably best to keep working on that anomaly over in that thread.
It does seem almost certain that there is something wrong with your REW process.
Over in the other thread I will post a FuzzMeasure sweep which you can play and record the room response outside of REW....


DD
I really do hope it's just the REW process thing. Thanks for all your help, DanDan.
Old 18th June 2017
  #56
Old 1st August 2017 | Show parent
  #57
Here for the gear
 
Quote:
Originally Posted by jhbrandt ➑️
Dan and all,

I keep upgrading these calculators and adding stuff, so check from time to time for new versions.

-- John
Hi John,
do you have a version that goes out to 20kHz. I am using it to calc reflections between mic and speaker for off axis ground plane measurements.
Leon
Old 2nd August 2017 | Show parent
  #58
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jhbrandt's Avatar
 
🎧 10 years
Quote:
Originally Posted by lsievers ➑️
Hi John,
do you have a version that goes out to 20kHz. I am using it to calc reflections between mic and speaker for off axis ground plane measurements.
Leon
Leon,

No. Sorry. The function of this spreadsheet wouldn't cover what you are trying to do and it's irrelevant to the function of room modes to list refections above 250 - 350 Hz.

I think EASE has a function like that but I haven't used EASE in a very long time.

Cheers,
John
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