Go Back   Cockos Incorporated Forums > REAPER Forums > Recording Technologies and Techniques

Reply
 
Thread Tools Display Modes
Old 03-23-2012, 08:40 AM   #1
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default DIY bass traps/acoustic panels - my photo diary

There you go, just finished up today with my three panels, I'll "hang" my cloud on the cealing tonight or tomorrow

http://www.ukkohapponen.fi/pages/kuv...?gallery_id=81
__________________
REGISTERED USER
My music, studio and bands

Last edited by Finnish; 03-29-2012 at 04:13 AM.
Finnish is offline   Reply With Quote
Old 03-23-2012, 12:11 PM   #2
bogo
Human being with feelings
 
bogo's Avatar
 
Join Date: Jun 2006
Posts: 761
Default

Good work.
bogo is offline   Reply With Quote
Old 03-23-2012, 01:53 PM   #3
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Thanks!

Also my "cloud" is 99% ready, I need to cover it with black fabric and I'm good!

__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 03-23-2012, 02:16 PM   #4
mixer
Human being with feelings
 
Join Date: Sep 2010
Posts: 459
Default

Looks like a hanging mattress. Put a couple pillows up there, use it as a bedroom loft AND bass panels and free up some floor space!
mixer is offline   Reply With Quote
Old 03-23-2012, 02:24 PM   #5
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Quote:
Originally Posted by mixer View Post
Looks like a hanging mattress. Put a couple pillows up there, use it as a bedroom loft AND bass panels and free up some floor space!
Bwahahahaa! No wonder it looks like a bed, it's covered with sheet right now.. I guess you know now why I want to cover it with black fabric.. Work in progress!
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 03-23-2012, 02:46 PM   #6
trevlyns
Human being with feelings
 
trevlyns's Avatar
 
Join Date: Dec 2011
Location: Rhode Island, New England
Posts: 1,665
Default

Nice!

I'm doing something very similar. Finished the first one yesterday - took today off to rest
__________________
Retired Home Music Producer
Sample Projects https://soundcloud.com/trevs_audio
trevlyns is offline   Reply With Quote
Old 03-29-2012, 04:13 AM   #7
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Added more photos!
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 03-29-2012, 08:06 AM   #8
HOFX
Human being with feelings
 
HOFX's Avatar
 
Join Date: Jan 2008
Location: Oslo, Norway
Posts: 381
Default

This is very useful as I'll be doing something very similar in a few months. Thanks for posting!
HOFX is offline   Reply With Quote
Old 03-29-2012, 11:55 AM   #9
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

The difference in the room with/without traps is HUGE! Reverberation is (almost, almost..) gone, soooo happy now. I don't have a measurement mic at the moment, will be taking REW tests as soon as possible.

I made four 125cm x 70cm traps, one 145cm x 70cm and one about 140cm x 140cm (cloud). Overall costs were about 60-70€ total. I'll make three 125cm x 70cm traps and one cloud more in the near future, those will be for "main recording room" or my living room, whatever you wanna call it..
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 03-29-2012, 01:55 PM   #10
planetnine
Human being with feelings
 
planetnine's Avatar
 
Join Date: Oct 2007
Location: Lincoln, UK
Posts: 7,924
Default

Don't try to eliminate reverberation entirely, the idea is to even up the frequency response of the room, not deaden it entirely. If you kill the conventional mid and HF ambience the room will sound odd, unleash any remaining LF gremlins and it won't be helpful to mix in. You may also add more reverb FX than you might want in an overdry room.

Try getting a radio shack sound level meter to use as a mic. You need a meter for sweeps really anyway, and its not that bad for the bottom four octaves where it counts. It'll show peaks and troughs.

If your room has any rectangular features, measure it and work out some nodes. That and a sweep will help you understand which walls or dimensions (LWH) are causing the nodes and help you control them. Sweeps from other than the listening position will clarify these nodes, and playing sine waves at the anomalous frequencies (watch your levels) will open your eyes and ears to how your room ticks -move your head and measuring mic around and you'll be astonished at the level differences!

Once you get somewhere towards taming your room, and knowing your problem frequencies and dimensions, remember that for broadband traps generally, doubling the thickness of a trap will increase its LF reach and reasonably evenly increase it's absorption (although usu not much inc at the top end), whereas doubling the area will only increase the absorption properties that it already possesses. You can use this to help you home in on any LF gremlins remaining. Beyond that it's tuneable pots and chambers and other voodoo

Sorry if I'm misinterpreting your level of understanding, REW is a great tool, even with an uncalibrated meter as a mic, and it can really help you understand what's going on acoustically and treat what you can. Slide the cursor up and down the curve, play sines at those Freqs, move or double-up traps while they're playing -it'll teach you so much.

Read everything on the Real-Traps site, Ethan is good at what he does and not all his opinions are not as bad as some would have you believe. Read the theory and digest, convert the spreadsheets to metric. Measure, calculate, sweep, listen, learn. It's great fun and very educational.

Feel free to ask any Qs. It's ages since I've set up a room and I'll follow this with interest.

>
__________________
Nathan, Lincoln, UK. | Item Marker Tool. (happily retired) | Source Time Position Tool. | CD Track Marker Tool. | Timer Recording Tool. | dB marks on MCP faders FR.
planetnine is offline   Reply With Quote
Old 03-29-2012, 02:00 PM   #11
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Thanks for posting, planetnine.

Here's my previous acoustic project on my older recording space: http://www.ukkohapponen.fi/pages/kuv...?gallery_id=47 There are some REW pictures in the end of gallery

I'll dig deeper into this world when I'm able to do some measurements etc, it's a very interesting world I'd say!
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-01-2012, 06:19 PM   #12
ObiK
Human being with feelings
 
ObiK's Avatar
 
Join Date: Feb 2011
Location: Salt Lake City, UT
Posts: 1,095
Default

Really neat catalog of your work. About to start my own for a new studio build in the next few weeks. I'll be sure to post mine too!
__________________
IKMultimedia.com
Musicians first. Follow us on Facebook, Twitter & Tumblr!
ObiK is offline   Reply With Quote
Old 04-02-2012, 03:28 AM   #13
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Thanks, ObiK! I had very little info when I started my projects, I lurked at Gearslutz a lot and learned from there. Always nice to see how people build their traps, different methods, facilities, building materials etc. I try to do some measurements this week, I need to borrow a proper mic and SPL-meter somewhere.
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-08-2012, 10:48 AM   #14
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Removable "wall":


I'm really really about to purchase IK Multimedia ARC, I need a measurement mic and ARC includes mic, so...
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-09-2012, 08:14 AM   #15
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

I made another removable wall, I'll do the cloud above drum corner tomorrow of wednesday. After that I'll have a break with building stuff!

__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-09-2012, 02:49 PM   #16
Marcostenik
Human being with feelings
 
Marcostenik's Avatar
 
Join Date: Mar 2012
Location: Italy
Posts: 122
Default

this is my studio control room.
I made all the traps by my self... not too expansive but works greate.
Sorry for my pure english.
Attached Images
File Type: jpg foto.jpg (64.0 KB, 372 views)
Marcostenik is offline   Reply With Quote
Old 04-09-2012, 11:06 PM   #17
Tomas Ve
Human being with feelings
 
Tomas Ve's Avatar
 
Join Date: Apr 2009
Location: Vilnius, Lithuania
Posts: 36
Default

Quote:
Originally Posted by Finnish View Post
I'll do the cloud above drum corner tomorrow
Do you have any comments or pointers to how do these hanging clouds work, on what principle they're based and how their build influences various audio parameters?
Tomas Ve is offline   Reply With Quote
Old 04-10-2012, 04:14 PM   #18
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

I just ordered these, hopefully receive 'em before weekend:

http://north-america.beyerdynamic.co...ones/mm-1.html

http://www.bercu.be/EN-EJBAZ8921.htm

Measurements, measurements, baby!
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-11-2012, 05:21 AM   #19
ivansc
Human being with feelings
 
Join Date: Aug 2007
Location: Near Cambridge UK and Near Questembert, France
Posts: 22,754
Default

Quote:
Originally Posted by Marcostenik View Post
this is my studio control room.
I made all the traps by my self... not too expansive but works greate.
Sorry for my pure english.

We are all officially jealous and WE ALL HATE YOU!

Lovely job......and seriously, well done if it was DIY.
ivansc is offline   Reply With Quote
Old 04-11-2012, 07:32 AM   #20
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Quote:
Originally Posted by ivansc View Post
We are all officially jealous and WE ALL HATE YOU!

Lovely job......and seriously, well done if it was DIY.
Agreed... That's a one truly awesome lookin' place you got there Marcostenik!
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-11-2012, 10:54 AM   #21
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Well, took a whole day but drum corner with cloud is almost ready!

__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-12-2012, 02:10 PM   #22
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Drum "booth"
Attached Images
File Type: jpg 36 drum booth.jpg (48.9 KB, 507 views)
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-19-2012, 01:47 PM   #23
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Got the mic and the SPL meter... First I wanted to measure my "recording area" aka living room, mic was positioned where I use to sit on my sofa. Just wanted to see how to improve my home theatre experience also. I'll measure my mixing room tomorrow, hope so.

Attached Images
File Type: jpg 37 living room graph.jpg (41.2 KB, 1572 views)
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-19-2012, 04:06 PM   #24
RJHollins
Human being with feelings
 
Join Date: Dec 2011
Posts: 2,161
Default

? you ARE shooting the room using only a single monitor at a time ???

correct !!! ??

BTW ... congrats on getting up to do the treatment. You'll want to KICK yourself for waiting so long to do it.

Also ... had not seen if you have 'side wall' absorbers ?? If so ... be certain they are positioned at first reflection points. You can use the math formulas ... OR ... you can use the 'mirror' technique.

Keep us posted! You are gonna take your audio work to a whole new level!

Sincerely.
RJHollins is offline   Reply With Quote
Old 04-19-2012, 05:00 PM   #25
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Well, as a matter of a fact.. I didn't measure with a single speaker but both at the same time, so that leads me bit astray or does it? Anyway, here's a picture from the opposite corner. As you can see it looks like a living room.. The mic is about 4 meters from the speakers. It's obvious I need to make more traps but this room is not my main concern, my bedroom is my mixing room and I've treated first reflection points there. But since this is my "drum room" it won't hurt if I treat it so it would just sound better. It'd be nice to have a better home theater at the same time..



Oh, here's also a waterfall:

Attached Images
File Type: jpg Living room picture far away.jpg (44.5 KB, 1876 views)
File Type: jpg Living room sub waterfall.jpg (57.1 KB, 1560 views)
__________________
REGISTERED USER
My music, studio and bands

Last edited by Finnish; 04-19-2012 at 05:11 PM.
Finnish is offline   Reply With Quote
Old 04-20-2012, 12:41 AM   #26
RJHollins
Human being with feelings
 
Join Date: Dec 2011
Posts: 2,161
Default

Room shoot outs ...

ONE monitor at a time.

In this way, the sonic 'symmetry' can also be identified.
RJHollins is offline   Reply With Quote
Old 04-20-2012, 03:52 AM   #27
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Redoing measurements today!
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-20-2012, 09:37 AM   #28
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Ok, now testing again. This time I used C-weighting on Preferences and on my SPL meter, manual suggests it so it's ok to use that?

Anyway, I did left/right measurements. I noticed that there's a 3db difference with left and right, I guess my old Onkyo amplifier is doing some tricks.. Here are the new results.







The ringing on right speaker continues over 1500ms, so that's quite bad.
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-20-2012, 01:48 PM   #29
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Ok, here's my mixing room. I'm quite suprised, those graphs look so sad..





__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-20-2012, 11:51 PM   #30
RJHollins
Human being with feelings
 
Join Date: Dec 2011
Posts: 2,161
Default

Hi Finnish,

What was the SPL level that you used to shoot ???

Remember ... You need to drive the room to around 80-85 dB in order to
'excite' it to the proper measurement level.

Again, I'm just trying to help on things that have been said to me via my studio designers. Using REW, and interpreting the various graphs is still a new area for me ... but I am trying to understand.

As to your graphs ... it's GOOD that you used NO 'smoothing' in the posted pix. I'm sure you notice there are some issues yet to resolve ... a word of 'consolation' .... if you can get your room response into a +-6dB variation ... you've done quite good.

Something you might want to check out .... look for a 'Room Mode' calculator on the net ... I don't have a link handy ... but you should plug in your room dimensions and see the resultant modes. This may help identify the nasty areas. In particular, the floor to ceiling height ... I see a canceling node that looks familiar.

Again ... just try to help ...
RJHollins is offline   Reply With Quote
Old 04-21-2012, 02:45 AM   #31
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Hi RJHOllins,

Thanks for your input!
Quote:
What was the SPL level that you used to shoot ??? Remember ... You need to drive the room to around 80-85 dB in order to
'excite' it to the proper measurement level.
Well, here's something that needs a rerun, I was using 75db or below SPL levels. Gonna do it again today, with 85db levels.

Quote:
As to your graphs ... it's GOOD that you used NO 'smoothing' in the posted pix. I'm sure you notice there are some issues yet to resolve ... a word of 'consolation' .... if you can get your room response into a +-6dB variation ... you've done quite good.

Something you might want to check out .... look for a 'Room Mode' calculator on the net ... I don't have a link handy ... but you should plug in your room dimensions and see the resultant modes. This may help identify the nasty areas. In particular, the floor to ceiling height ... I see a canceling node that looks familiar.

Again ... just try to help ...
Here's what I found out about room modes, my room dimensions are in that calculator (calculator here http://www.marktaw.com/recording/Aco...WaveCalcu.html:



So, I'd say room modes has a big influence here! But how to manage it or deal with it?
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-21-2012, 10:30 AM   #32
RJHollins
Human being with feelings
 
Join Date: Dec 2011
Posts: 2,161
Default

flying by ....


Here's another 'Room Mode Calc':

http://www.bobgolds.com/Mode/RoomModes.htm
RJHollins is offline   Reply With Quote
Old 04-22-2012, 12:49 AM   #33
ivansc
Human being with feelings
 
Join Date: Aug 2007
Location: Near Cambridge UK and Near Questembert, France
Posts: 22,754
Default

Intersting... and amazingly my tiny 4x3x2.3 metre room doesnt look too bad!
ivansc is offline   Reply With Quote
Old 04-22-2012, 04:49 AM   #34
planetnine
Human being with feelings
 
planetnine's Avatar
 
Join Date: Oct 2007
Location: Lincoln, UK
Posts: 7,924
Default

Quote:
Originally Posted by Finnish View Post
Hi RJHOllins,

Thanks for your input!


Well, here's something that needs a rerun, I was using 75db or below SPL levels. Gonna do it again today, with 85db levels.



Here's what I found out about room modes, my room dimensions are in that calculator (calculator here http://www.marktaw.com/recording/Aco...WaveCalcu.html:



So, I'd say room modes has a big influence here! But how to manage it or deal with it?


There is something very wrong with those frequencies Finnish, I havent worked out what you've done yet, but these are the actual figures for axial modes for that room...



Code:
x	y	z	freq(Hz)
1			39.88372093
	1		45.73333333
		1	68.05555556
2			79.76744186
	2		91.46666667
3			119.6511628
		2	136.1111111
	3		137.2
4			159.5348837
	4		182.9333333
5			199.4186047
		3	204.1666667
	5		228.6666667
6			239.3023256
		4	272.2222222
	6		274.4
7			279.1860465
8			319.0697674
	7		320.1333333
		5	340.2777778
9			358.9534884
	8		365.8666667
10			398.8372093


I've sorted them into frequency order for you -watch out for that 136, 137Hz conjunction!!
(and 275Hz!)

Edit: I used c=343m/s rather than your 344, but very small difference. c(sound) is 343m/s at 20 degC.


>
__________________
Nathan, Lincoln, UK. | Item Marker Tool. (happily retired) | Source Time Position Tool. | CD Track Marker Tool. | Timer Recording Tool. | dB marks on MCP faders FR.

Last edited by planetnine; 04-22-2012 at 06:30 AM.
planetnine is offline   Reply With Quote
Old 04-22-2012, 06:16 AM   #35
planetnine
Human being with feelings
 
planetnine's Avatar
 
Join Date: Oct 2007
Location: Lincoln, UK
Posts: 7,924
Default

Just double-checked these (I made up a spreadsheet from the mode equations and then sorted them in frequency order).

If I set my speed of sound to 344m/s, my list matches that of the axial frequencies of Bob Gould's online calculator:

http://www.bobgolds.com/Mode/RoomModes.htm

This will give you a list of Tangential and Oblique modes in addition to the Axial ones. Axial modes are the most significant in evening out a room (look at the "percentages" for relevance), many acoustic engineers ignore anything but Axial, but the lower value Tangential modes do have an effect in a room (especially if they coincide with another mode) and are worth noting for reference. The strongest mode for a room dimension will have a frequency whose wavelength is twice than of the room dimension. The next will be double this frequency, the next, three times, etc.

It is worth noting that these mode calculations are for dimensions between reflecting surfaces, and with numerous construction techniques might not be the surface you see. With lower frequencies, the sound energy may mostly pass through some surfaces and reflect off a more distant surface. This will obviously effect the wavelength of the LF modes; the most obvious example of this is a suspended ceiling (actually a great place to stuff dense trapping material if it can be done safely).

A rule of thumb to check these figures is 70Hz will have a wavelength of about 8 feet (about 6cm short of 2.5m), so for an 8-foot dimension the primary mode will be 16-foot wavelength or 35Hz. Add half again to the dimension (3/2 or 150%), multiply the wavelength by that, or the freq by 2/3 (inverse fraction or reciprocal) -so about 23Hz. Double the dimension, halve the freq (2/1 and 1/2) so for 16 feet it would be 70Hz (ish), and every other mode would be a integer multiple of this (x2, x3,x4, etc).

If you can hold this in your head, you'll know if these figure coming back are factors out...


Edit: It's the commas that screwed your figures up -I've duplicated it, put decimal points in there instead and they come out correctly.



>
__________________
Nathan, Lincoln, UK. | Item Marker Tool. (happily retired) | Source Time Position Tool. | CD Track Marker Tool. | Timer Recording Tool. | dB marks on MCP faders FR.

Last edited by planetnine; 04-22-2012 at 06:23 AM.
planetnine is offline   Reply With Quote
Old 04-22-2012, 07:01 AM   #36
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Thanks, planetnine!!!

I've rearranged my traps in mixing room, I'll post new measurements today.
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Old 04-22-2012, 10:08 AM   #37
planetnine
Human being with feelings
 
planetnine's Avatar
 
Join Date: Oct 2007
Location: Lincoln, UK
Posts: 7,924
Default

-Use REW to store named responses of your room, and then as you move/change things around you can compare the graphs directly.

-Read the setup instructions on REW and use your SPL meter to measure at 85dB.



Remember that the nodes (cancellation point) of any room dimension's f1 axial mode is in the middle of that dimension (antinodes or max SPL are at the dimension boundary);

f1




the nodes (cancellation points) of any room dimension's f2 axial mode is at a quarter of the dimension in from each boundary (antinodes or max SPL are at the dimension boundary and at the dimension's centre);

f2




the nodes (cancellation point) of any room dimension's f3 axial mode is in the middle of that dimension and 1/6th of the dimension in from each boundary (antinodes or max SPL are at the dimension boundary and at 1/3 (2/6) of the dimension in from each boundary).

f3





the nodes (cancellation point) of any room dimension's f4 axial mode is at 1/8th and 3/8ths of the dimension in from each boundary (antinodes or max SPL are at the dimension boundary, in the middle of that dimension and at 1/4 (2/8) of the dimension in from each boundary).

f4





I've linked to this from the German Sengpiel Audio website -a very good resource for calcs and diagrams for audio physics.



These Axial Mode nodes and antinodes are actually planes, parallel to the dimension boundaries. Think of these when moving your head around your room at the problem frequencies. You should get REW to produce a sinewave and drag the frequency cursor to the peaks and the troughs of your response curves and then listen to see if the dropout (node) or hotspot (antinode) is in a plane (sheet area) -it will be parallel to the walls it is bouncing between and will need broadband trapping on those surfaces. This is a glimpse into the fun techniques you will use to get rid of the extremes of those graphs. If you get within 12dB you will have a good room to mix in; within 6dB it will be a very good room to mix in


Once you've got your head around axial modes, try tangential and oblique...



With tangiential, the sound waves use two of the three pairs of boundary surfaces in a room to reflect from. This can be in a quadralateral pattern as shown in the diagram (equal mode numbers for each) or can actually be a first mode in one dimension and a second or third mode in another. nodes and antinodes tend to be at boundary intersections and in lines at the intersection of planes parallel to the dimension boundaries being used by the standing wave..

Oblique modes are where all three pairs of boundary surfaces are used in the standing wave. The sound path is a three-dimensional twisted figure of eight around the room for equal modes across dimensions, or even more manic 3D lissajous figures for unequal mode numbers across dimensions. The good news is that only the very lowest mode numbers and simplest paths are of actual significance in real rooms, or when they tend to combine with other modes reinforcing certain frequency ranges. Nodes and antinodes are in corners and at points formed by constructive and destructive interference created by the diferent modes on all six boundaries.

The three pairs of numbers in mode calculators are for the modes in the three dimensions: 1 0 0, 0 1 0 and 0 0 1 are the first axial modes in each dimension (x, y and z for length, width and height). 2 0 0 would mean the second axial mode for the length, 0 3 0 would be the third axial mode for width. 1 1 0 would be a tangential mode across the walls (length and width) involving first mode or f1 frequencies for the tangential wave path. 1 2 0 would be first mode of length and second mode of width (a sound path going twice across the width and once along the length) the sound path length is a function of the squares of the multiples of each dimension (based on multiple being the mode number).
Still following?

Oblique modes use all three dimensions and so use all three numbers of the matrix. 1 1 1 would be an oblique path using each surface once, and its sound path length is a function of the squares of all three room dimensions. Use a dimension more than once and the mode number increases to that multiple and the factors go up in calculating the path length. You need computerised 3D plotting applications to show the nodes and antinodes for these (or lots of pretty paints and some hallucinogens).

Most good mode calculators use all combinations of all three dimension mode numbers up to about 10, calculate the modes, order them by frequency and disregard any with frequencies over about three or four hundred Hertz. Other useful information is mode stregth and a graphical display of mode clustering, where modes gang up on you at close frequencies. See Ethan Winer's DOS MODECALC.EXE for an example, which uses different colours for axial, tangential and oblique modes. There is also something similar on Bob Goulds online calculator.


Oher useful information is a trace called a Bonello Distribution graph. This shows how modal density in your room is distributed across the concerning bottom 300Hz frequency range. It is often mapped against an ideal distribution curve and the idea is to get your line below the other, an even distribution of modes with no bumps which would mean clumps of modes within a frequency band giving modal combinations that might be hard to treat for.

Bonello Distribution



This leads us on to ideal ratios of dimensions for a rectangular room. Certain ratios of length, width and height dimensions give desirable spacings of standing wave modes. Your better mode calaculator will calculate the ratios of your space and point out how non-ideal your room dimension ratios are

Remember through all this that these calculations are for an ideal reflective room of uniform construction with no doors and windows, and the introduction of these and such frivolities as carpets, furniture, desks and audio equipment will mask and smear the real values, hiding the modes and their effects. Add in some broadband traps and other acoustic treatment and it can be hard to compare the theoretical and the empirical.

If you ever get to build a studio from scratch, make sure there are no parallel walls and the roof is at an angle!!


I am having some fun with you here, but I hope you do actually follow some of this, it will open your eyes (ears?) and make some of it mean something while you are plodding about with your traps and measuring gear. I hope it contributes and gets you great results in the end



>
__________________
Nathan, Lincoln, UK. | Item Marker Tool. (happily retired) | Source Time Position Tool. | CD Track Marker Tool. | Timer Recording Tool. | dB marks on MCP faders FR.

Last edited by planetnine; 04-22-2012 at 10:15 AM.
planetnine is offline   Reply With Quote
Old 04-22-2012, 10:41 AM   #38
planetnine
Human being with feelings
 
planetnine's Avatar
 
Join Date: Oct 2007
Location: Lincoln, UK
Posts: 7,924
Default

Here's the first 300Hz of modes for your room, Finnish...


Code:
c	344	ms^-1				Feet	Inches	
L	4.3	m				14	1.3	
W	3.75	m				12	3.6	
H	2.52	m				8	3.2	


			x	y	z	freq(Hz)	Mode type
			1	0	0	40.0		Axial
			0	1	0	45.9		Axial
			1	1	0	60.9		Tangential
			0	0	1	68.3		Axial
			1	0	1	79.1		Tangential
			2	0	0	80.0		Axial
			0	2	0	91.7		Axial
			2	1	0	92.2		Tangential
			1	2	0	100.1		Tangential
			2	0	1	105.2		Tangential
			0	2	1	114.3		Tangential
			3	0	0	120.0		Axial
			1	2	1	121.1		Oblique
			2	2	0	121.7		Tangential
			3	1	0	128.5		Tangential
			0	0	2	136.5		Axial
			0	3	0	137.6		Axial
			3	0	1	138.1		Tangential
			2	2	1	139.5		Oblique
			1	0	2	142.2		Tangential
			1	3	0	143.3		Tangential
			0	1	2	144.0		Tangential
			1	1	2	149.5		Oblique
			3	2	0	151.0		Tangential
			0	3	1	153.6		Tangential
			2	0	2	158.2		Tangential
			1	3	1	158.7		Oblique
			2	3	0	159.2		Tangential
			4	0	0	160.0		Axial
			0	2	2	164.5		Tangential
			2	1	2	164.7		Oblique
			3	2	1	165.8		Oblique
			4	1	0	166.4		Tangential
			1	2	2	169.3		Oblique
			2	3	1	173.2		Oblique
			4	0	1	174.0		Tangential
			3	0	2	181.8		Tangential
			3	3	0	182.6		Tangential
			2	2	2	182.9		Oblique
			0	4	0	183.5		Axial
			4	2	0	184.4		Tangential
			3	1	2	187.5		Oblique
			1	4	0	187.8		Tangential
			0	3	2	193.8		Tangential
			3	3	1	194.9		Oblique
			0	4	1	195.8		Tangential
			4	2	1	196.7		Oblique
			1	3	2	197.9		Oblique
			1	4	1	199.8		Oblique
			5	0	0	200.0		Axial
			2	4	0	200.1		Tangential
			3	2	2	203.6		Oblique
			0	0	3	204.8		Axial
			5	1	0	205.2		Tangential
			1	0	3	208.6		Tangential
			2	3	2	209.7		Oblique
			0	1	3	209.8		Tangential
			4	0	2	210.3		Tangential
			4	3	0	211.0		Tangential
			5	0	1	211.3		Tangential
			2	4	1	211.5		Oblique
			1	1	3	213.6		Oblique
			4	1	2	215.3		Oblique
			3	4	0	219.2		Tangential
			2	0	3	219.8		Tangential
			5	2	0	220.0		Tangential
			4	3	1	221.8		Oblique
			0	2	3	224.4		Tangential
			2	1	3	224.6		Oblique
			1	2	3	227.9		Oblique
			3	3	2	228.0		Oblique
			0	4	2	228.7		Tangential
			0	5	0	229.3		Axial
			4	2	2	229.5		Oblique
			3	4	1	229.6		Oblique
			5	2	1	230.4		Oblique
			1	4	2	232.2		Oblique
			1	5	0	232.8		Tangential
			3	0	3	237.3		Tangential
			2	2	3	238.2		Oblique
			0	5	1	239.3		Tangential
			6	0	0	240.0		Axial
			3	1	3	241.7		Oblique
			5	0	2	242.1		Tangential
			2	4	2	242.3		Oblique
			1	5	1	242.6		Oblique
			5	3	0	242.8		Tangential
			2	5	0	242.9		Tangential
			4	4	0	243.4		Tangential
			6	1	0	244.3		Tangential
			5	1	2	246.5		Oblique
			0	3	3	246.7		Tangential
			6	0	1	249.5		Tangential
			1	3	3	249.9		Oblique
			4	3	2	251.3		Oblique
			5	3	1	252.2		Oblique
			2	5	1	252.3		Oblique
			4	4	1	252.8		Oblique
			3	2	3	254.4		Oblique
			6	2	0	256.9		Tangential
			3	4	2	258.3		Oblique
			3	5	0	258.8		Tangential
			5	2	2	258.9		Oblique
			2	3	3	259.3		Oblique
			4	0	3	259.9		Tangential
			4	1	3	263.9		Oblique
			6	2	1	265.8		Oblique
			0	5	2	266.9		Tangential
			3	5	1	267.7		Oblique
			1	5	2	269.9		Oblique
			5	4	0	271.4		Tangential
			0	0	4	273.0		Axial
			3	3	3	274.3		Oblique
			0	4	3	274.9		Tangential
			0	6	0	275.2		Axial
			4	2	3	275.6		Oblique
			1	0	4	275.9		Tangential
			6	0	2	276.1		Tangential
			6	3	0	276.6		Tangential
			0	1	4	276.8		Tangential
			1	4	3	277.8		Oblique
			1	6	0	278.1		Tangential
			5	3	2	278.5		Oblique
			2	5	2	278.6		Oblique
			4	4	2	279.1		Oblique
			4	5	0	279.6		Tangential
			1	1	4	279.7		Oblique
			5	4	1	279.9		Oblique
			6	1	2	279.9		Oblique
			7	0	0	280.0		Axial
			0	6	1	283.5		Tangential
			7	1	0	283.7		Tangential
			2	0	4	284.5		Tangential
			6	3	1	284.9		Oblique
			5	0	3	286.2		Tangential
			2	4	3	286.3		Oblique
			1	6	1	286.3		Oblique
			2	6	0	286.6		Tangential
			4	5	1	287.8		Oblique
			0	2	4	288.0		Tangential
			2	1	4	288.2		Oblique
			7	0	1	288.2		Tangential
			5	1	3	289.9		Oblique
			1	2	4	290.8		Oblique
			6	2	2	290.9		Oblique
			3	5	2	292.6		Oblique
			4	3	3	294.0		Oblique
			2	6	1	294.6		Oblique
			7	2	0	294.6		Tangential
			3	0	4	298.2		Tangential
			2	2	4	298.9		Oblique
			3	4	3	300.0		Oblique

Calculations are dead easy, I did this on an Excel spreadsheet, just needs tidying up and some pretty graphs.
Your Bonello distribution isn't too bad...






>
__________________
Nathan, Lincoln, UK. | Item Marker Tool. (happily retired) | Source Time Position Tool. | CD Track Marker Tool. | Timer Recording Tool. | dB marks on MCP faders FR.

Last edited by planetnine; 04-22-2012 at 01:35 PM.
planetnine is offline   Reply With Quote
Old 04-22-2012, 12:56 PM   #39
RJHollins
Human being with feelings
 
Join Date: Dec 2011
Posts: 2,161
Default

Hey ... good stuff Planetnine !

Those that are REALLY interested in having their audio work translate more predictably should appreciate!

Sincerely.
RJHollins is offline   Reply With Quote
Old 04-22-2012, 01:30 PM   #40
Finnish
Human being with feelings
 
Finnish's Avatar
 
Join Date: Jun 2006
Location: Finland, Kuopio
Posts: 911
Default

Gotta look these with serious thought tomorrow!
__________________
REGISTERED USER
My music, studio and bands
Finnish is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 08:48 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.