Greeting from Japan.

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bassmothership

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Greeting from Japan.
« on: 21 May 2020, 04:26 am »
Hi there.

I'm a bedroom mixing engineer. Absolute noob in acoustics. I need help with sound absorption (specifically to tame the range below 200Hz) and learn ways to DIY my own panels without using any Mineral Wool material.
I wanna learn about the options of "healthy" materials that can make my bedroom stop fooling my ears too much. :cry:

To add to the difficult of doing this work is that, Japan seems to be in the stone age of acoustic treatment.
There's not much happening here regarding home studio DIYers, (there are no companies coming up with effective Bass Traps solutions, credible audio forums, etc...)
People here basically follow the trend and instead of DIYing acoustic panels and bass traps, they spend money with foam materials. (Auralex stuff is everywhere here). There are some DIYers working with mineral wool here and there, and that's basically it.

In other words, I'm totally on my own here.

Hope I can get much needed help and education here.
Here's attached my mixing room plan.




FullRangeMan

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Re: Greeting from Japan.
« Reply #1 on: 21 May 2020, 04:35 am »
Welcome  :thumb:
I came to good results with the car hood brown blanket 15mm.

Wind Chaser

Re: Greeting from Japan.
« Reply #2 on: 21 May 2020, 05:28 am »
Welcome to Audio Circle.  :D

Maybe a volunteer can move this inquiry where it will get more attention, like...

https://www.audiocircle.com/index.php?board=73.0

FullRangeMan

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Re: Greeting from Japan.
« Reply #3 on: 21 May 2020, 05:37 am »
Welcome to Audio Circle.  :D

Maybe a volunteer can move this inquiry where it will get more attention, like...

https://www.audiocircle.com/index.php?board=73.0
Moved as requested.

bassmothership

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Re: Greeting from Japan.
« Reply #4 on: 21 May 2020, 06:13 am »
Welcome  :thumb:
I came to good results with the car hood brown blanket 15mm.


Are the cute cats helping with low end absorption to some extent as well?   :lol:

bassmothership

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Re: Greeting from Japan.
« Reply #5 on: 21 May 2020, 06:16 am »
Welcome to Audio Circle.  :D

Maybe a volunteer can move this inquiry where it will get more attention, like...

https://www.audiocircle.com/index.php?board=73.0

Thank you. I think I should have changed the title to something more appropriated. Or should I start a new thread?

Phil A

Re: Greeting from Japan.
« Reply #6 on: 21 May 2020, 12:37 pm »
Welcome!

JLM

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Re: Greeting from Japan.
« Reply #7 on: 21 May 2020, 02:39 pm »
Welcome!

Suggest reading Floyd Toole's "Sound Reproduction" 3rd edition, the consummate primer to learn how speakers/subwoofers behave in-room.  I assume that you've measured your room to come up with your 200 Hz and below compliant.  If not you'll need to.

First, your room is in horrible ratios, nearly 1:2, meaning that primary resonances will double up.  In your case primary resonances are at 80 Hz and 150 Hz, then 160 Hz 240 Hz, 300 Hz, and 320 Hz.  Recommend putting up some sort of acoustic barrier to create a 7'-6" by 10ft space with another door into it.  That would change the primary resonances to 113 Hz and 150 Hz, then 226 Hz, 300 Hz, 452 Hz, etc.  My room follows the Fibonacci ratios:  8ft x 13ft x 21ft and I use a mid-field setup with speakers 5'-6" from the front wall. 

Second, what monitors are you using?  Hopefully some quality active studio monitors.  Recommend something like Adam A7X, Dynaudio LYD 7, Genelec 8040B, or Neumann KH120.  All are European designed/built.  The Adam uses a ribbon tweeter, the Genelec and Neumann use controlled directivity design.

Third, to produce good recordings you need to hear the lowest frequencies, either via headphones or subwoofer(s).  I say plural on subwoofers because every room inherently has bass peaks/dips and to which multiple subs is the best solution (as per Toole).  I use 3 carefully placed subs in my audio system.

For bass treatment recommend GIK (here at Audio Circle) 244 panels that use Owens Corning 703 high density fiberglass, very effective for bass absorption.  I own ten 244 panels.  A backup material is Rockwool.  Always check the material specifications.  Avoid open cell foam at all costs!  Thicker is better.  Forget about curtains and the like.  And add panels a few at a time and experiment with placement.  Any material needs to be encapsulated to contain breathing in small particles. 

Diffusion is only practical down to about 1100 Hz due to the size of sound waves and the corresponding thickness/weight of panels needed.  Walk away from thin lightweight plastic panels that can't effectively reflect sound. 

Tyson

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Re: Greeting from Japan.
« Reply #8 on: 21 May 2020, 02:49 pm »
I understand not wanting to use Rockwool as that stuff is pretty nasty.  When I did my DIY acoustic panels, I used denim insulation which is made from recycled blue jeans.  It's more expensive, but worth it, IMO.

bassmothership

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Re: Greeting from Japan.
« Reply #9 on: 22 May 2020, 06:15 am »
Welcome!

Suggest reading Floyd Toole's "Sound Reproduction" 3rd edition, the consummate primer to learn how speakers/subwoofers behave in-room. 

Great! I really need literature to educate myself and be able to communicate with you guys. Gonna study this book. Thank you.


First, your room is in horrible ratios, nearly 1:2, meaning that primary resonances will double up.  In your case primary resonances are at 80 Hz and 150 Hz, then 160 Hz 240 Hz, 300 Hz, and 320 Hz.

I'm sorry, I don't understand this language yet.  What exactly is this ratio called in acoustics? How do you come up with the 1:2 ratio value by looking at my room's plan?

Recommend putting up some sort of acoustic barrier to create a 7'-6" by 10ft space with another door into it. 

I cannot fathom what exactly that mean. Would you please elaborate more on that?

My room follows the Fibonacci ratios:  8ft x 13ft x 21ft and I use a mid-field setup with speakers 5'-6" from the front wall. 

Would that be possible to share some pictures as examples, or direct me to a link where I can see what you mean?

Second, what monitors are you using?  Hopefully some quality active studio monitors.  Recommend something like Adam A7X, Dynaudio LYD 7, Genelec 8040B, or Neumann KH120.  All are European designed/built.  The Adam uses a ribbon tweeter, the Genelec and Neumann use controlled directivity design.

I'm a bedroom mixing engineer. I use a a pair of Yamaha HS50M, an old onkyo CD player and cheap speakers as a grotboxes, for mixing referencing.

Third, to produce good recordings you need to hear the lowest frequencies, either via headphones or subwoofer(s).  I say plural on subwoofers because every room inherently has bass peaks/dips and to which multiple subs is the best solution (as per Toole).  I use 3 carefully placed subs in my audio system.

I have no subwoofers. I listen to bass frequencies through Audio Techinca ATH-M50x headphones.

For bass treatment recommend GIK (here at Audio Circle) 244 panels that use Owens Corning 703 high density fiberglass, very effective for bass absorption.  I own ten 244 panels.  A backup material is Rockwool.  Always check the material specifications.  Avoid open cell foam at all costs!  Thicker is better.  Forget about curtains and the like.  And add panels a few at a time and experiment with placement.  Any material needs to be encapsulated to contain breathing in small particles.   

I won't use mineral wool/fiber glass materials inside my room. Would you please give some suggestions of any material other than mineral wool or fiberglass?

Isn't it better I upload my REW measurements here? If yes, which graphs should I post here that are useful to get better feedback from you guys?

bassmothership

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Re: Greeting from Japan.
« Reply #10 on: 22 May 2020, 06:17 am »
I understand not wanting to use Rockwool as that stuff is pretty nasty.  When I did my DIY acoustic panels, I used denim insulation which is made from recycled blue jeans.  It's more expensive, but worth it, IMO.

I've been searching for denim insulation, haven't found anything so far. It's so hard to find these things here in Japan  :(

Tyson

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bassmothership

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Re: Greeting from Japan.
« Reply #12 on: 22 May 2020, 07:27 am »

JLM

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Re: Greeting from Japan.
« Reply #13 on: 22 May 2020, 12:02 pm »
Great! I really need literature to educate myself and be able to communicate with you guys. Gonna study this book. Thank you.


I'm sorry, I don't understand this language yet.  What exactly is this ratio called in acoustics? How do you come up with the 1:2 ratio value by looking at my room's plan?

I cannot fathom what exactly that mean. Would you please elaborate more on that?

Would that be possible to share some pictures as examples, or direct me to a link where I can see what you mean?

I'm a bedroom mixing engineer. I use a a pair of Yamaha HS50M, an old onkyo CD player and cheap speakers as a grotboxes, for mixing referencing.

I have no subwoofers. I listen to bass frequencies through Audio Techinca ATH-M50x headphones.

I won't use mineral wool/fiber glass materials inside my room. Would you please give some suggestions of any material other than mineral wool or fiberglass?

Isn't it better I upload my REW measurements here? If yes, which graphs should I post here that are useful to get better feedback from you guys?

Sorry your english was so good thought you were a native speaker.  Your room is roughly twice as long as wide (1:2 ratio) which is almost the worst possible ratio for bass echo (1:1 is the worst which you already very nearly have with width to height ratio).  What I suggested was to build a wall inside your room to create a 10'-0" long room that would give a better length to width ratio.  Fibonacci ratios (google it) are what a nautilus shape is based on, Fibonacci ratios include 3:5:8, 5:8:13, 8:13:21, etc.  The ancient Greeks used what they called the "Golden Rectangle" (5:8) to achieve what they deemed the ideal visual proportions (and worked great in their stone temples).  Visit Cardas.com room advice for images.  Toole's book will explain further.

Toole's book will also explain that the best way to control bass in-room is with multiple subs, that's why I use 3 carefully placed subs.  Room treatment (absorption) is the second recommended step.  DSP room correction (such as REW) is the last and least recommended option.  Best to solve physical problems via physical means.  DSP will only compensate for a single location in the room via artificially exaggerating responses elsewhere in the room.

Sorry no better materials than Owens Corning 703 or Rockwool as a secondary choice.  I have asthma, allergies, and am 63 years old.  We use a high efficiency furnace filter and central vacuum (so all dust leaves the house), so am sensitive to what you're saying about not wanting loose fibers in the home.  But I have ten large GIK 244 panels in my room and have no issues.  The panels are wrapped, so no fibers get out.  For a lower cost option try overstuffed cloth covered furniture and thick floor rugs. 


bassmothership

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Re: Greeting from Japan.
« Reply #14 on: 24 May 2020, 12:48 pm »
Sorry your english was so good thought you were a native speaker. 

I was referring to doing the ratio maths. I don't understand how the calculation of ratios work in the context of room sizes. I have to do my homework on that.

DSP room correction (such as REW) is the last and least recommended option.  Best to solve physical problems via physical means.  DSP will only compensate for a single location in the room via artificially exaggerating responses elsewhere in the room.

Ow yes, I'm totally aware of that. I'm just using REW as a tool to diagnose how bad my room sounds.
Would you please have a look at the attached files. I made some measurements and I see those dips and peaks but I just don't fully understand yet what these measurements are telling me.










JLM

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Re: Greeting from Japan.
« Reply #15 on: 24 May 2020, 02:30 pm »
Your longest room dimension is 14'-2" = 14.17ft.  Speed of sound is 1130 feet per second.  Dividing speed of sound by the longest room dimension = the lowest (first) primary room echo = 1130/14.17 = 79.7 or 80 Hz. 

Your room width is 7'-6" = 7.5ft.  So the second primary room echo = 1130/7.5 = 150.6 or 150 Hz. 

Those numbers correlate well with what REW shows, especially taking into account the amount of clutter in the room.  For instance I see a 20 dB dip at 90 Hz and a 10 dB peak at roughly 145 Hz with smaller dips and peaks at multiples of those frequencies.  Not unexpected or abnormal.  You're right that bass peaks/dips (below 200 Hz) is what room correction is all about. 

You don't appear to have much wall space available for treatments or room to move your setup away from the window, so your options will be limited.  The thin white window treatment is doing virtually nothing.  I'd move your setup further away from the window and buy six GIK 2ft x 4ft 244 panels,  put two in front of the window, two on the opposite wall, and one on either side of your setup half way between your speakers and the listening position. 

bassmothership

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Re: Greeting from Japan.
« Reply #16 on: 24 May 2020, 03:56 pm »
Your longest room dimension is 14'-2" = 14.17ft.  Speed of sound is 1130 feet per second.  Dividing speed of sound by the longest room dimension = the lowest (first) primary room echo = 1130/14.17 = 79.7 or 80 Hz. 

Your room width is 7'-6" = 7.5ft.  So the second primary room echo = 1130/7.5 = 150.6 or 150 Hz. 

Those numbers correlate well with what REW shows, especially taking into account the amount of clutter in the room.  For instance I see a 20 dB dip at 90 Hz and a 10 dB peak at roughly 145 Hz with smaller dips and peaks at multiples of those frequencies.  Not unexpected or abnormal.  You're right that bass peaks/dips (below 200 Hz) is what room correction is all about. 

You don't appear to have much wall space available for treatments or room to move your setup away from the window, so your options will be limited.  The thin white window treatment is doing virtually nothing.  I'd move your setup further away from the window and buy six GIK 2ft x 4ft 244 panels,  put two in front of the window, two on the opposite wall, and one on either side of your setup half way between your speakers and the listening position.

I really appreciate your thorough explanation. Now I understand. Thank you!

GIK and all other acoustic brands I've heard of don't exist/don't ship to Japan, except Auralex.  :cry: I guess, that's due to not existing demand for such products, the Japs only buy foam.

I went looking at home centers for anything and I found Polyethylene (PET) sheets 50mm thick, 415mm x 1215 mm


Does PET work as bass trap?

Also I found needle felt


Cant I make a very thick wooden frame and fill with needle felt to work as bass trap? Also, there are lots of urethane and polystyrene available here. Will any of these materials work as bass trap?

 

JLM

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Re: Greeting from Japan.
« Reply #17 on: 25 May 2020, 01:01 pm »
Again check manufacturer's acoustic specifications and compare to Owens Corning 703, but doubt if you'll find anything on PET or felt.  Going of intuition is a recipe for disaster.  Nearly all materials do poorly at lower frequencies.

bassmothership

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Re: Greeting from Japan.
« Reply #18 on: 25 May 2020, 05:25 pm »
Again check manufacturer's acoustic specifications and compare to Owens Corning 703, but doubt if you'll find anything on PET or felt.  Going of intuition is a recipe for disaster.  Nearly all materials do poorly at lower frequencies.

I see. Well... it seems there's no light at the end of the tunnel for me. Nothing else left to do as long as I live in this country as there's no proper means to buy or make acoustic panels. Pretty depressing.
I'll finish reading the book anyway. Very enjoyable reading.
Thank you very much for all your suggestions and guidance.

JLM

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Re: Greeting from Japan.
« Reply #19 on: 26 May 2020, 12:37 pm »
If decent materials are unavailable I'd just apply room correction and call it a day.  But be careful to not over boost the dips as the relationship between sound pressure levels and wattage is logarithmic (for instance a 20 dB dip would require 100 times the wattage - leading to severe amp clipping and speaker damage).  Fortunately the ear passes over narrow frequency dips.