[bpape]

Can you get cotton or polyester batting like they use to stuff quilts and pillows?  That can be compressed to work decently.

[Guy 13]

Can you get cotton or polyester batting like they use to stuff quilts and pillows?  That can be compressed to work decently.

Hi bpape and all Audio Circle members.
I will have to go the textile market and see what they have,
maybe they have cotton or polyester, but at what price?
I will let you know my findings, but it might take some time,
because if I go alone, as a foreigner, they will charge me more $ $ $
Thanks.

Guy 13

[JLM]

Hmm, I've always wondered why diffusors are made out of wood  always seemed odd to me since I've only used foam products for wall treatment.
So basically diffusors work based on overall size, width and depth of the gaps/valley's rather then absorbing like foam?   
Make's me think that a diffusor must be at least 4" thick in order to work properly, sound about right?

 

Yes diffusion basically is randomized reflection (scatter).

Think of a light ray hitting a mirror on an angle.  That's what a flat surface does with a sound wave (a clear reflection is produced).  Now replace the flat surface with square teeth of different sizes, say 1 inch, 1.3 inch, and 3.1 inch (just to pick somewhat random sizes) and let a wave with a length of 1/2 inch hit it on an angle.  The wave will bounce around in the teeth and come out different times and directions.  Now fully randomize the tooth sizes, frequencies, and directional angles and you'll get an idea of how a diffusor works.  To make construction easier many designs run the teeth long in the direction at right angles to the primary direction that the sound is coming from.  Another DIY design is to simply use square wooden blocks of different heights stacked next to each other (but this can get heavy).

To randomize the tooth/block sizes most effectively math (fractal or quadratic series) are used.

Sound waves are 13,200 inches/frequency long, so a 1,000 Hz sound wave is 13.2 inches long, a 100 Hz sound wave is 132 inches long, and a 10,000 Hz sound wave is 1.32 inches long.  Hopefully you can see how diffusion can't be used for bass frequencies.

[WireNut]

JLM,

Thanks for this info makes since to me now 

It would seem that a diffuser using small blocks of different lengths would be a better approach then a diffuser that uses long vertical slots as in the pics below. Then, basically the idea behind a diffuser is to break up the wave lengths as much as possible?
Could it be that other materials rather then wood might work which could be very heavy due to size?

Someone here on AC built a DIY diffuser out of small blocks of something like Styrofoam, forgot his name, but maybe that wasn't to bad of an idea 


This approach seems better to me:



Vertical slots:





Found it. Rclark of AC made these, I think out of syrofoam, interesting project.........
http://www.audiocircle.com/index.php?topic=116052.40





 

     

[Austin08]

Guy13,

If passive treatment is impossible then why not try active treatment. Something like minidsp, antimode dualcore 2.0 or manually adjust with REW and Behringer BDF.

[Guy 13]

Guy13,

If passive treatment is impossible then why not try active treatment. Something like minidsp, antimode dualcore 2.0 or manually adjust with REW and Behringer BDF.

Hi Austin08 and all Audio Circle members.
Passive treatment is possible for me,
if I had the money to import some fiberglass sheets.
Which will happen, but not now, later.
I might be old fashion,
but I try to make everything simple,
therefore no active crossover
and now I am going extended range drivers (Omega 7F)
which means no cross over.
Simple is good.
Thanks for the advice
and I don't think your approach is not good,
I guess it a mater of choice,
like choosing Ford over GM.

Guy 13

[Guy 13]

Can you get cotton or polyester batting like they use to stuff quilts and pillows?  That can be compressed to work decently.

Hi (Again) bpape and all Audio Circle members.
I've been thinking a lot about your idea to substitute cotton/polyester
to fiberglass and this is definitely a good alternative,
now the question is:
How much they will ask for their cotton/polyester ? ? ?
I will try to go to the market with my wife on Saturday
and report my findings.
Thanks again, your words and suggestions are encouraging,
for a minute, I was a little depressed.

Guy 13

[FullRangeMan]

Nice room Guy congratulations.
Main reason of good/bad sound in a room is the room shape,
seems the best is this shape I found on Cardas site:

[Guy 13]

Hi FULLRANGEMAN and all Audio Circle members.
Thanks for the compliment about my listening room,
you are the only Audio Circle members that compliment me
for something that I have put many hours to set up.
I already have the sketch you have posted
and the contractor that built our house was supposed to build my listening room according to the sketch you have posted, but he did not.
Now I only have one wall that is not parallel to the facing one.
Sad and frustrating, but I have to live with that.
Thanks again for the suggestion and compliment,
it's highly appreciated,
especially during a very depressing time/period in my life.
If we can rent our other house next door,
I would get a few extra $ $ $ and order/import some 703 fiberglass sheets
to make some bass traps and absorbers.

Guy 13

[FullRangeMan]

Your wife also congratulated for the fine decor, beautiful work from her.

[JLM]

Wirenut,

The problem with styrofoam blocks is that they are relatively acoustically transparent, so the sound would travel right through them and negate the whole diffusive effect.


Austin08,

EQ is only good for a few dB and then only at a single location (where hopefully a microphone was used).  The recommended order to go (and of importance):  proper room size (bigger is almost always better) and shape (width/length/height ratios avoid whole number multiples); set-up (nearfield is best, again avoid distances from surfaces that are multiples of each other); swam of subwoofers (ala Toole); treatment (shouldn't need a lot if size/shape/set-up/swam advice is followed, but sketch from this thread's first post is pretty ideal, maybe a bit over the top IMO); EQ to polish/tweak (should avoid boosting the signal more than a couple of dB as you're pushing amps).

[Hipper]

What you call armoured concrete is I think what we call re-enforced concrete - concrete with steel rods in it to add strength.

[Guy 13]

What you call armoured concrete is I think what we call re-enforced concrete - concrete with steel rods in it to add strength.

Hi Hipper and all Audio Circle members.
Re-enforced concrete is what my house and most of the concrete built houses are
made of.
Thanks for clarifying this.
Not easy to drill holes thru it.

Guy 13

[MarvinTheMartian]

Guy:
If your room is truly a 12'x12'x10' concrete echo echo echo box, I would suggest buying a good set of headphones.
BUT your pictures suggest you are describing the listening area only, you must also include your office area into the equation. Acoustically a curtain divider does not define the room, it is the area between the "hard" walls that is important.

Now in your real room you have four potential bass trap corners available again, the front corners are ideally suited for typical 45 degree floor to ceiling corner bass traps, the back corners are somewhat complicated by the door and the office window.
The pictures do not show the office window area clearly but the shallow alcove behind the door would also be a perfect candidate for a 6" deep flat floor to ceiling trap.

Then start on the 1st reflection side wall absorbers, curtains are a start but they have to be pretty thick, maybe backup your current setup with cheap felt/cotton shipping blankets.

We really need to see a more accurate floorplan of your actual listening "room" to make detailed suggestions.
As for the textiles required check into local industrial sources for fiberglass insulation, felt blankets ?? they may be cheaper than the local shops.

I envy you, my fingers are starting to go numb, as I type this response in my smoking area / garage, it's getting colder 4C.

Shawn   


 

[Guy 13]

Hi MarvenTheMartian and all Audio Circle from the planet Earth.
He re is Guy 13 from the planet Vietnam.
Thanks for your nice write up.
I will get back to you later on today for me
or tomorrow for you with a few picture to help you, help me.
Thanks.

Guy 13

[Guy 13]

Hi MarvinTheMartian and all Audio Circle members.
I did not do what I said I would do and that's:
Getting back to you.
My only excuse is... Unexpected emergencies...
However, this coming Sunday I will have all day to gather all the necessary information to guide me to acoustic heaven.
By the way, I might be able to import some 703 acoustic Fiberglass, I am trying to revise my budget and cut on other not too important miscellaneous stuff.
Stay tune, I will be back, don't want to miss the chance to be guided by someone that knows what he's talking about and someone that knows how to write in a not too direct way.

Guy 13
 

[WireNut]

Hi Guy13,

I know you are on a tight budget as well as most folks here on AC. The site below will give you a wealth of information.........

http://rpginc.com/


   

[Guy 13]

Hi Guy13,

I know you are on a tight budget as well as most folks here on AC. The site below will give you a wealth of information.........

http://rpginc.com/


 

Hi WireNut and all Audio Circle members.
Tight budget you say.
The word is a little weak,
I am on a microscopic budget, that would be more like it.
So that you have an idea that I don't exaggerate,
my budget is 500 USD material, labor, custom tax and import.
I have already tried to find what I need here in Vietnam,
but was unsuccessful.
Thanks for the link, quite interesting.

Guy 13

[Guy 13]

Guy:
If your room is truly a 12'x12'x10' concrete echo echo echo box, I would suggest buying a good set of headphones.
BUT your pictures suggest you are describing the listening area only, you must also include your office area into the equation. Acoustically a curtain divider does not define the room, it is the area between the "hard" walls that is important.

Now in your real room you have four potential bass trap corners available again, the front corners are ideally suited for typical 45 degree floor to ceiling corner bass traps, the back corners are somewhat complicated by the door and the office window.
The pictures do not show the office window area clearly but the shallow alcove behind the door would also be a perfect candidate for a 6" deep flat floor to ceiling trap.

Then start on the 1st reflection side wall absorbers, curtains are a start but they have to be pretty thick, maybe backup your current setup with cheap felt/cotton shipping blankets.

We really need to see a more accurate floorplan of your actual listening "room" to make detailed suggestions.
As for the textiles required check into local industrial sources for fiberglass insulation, felt blankets ?? they may be cheaper than the local shops.

I envy you, my fingers are starting to go numb, as I type this response in my smoking area / garage, it's getting colder 4C.

Shawn

Hi Shawn the Martian.
Before hanging some curtain and laying down a carpet,
my listening room was an echo, echo, echo, box box, box, box…
Not it’s better, for the mids and the highs, but the bass is the one that has to be taken care of.
Your suggestion about buying a good pair of headphones arrive a little late, because I have already bought a pair of Sennheiser HD-650 and the Bottlehead Crack headphone amplifier is on the way.
However, nothing to compete with a good pair of speakers (I have that already) in a good acoustically treated listening room.
Please find herewith a more informative hand sketch with some more pictures of the problematic corners in my office.
I could easily fit at 45 degrees a 6” thick bass trap, between the window and the desk that can be moved to the right.
In the door area, I could fit a 4” thick absorber or bass trap (Whatever you call it) behind the door.
At night the door is open, therefore a 4” thick panel can fit behind the open door.
As for the curtains I’ve tried to blow thru them, not much air goes thru it. I wonder if having some 2” thick Fiberglass behind the curtain would be a waste of money, maybe a large absorber panel (4’ X 4’) 2” thick instead of the curtain, might be more efficient.
I gave up looking for acoustic stuff that in USA you take for granted. Here it’s Vietnam, it’s not what you want, it’s what they want to sell you.
I have checked carefully my budget and I have 500 USD for four (04) boxes of 6 pk of 703 Fiberglass, total cost : 268 USD from ATS Acoustic. They have cheaper stuff, like their own brand and some Roxul, but not sure of the efficiency of those products, even with the technical data.
Of course included in the 500 USD there is transport, custom, local wood frame, etc…
If I could sell some of my audio stuff that I don’t use anymore, that would solve my $ $ $ problem, but here, if it’s not a well know brand, they don’t even look at it.
Don’t forget the reinforced concrete ceiling.
Just want to add that I found some Made in Vietnam Styrofoam diffusers, (The one with different length cubes) at 7 USD each for 2’ X 2’.
Not sure if this could be of some help?
That’s it, I hope you have enough information to start educate me on listening room acoustic treatment.

Guy 13

[Guy 13]

Hi (Again) Shawn and all Audio Circle members.
So, in your garage it's only 4C,
well here in Vietnam it's 4C + 30 more C,
that's makes it 34C with 55% humidity.
Why don't you come see me to help me with my acoustic treatment
and at the same time your body will stock some heat
for the coming winter.

Guy 12 in Vietnam or in hell,
it's about the same thing with 34C.