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Room acoustics and room treatment

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ellisdj

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Dec 11, 2008
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What is your rt60 time??

Also that calculator looks excellent need some time have a play with it.
 

insider9

Well-known member
Sep 20, 2016
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Usually RT60 around 350ms-400ms without any correction or treatment. Different positions measured as well as variety of speakers and amps I've had.

Current listening position with the speakers I'm using right now measures around 400ms but with "treatment" I got it down to under 300ms. Was it to then apply correction I'm certain it could go down to under 200ms.
 

ellisdj

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Dec 11, 2008
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Thats the wrong number it will be a time in seconds probably 0. Something.

You get it from the rt60 overlay unless you have a different graph scale to me??
 

insider9

Well-known member
Sep 20, 2016
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400ms is 0.4s

I usually get 0.3s if you prefer which I find easier to write as 300ms

EDIT
Somehow 0.3s looks wrong but 300ms looks right to me :)
 

ellisdj

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Dec 11, 2008
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Do you have a photo because normally it will track differently depending on freq.

Its advised between 0.3 and 0.2 and as linear as possible

Its only 500 - 2khz thats important i think.
 

insider9

Well-known member
Sep 20, 2016
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No probs, I'll post one tomorrow as it's on a pc. With "treatment" it's quite linear. Not so much without.

EDIT

Here's one with "treatment" as wife is still not in bed - here
 

ellisdj

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Dec 11, 2008
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Your 100hz goes off the chart same as mine. The rest is spot on

Looking at it again i wonder if there is not room for improvement when using proper products for the job over a mattress.

So there is more 200hz area smoothing affect and slightly less affect on treble so the line is more smiley face in shape. Keeping the treble a little higher in reverb.

You are inspiring me dude really impressed with how you have taken this all on.

This is what a hifi forum should be about. People inspiring others to do better. Thanks insider
 

insider9

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Sep 20, 2016
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I treat it as merely giving back. Your many great contributions over the last year are and important factor in this. I particularly fondly remember Gazzip's thread that really got me thinking. And you're quite right that's how it should be.

When it comes to the mattress I've used I fear it lacks in density so can quite so the best of jobs in bass. I must say I was impressed how it worked nevertheless.

It's funny how it took me nearly a year to undertake such an important job.

I'll try experimenting treating first reflections at some point today with my little boy's old cotbed mattress :biggrin:
 

ellisdj

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Dec 11, 2008
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Its not so much the density that works to lower freq - its the airgap behind it that extends the performance in terms of freq.

Try with a 2inch gap behind it or 4"

This is also where the corners are supposed to have the biggest impact.

in my room the side walls dont really have much effect on bass - that probably where I have gone wrong - too thick panels used on the sidewalls - not thick enough on the ceiling. Its hard working it all out on your own

Gazzip inspired me to do better also, as did Electro, HiFi Live Show and a few other demos last year.
 

insider9

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Sep 20, 2016
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The air gap and the panel positioning is important. I intend to build mind hollow to the back (with a frame deeper than the insulation) so when pushed right against the wall the air gap will still be there. So depending on timber I get I might have 8" panels that are half filled. I think it'll look and work better.

It is interesting as in real terms not just the speakers should be free of walls and the panels should be quarter of the wavelength away from wall as well. I'm beginning to think God is American as our UK homes are simply too small for all this :)
 

ellisdj

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Dec 11, 2008
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Thats how initially built mine - however a better design would have access all around the panel to the wall - not closed off with wood. To allow air in and out freely.

It will look like its hanging off the wall but I am pretty sure thats a better design, I am sure I read that somewhere.

Go thick in the important places - for me its rear wall I have got a load of thick absorption on there - a lot of it is membrane covered to not absorb the high end.

However my RT60 comes in the extreme low range - its probably too low. Higher RT60 sound is more enveloping.

When I added the duffors thats excactly what happened the sound became more enveloping - makes sense now.

I could likely get a more detailed sound with a higher RT60 - its a new project, like I need one of them right now :)
 

insider9

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Sep 20, 2016
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I know that wooden frames are not optimal but I'd probably struggle without. I need them fairly rigid for testing at least as I won't drill holes without checking positioning etc.
 

ellisdj

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Dec 11, 2008
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They need to be rigid insulation is heavy - you can just make them and prop them up on something to test them out.
 

insider9

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Sep 20, 2016
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At first I though I'd use either fiberglass of mineral wool both come in sheets. Having reconsidered I now sway towards sheep's wool only seen it in rolls. Shame would prefer flat packed.

It's non irritant, natural, can help regulate humidity and purify air. Started looking into it as had concerns as my wife has some allergies. I'd rather avoid

The humidity aspect particularly is an interesting property as the speed of sound depends on temperature and humidity. I know the differences would be small maybe a percentage point but I'll take any advantage I can get.

Also, I could not find sound absorption data for Rockwool and Knauf Eartwool.
 

ellisdj

New member
Dec 11, 2008
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You are lucky you know me

I did all this research ages ago

http://www.bobgolds.com/AbsorptionCoefficients.htm

https://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/685691-oc-703-alternative-eu.html

These are the bookmarks I kept.

If you use the earthwool its not really very itchy and kind to the air

However using rockwall it is - I insulated my ceiling with that to stop sound leakage to upstairs - had to go full getup for that



In looking for that one I found this one



Thats whats on my front wall and how I used to aggressively toe in my last speakers.

Thats 4 Diffusors 2 polystyrene style and 2 wood ones coverd in camira fabric.

In the middle is a GIK 244 with a wood scatter built in

I am wondering on a few changes - its missions for me to make them now though, just need to motivate myself
 

newlash09

Well-known member
Aug 28, 2015
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and different from the usual run of the mill threads here. I strongly believe that once components of a certain quality are in place, room correction and treatment will give the biggest improvement, as compared to upgrading more boxes.

That said, I can't really use room treatment in my listening area, as it is the shares dining space in the house. At most I could add a rug on the floor, and paste one on the ceiling.

But Iam serious about the minidsp Dirac being my next purchase. Especially as I plan to use a sub with a 60 Hz cross over placed under the hand wash, and it will be perpendicularly to the left of my listening position, when facing my QA concept 40 floor standers. The parasound halo amp has good bass management with high pass filter as well. But I will need the minidsp to get the delay on the sub right, as it is closer to my listening position, than the speakers. Fondly hope some how it all works.

I have another query. I was also planning on a getting a Sony hap z1es music server as source. However it only outputs via analogue RCA and XLR. So will the minidsp also work in the analogue domain. Thanks.
 

ellisdj

New member
Dec 11, 2008
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2 Suggestions.

1 you can get mini dsp units that will convert A/D - however I would say keeping the signal digital is better.

There are literally hundreds of music servers on the market - at all prices. Its probably better to select a different music server that has a digital output if you dont already own it.

2. Are you placing the sub in that position for aesthetic reasons or because its the best spot in the room?

Also - even I dont think I would rug the ceiling in your position :)
 

Electro

Well-known member
Mar 30, 2011
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What do people think about the idea of putting a small palm tree or Yucca with a thick fibrous trunk into a corner behind the speaker and what effect it might have on the sound.

I guess it would be quite a good diffuser and would provide a small amount of bass absorbtion.

It would also be very domestically acceptable. ( WAF ) *smile*

The idea sprung into my head when thinking about Mac's room and the offending corner .

What are your thoughts .
 

insider9

Well-known member
Sep 20, 2016
740
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Electro said:
What do people think about the idea of putting a small palm tree or Yucca with a thick fibrous trunk into a corner behind the speaker and what effect it might have on the sound.

I guess it would be quite a good diffuser and would provide a small amount of bass absorbtion.

It would also be very domestically acceptable. ( WAF ) *smile*

The idea sprung into my head when thinking about Mac's room and the offending corner .

What are your thoughts .
I'm in the process of such experiments with domestically available items. Don't have any palm trees though. I would say that as far as a scatterer it would work for certain frequencies but not as a diffuser. The difference being diffuser will be predictable in use and when used correctly will be beneficial. Scatterer won't be predictable and as such it will be difficult to assess it's benefits.
 

newlash09

Well-known member
Aug 28, 2015
163
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The sub can't be placed between the floor standers for aesthetic reasons. My better half would never agree to placing another box in the dining room. So I thought I could shove it under the hand wash, and go unnoticed.

Well noted regarding going for a server with digital out. Will search for one with a remote app to control via a tab like the Sony. Agree that having digital out will give the possibility of keeping up with dac improvements.
 

insider9

Well-known member
Sep 20, 2016
740
301
5,270
newlash09 said:
The sub can't be placed between the floor standers for aesthetic reasons. My better half would never agree to placing another box in the dining room. So I thought I could shove it under the hand wash, and go unnoticed.

Well noted regarding going for a server with digital out. Will search for one with a remote app to control via a tab like the Sony. Agree that having digital out will give the possibility of keeping up with dac improvements.
Why not use a large USB drive with your Yamaha WXC-50? You then have an optical or coax out.
 

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