John Sayers' Design Forum

John Sayers' Recording Studio Design Forum

A World of Experience
Click Here for Information on John's Services
It is currently Thu Mar 04, 2021 10:01 pm

All times are UTC + 10 hours




Post new topic Reply to topic  [ 9 posts ] 
Author Message
PostPosted: Wed Jul 22, 2020 7:13 am 
Offline

Joined: Wed Jul 22, 2020 7:02 am
Posts: 1
Hey guys,

First post here and I'm gonna make it a quick one!

Looking to tame my room a bit for tracking and mixing, but I'm in a temporary location, so I have not used REW or anything like that. However, I'd still like to invest in building some acoustic treatment now, so it think panels will be the best move. It looks like Lowe's has the best bang for your buck deal with 3 packs of 8 24x48x3 safe n sound panels for ~$200 while it would cost about $100 for just one from Amazon shipped. I'm planning to get the 3 pack, but I'm not sure how I should split them up. From my understanding, 4" is where low end starts being absorbed, so I figure I would take 16 of the panels and make 2 6" deep panels for each corner, then I could use the other 8 panels to make 3" broadband absorbers to place selectively around the room. Alternately, I could just double up all of the panels and make 12 6" deep.

I'm not sure which option would get me the most mileage: less depth with more room coverage or more depth with less coverage

Thanks for your help in advance!


Report this post
Top
 Profile  
 
PostPosted: Wed Jul 22, 2020 9:06 am 
Offline
Senior Member

Joined: Sun Mar 02, 2014 8:42 am
Posts: 571
Location: Wales, UK
jwardoin wrote:
Hey guys,

First post here and I'm gonna make it a quick one!

Looking to tame my room a bit for tracking and mixing, but I'm in a temporary location, so I have not used REW or anything like that. However, I'd still like to invest in building some acoustic treatment now, so it think panels will be the best move. It looks like Lowe's has the best bang for your buck deal with 3 packs of 8 24x48x3 safe n sound panels for ~$200 while it would cost about $100 for just one from Amazon shipped. I'm planning to get the 3 pack, but I'm not sure how I should split them up. From my understanding, 4" is where low end starts being absorbed, so I figure I would take 16 of the panels and make 2 6" deep panels for each corner, then I could use the other 8 panels to make 3" broadband absorbers to place selectively around the room. Alternately, I could just double up all of the panels and make 12 6" deep.

I'm not sure which option would get me the most mileage: less depth with more room coverage or more depth with less coverage

Thanks for your help in advance!


Hi,

4" of safe and sound will be ineffective below 200hz.

However, thicknesses above 4" of semi rigid insulation are also ineffective below 200hz, once you go above 4" you really should be using low density, cheap fluffy insulation at greater thicknesses if bass absorption is your aim.

With your current plan all you will do is suck all the highs and high mids out of your space leaving the low mids and lows to ring out and worsen the sound of your room.

A very basic way to treat a space with temporary panels is like this: Build effective bass traps first in the corners and the entire rear wall (1'-3' thick) then first reflection panels (8" thick) including an over head cloud and you'll find that should be enough if the rest of your space is reflective.

Use http://www.acousticmodelling.com/8layer ... 82CulDpJMM for working out what products and thicknesses you should use in order to absorb the desired frequency range in your room. You'll need to know the gas flow resistivity data for each product which can be found on gearslutz and bobgolds.com if the manufacturer doesn't provide it. But to get you started; low density fluffy insulation has a GFR of about 5600rayls, semi rigid safe and sound (Rockwool) has a GFR of about 25000rayls. Anything with a co-efficient below 0.6 should be considered ineffective in my opinion.

Hope this helps,
Paul

_________________
Paul


Report this post
Top
 Profile  
 
PostPosted: Thu Jul 23, 2020 3:43 am 
Offline
Senior Member

Joined: Tue Mar 25, 2008 3:31 am
Posts: 445
Location: Cork Ireland
Welcome jwardoin, I would prefer a 4" thick material, but your 6" straddling the corners floor to ceiling is a very good bang per buck idea.
Hi Paul, seems like we are at the opposite sides of a perpetual dispute based on the quarter wavelength notion.
100mm semi rigid fibre such as 703 and 705 has an absorption factor of about 85% in the 125Hz Octave band.
With a 100mm airgap and reasonable area these materials are almost as good as a full 200 of less dense fibre.
Straddling corners they benefit from a damped resonance which greatly helps.
We don't have SnS here I think it is 2.5 pcf so I would guess the GFR to be about 14000. Afaik Roxul are a premium manufacturer.
http://forum.studiotips.com/viewtopic.php?f=8&t=534

_________________
DanDan FitzGerald MIOA MAES
http://www.irishacoustics.com
http://www.soundsound.ie


Report this post
Top
 Profile  
 
PostPosted: Thu Jul 23, 2020 5:27 am 
Offline
Senior Member

Joined: Sun Mar 02, 2014 8:42 am
Posts: 571
Location: Wales, UK
DanDan wrote:
Welcome jwardoin, I would prefer a 4" thick material, but your 6" straddling the corners floor to ceiling is a very good bang per buck idea.
Hi Paul, seems like we are at the opposite sides of a perpetual dispute based on the quarter wavelength notion.
100mm semi rigid fibre such as 703 and 705 has an absorption factor of about 85% in the 125Hz Octave band.
With a 100mm airgap and reasonable area these materials are almost as good as a full 200 of less dense fibre.
Straddling corners they benefit from a damped resonance which greatly helps.
We don't have SnS here I think it is 2.5 pcf so I would guess the GFR to be about 14000. Afaik Roxul are a premium manufacturer.
http://forum.studiotips.com/viewtopic.php?f=8&t=534


Hi Dan, I base all my estimations on the predictions calculated by the multi-layer absorber calculator.

703 has a GFR of about 27000, 0.6 co efficient@200hz which steeply drops off below that.

Indeed we do not have safe and sound here, I assumed they come in semi rigid batts similar to the other common Rockwool products, but on further research it seems safe and sound has a GFR of around 8000rayls.

100mm safe and sound will be good down to about 250hz
350mm safe and sound will be good down to about 60hz

Paul

_________________
Paul


Report this post
Top
 Profile  
 
PostPosted: Fri Jul 24, 2020 1:11 am 
Offline
Senior Member

Joined: Tue Mar 25, 2008 3:31 am
Posts: 445
Location: Cork Ireland
OC703 which is 3 pcf has a GFR of 1650 if I remember correctly. That is a figure which Andre Vare got from OC quite recently. 705 is the one up around the 30K.
Afaik, SnS is 2.5 pcf and about 10000 https://www.gearslutz.com/board/studio- ... ers-2.html
The online PAC fun as far as it goes, but there are quite a few aspects of reality it does not include, e.g. Corners and Damped Resonance of the more rigid fibres.
More disturbingly it predicts a 100Hz Alpha of 0.4 for 100 mm OC703 but Bobgolds.com shows Lab tests with Alpha 0.85
Also SnS 0.3 Predicted, 0.52 Measured.

_________________
DanDan FitzGerald MIOA MAES
http://www.irishacoustics.com
http://www.soundsound.ie


Report this post
Top
 Profile  
 
PostPosted: Fri Jul 24, 2020 1:41 am 
Offline
Senior Member

Joined: Sun Mar 02, 2014 8:42 am
Posts: 571
Location: Wales, UK
DanDan wrote:
OC703 which is 3 pcf has a GFR of 1650 if I remember correctly. That is a figure which Andre Vare got from OC quite recently. 705 is the one up around the 30K.
As SnS is 2.5 pcf about 14000, but I have also seen this quoted. Probably in my GFR thread on NorthSlutz.
The online PAC fun as far as it goes, but there are quite a few aspects of reality it does not include, e.g. Corners and Damped Resonance of the more rigid fibres.
More disturbingly it predicts a 100Hz Alpha of 0.4 for 100 mm OC703 but Bobgolds.com shows Lab tests with Alpha 0.85


The figures I got for the OC703 are from NASA apparently. No idea who is correct or if it even matters.

Yes, the online calculator can only predict so much, but is fairly accurate according to John Brandt and Jens from gearslutz, amongst others. I have had very similar predictions from sound flow, so I don't think one can go far wrong by using it.

Of course, real world measurements are the only way to know what is going on.

Paul

_________________
Paul


Report this post
Top
 Profile  
 
PostPosted: Fri Jul 24, 2020 6:42 am 
Offline
Senior Member

Joined: Tue Mar 25, 2008 3:31 am
Posts: 445
Location: Cork Ireland
Yes NASA did publish that a very long time ago. Since then Owens Corning have responded with various figures over time.
They told Andre Vare it was 18K quite recently. Given the density, credible IMO.
https://www.gearslutz.com/board/showpos ... tcount=173

Sorry to disagree paul but the tested Alphas for 703 and SnS are twice those predicted by that calculator.
Why would we trust testimonials from dubious characters who are not here vs irreconcilable data?
Those calculators are fun but there is just more to it which their algorithms just don't take account of.
I find it similar to the ubiquitous fascination with Mode Calculators. Their 'qualifiers', Bolt etc. have been found not to scale to small rooms.
Attachment:
OCJP.jpg


You do not have the required permissions to view the files attached to this post.

_________________
DanDan FitzGerald MIOA MAES
http://www.irishacoustics.com
http://www.soundsound.ie


Report this post
Top
 Profile  
 
PostPosted: Sat Jul 25, 2020 12:53 am 
Offline
Senior Member

Joined: Sun Mar 02, 2014 8:42 am
Posts: 571
Location: Wales, UK
DanDan wrote:
Yes NASA did publish that a very long time ago. Since then Owens Corning have responded with various figures over time.
They told Andre Vare it was 18K quite recently. Given the density, credible IMO.
https://www.gearslutz.com/board/showpos ... tcount=173

Sorry to disagree paul but the tested Alphas for 703 and SnS are twice those predicted by that calculator.
Why would we trust testimonials from dubious characters who are not here vs irreconcilable data?
Those calculators are fun but there is just more to it which their algorithms just don't take account of.
I find it similar to the ubiquitous fascination with Mode Calculators. Their 'qualifiers', Bolt etc. have been found not to scale to small rooms.
Attachment:
OCJP.jpg


Hey Dan, no need to be sorry - I am not here to win debates or start nonsensical arguments, I'm much more interested in learning. I am just relaying the information that I have found, which may be outdated and am happy to be corrected.

I don't think we can compare the results of online calculators with manufacturer lab test data, especially data which doesn't go below 125hz and has coefficients above 1. Co-efficients above 1 are quite complicated to grasp, and again, real life results will vary greatly depending on construction, size of the space, diffuse field/normal incidence etc etc. More on the topic here:

https://www.gearslutz.com/board/studio- ... ients.html

http://forum.studiotips.com/viewtopic.php?t=3255

To help the OP, it is my opinion that any of the suggestions given by myself or Dan will greatly improve your space.

Paul

_________________
Paul


Report this post
Top
 Profile  
 
PostPosted: Sat Jul 25, 2020 3:23 am 
Offline
Senior Member

Joined: Tue Mar 25, 2008 3:31 am
Posts: 445
Location: Cork Ireland
I think the fact that the Calculator predicts twice what the Labs measure causes great uncertainty regarding both.
Particularly as the PAC Algorithms are at least partly empirical, derived from Lab practice.
Labs have to deliver to legal standard, thus the variables have to be well aired.
Apart from corners and damped resonance, another big issue with Prediction is the complete absence of an Area factor. e.g. A single 25mm ceiling tile has pretty much no acoustic effect, but a suspended ceiling has excellent absorption down to 50Hz.
I concur with your excellent suggestions acoustically. But the OP is in a temporary location, thus my perspective on the standard MiniTrap or GIK 244.
A big amount (Area) of such devices, say 20, will improve a typical small room a lot. If space money and the predicted relocation allow, instead of panel traps, go for big square corner traps.

_________________
DanDan FitzGerald MIOA MAES
http://www.irishacoustics.com
http://www.soundsound.ie


Report this post
Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 9 posts ] 

All times are UTC + 10 hours


Who is online

Users browsing this forum: No registered users and 19 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Jump to:  
Powered by phpBB® Forum Software © phpBB Group