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Tackling room resonances

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Re: Tackling room resonances

Postby Mike Stranks » Sun Jul 28, 2019 10:20 pm

Sam Spoons wrote:Or for corner traps, a stack of triangular pieces filling the corner with a 12"-18" front face are even more effective ('cos the cut edges are more absorbent than the treated faces and 'cos the effective depth is greater).

Yup! As taught to me by Studio Support Gnome!
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Re: Tackling room resonances

Postby Wonks » Sun Jul 28, 2019 10:25 pm

If you struggle to get rockwool of a suitable density, glass fiber is far more widely used in the US for bass and broadband traps than in the UK. Similar issues with loose fibers causing irritation and similar remedies utilised, but the absorption performance is comparable. (US spelling of 'fibre' used).
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Re: Tackling room resonances

Postby Sam Spoons » Sun Jul 28, 2019 10:28 pm

Mike Stranks wrote:
Sam Spoons wrote:Or for corner traps, a stack of triangular pieces filling the corner with a 12"-18" front face are even more effective ('cos the cut edges are more absorbent than the treated faces and 'cos the effective depth is greater).

Yup! As taught to me by Studio Support Gnome!

Me too, SSC's, or to give them their full title "Studiotips Super Chunks". :thumbup:

Glass fibre is not as kind to your body as Rockwool mineral fibre (it's more likely to cause irritation and so on) but no reason why it should be less effective AFAIK.
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Re: Tackling room resonances

Postby Eddy Deegan » Mon Jul 29, 2019 2:59 am

blinddrew wrote:what you're after is RW3, 45 - 60kg/m3 is the density you want to be looking for. Or at least I hope it is because it's on my shopping list... :)

James Perrett wrote: for panels the 60kg/m3 density seems to be the best compromise. If you can mount them so that they are spaced slightly away from the wall they become effective down to a slightly lower frequency.

Checking my notes, Max was of similar opinion - 60kg/m3 was the magic number, at least in my case. Of the five bass traps in the plan he formulated for me, 3 are spaced from the wall and 2 are thick enough (due to a good window indent depth) to not need it.
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Re: Tackling room resonances

Postby Martin Walker » Mon Jul 29, 2019 12:21 pm

+1 for 60Kg/m3

After installing half a dozen RealTraps after reviewing them for SOS years back, I still needed more trapping, so I bought some 45Kg/m3 rockwool that I assembled into 4' by 2' by 1' megachunks, sprayed with the recommended dilute PVA adhesive (to stop the fibres shedding), and then simply wrapped them in butter muslin.

They made a very real difference, but have sagged a bit since. Mine were all floor-mounted, so if you're considering wall-mounted traps then 60Kg/m3 makes a lot more sense.


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Re: Tackling room resonances

Postby Wonks » Mon Jul 29, 2019 12:53 pm

*kg/m³
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Re: Tackling room resonances

Postby TNGator » Mon Jul 29, 2019 1:32 pm

Martin Walker wrote:+1 for 60Kg/m3

After installing half a dozen RealTraps after reviewing them for SOS years back, I still needed more trapping, so I bought some 45Kg/m3 rockwool that I assembled into 4' by 2' by 1' megachunks, sprayed with the recommended dilute PVA adhesive (to stop the fibres shedding), and then simply wrapped them in butter muslin.

They made a very real difference, but have sagged a bit since. Mine were all floor-mounted, so if you're considering wall-mounted traps then 60Kg/m3 makes a lot more sense.


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Hi Martin
I have a roll of what i believe is mineral wool. Well not a full roll but darn close. It was left over from building work we had done a few years back. Its too expensive to simply dump so I mailed the manufacturer to ask what it was and explained what I need it for. They replied after a while and said they wouldnt recommend for sound treatment and sent a link for some other stuff but Id need to order it online. So I might have to simply buy those rock wool slabs or got to Thomann who do a good range of actual sound treatment products. You know if my test mic would just get here soon I could test what i have using the REW software.
oh....quick question guys. Theres a builder doing work next door. Nice lad from England so i was talking to him just now about what Im at. He wasnt sure of course about sound treatment but....as far as making a light weight frame was concerned he showed me the aluminum studding they use now. Weighs nothing. But would an aluminum frame on your absorber defeat the purpose due to reflections? I could probably cover the frame with fabric. I dont have a pic but I could probably send one.
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Re: Tackling room resonances

Postby TNGator » Mon Jul 29, 2019 1:33 pm

TNGator wrote:
Martin Walker wrote:+1 for 60Kg/m3

After installing half a dozen RealTraps after reviewing them for SOS years back, I still needed more trapping, so I bought some 45Kg/m3 rockwool that I assembled into 4' by 2' by 1' megachunks, sprayed with the recommended dilute PVA adhesive (to stop the fibres shedding), and then simply wrapped them in butter muslin.

They made a very real difference, but have sagged a bit since. Mine were all floor-mounted, so if you're considering wall-mounted traps then 60Kg/m3 makes a lot more sense.


Martin
Hi Martin
I have a roll of what i believe is mineral wool. Well not a full roll but darn close. It was left over from building work we had done a few years back. Its too expensive to simply dump so I mailed the manufacturer to ask what it was and explained what I need it for. They replied after a while and said they wouldnt recommend for sound treatment and sent a link for some other stuff but Id need to order it online. So I might have to simply buy those rock wool slabs or got to Thomann who do a good range of actual sound treatment products. You know if my test mic would just get here soon I could test what i have using the REW software.
oh....quick question guys. Theres a builder doing work next door. Nice lad from England so i was talking to him just now about what Im at. He wasnt sure of course about sound treatment but....as far as making a light weight frame was concerned he showed me the aluminum studding they use now. Weighs nothing. But would an aluminum frame on your absorber defeat the purpose due to reflections? I could probably cover the frame with fabric. I dont have a pic but I could probably send one.

Ah...the rockwool Im looking at here is only 38K. Too light? If I used two slabs does that double it up? https://www.goodwins.ie/products/Rockwo ... filter_set[]=1413,1451
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Re: Tackling room resonances

Postby Hugh Robjohns » Mon Jul 29, 2019 2:12 pm

TNGator wrote:But would an aluminum frame on your absorber defeat the purpose due to reflections?

Not as long as you're talking thin metal corner pieces and struts, or panels with a lot of holes/slots in it. Most of the commercial traps use metal framing, such as these Realtraps MiniTrap panels:

Image

H
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Re: Tackling room resonances

Postby TNGator » Mon Jul 29, 2019 2:44 pm

Hugh Robjohns wrote:
TNGator wrote:But would an aluminum frame on your absorber defeat the purpose due to reflections?

Not as long as you're talking thin metal corner pieces and struts, or panels with a lot of holes/slots in it. Most of the commercial traps use metal framing, such as these Realtraps MiniTrap panels:

Image

H
Yes very similar to the pic Hugh. Apparently builders are using these now instead of 2x4 studs. They have a mesh type design. Some spray paint and you could have something very cool n trendy lie the ones you've shown here. .
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Re: Tackling room resonances

Postby Martin Walker » Tue Jul 30, 2019 10:34 am

TNGator wrote:Ah...the rockwool Im looking at here is only 38K. Too light? If I used two slabs does that double it up? https://www.goodwins.ie/products/Rockwo ... filter_set[]=1413,1451

38Kg/m3 would still provide some absorption., but is indeed a little on the light side. You would get significantly more effective results with 60Kg/m3, and that would be easier to place within the frames you're discussing without sagging and flopping about.

Yes, you can double up two thicknesses of 50mm to give exactly the same effect as one 100mm slab, but once again a single slab of 60Kg/m3 will be easier to work with and should cost the same or even very slightly cheaper - it's largely the amount of material that determines the cost.


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Re: Tackling room resonances

Postby TNGator » Tue Jul 30, 2019 10:39 am

Martin Walker wrote:
TNGator wrote:Ah...the rockwool Im looking at here is only 38K. Too light? If I used two slabs does that double it up? https://www.goodwins.ie/products/Rockwo ... filter_set[]=1413,1451

38Kg/m3 would still provide some absorption., but is indeed a little on the light side. You would get significantly more effective results with 60Kg/m3, and that would be easier to place within the frames you're discussing without sagging and flopping about.

Yes, you can double up two thicknesses of 50mm to give exactly the same effect as one 100mm slab, but once again a single slab of 60Kg/m3 will be easier to work with and should cost the same or even very slightly cheaper - it's largely the amount of material that determines the cost.


Martin
Yeah Ive noticed its the wood seems to be the most expensive. You want nice decorative wood not old pallets from the warehouse. But...that metal studding I mentioned is cheap enough. And you the funny thing? Thomann have a set of 12 smallish panels and the cost isnt that much more.
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Re: Tackling room resonances

Postby Martin Walker » Tue Jul 30, 2019 3:42 pm

TNGator wrote:And you the funny thing? Thomann have a set of 12 smallish panels and the cost isnt that much more.

Yep, economies of scale do often mean that companies who manufacture a lot of acoustic treatment components can do so at prices only slightly above taking the DIY approach.

Sad but true! ;)


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Re: Tackling room resonances

Postby Wonks » Tue Jul 30, 2019 3:52 pm

TNGator wrote: And you the funny thing? Thomann have a set of 12 smallish panels and the cost isnt that much more.
Can you link to the ones you mean? There are a lot of light panels out there that are only really good for high frequencies.
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Re: Tackling room resonances

Postby Sam Spoons » Tue Jul 30, 2019 4:06 pm

I saved about 40% by going DIY (compared with Gik panels and using Cara fabric bought from them). Total cost for 10 various sized panels was around £350.
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Re: Tackling room resonances

Postby TNGator » Tue Jul 30, 2019 4:14 pm

Wonks wrote:
TNGator wrote: And you the funny thing? Thomann have a set of 12 smallish panels and the cost isnt that much more.
Can you link to the ones you mean? There are a lot of light panels out there that are only really good for high frequencies.

So Thoman have their absorbers listed by 2 categories. Bass traps and Broadband absorbers. The list of broadband is quite a lot and it is here.
https://www.thomann.de/ie/standard_absorbers.html

So for example, under the broadband family they have a 6 piece set for about 40 euro
https://www.thomann.de/ie/the_t.akustik ... cs_set.htm
Im just taking this one as an example. It doesn't show a coefficient rating so i dont know if it rates at 0.7 or .8 etc. Its density seems a bit low at 17kg but then again it isnt a bass trap. Im not sure if its more important to buy a bass trap first and then save for normal absorbers. In a small cube room like mine 10 ft by 11 ft and 8 high maybe bass in the corner might be the biggest problem to deal with.
PS.... my test mic arrived a few minutes ago so I'll try and figure out how to use REW and see what my room is doing.
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Re: Tackling room resonances

Postby Sam Spoons » Tue Jul 30, 2019 4:58 pm

Bass traps will often also absorb higher frequencies as well, those foam tiles will probably be next to useless. If you look at all of Thomann's Clearsonic 'Sorber' full range absorbers I(their cheapest 'proper' panels) they are slightly more expensive than the Gik ones (Cleasonic = £98/m2, Gik = £89/m2). This others are more expensive still as far as I can tell.
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Re: Tackling room resonances

Postby TNGator » Tue Jul 30, 2019 5:26 pm

Sam Spoons wrote:Bass traps will often also absorb higher frequencies as well, those foam tiles will probably be next to useless. If you look at all of Thomann's Clearsonic 'Sorber' full range absorbers I(their cheapest 'proper' panels) they are slightly more expensive than the Gik ones (Cleasonic = £98/m2, Gik = £89/m2). This others are more expensive still as far as I can tell.

Thanks for the info Sam :bouncy: That will save me time and money running after egg cartons.
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Re: Tackling room resonances

Postby Mike Stranks » Tue Jul 30, 2019 5:53 pm

I don't where you're based TNG, but I've treated my small room with these fibreglass panels:

https://www.studiospares.com/Studio-Gear/Acoustic-Panels/Acoustic-Panel-1200-x-600mm-Grey_465220.htm#rtabs3

set 25mm off the wall - ie total depth is 50mm. I have consciously chosen to use small (10mm woofer) speakers so as to keep bass excitement to a minimum, but it's still an issue in my small room. For mixes with significant bass then I switch to headphones. A good compromise in my small room otherwise the treatment would preclude me from getting in here!

Blue Frog also have a good range of treatments: http://www.bluefrogaudio.co.uk/

and they're well thought of.

and there's one very simple guideline for acoustic treatment... never use foam! :lol:
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Re: Tackling room resonances

Postby Studio Support Gnome » Tue Jul 30, 2019 10:57 pm

Just a note on density and absorption coeffiecents and which to use why.


the absorption curve of 60 and 45 is very similar, although slightly different.... , 60 on edge gives something closer to 45 flat fronted. Edge performance is higher as the gas entry impedance is lower.

I recommend 60 not necessarily because it is the best all round absorber, at the ultimate edge of theoretical performance , because it's not, but it's close enough to 45 to make bugger all practical difference in terms of real world performance, but I generally recommend it for DIY use as well as paid labour use, because it is by far the most practical , easiest material to actually build with.

As well as being easier to handle, easier to cut accurately, and least messy, generating far less fluff and dust , , and on top of that 60Kg is dense enough to be structurally self supporting when laid flat , with edge facing the room, up a 2.5-3 metre high stack.... no great problem, Higher if you're careful and precise with the edge bracing... so framing it is just a matter of a braced edge frame, and fabric finish over it... and building the thing only requires two uprights one at each face corner... placed so you :"just" have to tuck the corners of the slabs in to the upright. and you can use these uprights as the edge of the fabric mount as well

45 will "spring out in the middle when you try and stack it that high, so requires far more bracing and framing to make it stay still.... especially if you build a "super duper chunk" 4 feet across the front....

this then also makes getting a flat finish on the fabric harder , unless you also eat up more space by spacing it further away from the absorption material


When faced with building a number of these devices.... especially if paying for the labour, speed and ease of construction is a matter of some concern. The minimal trade off of absorption at some frequencies is more than made up for in the saving on costs. (labour being far more expensive than the materials of any density )

even bigger ones are built using a front section of 60, but the infill behind it is lower density... at that point using 30kg stuff is fine.... indeed layering different densities can give additional loss effects as the impedance change point between densities is a transmission medium interface .

and Studio tips did NOT invent the "large absorption mass " design. to give it a more PROPER name... ... this technique was around a LONG time before the internet even existed ...

thus I have always treated their appropriation of it as their territory with the contempt it deserved.

60Kg also has the benefit of maintaining a more consistent density once you start building properly large devices..... I've built traps 4 metres high with it with no discernible change in density , you try that with 45kg and you can SEE the lower section compress into denser material... just before the entire stack springs out of the corner , from the middle ,spraying itself all over the room. . (bitter experience in early days , before forums were a thing... )

45kg works equally well , and provides higher absorption performance at higher frequencies , but since we are primarily concerned with the lo end it's of little practical import, and it's a lot harder to build large devices with, but it works fine for smaller ones and flat framed panels.

similarly 30Kg is a viable absorption media , but an absolute twat to build with..... more so than 45 by a long stretch.

buit as infill behind a layer of denser material, it works well.

I have endless designs for such devices....

there's some I use more often than others, because they're practical to implement , and easy to adjust for odd specific elements of individual rooms .... and they can be delivered in a predictable time , at a fixed cost....

It is all to easy for the DIY evangelists to dismiss the time and ease of build concerns.... but before being swayed by these , you should ask yourself, quite seriously, what your time is worth to you, and your family.... and your clientele , if you're of the semi-pro persuasion....

is it better to spend a year building a studio that is 1% "better" than one you could have built and been ready to work in in 3-4 months ?

My rather pragmatic view is that it is not.... not even if you're trying to build a mini abbey road... 10 or 20% , then you'd have a valid argument, but 1% ?? I think not.

The difference in monitor speaker quality and set up in the room will make more odds than the 1% on that corner trap .

Where i DO like to go bananas on detail is in isolation design.... room geometry , ergonomics, and wiring .

Making the place a nice environment to be in , as well as and accurate monitoring environment, is key to productivity in actual use.
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