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Bass traps in room

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Re: Bass traps in room

Postby blinddrew » Thu Oct 24, 2019 9:58 pm

They'll take the edge of the top end but they're not going to do much in the mid range.
I have a similar set and they can be useful if you're getting a bit of ringing, but I think the last time I used them was to put under the guitarist's foot when he was tapping it a bit loudly. :)
For decent mid-range absorption have a look at Luke W's thread about setting up his attic room.

EDIT - this one: https://www.soundonsound.com/forum/view ... 24&t=67269
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Re: Bass traps in room

Postby CS70 » Thu Oct 24, 2019 9:59 pm

Danny_79 wrote:I found something(link below) meant to absorb mid and high frequencies. So i suppose it's some kind of broadband absorber. Can anyone tell me a good place to install them, and why they are shaped the way they are? Does the shape have anything to do with leaving space behind them or something? I mean, they don't look like the broadband absorbers in that shared picture in this thread. So i don't know if the same "rules" applies to them. https://www.thomann.de/se/eq_acoustics_ ... e_grey.htm

Yes the shape does help (any corrugated panel allows more surface per square cm and the shape also acts a little like a diffuser, randomizing the reflections).

However, while better than nothing, these pieces of foam tend to be far less effective than other materials (they look good tough so don't need treating and covering like say Rockwool)
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Re: Bass traps in room

Postby Wonks » Fri Oct 25, 2019 8:09 am

However the shape means the tile's average depth isn't very thick, which makes them less effective than a similar tile that's solid/flat on both sides.

They are meant to have the flat side to the wall, but will perform better if you can mount them pointy side to the wall.

They will absorb some treble and a small amount of upper mids, but almost all of that type of tile are too thin to do any real broadband absorption.
Yes, they can help cure flutter echos as Blinddrew said, but you really need to find much thicker panels if you go the foam route and don't want to remove just the treble from the room.

Rockwool panels of the same thickness will outperform foam and work to lower frequencies.
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Re: Bass traps in room

Postby Hugh Robjohns » Fri Oct 25, 2019 9:48 am

The wedge shape is mostly a fashion thing. It looks technical, and you can make pretty patterns if you vary their orientation when you mount them adjacent to each other... It's also claimed to improve the aborption for sounds arriving at an angle... but I'm not convinced. ;-)

Everything you need to know about commercial acoustic foam panels is in this article:

https://www.soundonsound.com/reviews/choosing-using-porous-absorbers
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Re: Bass traps in room

Postby Sam Spoons » Fri Oct 25, 2019 11:32 am

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Re: Bass traps in room

Postby Danny_79 » Sat Oct 26, 2019 1:40 pm

Thanx to everyone for warning me about these foam pieces....i was close to order some :D There seem to be very few(if any) absorbers that can handle all frequencies. Like a combination of broadband and bass absorber.
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Re: Bass traps in room

Postby Sam Spoons » Sat Oct 26, 2019 2:58 pm

A bass trap of the kind sold by Gik Acoustics will, usually, also absorb higher frequencies too, shallower panels only work down to the mid range. The main reason for treating bass traps and broadband absorbers (i.e. mid and high frequency 'traps') differently is the practicalities of positioning. Panels deep enough to absorb bass and low mid frequencies are can't usually be placed at the 'mirror points' where you need mid/high absorption to control first reflections which mess with balance and stereo imaging so we use BB absorbers in those positions, LF is pretty much omnidirectional so the absorbers/traps can be placed almost anywhere that is practicable and they will still have a beneficial effect.

What we are trying to achieve in a small home/project studio is a fairly dry acoustic but one that doesn't absorb certain frequencies more than others (usually too much HF absorption making for a 'boxy' sounding room). For mixing you want the frequency balance as flat as possible at the mix position and the acoustic treatments symmetrical around the mix position. For recording, usually pretty dry where the mic/musician is placed.

In practice you can't have too much bass trapping in a small room as the laws of physics mean you'll never achieve a completely flat bass response, then add BB absorbers at the mirror points (walls and ceiling where if you placed a mirror you'd see the monitor speakers when sitting at the mix position) not forgetting the back wall.
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Re: Bass traps in room

Postby Danny_79 » Sat Oct 26, 2019 4:54 pm

Sam Spoons wrote:Most (if not all) 'budget' foam tiles are pretty useless TBH, you need this kind of thing if you plan to do the job properly

https://www.thomann.de/se/the_t.akustik_pro_series_a1_absorber_grey.htm?ref=intl&shp=eyJjb3VudHJ5Ijoic2UiLCJjdXJyZW5jeSI6IjIiLCJsYW5ndWFnZSI6InN2In0%3D

https://www.gikacoustics.com/product/gik-acoustics-spot-panel/

Blinddrew came up with a good tip on how to attach foam traps at the previous page of the thread. But the absorber at your first link is a bit heavier. So what would be a good way to attach that one to the wall and leave space behind? Attach strong hooks to the wall or something? The mirrorpoints of my walls are unfortunetaly of rocky/stony material so nails are out of the picture i think. Either drill holes or using very strong glue to attach hooks or something. Edit: just read that 4 mounting clips for the wall is included in that one, but not screws....since those walls are of rocky material, i suppose i must drill holes...damn! haha :lol:
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Re: Bass traps in room

Postby Sam Spoons » Sat Oct 26, 2019 5:35 pm

Mine are hung off a horizontal batten screwed into the studs behind the plasterboard, you could use rawlplugs in the wall to fix the battens, then devise a way of hanging the panels. TBH a single plug and screw would easily hold the weight, a little ingenuity is all that is then required (TBH I can't remember precisely I fixed mine and am not at home so I can't go and look/take a photo).
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Re: Bass traps in room

Postby Danny_79 » Sun Oct 27, 2019 6:02 pm

Sam Spoons wrote:Mine are hung off a horizontal batten screwed into the studs behind the plasterboard, you could use rawlplugs in the wall to fix the battens, then devise a way of hanging the panels. TBH a single plug and screw would easily hold the weight, a little ingenuity is all that is then required (TBH I can't remember precisely I fixed mine and am not at home so I can't go and look/take a photo).

I googled it and had a look at a few photos/pictures, so i'm beginning to understand how it all works. In my case, i might have to compromise with the position of the broadband absorbers. I may not be able to install them at exact mirrorpoints at my wall. Almost but not quite. It will probably be slightly above cause of furniture occupying some space. Will they still work pretty good?
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Re: Bass traps in room

Postby Sam Spoons » Sun Oct 27, 2019 6:53 pm

Soft furnishings will act as pretty efficient broadband absorbers so it should work pretty well. Sometimes pragmatism has to come into play and any acoustic treatment will improve the sound of a domestic living room. You'll never achieve perfection in a small room unless it has been purpose built from the ground up but you should be able to end up with a usable space.
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Re: Bass traps in room

Postby Danny_79 » Sun Oct 27, 2019 7:08 pm

Sam Spoons wrote:Soft furnishings will act as pretty efficient broadband absorbers so it should work pretty well. Sometimes pragmatism has to come into play and any acoustic treatment will improve the sound of a domestic living room. You'll never achieve perfection in a small room unless it has been purpose built from the ground up but you should be able to end up with a usable space.

Good to know man :thumbup: What about furnishings of harder material, such as wood?
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Re: Bass traps in room

Postby Sam Spoons » Sun Oct 27, 2019 7:12 pm

They will act as diffusion (the classic improvised diffuser is a bookcase, especially of you fill it with Mike Seniors books which will do as much to improve your mixes as room treatment ;) )

Probably not as useful in a small room and you definitely need to avoid hard flat surfaces which might reflect sound from the monitors towards the mixing chair.
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Re: Bass traps in room

Postby Studio Support Gnome » Sun Oct 27, 2019 11:13 pm

Many soft furnishings are not terribly efficient broadband absorbers....

for what should be fairly obvious reasons, the top surfaces of padding foams are generally closed cell not open cell....

and inside other types is often an empty space full of metal springs....

they're not terribly reflective though... and that is usually a bonus ./
but compared to an actual trap... they're not what I'd call efficient absorbers.


and book cases need to be PART filled (with Mike Senior's book) not fully filled.
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Re: Bass traps in room

Postby Sam Spoons » Mon Oct 28, 2019 5:57 pm

I stand corrected :thumbup:
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Re: Bass traps in room

Postby CS70 » Mon Oct 28, 2019 6:39 pm

The essential element is, in conclusion, Mike Senior's books.

Go Mike! :D
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Re: Bass traps in room

Postby Danny_79 » Mon Nov 04, 2019 7:06 pm

One thing about broadband absorbers i wonder is: I understand they work best when space is left between them and the wall. But should they still be close to the wall? Or could one just place them close to where you sit?
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Re: Bass traps in room

Postby Hugh Robjohns » Mon Nov 04, 2019 7:13 pm

Danny_79 wrote:One thing about broadband absorbers i wonder is: I understand they work best when space is left between them and the wall.

It's not really a case of 'working best'. The gap just allows them to work to a lower frequency than would be the case if they were mounted flat against the wall.

The absorber works by absorbing kinetic energy from the movement of air particles. The peak air particle velocity due to a sound wave occurs at a quarter wavelength from the boundary surface. And the lower the frequency, the longer the wavelength. So, by placing more of the absorber further from the wall, it will interact with lower frequencies more efficiently.

But should they still be close to the wall?

Ideally, yes.

Or could one just place them close to where you sit?

This can be done -- like gobos around a guitar amp in a studio... but you then only benefit from the panel's natural mid and HF absorption. You lose the extension to lower frequencies that wall placement provides.

H
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Re: Bass traps in room

Postby Danny_79 » Mon Nov 04, 2019 9:01 pm

Hugh Robjohns wrote:
Danny_79 wrote:One thing about broadband absorbers i wonder is: I understand they work best when space is left between them and the wall.

It's not really a case of 'working best'. The gap just allows them to work to a lower frequency than would be the case if they were mounted flat against the wall.

The absorber works by absorbing kinetic energy from the movement of air particles. The peak air particle velocity due to a sound wave occurs at a quarter wavelength from the boundary surface. And the lower the frequency, the longer the wavelength. So, by placing more of the absorber further from the wall, it will interact with lower frequencies more efficiently.

But should they still be close to the wall?

Ideally, yes.

Or could one just place them close to where you sit?

This can be done -- like gobos around a guitar amp in a studio... but you then only benefit from the panel's natural mid and HF absorption. You lose the extension to lower frequencies that wall placement provides.

H
Cheers m8, learned something new once again :thumbup: One "wall" that mirrors my monitors is a door made of glass and wood. You know, a window door sorta. Is that equal to a wall reagarding placement? Assuming the door is closed of course :lol:
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Re: Bass traps in room

Postby Hugh Robjohns » Mon Nov 04, 2019 9:08 pm

A door/window will reflect HF very strongly, like a wall, and also most midrange frequencies. But unless it's a really heavy, solid, door with an airtight seal it will tend to leak low frequencies, so it effectively becomes a low efficiency bass trap.
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