Why Your Bass Traps Don't Work

8/3/2019 Why Your Bass Traps Don't Work

1/9

Articles Making Better Recordings Why Your Bass Traps Don't Work

It seems that a whole lot of bass traps don't actually trap

bass.

I've

been behind on Pensado's Place and I did some catching

up the other night.

They had a super dooper acoustics dude on. His name is

Thomas Jouanjean and he works at Northward Acoustics

Engineering, the firm that built Focal's facili ty for testing

their monitors, among many other ultra high end studios.

Why Your Bass Traps Don't Work

New To Audio Recording? Download Killer Home Recording: Setting Up FOR FREE!

Why Your Bass Traps Don't WorkThis is an article on Why Your Bass Traps Don't Work part of the Home Recording Forum community: It seems that a whole lot ofbass traps don't actually trap bass. I've been behind on Pensado's Place and .

Remember Me?

User Name Password Log in RegisterHelp

Forum Blogs Contact Products Tools Advertise

What's New?Making Home Recordings Pro RecordingsAdvanced Search

Welcome to RecordingReview.com

If you would like to.....

Make better recordings NOW

Get help buying the best gear for your needs

Solve technical problems

Be part of an annoying community

...then you have come to the right place!

You'll have more fun recording immediate ly.

YES! I want to register an account for free

p.s.: For registered members has minimal ads.

by

Published on 11-22-201110:40 AM Number of Views:

3179

10 Comments

brandondrury Rate this article

Home Join

y Your Bass Traps Don't Work http://forum.recordingreview.com/content/why-your-bass-traps-don-t-w...

9 23.11.2011 19:02


2/9

While I'm not exactly sure why, anytime they start REALLY

hitting on super information that gets me excited, Dave

Pensado tends to get goofy talking about the NBA. I'm all

for goofy both before and afterward, but I guess I REALLY

wanted to hear what this French dude had to say. Oh well,

I'm not complaining. There were some HUGE points made

in this video.

@26:40 Thomas Jouanjean talks about not using a

high-pass crossover filter on studio monitors when using a

sub, which lead to this discussion....No High Pass On

Monitors With Sub

@32:31 He starts to ta lk about the difference between

using fiber-based absorption vs membrane based

absorption. It turns out that 703 or Rockwool place right

up against the wall does a lmost nothing for the low end.

DanTheMan brought up this very same concept in a really

awesome thread on optimizing bass traps here.

@35:20 He says that he wouldn't recommend working

with less than 4-6 thickness of Roxul/703. That's not a

breakthrough or anything, but I see a lo t of people

dabbling with 2 703 when it's clear that greater

thicknesses are necessary.

@36:30 Dave Pensado asks what's the lowest frequency a

frame with 4-6 thick of rockwool/703 spaced 4-6 off the

wall will absorb. It's important to note that this is

accepted as a bass trap in home recording land. Most

people don't even go this far with depth or a ir space from

the wall.

Thomas Jouanjean says that the wavelength thing

applies.

The home run came at TIME where Thomas Jouanjean

said, These systems based on rockwool or owens-

courning [703] do not work so well under 100Hz.

Going back to this wavelength busies. I'm not sure

where you measure from. I'm assuming when dealing with

a 4 sheet of rockwool that is 4 from the wall means we

can call that 8 inches. If that's the case we need to find a

wave with a wavelength of 32 inches and that's what we

are optimally absorbing. I just came up with about 423Hz.

YUCK!!! That's not a bass trap. That's a boxiness trap (not

that we don't need those, too).

Assuming 6 of 703 and 6 of air space from the wall, we

are looking at frequency of 282Hz. YUCK!! This is when

sacrificing 12 of space! Who can do that in their bedroom

studio?

To get down to 100Hz we need more li ke 3 feet of space

from the wall. That's not gonna happen in any bedroom

converted to a studio.

The most horrifying...

PannelliFonoassorbentiCorner Bass Trapssuperiori anche aicostosi Tube? Guardale analisi!www.oudimmoacousticdesig

Learn Production

OnlineStudy musicproduction onlineanywhere withBerklee faculty.www.berkleemusic.com

Acoustic PanelsFind Industrial GoodsSolutions For YourBusiness. Get It DoneNow!www.business.com

Master RestorationSuiteProfessional noisereduction andrestoration plug-inswww.WaveArts.com

Masterdisk EuropeStudio de MasteringWorld Class. Le sonNew Yorkais Paris,France.www.masterdiskeurope.com


9 23.11.2011 19:02


3/9

@41:36 Phil's got a 7' ceiling in his studio. Pensado asks,

A lower ceiling can sound good, right? Thomas

Jouanjeanrespondss, No! AHHHHHHHH!!!!!

Don't Shoot The MessengerWhile most of this info is not good news for the guy

recording and mixing at home, it's nice to have a lot of

gray areas FULLY confirmed. Few people are in a position

to say, Definitely do NOT do X. When it comes to

acoustics. I think that makes this video insanely valuable

and a good thing.

Solutions To Our Bass Trap ProblemThere are still solutions to bass trapping. I'm talking real

solutions that will work effectively without chewing up

enormous amounts of space.

1 Membrane absorbers.

DIY Membrane Bass Trap Plans) Membrane bass

traps by stretching deadsheet or even plywood over a

sealed area with 703/Roxul stuffed inside. These have to

be tuned specifically but they can absorb very deep

frequencies without chewing up a ton of space in your

studio. Also, they avoid the HUGE problem that occurs

with an excessive number of broadband absorbers in theroom. They reflect high end back into the room keeping

the room from sounding stuffy.

2 Commercial bass traps

With so much that can go wrong with a bass trap design,

I'm starting to wonder if it just wouldn't be CHEAPER to go

with commercial bass traps. These guys have no choice.

They need bass trap designs that go very deep but also

are shippable.

Everyone seems to rave about the Real Traps. Ethan

Winer is around here all the time and is extremely

generous with his acoustics knowledge and I've never

heard anyone complain about bass trapping and diffusorproducts.

While a bit cheaper, I did pick up a pair of Gik Monotraps

this summer. I can personally say that, without a doubt,

the low end cleaned up when I used them. I only have

two in my room on my back wall (compared the zillions of

unopened bags of Roxul I also have). The difference in

low end was not subtle. This was an eye opener. It

showed just how effective commercial traps could be, but

also how that my superchunk bass traps weren't nearly

as effective as I had thought.

Now I know why my Roxul-in-package bags weren't all

that successful. The video above explained that. (I'm still

trying to figure out Roxul In Plastic: What's The Verdict?)

3 Helmholtz Resonators

Are blown into a coke bottle? When you get it right, the

entire bottle starts to ring. This is a Helmholtz Resonator

that just happens to be tuned rather high. When tuned

lower, Helmholtz Resonators can be very, very effective at

absorbing low frequencies.

If anyone has any plans for Helmholtz Resonators, let me

know. The only ones I've came across are in Alton

Everest's Master Handbook of Acoustics.

ConclusionWe should no longer call 703/rockwool wrapped in fabricand mounted 4, 8, or even 12 from the wa ll bass

traps. They aren't trapping a significant amount of bass.

It's time to move on from that model and push for designs

that really do work in the confines of the home studio.


9 23.11.2011 19:02


4/9

This means going to either go membrane, go Helmholtz,

or go commercial.

Brandon

Categories:Acoustics and Studio Construction

10 Comments

Share

EnSkorSang - Yesterday, 11:41 AM

Nice blog, that video is a real information

gold mine (although pensado seems to

make things a bit confusing).These

membrane traps - so these things arebasically the 'bad' version of bass traps

(some inches of rockwool) but covered in

plywood/'deadsheet' ?

Reply

Lance - Yesterday, 12:14 PM

Damn it! I literally just picked up a

couple of bundles of Roxul Safe and

Sound, 20 meters of Fabric and some 1

by fours to start making some broadband

obsorbers and corner bass traps! I guess

all I can do is make them twice as thick

as I had origionally planned. 6" instead of

3"

Reply

brandondrury - Yesterday, 01:36 PM

Sorta. That sentence could be taken the

wrong way, but it's my understandingthat the membrane is tuned to absorb X

frequency. It's the front panel that does

the real work, but having the fiber inside

it improves it.In Recording Studio Design,

there is a chart that shows Helmholtz

Resonators with and without fiber inside.

The with-fiber method (sounds like a

cereal) was much more effective in the

low frequencies. The tricky part is

figuring out the exact thickness and

dimensions.

Mr Dave is being a tv host (mostly) and

playing devil's advocate. He's trying to

dumb it down for beginners, but guys in

These membrane traps - so

these things are basically

the 'bad' version of bass

traps (some inches of

rockwool) but covered in

plywood/'deadsheet' ?

pensado seems to make

things a bit confusing

MusicProduction

Diploma

sound engineering,

production, music

business, mixing,

masteringwww.londonschoolofso

Acoustical

PanelsAny Size - Fabric

Covered

Stand-alone and

Full-wall Solutionswww.fabricmate.com

CD Mastering

Mastering zoals

muziek bedoeld is.

Singer Songwriter,

Rock/Pop, HipHopmasterenzo.nl

Room Acoustics

SoftwareAcoustic

Calculation

Loudspeakers and

Auralisationwww.Odeon.dk

Reply


9 23.11.2011 19:02


5/9

101 stage aren't watching the show. It's

guys like us who already have fancy

preamps and such and are trying to

figure out how to move to the next level .

Then again, sometimes he seems

legitimately confused with rather simple

stuff. Other times he OBVIOUSLY knows

his shit. It's all the mystery that is Dave

Pensado.

You are lucky! You could have figured out

that your bass traps are mostly useless 3years from now after spending all that

money AND doing all that work. This

wasn't a happy article for any of us.

However, I'd rather get the truth out

ASAP because no one was telling me that

spaced roxul panels were a waste of time

for solving 100Hz problems. Now we

KNOW.My advice would be to dig deeper

on the membrane front. That's where the

money is at, it seems. Brandon

Damn it! I literally just

picked up a couple of

bundles of Roxul Safe and

Sound, 20 meters of Fabric

and some 1 by fours to

start making some

broadband obsorbers and

corner bass traps! I guess

all I can do is make them

twice as thick as I had

origionally planned. 6"

instead of 3"

Robert200 - Yesterday, 02:06 PM

I saw that interview last week... He reallycontradicts a lot of the generally held

beliefs... I love Pensados Place but I do

wish they would take a media lesson on

when to shut up... a lot of times the

guest will be talking and right when they

get to the money line... the other two will

pipe up with something and make the

key sentence indistinguishable ....

Regarding sound absorption and

proofing... this stuff is supposed to

soundproof a room... is you do the whole

room and fill the cracks and air spaces...

etc... Mass Loaded Vinyl, MLV for

Soundproofing Your Walls and Ceilings

I'm just wondering .. what would happen

if you sandwiched a sheet of this stuff

between 2 pieces of the 703 or the rock

wool... maybe you wouldn't need the 2nd

piece... maybe you wouldn't need any...

just tack up a piece of this vinyl in a 2' x

4' frame.... ... it gets back to absorption

versus soundproofing... if this is for sound

proofing... not sure how it would work in

a bass trap scenario....

Reply

Robert200 - Yesterday, 02:14 PM

I forgot to add this... a lot of goodinformation on the options for

acoustically treating a room....

Soundproofing 101 - How to Soundproof

Reply


9 23.11.2011 19:02


6/9

Your Room's Ceiling Wal ls and Floors

Lance - Yesterday, 02:47 PM

You are lucky! You could have figured out

that your bass traps are mostly useless 3

years from now after spending all that

money AND doing all that work. This

wasn't a happy article for any of us.

However, I'd rather get the truth out

ASAP because no one was telling me thatspaced roxul panels were a waste of time

for solving 100Hz problems. Now we

KNOW.My advice would be to dig deeper

on the membrane front. That's where the

money is at, it seems. Brandon[/QUOTE]

I agree 100 percent. I am glad I was able

to catch this article and video before I

started building today! Now I think I will

start with building smaller broadbands to

handle first reflections, and continue to

research bass traps. It was definately a

little dissapointing, but very informative!

Reply

doug hazelrigg - Yesterday, 03:44 PM

I've never thought of 703 as a bass freq

absorber, mostly HF reflections. In my

studio,

I use regular 2x2' Auralex panels to

attenuate reflections, and the triangular

corner traps

do a decent job of absorbing bass

accumulation. Also, using non-ported

monitors helps.

But after a certain point, it's just best to

know your room and your monitors

Reply

retrogradeorbit - Yesterday, 08:40 PM

As a graduate physicist I just want to

chime in and work on some of these

perceptions. Yes everything he says is

technically true. Yes the quarter

wavelength applies (this is because the

wall must be a node, and your first wave

antinode is 1/4 of the wavelength into

the wave). If you were doing the

calculation you'd use the middle of the

trap, not the front face. So 4 inches of

rockwool, 4 inches from the wall puts the

center at 6 inches from the wall, which isby my calculations (using speed of sound

to be 346 ms-1) a frequency of 567Hz!!

That being said, this calculation

determines the place of *optimal*

efficiency. Such a trap wi ll have maximum

attenuation at this bottom frequency. But

there is a bandwidth to its attenuation.

It's not like 567Hz is absorbed and 566Hz

is left untouched. The absorption will

continue all the way down to 0Hz, but

with lessening attenuation. Think of it

like efficiency. Placing such a trap catches567Hz extremely well. 500 Hz very well.

300Hz ok. 200Hz somewhat. 100Hz a

little bit. 50Hz a smidge. etc. The

absorption band is like a curve with its

Reply


9 23.11.2011 19:02


7/9

maximum at the 567Hz point. That curve

into the LF improves with spacing from

wall, thickness of panel, and density of

rockwool.

So things to avoid is placing them right

against the wall. This places them in the

nodal point of the waves and pushes that

curve way out. So all your low

frequencies are untouched. And thesecond thing is making them as thick as

possible, as this increases the absorption

coefficient for low frequencies. But I think

to say we should stop calling a decent

slab (say 5 inches thick) of dense

rockwool (say 100 kgm-3) a good

distance (say 4 inches) from the wall a

bass trap is wrong. They _are_ bass

traps. They _are_ taking out bass

frequencies. Maybe not as much as say a

helmholtz resonator tuned to a low

frequency would, but they are taking low

frequencies out. Maybe they should be

called low-mid traps as they take out

even more of this!

You can prove this all to yourself by

removing all such bass traps from your

room and measuring the room response.

Then placing them back and measuring

again. And then comparing the empirical

data. You can also see this by empirical

absortion data like this:

http://www.bobgolds.com

/AbsorptionCoefficients.htm

Notice that the coefficients of absorptionare never 0. Even right against the wall

they take a little bit of the low end. Lets

go full circle though and say that despite

this, most peoples home made traps are

probably too thin, too light and too close

to the wall. And thus are taking out less

LF than they may have thought.

All this being said, one should not just

place treatment in their rooms randomly.

One should buy a measurement

microphone and maybe measurement

software (unless you want to do it by

hand) and actually measure their room

response. Then from that make decisions

about what treatments are needed. Then

try them in places and remeasure.

Without measuring your room you really

have no idea what they are doing to the

room's sound in various positions. You

can't just go by eye.

That's my 2c.

ManAbyss - Today, 06:37 AM

When you refer to "Gik Monotraps" which

excactly do you mean? Because there are

no traps by that name in Gik. I'm asking

because I'm really interested in buying

Reply


9 23.11.2011 19:02


8/9

some acoustic treatment from that

company since all I hear are good

comments about them.

Desolation - Today, 09:43 AM

I'm not an acoustics expert but as an

architect I have used MLV for reducing

sound transmission. It really works best

in that application when it can felx

slightly, i.e. with an air space behind it.The normal installation is directly behind

gyp. bd. in the walls or ceiling so if it is

placed over furring strips that provide an

air space between the MLV and the cavity

wall or ceiling insulation the STC will be

greater. In theory it will work as a

membrane for a bass trap but I haven't

seen any definitive performance data.

There is one company that produces a

curved base trap with a MLV membrane,

see http://www.acousticgeometry.com

/pdf/...rve_System.pdf

Originally Posted byRobert200

I saw that interview last

week... He reallycontradicts a lot of the

generally held beliefs... I

love Pensados Place but I

do wish they would take a

media lesson on when to

shut up... a lot of times the

guest will be talking and

right when they get to the

money line... the other two

will pipe up with something

and make the key sentence

indistinguishable ....

Regarding sound absorption

and proofing... this stuff issupposed to soundproof a

room... is you do the whole

room and fill the cracks and

air spaces... etc... Mass

Loaded Vinyl, MLV for

Soundproofing Your Walls

and Ceilings I'm just

wondering .. what would

happen if you sandwiched a

sheet of this stuff between

2 pieces of the 703 or the

rock wool... maybe you

wouldn't need the 2nd

piece... maybe you wouldn't

need any... just tack up a

piece of this vinyl in a 2' x

4' frame.... ... it gets back

to absorption versus

soundproofing... if this is for

sound proofing... not sure

how it would work in a bass

trap scenario....

Reply


9 23.11.2011 19:02


9/9

All times are GMT -6. The time now is 11:54 AM.

Home Recording Forum by vBulletin Version 4.1.7

Copyright 2011 vBulletin Solutions, Inc. All rights reserved.

Search Engine Optimization by vBSEO 3.6.0

-Home -Recording Forum -Music Recording Blog -Blog Archive Contact Us -Affiliate ProgramHome Recording Blogs Archive -Audio Interface -Electric Guitar Recording -Recording Studios -Killer Home Recording

-

Privacy

Policy Sitemap


Documents

Why Your Bass Traps Don't Work