Acoustic treatment

sei046

Well Lads,
Just in case I hadnt made enough threads!

I dont have a great sounding tracking room, or mixing room for that matter!

It is around 12foot by 8 foot? (im kind of pulling them figures out of my ass)

I was thinking, is it possible to pick a corner and treat it so it works as an iso booth? I have two large office divider jobbys, could i cover them in aurelex type stuff in an L shape and have the mic facing in between? how good/bad would this be?

OR! should i just go with a se reflexion filter

dav nagle

Hi sei046,


I have a 10 x 10 Ft room and the idea of building a booth seemed a bit bonkers. I built a booth and covered it in aurelex acoustic treatment and the sound improvement was huge. I would say GO 4 IT and dont let anyone tell you any different!

D

sei046

How did you build the booth? any pics? How expensive did it work out?

dav nagle

Well on the outside of the booth and in the ceiling on the inside we used tongue and groove wood strips. the booth is big enough to sit a guitarist or amp or vocal mic in, not drums. the booth walls were packed with 5 materials. foam and leather and stuff. It cost about €800
not including the small gooseneck lamp

sei046

Hmm.... Something to think about. I will definitely do something. So an open booth is no good? As in a L shape with foam covering it, singers back to the corner and the mic facing him with padding directly behind it?

dav nagle

The closed booth should be more effective. Thick door, small window, nice light and then you will have a nice vibe

sei046

Im just not sure If i have the room. My tracking room is packed at the minute!

dav nagle

If i can do it in an attic then so can you

sei046

The acoustic foam should be fairly expensive. How soundproof is your booth?

dav nagle

The real Aurelex stuff is very expensive but its dense material is a proper bonus and has a great advantage over the cheaper stuff. The vocal booth I have is not fully sound proofed. I would say 65% at best. But don't under estimate 65%, that is a considerable amount of noise reduction and you will notice a big change in the sound of recordings. People told me it couldn't be done and its not worth your while but now when people come up to my home studio they go wow 'you have a window, real tight' . The bottom line is if 3 people are cutting grass I can record no problem. If someone is cutting concrete I have a problem. If I move out to a larger facility I will be throwing money at my sound booth and drum room but for now what I have works and looks very nice. The booth is at an angle impossible for taking a shot but if you are around next weekend you are more than welcome to come up and see what I have done. I am very proud of it. You will be glad you came up. It helps when you see ideas that work, hopefully it will get you excited.

D

sei046

dav your a gent. I wonder how good the cheaper stuff is.

dav nagle

sei046 wrote: »

dav your a gent. I wonder how good the cheaper stuff is.

Well I packed the cheaper stuff into the walls (or should I say I had the carpenter pack the cheaper stuff into the walls. The cheaper stuff is a hundred times cheaper than the expensive stuff. I have my control room padded out with the expensive stuff and this enables a fine dense sound for mixing purposes. You are talking about a 70% difference in density. I have used both and there is no comparison, Aurelex is the real deal but 1 box and a couple of aurlex bass traps and you will hear the difference. There are other materials like rock wool (especially hard fabric with small bits of what I think is glass or something) Mix it up! Use whatever you can afford and perhaps try a mix of each component. You dont need 3 boxes of Aurlex. 1 BOB of aurelex square sheets a few aurlex bass trappings and loads of cheap stuff light foam and you will be wondering why you didn't think of this earlier!!!

sei046

Ok. just did some looking and clearing of rubbish. The room would be 2.1 metres high, 1.4 metres long and 1.2 metres wide. Sounds small but more than enough for a singer, guitar amp.

What you reckon? Will just do it with studwalling based to struts which run across the ceiling and to the floor. How would you treat this?

dav nagle

I would treat it would a few square panels on the inside, not too much as you wan to conserve the space and make it look bigger than it is. I would spend some work at the final stage using tongue and groove wood on the ceiling and outside of the booth, It has a great look, smell nice and have a nice acoustic sound. Then you might want to have a thick door built with a small cutting in its middle for a small but effective looking window. People don't like feeling trapped even if it is a gimmick. I would buy tons of the cheap stuff foam and pack it onto the walls. Use a thick wool as a fabric and perhaps go shopping in town into carpet place, you would be amazed by the amount of interesting suitable fabrics that are available. Last but no lease use a rubber mat or something to catch the sound as it hits the floor. You should look at thick carpet rolls for this or simply car mats attached together. Perhaps by a cheap leather imitation to give a sense of finish on the 4 walls. Don't forget if you can line the booth so that there are no horizontal or vertical lines the sound will absorb better.Oh and remember your ceiling does not have to be high, the smaller the better for vocal work and guitar work, bass amp and guitar amp recordings!

sei046

What about lining the ENTIRE inside in that eggbox foam with a pillar of foam on the four sides

sei046

Its not sound isolation as much (iso booth......duh) as wanting a completely dead sound

dav nagle

sei046 wrote: »

What about lining the ENTIRE inside in that eggbox foam with a pillar of foam on the four sides

Yes! Once you have built the booth it will take time, money, taught and recording in it before you start to make changes. So look at the project as an ongoing project that will evolve. At first I certainly didn't have the cash to get everything right first go. It takes time to develop the room within a room. It takes experimentation with fabrication. Some ideas you try will work others wont. But if you keep working on the project it will look and sound great eventually. Are you recording people professionally? Do you care how it looks? Whatever the case put as much work and development into it as you have your skills and eventually you will never look back.I have been developing my booth over the last few years.My third effort will be a better effort if you catch my drift. At first it sounded good but looked cramped and un appealing on a professional level. Then I fixed those issues

My booth history:

Booth A - Nice sound, bad look
Booth B - Nice look, nice sound but still a bit small
Booth C - Large, looks nice and sounds amazing!
Thats my 3 steps, now hopefully if I get to step C (Professional, commercial studio with great booth) I will have succeeded...

sei046

Cheers man. So completely line the inside with that eggbox foam. the solid foam pillars at every corner, small window, door with foam on it and a nice airtight seal.

dav nagle

sei046 wrote: »

Cheers man. So completely line the inside with that eggbox foam. the solid foam pillars at every corner, small window, door with foam on it and a nice airtight seal.

Sounds like a perfect start best of luck with it, keep me updated with the progress!

sei046

Great Will do. If anyone knows anywhere that sells that cheap eggbox foam i would love to know. I know the german spots do it

sei046

Here is a plan of the studio. I realise its the most useless plan ever without any dimensions or materials but does anyone see some nice place for bass traps?

Every corner in the mixing room? Some panels behind my monitors?

dav nagle

sei046 wrote: »

Here is a plan of the studio. I realise its the most useless plan ever without any dimensions or materials but does anyone see some nice place for bass traps?

Every corner in the mixing room? Some panels behind my monitors?

Yes I would put one in each corner behind the mixer and possibly 2 at the back left and right corners

sei046

Just wondering lads, is this going to sound very boxy?

dav nagle

egg cartons might make it sound boxy if you dont build a portioned wall over them and use some foam and sponge

PaulBrewer

http://www.acoustics101.com/

Neurojazz

Don't know if this really helps... but i paid about 500 quid for a load of videos from a german studio guy who really knows his stuff and goes into room modes and how to test sound-proofing, sub positioning etc.... the whole shaboo shebang - but, after watching it he basically says that if you don't know what the room mode is get a professional to help you out or all your mixes will retain the mode of the room they were mixed in... i'll try to explain, but i'm a newboy at this stuff.

The distance from wall to wall causes a wave to come back to the listeners sweetspot - now imagine a frequency that causes phasing at that sweetspot... you would eq it down as you'd be imagining it louder - really annoying! - this causes the imprint on your eqing efforts and is real pain - and this is just one of many problems when it comes to sound proofing! - i aright pain in the butt.

If you want me too i'll try to rip as much info from the videos and type it out manually lol - because all your efforts to try and supress the sound bouncing around will be in vain if a fundamental thing such as the room mode is overlooked - the guy goes into testing at 85db (when the curve of frequencies are most balanced for hearing), and is mainly aimed at mastering - but again really detailed in the video...

There are workarounds once you become aware of these phenomena, but very few unfortunately! - the mode of the room ruins everything, but there are charts and some math for telling you what your room mode is (so you know what frequency will be boosted and therefore rectify it via EQ.

Again you can poke me if you want the formulas in more detail.

PaulBrewer

Neurojazz wrote: »

get a professional to help you out or all your mixes will retain the mode of the room they were mixed in...

There are workarounds once you become aware of these phenomena, but very few unfortunately! -

I agree!!

sei046

I say.... A gathering at my studio, load of wood, load of foam, nails, drill, glue, 2 crates of miller and tiger beer and a BBQ

ogy

if you don't know what the room mode is get a professional to help you out or all your mixes will retain the mode of the room they were mixed in

just thought id share my understanding of room modes, im sure some of you know this stuff inside out but thought id throw it up anyway:)

Every frequency has a wavelength. wavelength = speed of sound/frequency (s.o.s. is approx 346 m/s)

If you have an 80hz sine wave the wavelength = 346/80 = 4.325 metres. if your room is 4.325 metres long (or a multiple of it) any 80hz waves are gonna bounce from one wall to the over perfectly, constructively interfering with itself (!) and getting stronger and stronger. so this frequency will be a primary mode of the room and the main one you have to watch out for. A secondary room mode is one that bounces off 2 walls that gets stuck in the loop, won't be as strong as the primary but still one to watch out for. These standing waves are the ones that you will EQ out even thought there not too strong on the recording at all. Other standing waves/loops can build up by bouncing off 2/3/4/5... walls, these are 2nd,3rd, 4th order room modes, and are less troublesome the higher the order.

2.1 metres high, 1.4 metres long and 1.2 metres wide

So daves 3 primary(1st order) room modes would be:
346/2.1 = approx 165hz
346/1.4 = approx 247hz
346/1.2 = approx 288hz

Also halves/quarters/eighths and multiples of these frequencies will be problematic cos theyll form these loops too.

Theres some free room mode calculators online to get the higher orders which are more complicated to calculate, and remember, wiki is your friend:)

sei046

Cheers man. Im grand on the physics side so i must do some reading to see how i can sort these problems

frobisher

sei046 wrote: »

I have two large office divider jobbys, could i cover them in aurelex type stuff in an L shape and have the mic facing in between? how good/bad would this be?

Great idea, they're called gobos! Those office dividers are a great money saving way of doing it. They actually have acoustic ratings as part of their design. Obviously for a very different application but they're still useful. As has been said many times round here, acoustics is a whole world of pain that falls outside the normal sound blokes remit or area of training. Try various things to see what works in your room and position. Until I moved house a few months ago I had the room from f**king hell. I used to make a L shape with homemade gobos with the mic at the deepest point of the L. Then Paul White from Sound On Sound mixed a tune and he said that I would have been better off putting the gobos parallel with the mic close to one of the gobos. Makes sense when I think of it now.

There's a guy selling acoustic material in Dublin somewhere and apparently he's quite happy to drop out and check out your space and advice you. I know someone who wanted to spend a wad load of cash with him and he advised them not too as they wouldn't achieve what they were after. Honest guy it seems. I'll find out his details and post them here.

sei046

Cheers man.

jtsuited

don't know if someone has already said it but this month's Futuremusic has a good DIY guide to making acoustic panels.

*Gets macho voice and stance ready for trip to the builders' providers*

sei046

Ok.. I might not go for the booth, I really need to treat my mixing room but as you can see from the drawing its an awkward shape! I have very little depth. Does anyone know a supplier in ireland for that eggcrate foam?

PaulBrewer

A small vocal booth needs to be very dead as any ambience left in it will be ugly.

Hence only thick (4 inchish) treatment is of any use .

Thinner foams will only attenuate the higher frequencies leaving the low mid and bass frequencies to roll around the place leaving a very unattractive sound to record.

sei046

Yup so i think I might just stick with gobos. I will make some bass traps and and there are a few spots i want to just put up some egg crate

Neurojazz

By the way, here's a top tip - sry if you already know this

Get a SPL meter (cheap as chips) - and mount it where your head is going to be with a decent mike (so both in your sweet spot).

Get cooledit/soundforge to make a long passage of white noise or rising frequency (so you get the whole tonal range) and turn it up to 85db - set the mike to record and leave the room/hide in corner screaming 'my ears!, my ears!' - then after a little bit stop the recording...

(this is not perfect, but you'll get the idea)

Now preview what's been recorded through the mike - you should see the rooms mode as the loudest frequency (so remember this frequency and Eq this down from your mixing [make a mastering preset that does this for you as it will be universal on all your mixes])

There should be dips and peaks according to what's been damped and what hasn't - ideally in perfect 25k studio it will be flat (and also your wallet!)

Hope that's helpful.

PaulBrewer

Neurojazz wrote: »

By the way, here's a top tip - sry if you already know this

Get a SPL meter (cheap as chips) - and mount it where your head is going to be with a decent mike (so both in your sweet spot).

Get cooledit/soundforge to make a long passage of white noise or rising frequency (so you get the whole tonal range) and turn it up to 85db - set the mike to record and leave the room/hide in corner screaming 'my ears!, my ears!' - then after a little bit stop the recording...

(this is not perfect, but you'll get the idea)

Now preview what's been recorded through the mike - you should see the rooms mode as the loudest frequency (so remember this frequency and Eq this down from your mixing [make a mastering preset that does this for you as it will be universal on all your mixes])

There should be dips and peaks according to what's been damped and what hasn't - ideally in perfect 25k studio it will be flat (and also your wallet!)

Hope that's helpful.

I feel this is 'incomplete' science as it doesn't allow for frequency/phase response of either the speakers or the mic preamp etc.

ogy

that approach really only works well in a fairly diffuse sound field.

in a control room thats not treated very well there will be frequency peaks and troughs all over the gaff, so eqing your monitors can be dodgy, a walk around the room, or even a slight tilt of your head, and you'll be hearing something totally different. no point pinking your bedroom!:)

frobisher

sei046 wrote: »

I have very little depth. Does anyone know a supplier in ireland for that eggcrate foam?

Remember that different foams have different ratings and that as far as I know foam is rarely an effective broadband absorber. Some foams are basically nothing more than multi purpose storage foam cut to look like acoustic foam and have properties a couple of points above useless. Have a look here for some info: http://www.gearslutz.com/board/studio-construction-acoustics/

sei046

Ah I know yeah. The plan is to do up a few 2x4 bass traps

PaulBrewer

sei046 wrote: »

Ah I know yeah. The plan is to do up a few 2x4 bass traps

Here's the Test Data for Auralex products -

http://www.auralex.com/testdata/

PaulBrewer

http://www.esoundproof.com/Screens/Basics/Academy/Sound%20Measurement/Sabins/Sabins.aspx

and there's a link to help understand the above Auralex link

sei046

Cheers paul. Will take some research!

Neurojazz

PaulBrewer wrote: »

I feel this is 'incomplete' science as it doesn't allow for frequency/phase response of either the speakers or the mic preamp etc.

as per the original thread '(this is not perfect, but you'll get the idea)' - i know it's far from the perfection of a 25k budget and all the problems inbetween, but think about catching a glimpse of what the room is doing (especially that 'mode' which is a isolated spot and quite a peak) - unless your a genuis with math and have an accurate knowledge, it's a very, very cheap way of giving you an insight of what the single largest bane of most studio mixes is - it's not the windows, or the stuffed toys in the corner, or that matress tied to the ceiling, but the room mode.

Anything that shows you that is a blessing! - if you still think i'm mad i'll post the math

dav nagle

sei046 wrote: »

Ok.. I might not go for the booth, I really need to treat my mixing room but as you can see from the drawing its an awkward shape! I have very little depth. Does anyone know a supplier in ireland for that eggcrate foam?

I would not agree! go for the booth

jtsuited

actually speaking of which, does anyone here know which building providers definitely stock Rockwool?

PaulBrewer

Neurojazz wrote: »

as per the original thread '(this is not perfect, but you'll get the idea)' - i know it's far from the perfection of a 25k budget and all the problems inbetween, but think about catching a glimpse of what the room is doing (especially that 'mode' which is a isolated spot and quite a peak) - unless your a genuis with math and have an accurate knowledge, it's a very, very cheap way of giving you an insight of what the single largest bane of most studio mixes is - it's not the windows, or the stuffed toys in the corner, or that matress tied to the ceiling, but the room mode.

Anything that shows you that is a blessing! - if you still think i'm mad i'll post the math

The simplest way is by maths on a regular room - there are lots of online mode 'finders' - Generally acousticians I've worked with are only interested in primary modes. Secondary ones sort themselves out within the treatment for RT time.

sei046

Do you have bass traps in your booth? what foam did you use dav

sei046

For anyone who is interested here is a pic of my mix area.

It extends twice that to the right so as you can see its not an ideal position.
I was standing at the door taking it so there is not a MASSIVE amount of space between the back wall and me.

dav nagle

sei046 wrote: »

Do you have bass traps in your booth? what foam did you use dav

Hey man,

No I don't use bass traps in my booth but I do in my mixing room! They suck up the sound in a good way. When I posted you earlier on in this thread explaining ''just go for it'' I really meant it. It is very hard trying to get the dimensions and sound right at the first go but it 'IS' worth it if you go ahead with it. On boards you are getting some excellent advice with regards to the booth but it is also slightly daunting advice and it would certainly scare me.