Basic Rehearsal Room Treatment

[GreenAsJade]

Hi,

 

I have "soundproofed" my shed for rehearsal ... so the interior is now all gyprock.

 

It's obviously bright as hell and horrid. For the immediate interim, I've hung blankets on angled panels to break it up a bit, but what should I really do to make it sound OK for rehearsal in there?

 

Thanks!

 

GaJ

[Ethan Winer]

 

what should I really do to make it sound OK for rehearsal in there?

 

 

See this:

 

http://www.ethanwiner.com/acoustics.html

 

Most of the article addresses listening rooms, but the same basic principles apply to a rehearsal room too.

 

--Ethan

[GreenAsJade]

Thanks Ethan - I found your page while searching elsewhere, and it's an excellent resource!

 

Much appreciated.

 

GaJ

[Rimmer]

 

Thanks Ethan - I found your page while searching elsewhere, and it's an excellent resource! Much appreciated. GaJ

 

 

I have a standard office style suspended ceiling in our rehearsal studio. It has reasonably thick acoustic tiles. The walls are quite bare though but this works very well for a live but controlled sound. Everyone that plays there loves the sound..

 

Rimmer

[myfipie]

 

Hi, I have "soundproofed" my shed for rehearsal ... so the interior is now all gyprock. It's obviously bright as hell and horrid. For the immediate interim, I've hung blankets on angled panels to break it up a bit, but what should I really do to make it sound OK for rehearsal in there? Thanks! GaJ

 

 

Do some searching around but the trick is 2 things. First you want to get as many bass traps in the corners. For these you want to use 4" or more thick of rigid fiberglass (OC 703 or OC 705) and straddle as many corners as possible. After bass trapping you would then want to build or buy 2" panels to spread around the room to help with the over all reflections in the room.

 

Glenn

[GreenAsJade]

Thanks with all this advice. Ethan's page and others are fantastic.

 

I used Bradford (Australian Company) Sound Screen in the walls. It's 75mm rockwool. It happened to be what a local place recommended for the soundproofing.

 

I can't find specs for it though: has anyone heard of it? Is it the right sort of stuff for bass traps?

 

On bass traps: if my room is horribly bright (which it is), then why do I want to absorb bass? I thought I would have been wanting to absorb high frequencies?

 

(A very related question: on Ethan's page the graphs of before and after bass traps seem to show _more_ bass (between the gaps that were there originally) after the traps are installed. Is that wierd?

 

I'm sure all this advice is the right thing to do, but I wish I understood _why_!!??

 

GaJ

[myfipie]

"On bass traps: if my room is horribly bright (which it is), then why do I want to absorb bass? I thought I would have been wanting to absorb high frequencies?"

 

I am sure the high end is very bright, but the trick is to even out the highs and the lows. If you only tame the high end the low end will still be bouncing around the room and really sound like crap. Absorbing bass is the hardest thing to do and that is what you may want to start with. After plenty of bass traps are in the room then put up thinner panels to absorb high end.

 

Glenn

[Ethan Winer]

 

It's 75mm rockwool.

 

 

If it's rock wool it should be usable.

 

 

Not weird at all. That's what's supposed to happen. Peaks and nulls are both caused by reflected waves, so adding bass traps reduces the strength of the reflections improving both the peaks and the nulls.

 

--Ethan

[mrbrown49]

Peaks and nulls are created by the reflected sound interacting with the original sound and the other reflections. Depending on how the sine waves hit each other they will either cancel part of each other out (null), or enhance the frequency(peak).

 

Try this. Play something with a lot of bass rather loud in an untreated room and walk around slowly. Sometimes you can actually hear where the peaks and nulls are. Walk over and put your ear near the wall and you will most likely hear an increase in the bass frequencies. You want to treat the room to minimize these things so that it sounds fairly consistent throughout the room.

[GreenAsJade]

Thanks ... I guess this makes sense: aim for evenness. But still, in a bare gyprock room 25'x15' thats painfully bright, I'm not 100% sure why tackling the bass first still will deliver the results (I believe you all, and will do it, don't get me wrong... I just don't understand it... ROFL!)

 

Also, here's a wierd thing: ethan explains that close to the wall the air is moving less (this is why bass traps have to be stood off the wall). So how come near the wall I would hear more bass? Surely it's high frequencies, with their short wavelength, that can get closest to the walls?

 

GaJ

[GreenAsJade]

 

If it's rock wool it should be usable. Not weird at all. That's what's supposed to happen. Peaks and nulls are both caused by reflected waves, so adding bass traps reduces the strength of the reflections improving both the peaks and the nulls. --Ethan

 

 

So what you're saying is that if you get rid of reflections, then there are actually places in the room where there was cancellation before that now don't have cancellation, so it looks as if you've "added" sound in the room! (Which is what those graphs look like).

 

Fasctinating, thanks!

 

GaJ

[mrbrown49]

 

So what you're saying is that if you get rid of reflections, then there are actually places in the room where there was cancellation before that now don't have cancellation, so it looks as if you've "added" sound in the room! (Which is what those graphs look like). Fasctinating, thanks! GaJ

 

 

I wouldn't say you added sound in the room in the whole, because you are minimizing the peaks as well. But yes, in the spot where you hear a null, you will actually hear more of the canceled frequency. The point is to flatten all that stuff so it sounds the same everywhere. And you are right, it is fascinating stuff. Good luck with your project.

[Ethan Winer]

 

So what you're saying is that if you get rid of reflections, then there are actually places in the room where there was cancellation before that now don't have cancellation, so it looks as if you've "added" sound in the room!

 

 

It takes time for sound to travel from the loudspeaker to a wall and back. So depending on the distance and frequency, sometimes the reflected sound arrives more or less in phase which gives peaks, or out of phase which gives nulls.

 

 

Great question. There are two factors at play here - sound velocity and sound pressure. "Porous" absorbers like fiberglass and acoustic foam act on wave velocity, but what we hear is wave pressure on the ear drum. If you're up on electric principles, velocity is like voltage and pressure is like amperes.

 

--Ethan

[bigolpimp]

Silly gooses.

 

What no one has mentioned here is that larger rooms can be treated with diffusors as well. Auralex charges way too much for what are the equivalent of large jello-molds (called T-fusors). If a room is relatively large and bright, reflections are sometimes more easy to control than trying to put absorbers/bass traps all over the place.

 

I'm not claiming that fiberglass/mineral wool won't help, but I've been taught that rooms larger than a certain size should be treated to diffuse reflections just as much/more than smaller rooms where standing waves can get out-of-hand.

 

Discuss.....

 

Note: Unlike others, I'm not trying to sell you anything.

[Rimmer]

Silly gooses. What no one has mentioned here is that larger rooms can be treated with diffusors as well. Auralex charges way too much for what are the equivalent of large jello-molds (called T-fusors). If a room is relatively large and bright, reflections are sometimes more easy to control than trying to put absorbers/bass traps all over the place. I'm not claiming that fiberglass/mineral wool won't help, but I've been taught that rooms larger than a certain size should be treated to diffuse reflections just as much/more than smaller rooms where standing waves can get out-of-hand. Discuss..... Note: Unlike others, I'm not trying to sell you anything.

 

Someone's trying to sell you something???

 

I suppose if we're proclaiming theory on larger room sizes, it's probably worth mentioning what you consider to be a large room..

 

Get your points though.

[myfipie]

>I'm not claiming that fiberglass/mineral wool won't help, but I've been taught that rooms larger than a certain size should be treated to diffuse reflections just as much/more than smaller rooms where standing waves can get out-of-hand.

 

I would agree with that, but the room really has to be big and about 90% of the rooms I come up against do not fall into that. But the point is that all rooms need bass trapping in them. Larger rooms may need less per cubic foot, but they still need them.

 

 

 

 

I am not sure if this is aimed at me, Ethan or both, but I can say that for myself (and I think Ethan also) that we are not here to "sell" anything. We are simply here to help people understand acoustics and how important it is. Through education it will payoff for us as a company, but I would rather see someone build there own then do nothing at all. Heck we tell you how to build them.

 

Glenn

[mrbrown49]

Through education it will payoff for us as a company, but I would rather see someone build there own then do nothing at all. Heck we tell you how to build them. Glenn

 

I thank you both for that! You were both very helpful when I was treating my room.

[Ethan Winer]

I'm not claiming that fiberglass/mineral wool won't help, but I've been taught that rooms larger than a certain size should be treated to diffuse reflections just as much/more than smaller rooms where standing waves can get out-of-hand.

 

The problem here is "I've been taught" versus having direct first hand experience.

 

Most large rooms are too live, so all diffusion will do is break up the "boing" sounds from flutter echo. But the room will still be too live for recording or mixing. You may be confusing the fact that diffusion is more appropriate in larger rooms when diffusion is warranted. But even really large million dollar control rooms have much more absorption than diffusion.

 

Another large/small factor relates to the types of problems in each room size. In a small room the main bass problems are peaks and nulls and modal ringing. In a large room (church or auditorium) reverb is the larger issue.

 

Finally, as Glenn said, I'm here to educate, not to sell stuff. In my mind acoustics and treatment are no more complicated than anything else in audio. Yet for some reason a lot of people misunderstand the basics, or fear it's too complicated for them to understand. Hey, I'm not a math guy either!

 

--Ethan

[GreenAsJade]

 

Great question. There are two factors at play here - sound velocity and sound pressure. "Porous" absorbers like fiberglass and acoustic foam act on wave velocity, but what we hear is wave pressure on the ear drum

 

 

Got it! Wow - it's nice to have an answer that makes sense.

 

Thanks!

 

GaJ

 

edit: BTW thanks for all your help (everyone). If anyone had taken even a cursory look at the fantastic DIY information you guys provide, they couldn't remotely think you're trying to "sell" something.

[GreenAsJade]

BTW: my "room" is 27' x 18'. Is that "large"?

[myfipie]

 

BTW: my "room" is 27' x 18'. Is that "large"?

 

 

No that would still be small.

 

Glenn

[GreenAsJade]

It's been quite some time since I started this project. Thanks so much for all your help in this thread and others.

 

Here's the result:

 

 

became

 

 

 

 

If you want to browse through pictures of steps along the way, you can clik on that picture to see the whole set.

 

GaJ

[bibleboy3]

ok how do you stop sound from going through a ceiling that only has sheet rock and NO insulation!!! how do you keep the upstairs neighbors happy with out breaking the bank..

[bibleboy3]

greenasjade,

that room looks AWESOME!!!

[nice keetee]

ok how do you stop sound from going through a ceiling that only has sheet rock and NO insulation!!! how do you keep the upstairs neighbors happy with out breaking the bank..

 

Give them good earplugs?