helmholtz resonator location

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zook250

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i have a very small controle room 6'x9'. can i install a resonator on the ceiling?does it matter where it is in the room?

thanks
 
Zook,

> i have a very small controle room 6'x9' <

A Helmholtz resonator in a room that small is a complete waste of time. You need rigid fiberglass, and lots of it, all around the room. See my Acoustics faq listed on my Articles page (10th in the list):

www.ethanwiner.com/articles.html

--Ethan
 
Yes you can put a resonator in the ceiling - here's a pic of one
Up6_11.jpg


Putting rigid insulation totally will create a really dead dead room with no high freq response. Slots like in the pic will give you some high end diffusion which is what you will need.

cheers
john
 
thanks for the info. does anyone know the best way to make this size room workable. my mixes turn out bass heavy. attached is a picture.
 

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John,

> Yes you can put a resonator in the ceiling <

Thanks for correcting me. But in a 6x9 room? On the ceiling? Really? :D

--Ethan
 
Not that I am pretending to know what I am talking about, but why not put one behind you?
 
Thanks for correcting me. But in a 6x9 room? On the ceiling? Really?
Click to expand...

yeah - why not?? Most people ignore the ceiling as a treatable surface yet in a small room it's possibly the only area you can get depth without loosing floor space.

cheers
john
 
i know nothing about acoustics, but he says his mixes turn out bass heavy, which means he's not hearing enough bass in the control room. Is this resonator actually adding bass by resonating at a specific frequency? I've heard of bass traps, but never acoutic treatment thats add frequencies, this is quite interesting!

Eric
 
The paradox is that using bass traps can INCREASE the amount of bass you hear in the room. What you are doing is keeping the low soundwaves from being cancelled by the echoes.

-lee-
 
In a small room like that, there's a very good chance that your head is located dead center in all three dimensions, or at least two - whatever frequencies those modes are at will be almost perfectly NULLED in the center, which would definitely make you turn up the bass.

Assuming an 8 foot ceiling (not mentioned) the primary modes are at 62, 70 and 94 hZ. Hearing little or none of those would make ME reach for the "Big Bottom" knob... Steve
 
John Sayers said:
yeah - why not?? Most people ignore the ceiling as a treatable surface yet in a small room it's possibly the only area you can get depth without loosing floor space.

cheers
john
Click to expand...

And most people, including myself over the years, forget that a ceiling is nothing more than a parallel wall to the floor, awesome way of getting standing waves.

That was a lesson I unfortunatly learned the hard way loooong time ago.
 
thanks for the comments. the ceiling is 7'-6. i have some time to build the resonator. i will let you know how it works, also i have a friend that works at an insulation supplier that carries 703. how do you know how much 703 is required.i will put 1" in the resonator , but how much on the walls?

when i mix , i am prety much dead center of the room

thanks for the help.
 
John,

> why not?? Most people ignore the ceiling as a treatable surface <

Well, sure, but I'd have thought 2-6 inches of 705 all over the entire ceiling would provide broader absorption and cover more of the bass range.

--Ethan
 
if i am understanding correctly, the reason why my mixes end up bass heavy is because the room is to small for the bass frequencies to develope, so if i absorbe more mid and high frequencies , the room will become more balanced thus letting me hear whatever bass there might be. does this sound right. if so then Ethans idea might be better than the resonator idea. do i want to try to suck out any more bass frequencies if that is actually the main component of the sound that i am not hearing correctly. the corners are very bass heavy so i need a bass trap regardless.
 
Zook,

> the room is to small for the bass frequencies to develope <

No, it doesn't work that way. These problems are always caused by reflections. Get rid of the reflections and you get rid of the problems.

> do i want to try to suck out any more bass frequencies if that is actually the main component of the sound that i am not hearing correctly <

Again, that's not the correct analysis. Please see my Acoustics article linked earlier in this thread, and you'll find these issues explained in great detail.

--Ethan
 
"when i mix , i am prety much dead center of the room" -

Take your entire mix station, and however you have to do it, get your head out of your (ahem) center...

By this, I mean move forward or back, up or down (stay centered left-to-right)

And while you're at it, measure and make sure that your speakers are NOT sitting at 1/4 of the long dimension away from the wall in front of you. Even 6-8" can make a noticeable difference. By that, I mean that if you are facing the long way in the room, your speakers should NOT be where their baffles are 27" from the front wall, or they will be "sucked dry" of bass that coincides with the 9 foot dimension of your room - If you have them at that distance AND your head is centered front to back, also maybe top to bottom centered, then you are not hearing more than maybe 10-20% of the bass your speakers are putting out, if even that much.

You still need to do the treatment mentioned by John, but move things around if you can and see what a difference it makes... Steve
 
In a room that small the main problem is in the low mids which are masking the actual bottom end. Take out the low-mid colouration and the lows will be fine as the existing walls are acting as low panel absorbers or the lows are going straightout of the room thru the walls.

That's why the 705 on the ceiling will not help because its taking all the highs with it whereas a slot resonator diffusses the highs and removes only the low mids.

cheers
john
 
Ethan Winer said:
John,

> why not?? Most people ignore the ceiling as a treatable surface <

Well, sure, but I'd have thought 2-6 inches of 705 all over the entire ceiling would provide broader absorption and cover more of the bass range.

--Ethan
Click to expand...
Well admittedly I am no accoustics expert but I was under the impression that 2 to 6 inches would do diddley for bass absorbtion.

Am I wrong?
 
sure - but in an 8 ft ceiling you can get 1 ft easily.

cheers
john
 
Jake,

> I was under the impression that 2 to 6 inches would do diddley for bass absorbtion. <

Good point, and I'm glad you brought it up.

First, six inches of 705 rigid fiberglass gives a substantial amount of absorption - more than the fluffy type of fiberglass and much more than the same thickness of typical sculpted foam. Even two inches of 705 does enough in the upper bass range to help at least a little.

More important, and I should have mentioned this, is to leave an air space between the fiberglass and the ceiling or wall. Four inches of 705 with a four-inch air gap makes a very credible bass trap. No, it won't absorb much at 40 Hz, but it will make a meaningful overall improvement in the room.

--Ethan
 
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