placement of treatments

[ciotime]

I'd like some advice on how to treat my HT room. The room is 14x21 with 8 foot ceilings. Right now its still bare cement walls. Im gonna be doing 2x4 studs with soft insulation in between then cover with drywall to add to isolation.

 

[ScottMayo]

I'd like some advice on how to treat my HT room. The room is 14x21 with 8 foot ceilings. Right now its still bare cement walls. Im gonna be doing 2x4 studs with soft insulation in between then cover with drywall to add to isolation.

If you do 2x6s, the room dimensions will be about 13'x20', which isn't too bad as room ratios go. There's more to a good room than a good ratio, but it makes a nice foundation to start with.

You don't get much isolation with standard insulation and a layer of drywall. Insulation is still a good idea, because in a 6" well, it starts to give you a little bass trapping.

You're at the right stage to plan your acoustics. Once the drywall is up, your options get a lot more limited.

 

[Ethan Winer]

Scott,

I don't have anything to add to this discussion as I've already given Cio my best advice in my own forum. But I wanted to tell you what a breath of fresh air your company's web site is. It's rare for someone who sells high-end audio to be so honest and forthright, and for that I salute you.

--Ethan

 

[ScottMayo]

It's rare for someone who sells high-end audio to be so honest and forthright, and for that I salute you.

Thank you sir! Obsession is founded on the idea of designing and selling what I know (from direct experience) works, with any BS ruthlessly removed. There will never be solid silver power cords, or curious, tiny triangle-shaped absorbers, magical dots, quantum anything, supernatural jars of shiny pebbles that reshape space/time, or any other frippery sold or specified by Obsession. Most of my clientele has been musicians, with a few engineers - and I'm darn proud of that fact.

Er, I think that's all the self-praise this site allows, so I'll get back to quietly warning people about the perils of putting 15", 1000w subwoofers in corners. But you're in the area - stop by sometime and see my showroom. I think you'd find it fascinating!

 

[Glenn Kuras]

Sounds like Ethan is in the market for some new gear for his room?
YES Scott great looking site>

ciotime have you thought about what you might be putting in for acoustics once your room is done?

Glenn

 

[ciotime]

As per advice I had gotten before its soft absorption on the entire front wall. Absorbers from 2'-6' on the side walls. Floor to 2' and 6'-8' will be FSK faces fiberglass. No idea yet for the back wall.

For Ethan..which is better? Panels traps or super-chunks on the corners? As I understand panels traps have an air gap at the back while super-chunks dont.

 

[Glenn Kuras]

As per advice I had gotten before its soft absorption on the entire front wall. Absorbers from 2'-6' on the side walls. Floor to 2' and 6'-8' will be FSK faces fiberglass. No idea yet for the back wall.

For Ethan..which is better? Panels traps or super-chunks on the corners? As I understand panels traps have an air gap at the back while super-chunks dont.

Super-chunks are going to work better because it has more over all fiberglass in it.

Glenn

 

[ScottMayo]

As per advice I had gotten before its soft absorption on the entire front wall. Absorbers from 2'-6' on the side walls. Floor to 2' and 6'-8' will be FSK faces fiberglass. No idea yet for the back wall.

Heads up on absorption on the entire front wall: if you decide to do a HT someday - and with great acoustics and good gear there's not much reason not to - having the front wall be entirely absorption leads to questions about how to do a screen. There are a lot of good solutions, but it's something you might want to think about. Not everyone likes dropdown screens. I opted to leave an area clear for a screen (with extra side wall absorption), and I'm very glad I did.

There's also some risk of overtreating in what you describe, but the nice thing about buying movable panels is that overtreatment has a simple cure.

 

[ehurnie]

What are a super-chunk and where is a good place to find them?
Thanks

 

[Glenn Kuras]

What are a super-chunk and where is a good place to find them?
Thanks

Super chunks are rigid fiberglass cut into triangles and stacked from floor to ceiling in the corner.

Glenn

 

[ciotime]

Actually this room is intended for HT. Im gonna have a motorized screen. I was thinking of just putting soft broadband absorbers on the front wall to the sides of the projector screen. No more absorbers at the back of the screen. The motorized screen by the way will be placed on some sort of cabinetry.

 

[blowinch]

Room Ratios.

If you do 2x6s, the room dimensions will be about 13'x20', which isn't too bad as room ratios go. There's more to a good room than a good ratio, but it makes a nice foundation to start with.

Just wondering about room ratios as I havent come across them before. Could you point me in the direction of some information? Thanks, Ryan.

 

[Ethan Winer]

> Just wondering about room ratios as I havent come across them before. Could you point me in the direction of some information? <

The screen shot below (click the link) is from my Acoustics FAQ, and it shows eight ratios commonly accepted as "good" for bass response. Understand that having a favorable ratio is only half of the equation. A room also needs to be large enough for the modes to be close together.

--Ethan

 

[Savant]

Hey Ryan,

Just wondering about room ratios as I havent come across them before. Could you point me in the direction of some information?

It's actually less about general room ratios, and more about the relationship between the specific dimensions of a room. The oft-published ratios, like the ones shown above, are very rough guidelines, but they won't produce the best possible results in most rooms. There are better tools:

John Griggs' ModeWizard is a great java tool with good accompanying documentation. It gives you the best dimensions within a user-specified range, and can make the evaulation based on many different room evaluation criteria. It will actually give you a list of usable dimensions. Much better results than those got by blindly applying the so-called "ideal" ratios found in many texts.

RPG's Room Sizer is a great tool that also optimizes the room dimensions over the given range considering different parameters. This one will set you back some $$, though, FWIW. (If you're only going to have to figure up your room dimensions once, I would suggest Griggs' ModeWizard.)

Personally, I also am partial to the Griggs tool because of its wide array of criteria to choose from - Bolt, EBU, Bonello, even one Griggs developed himself.

To reiterate, the current line of thinking on this is that the textbook ratios are quite limited in their usefulness. More folks are turning to tools like Room Sizer and ModeWizard to help figure up the best room dimensions for good distribution of modes.

 

[blowinch]

Cheers

Thank you Jeff and again to Ethan. Ethan- I found the FAQ handy, I'm sure I will try to pick your brain more when I have studied it further if you don' t mind. I'm am finding this forum a great source.

I'm currently studying a complex space if you have any suggestions. It's a nightclub with a big grim reverb time- around 1.7 seconds, and Im attempting to suggest treatment for it for a school project. The style and the atmosphere have to be taken into account so I can't go over board. The ceiling of the larger part of the room is hemi- cylinderical with a radius of 4.25m/14ft. I am mainly interested in treating the main room and I am going to work out the effect of treating the back wall of the stage and cutting out the hemi ceiling, making it flat as its already 4m high. I was going to suggest a single point source supended over the stage and main room boundry at a coverage angle that would just cover the dance floor. The stage behind the main room is raised by around .5 of a metre and has a metal floor. If you could suggest any treatments or criticise my plan it would be appreciated. the pic is an attachment.

http://forums.audioholics.com/forums/attachment.php?attachmentid=3055&stc=1&d=1147098158

Thanks. Ryan.

 

[blowinch]

griggs mode calc

Jeff,
I had a chance to mess around with Griggs Calc. I'm on a Mac so I couldn't get the others to work. Thanks for the heads up it seems like a neat application. Ryan.

 

[Ethan Winer]

Ryan,

> I found the FAQ handy, I'm sure I will try to pick your brain more when I have studied it further if you don't mind. <

That's what I'm here for!

> I'm currently studying a complex space if you have any suggestions. <

The general goal for reducing reverb in any space is to use absorption that's effective to as low a frequency as possible, spread around the room evenly. If you can identify a single large area as a specific source of echoes, or perhaps focusing as from the dome ceiling, those could receive additional absorption or even complete surface coverage.

--Ethan

 

[ehurnie]

What is better to use the superchunks or something like this?
http://cgi.ebay.com/Soundproofing-Foam-Acoustic-Bass-Absorbers-Traps-SP8_W0QQitemZ7413058767QQcategoryZ3278QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[jmprader]

What is better to use the superchunks or something like this?
http://cgi.ebay.com/Soundproofing-Foam-Acoustic-Bass-Absorbers-Traps-SP8_W0QQitemZ7413058767QQcategoryZ3278QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I'm nowhere near as bright as some of the others here, but for bass, stick with superchunks, the absorption figures for the foam product don't look very good down low.

However, for the smart guys, how about acoustical cotton rather than fiberglass for superchunk corners? Harder to work with in terms of cutting, but no itch and scratch, just dust...

 

[Ethan Winer]

What is better to use the superchunks or something like this?
http://cgi.ebay.com/Soundproofing-Foam-Acoustic-Bass-Absorbers-Traps-SP8_W0QQitemZ7413058767QQcategoryZ3278QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I guess it's time once again to point out that Foam By Mail sells cheap packing foam - not real acoustic foam. They stole the data from Auralex and publish it as their own. This is not a joke! I tested FBM corner foam in an acoustics lab and it proved far less effective than their claims.

--Ethan