broadband bass trapping

telefunken · Post by **telefunken** » Fri Dec 12, 2003 7:42 am

im considering doing broadband bass trapping on the back wall of my control room.

would these rough plans work?

there's 3 diagrams located here:

http://www.farewelltoarms-pr.com/index.htm

any other advice or ideas would be appreciated.

lovecow · Post by **lovecow** » Fri Dec 12, 2003 8:20 am

Dear telefunken,

Of what does the "Bass Trap" in your first figure consist?

Best regards,

Jeff D. Szymanski
Chief Acoustical Engineer
Auralex Acoustics, Inc.

Post by **John Sayers** » Fri Dec 12, 2003 8:54 am

Jeff - I assume he means Ethans panel traps on the rear wall and he's putting 705 in front of them to stop the reflections off the panels.

correct Telefunken?

cheers
john

telefunken · Post by **telefunken** » Fri Dec 12, 2003 12:15 pm

john,

yes that is correct. im sorry for not specifying, im so used to posting over on recording.org, where you say "bass trap" and everyone knows its ethans.

will this work?

Post by **John Sayers** » Fri Dec 12, 2003 12:48 pm

will this work?

yes I believe it will help significantly. The main thing is your rear wall will be dead in the highend and Ethan's panel absorbers (I don't call them bass traps because they are not traps! a trap is an area where the bass is trapped IMO - i.e. ceiling trap is an area above a timber ceiling full of hangers where the bass is trapped and absorbed.

A better term for Ethan's units would be panel resonators because that's how they work.

cheers
john

lovecow · Post by **lovecow** » Fri Dec 12, 2003 1:33 pm

John,

John Sayers wrote:A better term for Ethan's units would be panel resonators because that's how they work.

Aren't those the ones he's not making anymore? I thought he discontinued panel resonators and went with more traditional broadband absorber panels.

???

Best regards,

Jeff D. Szymanski
Chief Acoustical Engineer
Auralex Acoustics, Inc.

Post by **John Sayers** » Fri Dec 12, 2003 3:20 pm

Jeff.........This is from his site:

MiniTraps are real membrane absorbers, but they're much more affordable than our premium wood panel bass traps

IMHO these are both either membrane absorbers or panel absorbers or panel/membrane resonators....neither are traps as I understand the word.....No??

BTW - in no way do I intend to infer they don't work on anything - just the naming of them

cheers
john

Ethan Winer · Post by **Ethan Winer** » Sat Dec 13, 2003 4:15 am

Jeff,

> Aren't those the ones he's not making anymore? <

In 1995 Electronic Musician magazine published an article I wrote showing how to build panel traps. That article is on my personal web site, and people still build them and still have questions about them. So this comes up a lot in my RO forum. If you haven't seen that article, or any of my other articles over the years, have a look here:

www.ethanwiner.com/articles.html

--Ethan

barefoot · Post by **barefoot** » Sat Dec 13, 2003 5:16 am

John Sayers wrote:IMHO these are both either membrane absorbers or panel absorbers or panel/membrane resonators....neither are traps as I understand the word.....No??

I think this somewhat a matter of semantics, depending on how you view the problem. A panel absorber is essentially a pressure to velocity transformer. At its resonant frequency the panel absorber can be seen as basically reradiating a wave that is 180° out phase with the incident wave. The "trapping" occurs on the other side of the panel where energy is dissipated by viscous loss as the relatively high velocity air rushes through the absorbent material. So, from the room perspective it's not really a trap. It's a phase inverting resonator. From the perspective inside the absorber, it is basically a trap.

Since we tend to spend more time inside the room than we do inside the panels, and just for the sake of keeping our terminology consistent, I agree with John that "trap" is really the best name.

Thomas

Post by **John Sayers** » Sat Dec 13, 2003 6:45 am

I think this somewhat a matter of semantics

yup

:)

cheers
john

giles117 · Post by **giles117** » Sat Dec 13, 2003 6:50 am

Off Topic.

I Love the New Mini-Mains. WAAAY OUT My price range.

Good Job Barefoot. Bryston Amps. U dah Man....

I Am curious about that sc-2....

when will it be ready and priced.

barefoot · Post by **barefoot** » Sat Dec 13, 2003 8:01 am

giles117 wrote:Off Topic. I Love the New Mini-Mains. WAAAY OUT My price range. Good Job Barefoot. Bryston Amps. U dah Man....
I Am curious about that sc-2.... when will it be ready and priced.

Thanks giles!

Yeah, the MiniMains are definitely aimed at the high end of the market. However, they are VERY competitively priced when compared to other monitors "in their class" (i.e. ADAM, ATC, PMC) I use "in their class" in quotes because the MiniMain has really defined a whole new class. It's a true Main Purpose monitor, equally suited for use as an uncompromisingly accurate near field, or as a powerful main monitor - soffit mounted or not.

The Bryston amps are working out very well. They are able to supply me with extremely high performance and high quality modular components. They rock!

The SC2 should be available by the end of January. I don't have firm pricing worked out yet, but it will also be a high-end product.

As the business grows I want to develop a more affordable line of products. The production scales and associated capital investment are out MY reach right now (isn't it funny how that works!). So, if you want an affordable MiniMain derivative any time soon..... tell all your friends with the cash to buy the high-end units now!;)

Thomas

AndrewMc · Post by **AndrewMc** » Sat Jan 10, 2004 7:00 pm

Obviously I have no idea what they sound like, but if they sound as good as they look then I am sure they are wonderful.

Congratulations - they look incredible - you have done a beautiful job on those monitors - I'm blown away

cadesignr · Post by **cadesignr** » Tue Jan 13, 2004 1:04 pm

John Sayers wrote:

a trap is an area where the bass is trapped IMO - i.e. ceiling trap is an area above a timber ceiling full of hangers where the bass is trapped and absorbed.

Hello everyone. John, could you clarify this for me. The way I'm interpreting this is, IF I have a room, such as a normal room in a home, the attic area above the room could be used as a bass trap by hanging 703(?) panels from the interior side of the roof? If this is true, I have a couple of questions, as my little ole studio is in an upstairs room, with its own roof. No soundproofing in the room. just ordinary gyp bd construction. When you say this area will trap the bass via the hangers, doesn't bass normally travel through the cieling, and then on through the roof, if there is no soundproofing construction? Why would you want to trap it, if it is already leaving via sound transmission to the outside? I thought trapping was something you do "inside" of the room? I'm curious about this. As well as how you determine "how much" bass trapping you need? Is there such a thing as "too much"? And if all surfaces of a room were covered with panel resonators and mid/low absorbers, would this not kill any liveness in a room?
And what determines "how big" to make a panel "trap". I ask, as since the formula for a panel "trap" includes the thickness of a panel, I got to thinking. "Since" the thinner the panel is, the better it absorbs bass(correct), why not use a sheet of plastic laminate, which I can obtain in 5' x 12' sheets

If I made a frame of 8" wide mdf, with the ceiling as a back, and adhered the plastic laminate to the edges of the frame via aluminum extruded angle, screws and silicone, would that be a good bass absorber?(I would fasten and seal the frame at the ceiling also, or use a seperate back). Or do you even need it that large? Also, do panel traps only work if they are rectangle? Or can they be other shapes? Ok, I'm done. Hey John, I know it takes a book to answer these....take your time. Hehehehehehe! sorry.

[/quote]

cadesignr · Post by **cadesignr** » Tue Jan 13, 2004 1:56 pm

Ok, you know me John, I'm on a roll so bear with me.

IF, one of the parameters of slot absorbers, as well as "panel traps"
is the depth of the trap(box?), and IF, soundproofing were not an issue, I was thinking since my room is so small, I could build very deep and long traps that fit between the rafters of my ceiling, simply by cutting out the sheetrock and framing supports between them for either panel or slot absorber boxes. Would this work? Say, 2' deep, 14" wide, and 8 to 10' long? And if I decided to use slats, which way would be best to run them, across the width or the length? And which would work better, panel or slots? There is little issue with soundproofing where I live, and besides, the room is for my recording pleasure only. But I would like to have good bass absorption. I just don't know the principles behind sizing them, and how you apply them or what determines the sizes. That one has plagued me for a long time. I mean, how much square footage of slot equals 1 sabine of absorption? Or is that even how you are calculating the size? Or do you even need to? Thomas says the percentage of slot to overall size is the percentage of effeciency, but what are you really trying to accomplish in actual figures? Gads, this is burning my brain cells.......

fitZ