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Author Topic: Bass trap ideas?  (Read 7428 times)

brandondrury

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Bass trap ideas?
« on: April 28, 2004, 03:41:07 am »

Hey dudes,

Everyone (including myself) tends to agree that my live room sucks. It appears to have too much 400 Hz.  

My room is about 15x20x9 = 2700 cubic feet.

What sort of gadgets can I cheaply construct to absorb the lower frequencies?

I could just buy a bunch of Auralex or RPG bass traps, but I'm not really sure how long I'll be at my current location.  

Any ideas?

Brandon

Jim Dugger

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Re: Bass trap ideas?
« Reply #1 on: April 28, 2004, 08:11:40 am »

Can you give me measurements precise to the inch so I can run a mode program for you?  My bet is your real problem is related to that 9ft ceiling -- those cause modes in the 60 - 65hz range.

Also, do you use a DAW?  I'll have you run some sweeps and record them for analysis.  It's pretty easy to isolate the issues.

If it's true your problems are at 400hz, you are in for a treat.  Fiberglass and foam can be used to solve this sort of problem.  But my bet is your real issues are modes below 100hz, and only tuned port and diaphram absorbers do much in that range.

Just in case you were thinking the foam route, please take a look at the transfer functions below 100hz.  They do almost nothing.  It would take several feet of foam to be effective below even 200Hz.  You can do better with a a couple of $6 24x48x2 sheets of 703 fiberglass and some 1x8 boards to get it off the wall a couple of inches.
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Brian Young

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Re: Bass trap ideas?
« Reply #2 on: April 28, 2004, 11:41:26 am »

Don't buy into any of that foam crap, yeah I'll repeat it so it get's into your head: it'll do more to the mid-high frequencies then it will to lower bass frequencies (which are more important in your case)... Build or buy some real bass traps


also, why do you keep posting new of the same topics on this forum?
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Ethan Winer

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Re: Bass trap ideas?
« Reply #3 on: April 28, 2004, 12:04:35 pm »

Brandon,

> What sort of gadgets can I cheaply construct to absorb the lower frequencies? <

See the Acoustics FAQ, second in the list on my Articles page:

www.ethanwiner.com/articles.html

--Ethan

drumsound

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Re: Bass trap ideas?
« Reply #4 on: April 28, 2004, 05:32:48 pm »

Ethan's Mini Traps are great!  I need to get more.  And mount the ones I have.  Even sitting in the corners, they are very helpful!
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ratite

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Re: Bass trap ideas?
« Reply #5 on: April 29, 2004, 05:20:13 am »

I"d recommend calculating your room modes and then checking this against reality-ie wall materials and stuff in the room when you record.Pink noise and a FFT spectrum analyzer will confirm your suspicions.

It's very cheap and easy to build flat panel bass traps yourself, and having built a sealed trap, you can then tune it by drilling holes and making a hermholtlz resonator.

The ratio of hole area to total surface area is the key parameter.Having said that,I'm not sure what you can do with a 9 ft ceiling...I have the same problem and endlessly berate myself for stupidity in signing the lease.Then again, in Japan,it ain;t easy to find airy rooms Razz Oh, and as has been said,forget foam for low freq's.High density,fibreglass is your friend!!I got a lot of good info from the acoustics group on Yahoo but having obtained it I never went back...i guess i ain't no acoustician Cool.Good luck..and maybe record your drums in stairwells or elsewhere if it's feasable.  
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Richard Horner
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ratite

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Re: Bass trap ideas?
« Reply #6 on: April 29, 2004, 05:21:40 am »

I forgot to add,use corners (where 3 planes meet) for max efficacy in bass trapping!
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Richard Horner
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brandondrury

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Re: Bass trap ideas?
« Reply #7 on: April 29, 2004, 05:46:33 am »

Ethan,

You have the best website in the universe for a human in my position!  I appreciate the help.  It'll take me all month to absorb the tremendous amount of information.

I was amazed at the video where you installed 8 mini traps in a relatively small control room.  The difference was easy to tell on the worst pair of bookshelf speakers known to man on a compressed video download.  

I've been bouncing between ordering some of the foam products vs building things myself, etc.  I'll definetly keep the Realtraps in mind.  

As far as performance is concerned, how do the Minitraps compare to the Real Traps?  At this stage in the game, I care nothing about aethetics.  I'm just trying to make killer recordings.

It seams most of the info on your site is geared towards control rooms.  I'm very much interested in improving my live room.  My control room is a mess, but personally I feel that if I can record better tracks, than the need for flat control panel is less.  No mix ever passes through my studio without being tested in the car and on my home computer rig anyway.  

One last thing in regard to the Owens Corning 703 fiber glass.  Did I understand the article correctly?  You hang them on the wall and that's it, more or less?  


Thanks again,
Brandon Drury

John Ivan

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Re: Bass trap ideas?
« Reply #8 on: April 29, 2004, 09:11:51 am »

brandondrury wrote on Thu, 29 April 2004 04:46

Ethan,

You have the best website in the universe for a human in my position!  I appreciate the help.  It'll take me all month to absorb the tremendous amount of information.

I was amazed at the video where you installed 8 mini traps in a relatively small control room.  The difference was easy to tell on the worst pair of bookshelf speakers known to man on a compressed video download.  

I've been bouncing between ordering some of the foam products vs building things myself, etc.  I'll definetly keep the Realtraps in mind.  

As far as performance is concerned, how do the Minitraps compare to the Real Traps?  At this stage in the game, I care nothing about aethetics.  I'm just trying to make killer recordings.

It seams most of the info on your site is geared towards control rooms.  I'm very much interested in improving my live room.  My control room is a mess, but personally I feel that if I can record better tracks, than the need for flat control panel is less.  No mix ever passes through my studio without being tested in the car and on my home computer rig anyway.  

One last thing in regard to the Owens Corning 703 fiber glass.  Did I understand the article correctly?  You hang them on the wall and that's it, more or less?  


Thanks again,
Brandon Drury



Hey there:
The same concepts apply in both rooms ,sorta. The live end Dead end thing That I mentioned comes from control room "thinking" I've seen but, I have found this to be very useful in the tracking room also. I would not ignore these problems in your control room. It is very very important that what  comes out of your speakers represents what happened at the mic as closely as possible. As mentioned before, You wont get it perfect but you can make it very much better than it is. Now,damnit'' Go do it!!:-}. I know guys who have been threatening to fix they're rooms for YEARS now and they just "get used to it" instead. Don't do that to your self. I was in the back of a music store 4 years ago and my control room was WAY to small. We worked really hard at making it work and I couldn't believe that we got it sounding as good as we did.


I agree that Ethan's site is just outstanding! There is a lot of great info there and he clearly knows his stuff. Lucky us!. I am building a whole new room and I'll be talking with Mr. Winer,I'm sure. I'm building a control room and One big? tracking room and two iso rooms. I am going into this with the idea that I'm going to do it right,or not do it. All of this within the financial boundaries I face,of course.

Ivan........

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Ethan Winer

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Re: Bass trap ideas?
« Reply #9 on: April 29, 2004, 12:58:01 pm »

Rat,

> recommend calculating your room modes ... Pink noise and a FFT spectrum analyzer <

That's the way it used to be done, but more modern thinking shows that room dimensions and modes are almost irrelevant. If you get Electronic Musician magazine, see my article last month (April issue) that explains this in detail. This article is also now on the Articles page of my company's web site.

--Ethan

Ethan Winer

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Re: Bass trap ideas?
« Reply #10 on: April 29, 2004, 01:05:57 pm »

Brandon,

> how do the Minitraps compare to the Real Traps? <

Do you mean the wood panel traps we used to sell? We discontinued those last year because MiniTraps absorb even more and to lower frequencies, and they're less expensive to make and ship. So there was no point in continuing the panel trap line.

> I'm very much interested in improving my live room. <

As Ivan said, the concepts are the same. Often you want less absorption in a live room than a control room, but in both cases the best solution is broadband absorption that absorbs to as low a frequency as possible.

> if I can record better tracks, than the need for flat control panel is less. <

Some would argue the opposite - no matter what happens in the live room, your last chance to get things right depends on hearing accurately while mixing.

> 703 fiber glass ... You hang them on the wall and that's it, more or less? <

It depends on the goal. For general mid/high frequency ambience reduction and avoiding obvious echoes, rigid fiberglass flat on a wall works great and doesn't have to be particularly thick. But for substantial absorption at low frequencies you'll get better results if it's at least four inches thick and placed straddling the room corners.

--Ethan

brandondrury

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Re: Bass trap ideas?
« Reply #11 on: May 06, 2004, 05:33:06 am »

Hey Ethan,

After reading your booklike acoustics article several times, I must say that I'm amazed.  Never have I received that much information in a language that I can understand when it comes to acoustics.  Thank you very much!

Today, I finished recording vocal tracks and when I heard what was coming out of the mic, I jumped up and checked to make sure the mic was setup correctly because the sound was so different.

To remind you, my live room is 15x20x9.  It had a drop ceiling that I removed when I began using the room for recording about a year ago.  After reading your article, I put the drop ceiling back in.  

There are so many items on studio grocery list that I didn't want to wait to try real bass traps.  I purchased 4 rolls of insulation and just stacked them in the nearest corner.  I could hear a difference by just standing in the room and speaking!!!!!

I like the idea of having both stacked insualtion in the corner and then Real Traps in front of those stradling the corner.  I've always heard that the AKG was a very bright mic, and never really understood it.  My results were always much different.

Now, running the same vocalist through the same AKG 414 in the same location on the same mic stand through the same preamp and soundcard creates extremely different results!  I see what everyone was talking about in regard to my room being crap.  I could even hear a severe difference with one of my Octava mics that I use to monitor with.  (AKG 414 straight to Neve straight to soundcard, Octava to Mackie for headphone mix).

I've got big plans of finishing the hardwood floor, filling each corner excessively with rolls of insulation, and constructing some diffusors.  

I appreciate everyone's help.  I've gotten just a small sample of what even a decent room could do for my mixes.

Soon, I'll apply the same logic to my control room.  However, for the moment, my logic says that getting to instruments to hard disk as best as possible is more important than hearing them more accurately during mixing.  I mix lazily anyway and avoid eq and compression anyway.

I'm trying to figure out how bright or dark I want my live room to be.  The plan is to use this room for tracking drums (usually rock bands, but I'm open to anything), guitar amps, vocals, and just about anything else.  Do I want to make the room sound really live or should I go a subtle route?

I'm very interested in this whole diffusion thing.  I'm ready to start chopping up 2"x4"'s into triangles and glewing them all over the wall.  Is this the way to go?  I'm not paying $200 for a 15"x15" square diffusor.  I'd rather get creative with lattice and a power saw.  Are there any recommendations or tips for building diffusors?  links to plans? etc?

Everyone mentions diffusion, but seldom I see anyone get too deep into it.

Thanks again,
Brandon Drury  

Jules

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Re: Bass trap ideas?
« Reply #12 on: May 06, 2004, 06:49:48 am »

Points to add

1) I've been digging Ethans Real Traps in my live area and vocal both.

2) Is your live are dual purpous? I mean does it double as a chill out area (l;ike mine does) cause if it does and it is big enough to accomodate it a heavy leather couch works very well as a  bass trap. (v good for control rooms too!)

My 2 Euros

Vertigo

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Re: Bass trap ideas?
« Reply #13 on: May 06, 2004, 09:33:52 am »

I actually stumbled onto Ethan's site about 6 months ago when I was doing the initial construction on my studio. I copied his control room setup with the build-it-yourself membrane traps on his page and I'm VERY happy with the sound in my control room. I also used his mode calculator to find the nodes in my sound room.

Not to discourage any sales of the MiniTraps (because Ethan definitely deserves it), but I have to say the DIY traps are cheap to build and they sound great. They do take a lot of work to put together (I hope you like hammering upside down) and finding OC 703 isn't always easy, but they're definitely worth the investment of time and energy if you have it to spare.

Thanks Ethan Smile

-Lance
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josh

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Re: Bass trap ideas?
« Reply #14 on: May 06, 2004, 10:11:27 am »

Ethan,  I'm now very curious about your "mini traps"...

How (technically) do they differ from the membrane-type traps?  Are they different from the DIY-style membrane traps?

I guess what I'm getting at is on the matter of cost-to-benefit ratio, building a 2'x4' panel trap costs a whole lot less than buying one of your mini traps, but the recommendations for use of membrane traps are to nearly completely line the room with them, while the info page on your mini traps page refers to a much more "sparse" application of traps.

So...  at this point I have two applications where I need to add bass traps and mid-hi absorbers (one whole large wall behind the stage at my church, and also my home studio).  In both cases I'm extremely budget constrained.  So if I have a very small budget, then would I be better off buying a small number of mini traps (like 2-3 for my home studio, maybe 6 for my church), or building membrane absorbers and HF/mid absorbers from OC 703 & etc. as many as I can for the same cost?

One other thing, does anyone know where I could find OC 703 or equivalent in Austin, TX?  I can't seem to find it anywhere, and the HVAC contractors I have talked to are all reticent to get it for me.

thanks-

Rob Darling

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Re: Bass trap ideas?
« Reply #15 on: May 06, 2004, 02:42:12 pm »

A live room is not a control room.  Using the principles of creating a control room when trying to sculpt a live room will give you a very boring room.  You have to use your ears and experiment.

To that end, take 4 or 5 pieces of 4x8 half inch plywood, and cut them in half.  Buy a bag of r-11 fiberglass, stretch it and staple it down, and screw in eyes at each corner.  Now begin hanging them around the ceiling and walls with more eyes and a bunch of s-hooks.  Experiment with angles, one end vs the other, etc.  

Once you are happy, cover them with some kind of cloth that you like, and call it a day.  100$ and you'll get what you need.
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brandondrury

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Re: Bass trap ideas?
« Reply #16 on: May 06, 2004, 03:30:21 pm »

Plywood and R-11: Sounds like the perfect solution for my mid and high end absorbsion needs.  Assuming I can get the low end right, the next step is diffusion.

I read on Ethan's site that a room with proper diffusion will actual reduce bleed into other microphones.  At first, I thought this was nuts, but after thinking about it for a minute it made total sense.

Is the random plywood with R-11 placement applicable to diffusion as well?  I saw 4x8 sheets of lattice at the local hardward store for $6.  I figured I would just purchase 10 or 15 of these and put them in crazy concoctions all over the room.

I kind of want to make this particular room very live.  I want to record drums in it, toss in a few room mics and not have to worry about using plugins too much. I hate messing with reverb plugins!  I'd like to be able to use the same room for vocals and let the ambience of the room be enough.

I've got a smaller room that could be easily converted to a dead room for voiceover work, etc.

Brandon

josh

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Re: Bass trap ideas?
« Reply #17 on: May 06, 2004, 04:19:55 pm »

I don't think the R-11 on plywood is going to do what you want at all.  It will absorb high frequencies and that's it.  You'll end up with a dead-sounding, boomy room.

I also don't think that lattice is going to do what you want for a diffuser, but I'm not really very knowledgeable about diffusers.  There are ways you can make poor-man's diffusion devices, probably the cheapest and easiest of which is to take a piece of 1/8" masonite and bend it with a little bit of radius, attach it to the wall this way, voila you now have a diffusor (whether it sounds good is yet another question).  Diffusion can get extremely complicated when you begin to talk about broadband and 2D, 3D etc...  it makes my head spin.

If you want a live-ish room, then don't stick R-11 everywhere.  Realtraps Minitraps seem to have mostly reflective surfaces on them to preserve a bit of the reflective ambience at the top end, and hanging a couple of these at varying angles (particularly in the corners, where they are most effective anyway), can give you *some* diffusion.  Of course a book shelf with some books, CDs, other junk on it can work as a decent diffusor as well, just not really fine-tuned.

Ethan Winer

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Re: Bass trap ideas?
« Reply #18 on: May 07, 2004, 12:32:53 pm »

Brandon,

> Never have I received that much information in a language that I can understand when it comes to acoustics. <

Thanks very much!

> my logic says that getting to instruments to hard disk as best as possible is more important than hearing them more accurately during mixing. <

I'd argue the opposite - hearing accurately while mixing is important because it's your last chance to fix whatever may be wrong with the tracks.

> Do I want to make the room sound really live or should I go a subtle route? <

It depends entirely on how large the room is, and large rooms can get away with being more live sounding. But the same amount of reflectivity in a small room is a problem because the reflecting surfaces are all close to the performer and to the mikes. This creates problems with comb filtering and short, muddying echoes.

> I'm ready to start chopping up 2"x4"'s into triangles <

I'm not a diffusion expert, but I believe the best ones use a math sequence. As opposed to randomly sticking stuff on the walls.

--Ethan

Ethan Winer

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Re: Bass trap ideas?
« Reply #19 on: May 07, 2004, 12:40:27 pm »

Josh,

> I'm now very curious about your "mini traps" ... How (technically) do they differ from the membrane-type traps? <

MiniTraps are a sort of hybrid between a rigid fiberglass panel and a membrane trap. That is, they're based on rigid fiberglass, but we also add a membrane to enhance their absorption quite a bit at low frequencies. So they have the best features of both designs, absorbing even more and to a lower frequency than wood panel traps. They also absorb mid and high frequencies too, and the balance between the frequency ranges is intentional and part of the design.

> the recommendations for use of membrane traps are to nearly completely line the room with them, while the info page on your mini traps page refers to a much more "sparse" application of traps. <

Yes, that too. MiniTraps absorb low frequencies about twice as much as wood panel membrane traps, so fewer are needed.

> if I have a very small budget, then would I be better off buying a small number of mini traps <

I can't really answer that because I don't know how good you are with power tools nor do I know how much your time is worth to build them. I will say that four MiniTraps is a practical minimum for most rooms.

--Ethan

josh

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Re: Bass trap ideas?
« Reply #20 on: May 07, 2004, 03:28:12 pm »

Thanks, Ethan.  You're incredibly helpful as usual.

I'm pretty good with power tools but my time is also very sparse.  Particularly since my wife has recently become hooked on "Trading Spaces" and has lots of projects lined up for me.

I'll see if I can scam some Minitraps.  They certainly would reduce the whole "fuss" factor compared with DIY.

Thanks,
josh
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