How I built my bass traps...

[Scott@RealTraps]

It's not surprising at all that people would have difficulties using Room EQ Wizard (REW) with a Digidesign, RME or other pro audio interface. I know that REW and ETF are both designed to work with standard consumer sound cards and want to use the Windows (or Mac) system sound card mixer for volume adjustment, etc. They don't seem to like audio interfaces that have their own mixer software, etc.

It seems rather counterintuitive to design it that way . . . but . . . no worries. When you use REW or ETF, you are also running one channel's output back into that channel's input on your sound card, and REW and ETF measure the sound card via this loopback, and will make any necessary compensation for the cheap-ass sound card it's running through. ;)

I have an RME and an Emu 1820M, and I end up using my computer's onboard sound chip as well.

Originally Posted by xmostynx

hey dim- those graphs look nice! exp. in the low end...
i heard down the line that we actually hear is more representative (visually) if you put a 1/3 octave smoothing on that graph..

Nooooooo! That's that LAST thing you want to do! Doh!!!
Unless, of course, you are just trying to make it *look* better than it actually is! ;) But it really isn't the best choice to help you get the best idea as to how close you really are to ideal, or what what you may or may not want to do with regard to treating your room to get to the next level of improvement. In other words, there is some basis in truth to what you are saying about 1/3 octave smoothing, etc., but I'd say it is not so helpful for our purposes here.)

1/3 octave resolution will miss LOADS of stuff. It will also average out peaks and nulls in between those 1/3 octave bands, and, due to that averaging, you could even come up with what looks like a peak, when there is actually a huge null in a nearby frequency. Even measurements in 1 Hz increments are coarse enough that they can miss some very narrow band peaks or nulls.

Also, something the graphs you are using in the current form are not telling you is decay time.

Room modes cause peaks and nulls in the frequency response at various points in the room, but they also have effects in the time domain -- modal ringing.

If you look on the Room EQ Wizard home page, you will see a waterfall plot of a typical room (and that Swiss Alps look is very common for all small rooms). This shows both frequency response and decay time. Part of the purpose of bass traps is to manage excessive modal ringing (which can cause, for example, certain bass notes to ring longer than others in your room).

I recommend to use the sine wave sweep test method, then go up to the "View" pull down menu and select "low frequency waterfall", and click the "Generate Waterfall" button. That will give you the waterfall plots, so you can see the decay times as well.

But the real deal is that you have to be prepared to understand that most rooms will have some pretty wild frequency response curves, and if you can get them within 10 dB of flat across the entire frequency spectrum (and I don't mean with 1/3 octave smoothing), you are actually doing *very* well -- probably about as close to perfect as you will get in a small room.

[aapee]

Hi Scott!

Would you comment my charts with few words? These are measured from my control room with the finest resolution. My small CR is pictured earlier in this thread.

with respect,

aapee

[xmostynx]

Originally Posted by Scott@RealTraps

Nooooooo! That's that LAST thing you want to do! Doh!!!

hahaha booze on me man!! my bad!

[xmostynx]

hey guys- my new room's dimensions are like this...

12.5 length 10ft wide 7.5 high

its all in feet- so its 12 1/2 feet etc.

i'm on a mac so i can't use any of the cooler programs that would tell me the best place to put my monitors etc..anyone want to help?

should i put my monitors on the longer wall/shorter wall??

should i draw up a picture so you guys can see!!?!?!



i'm out to drink some Heinekens and watch the departed with the woman.

[SMC Productions]

Originally Posted by xmostynx

i'm out to drink some Heinekens and watch the departed with the woman.

Watched it last night...damn good flick!

[Narykcin]

what would be the disadvantage of not using a wood frame for a bass trap? Say instead of using wood frame you used no fram, or a styrofoam frame and covered it in fabric? Is a would frame used soley to provide support and asthetic?

[Sensater]

Originally Posted by xmostynx

hey guys- my new room's dimensions are like this...

12.5 length 10ft wide 7.5 high

its all in feet- so its 12 1/2 feet etc.

i'm on a mac so i can't use any of the cooler programs that would tell me the best place to put my monitors etc..anyone want to help?

should i put my monitors on the longer wall/shorter wall??

should i draw up a picture so you guys can see!!?!?!



i'm out to drink some Heinekens and watch the departed with the woman.

XMO-Pretty sure you would want the monitors to fire down the length of the room, so in other words, put the monitors against the short wall. Although since your room is just 2.5 ft off of being square, maybe it's not so important. Good luck with your new space...you'll be psyched to be done w/the combined bedroom/mixing room scenario.

Steve

[Glenn Kuras]

Originally Posted by Sensater

XMO-Pretty sure you would want the monitors to fire down the length of the room, so in other words, put the monitors against the short wall. Although since your room is just 2.5 ft off of being square, maybe it's not so important. Good luck with your new space...you'll be psyched to be done w/the combined bedroom/mixing room scenario.

Steve

Every inch helps so, YES fire down the longest wall.

Glenn

[xmostynx]

thanks steve

[Sensater]

Originally Posted by dim light

Hi!

Thanks.

The guys in the ceiling are absorbers - softis. Do you mean the other ones the bass traps?

When you say 2", 4" - can you please explain. I found a calculator for feets to m. But I'm not sure I understand 2", 4" and space them 2"

I'm hoping to save time - using the ones I already got.

I about 8 feets from the back wall so they should work. Sorry for all the questions - Hope you can clear things up - I'm probably going to start the build very soon so it would be helpful with some guidelines. To bad you don't live here - I have the coffee machine ready!

Dim,

2" means 2 inches, and there are 12 inches in one foot. According to http://www.manuelsweb.com/in_cm.htm, 2" = 5.1 cm. Hope that helps and good luck! I'm learning a lot from everyone's experience and questions here.

S

[xmostynx]

Originally Posted by myfipie

Every inch helps so, YES fire down the longest wall.

Glenn

Glenn- what about the program that was mentioned in SOS like 2 months ago on where to place the monitors? should i push them right up against the wall or pull them back some?

[Ethan Winer]

Originally Posted by xmostynx

where to place the monitors? should i push them right up against the wall or pull them back some?

See this:

http://www.realtraps.com/art_room-setup.htm

--Ethan

[xmostynx]

ethan your the man!

Originally Posted by Ethan Winer

See this:

http://www.realtraps.com/art_room-setup.htm

--Ethan

[xmostynx]

Originally Posted by dim light

You could analyse the room / bass respons with room eq wiz and see what work for you.

hey dim remember ( . ) ( . ) oh yea!

[Scott@RealTraps]

Originally Posted by aapee

Hi Scott!

Would you comment my charts with few words? These are measured from my control room with the finest resolution. My small CR is pictured earlier in this thread.

with respect,

aapee

Few words? Hehe . . . you're asking the wrong person if all you want is a few words. ;-) I bet it sounds pretty good in there, yeah? Looks like decay times are in pretty good shape, and overall your frequency response (at least in the range for which you show the full waterfall plot) looks pretty good.


Is there anything in particular you'd like me to comment on, or anything in particular you are looking to improve?

It's hard for me to tell exactly what's behind your listening position there, but it looks like maybe you are fairly close to the wall behind you? If that's the case, you'd probably make a noticeable improvement by putting another thick panel on the wall behind you at head height. That might get rid of that 600 Hz null (or at least improve it significantly). Also looks like you are getting a lot of comb filtering yet in the highs, a panel behind you would probably help that as well

One thing I might also comment on with regard to those NS-10s. While I know it's popular to mount them on their sides (e.g., on a meter bridge, you'd be better off standing yours vertically. The problem I see here is that you have the tweeters so close to the shelf they are on that you are most likely getting some screwy reflections (and therefore more comb filtering) off the part of the shelf that sticks out in front of the speakers. I can't imagine that is helping any. ;-) Also, the tweeters on all of your monitors should be at or very near ear height. I can't really see what is ear height for you in that picture, but if your other monitors have their tweeters at ear height, then the tweeters of your NS-10s should be that height as well. And, if standing your NS-10s vertically brings their tweeters above ear height, you can always get some Auralex MoPads or something similar and angle them down a bit -- but you really want to get those tweeters a bit further away from that bare shelf surface if you can.

If you want to improve that dip that you have around 175 Hz or so, you could help that by putting some more panels in the vertical (wall-wall) corners. It looks to me as though you don't have any panels in the vertical corners, correct? I would definitely recommend getting some treatment into those corners. Those are usually the *first* corners I would recommend treating.

I would imagine if you added a few thick panels in vertical corners and one on the wall behind you, you'd be able to smooth it out a fair bit further.

[Scott@RealTraps]

Originally Posted by dim light

YI was chocked how big difference it made to move the speakers to the meterbridge - I'm going to build these speaker stands - the brownish stuff is sand and the red guy is a weight. I'm building with MDF.

I haven't treated the ceiling yet - right now I have a rug on the console - that improved my graph - I guess the speaker placement will play a big roll in my acoustic game.

Yes . . . you will typically get a fair amount of comb filtering off the top of your desk, most particularly when you have your monitors on the meter bridge.

A couple of comments I could offer here as well with regard to the speaker stands you are proposing to build, and also the changes you are noticing with the different placement of your speakers.

For starters, from what I can see, you don't have any absorption at the first reflection points to the sides of the listening position -- correct? (To find the precise first reflection points on the sides and on the ceiling, use the mirror trick described in the article Ethan linked to above.) Also, I see some kind of diffusor-type thing on the wall to the right -- is that correct? (It also looks like you have only the one on the right side, and nothing on the left -- is that correct?)

I typically recommend *against* using diffusors at first reflection points, as it can mess with your imaging. You will get much more focused imaging if you use absorption at the first reflection points, and this will help you hear deeper into the mix. I also tend to recommend putting diffusors behind the listening position if the back wall is 10 feet or less behind your head.

So . . . I have a question here: When you had your speakers set up back behind the meter bridge a bit (rather than on the meter bridge), is it possible that this diffusor was exactly at the first reflection point, and then when you moved the speakers to the meter bridge, you moved the speakers forward enough so that the diffusor was no longer located right at the first reflection point? If that's the case, this might actually be the cause of the "improvement" you heard. And if I'm correct that you only have the one diffusor on the right side and nothing on the left, I would bet that your image became a little more balanced because you weren't dealing with the asymmetrical acoustics situation caused by the diffusor.

I'd recommend just making a few rigid glass/mineral fiber panels (the ones at first reflections only need be an inch or two thick) to put at those first reflection points.

As to the speaker stands -- one potential problem I can foresee with this design is that you could get some unwanted resonance putting speakers on a wooden shelf that extends out that far from the post on which it is mounted -- especially if you don't have some additional angled brackets to support the platform (but even then you could have a resonance problem with wooden stands). If you have low frequency resonances in your speaker stands, you could find that this very slight movement can smear your imaging, because the entire speaker box is moving (for example when the kick drum hits, etc.), perhaps imperceptibly, but enough that the entire tweeter is moving the same distance as the actual dome moves for some of the higher frequencies.

I would recommend that you look at treating your first reflection points with absorption first, and then consider building some speaker stands. If you can keep your speakers back behind the meter bridge a bit, it might give you some better options for building good, solid speaker stands.

The cheapest, easiest think I can think of for building good, heavy duty speaker stands is to stack up a bunch of cinder blocks (or breeze blocks, or whatever name you know them by). Concrete has a very low resonant frequency -- down into the single digits -- below the range of human hearing (and indeed lower frequency than your speakers will be putting out). So . . . putting your speakers on a heavy, dense material like cinder blocks can help tighten up the low frequency response and also help stabilise your imaging. Marble, granite, etc. are other materials that would be good for this. Also, if you are having any trouble with stability with your stack of cinder blocks (or just want to make sure that nobody will accidentally knock them over, you can always glue them together with something like construction adhesive . . . or you can use Green Glue, which will further help damp any unwanted resonance (though in this case, with smaller monitors, the Green Glue might be overkill).

[Scott@RealTraps]

Originally Posted by Narykcin

what would be the disadvantage of not using a wood frame for a bass trap? Say instead of using wood frame you used no fram, or a styrofoam frame and covered it in fabric? Is a would frame used soley to provide support and asthetic?

Yes -- the frame is pretty much solely for the purposes of providing support for the rigid fiberglass/mineral fiber panels, which can sag over time without support, and also to make it easier to hang the panels.

Otherwise, there is NO disadvantage doing them without a wood frame, and indeed there is an advantage that you expose that much more porous absorption material to the room.

[Glenn Kuras]

Dim,

Get that room done so we can hear some new songs from Country Pollution!!!

Glenn

[fcorl]

Finally finished the first couple wall reflectors/absorbers.... I haven’t mounted them yet, (need to build about 8 more). Then I will start on the corner traps. Here are some photos. I used Cojo's method of cutting out the holes in the frame, but covered the entire frame in burlap, then covered the insulation in a second color of burlap. The round molding finishes them off nicely, although I suck at cutting the coped angles of the molding. These are 3" thick insulation in 28"X48", 1"X4" frames. I will take some shots of the "upholstering work" and add to it next time around....


Frank

[fcorl]

FInished traps.....

[Cojo]

Originally Posted by fcorl

FInished traps.....

Very nice! Like the finish you got to them!

[xmostynx]

oh yea dim... (.) (.) nice blocks buddy

[Cojo]

Originally Posted by dim light

fcorl - nice work man!

I am known as the straight saw man in my country - thank good there is a rear and front on my Cinder Block Stands (trademark) -

I destroyed two saws and my arm got very tired!

Here they are - I will paint them and make them sexy when the cinder is dry.

HARDCORE!!!

[Glenn Kuras]

Originally Posted by dim light

Thanks man - I love my saw lines - I made them very gay - not straight!

almost forgot

( .)(. )

Tell me you where sobor when you did this.

[A27Hull]

Hello all,

I really enjoy this thread .

Here's my dilema:

A guy in town has a [garage] he wants to convert into a studio. It has an existing structure of about 24'x24' with several modifcations already made.

-Pat's Floorplan shows the structure as is.

-Pat's proposed floorplan shows what I'd like to do with it, namely, reinsulation the stud gaps with rockwool, and modify the extisting inner walls to be "soft", i.e., 4" thick frame with 4" rockwool/wire mesh/fabric construction.

-Pat's ceiling is a diagram of the existing ceiling space, which I would also like to modify it in a similar fashion as the internal wall structure. My thinking is that the pyramid attic space could serve as a band variable 'bass trap' of sorts for the entire structure.

-Pat's wall construction is a diagram of the basic wall/ceiling construction.

Other than cost, what fatal errors have I overlooked. I know that reintroducing controlled 'hard' surfaces will help with the building being anechoic in nature, and I am considering addtional DIY absorbers within the particular rooms.

Any comments would be much appreciated!