> My simple question is how to place the microphone? I am using for now the RS SPL meter mic. <

The RS meter has an omnidirectional microphone, so in theory it shouldn't matter which way it faces. I've used it with the capsule facing forward toward the speakers, and other times I've pointed it straight up. I don't recall ever pointing it toward the floor, but that should work okay too.

> How about you Ethan what's up with the new name? <

Say what? What new name?

I use ETF and R+D. Until recently there were a few things ETF did better than R+D, though mostly R+D does much more and does it better. Doug Plumb is working hard on R+D, making new versions all the time. He and I are working closely on this, and I've done a fair amount of testing for him both in my home studio and my living room home theater.

--Ethan

Geoff,

> At that point, my measurement file just looks like 32 nicely coloured waves on a graph and that's about as far as I get. <

Understand that R+D does a lot of things, and all of them may not be useful to you. For example, I have never used the feature that lets you average dozens of readings as an aid to setting a parametric equalizer.

I use R+D the same way I use ETF: I run a single test, then look at the LF response, LF ringing with the waterfall display, and sometimes I look at reverb time and individual reflections. But mostly I use the raw response and waterfall graphs. And only one at a time, or maybe a few at a time to assess whatever I'm experimenting with, like speaker or bass trap placement.

Does this help?

--Ethan

if you are having trouble using etf, look at the "demo room" on the etf site, its quite useful

narco

Interesting, because I it found not too useful for a studio, good for a home listening environment however, or maybe I'm just too stupid to know any better.

I've got a question about how the bass traps mount in corners. In every picture I see, the traps look a little out of place when they're mounted in the corner, be it wall to wall corner, or wall to ceiling corner. The bass traps being built are made out of a frame of wood and all the edges are square. That means when you mount it against the wall you're left with a sort of unsightly look under the frame. Would it worsen the bass absorption if you made the bass traps go tight against the wall? Much the same look you get if you stack a bunch of triangles of 703 in the corner. No right angles coming off the wall at a 45.

Am I explaining myself well enough?

you can make your traps that way it just takes more work for probably not a lot of acoustic benefit. or harm for that matter.

From what ethan explains, the unit going across the corner allowimg air flow behind it and it then works better than a triange that fills the whole corner. leaving a gap at the edge helps even more. Of coarse mass helps, so it may be better to have a thick triangular one that goes in tighter. I am not the expert, I'd like to hear Ethan's response to this but he never chimed back in.

Hi Ethan,

Sorry it's taken so long to get back to you on this. In answer to your question, I'm still none the wiser when it comes to how to read the graph from even a single measurement.

All I know is that if I take a very simple tone and run it up an octave in a chromatic scale there are several notes where the note realy booms in the room. It's almost as though my acoustic treatment is having little to no effect.

I was going to try and post a screenshot from RPlusD there, but to be honest I don't think it would help as I don't understand what I'm doing with it, let alone how to interpret the results and what I should be looking for to improve.

Could it be that my bass traps at the back of the room and high in the ceiling are really having no effect? This could exlain what SonicClang was talking about when he asked if it would be better to have them flush against the wall, unless they were talking about the mid-high frequency absorbers round the walls..

Still confused I'm afraid...

Geoff

Geoff,

> I'm still none the wiser when it comes to how to read the graph from even a single measurement. <

Can you at least get a graph at all? If so, post it here and I'll show you what to look for.

> It's almost as though my acoustic treatment is having little to no effect. <

I don't see how that's possible. It may be that you simply need more panels.

> I was going to try and post a screenshot from RPlusD there, but to be honest I don't think it would help as I don't understand what I'm doing with it <

If I could come over and help you in person I would gladly do so. In lieu of that I'm still happy to help with step by step instructions or whatever. Best is if you ask very specific "bite sized" questions. Then I can give very specific answers.

--Ethan

I'd be concerned about securing overhead traps to plaster lath. Might be fine, but if one fell on your
head it would hurt!
Sounds to me like you need more broudband "bass" corner traps. Do you have any more corners you can use?
If not, increase the thickness of what you have. The more volume, mass, and surface area you have the better.

Hi Ethan,

Thanks again for your on-going advice!!

(Edit: School Boy error with the graphics there on the first post, should be ok now).

Here are four screenshots. As you can see, result 1 and 2 are very different, or at least they seem that way to me. I don't know if I'm using the settings in the software correctly, but I'm opening the measurement file saved from the tests I performed, then I'm going to View | Frequency/Response | Bode/FFT. A tiny bump of all the readings shows in the bottom right hand corner of the graph.



I click anywhere on the graph and then get screenshots 1 and 2.





Then I go to View | Waterfall and it asks if I want to recalculate so I say yes and then this is what comes up.





How do these look to the trained eye?

Cheers

Geoff

For the waterfall graphs, I think you want to go from 20 to 800 hz or so.

Hi Nate,

Here's another attempt, this time selecting the frequencies you said (or as close as) by dragging a selection over the bode response (see screenshot)



Then calculating the waterfall. I've included 2 waterfalls as they're all quite different, but then that's because the mic was placed in a slightly different position in the room each time.





Does this look better?

Cheers

Geoff

Geoff,

You're 99 percent of the way there! Do this:

Under Gate Time click the lower button to switch from Small Gate Times to Large Gate Times. Then adjust the slider to be around 200 milliseconds. There's a "detent" at 227 Hz, and that's what I generally use. Then when you click inside the graph it will show a lower frequency range with more / better detail. And when you then switch to the waterfall display, that too will use the longer gate time and give more detail.

Then post those two graphs for response and ringing.

--Ethan

Hi Ethan,

How do these look?

Bode Response:


Waterfall:


Cheers

Geoff

Geoff,

> How do these look? <

Like a real measurement of a real room.

Okay, so now where were we?

--Ethan

Hehe! This RPlusD software is "fully operational"!

I'm guessing the stuff happening closer to the front of the graph is the ringing in the room and what needs to be addressed. The question is, how? Do I need to start constructing more panels and block more wall/wall/ceiling corners and more wall/ceiling edges?

I have to be realistic here though as I've not really got much budget left for anything on the scale of what I've built already.

Cheers

Geoff

Geoff,

> I'm guessing the stuff happening closer to the front of the graph is the ringing in the room and what needs to be addressed. The question is, how? >

Now you know why we always say you can never have too much bass trapping.

> Do I need to start constructing more panels and block more wall/wall/ceiling corners and more wall/ceiling edges? <

Yes, yes, and yes again.

--Ethan

Hey Ethan,

I won a watch today. I managed to blag four PRG ProCorners from a friend of a friend. He has a studio and has just moved premises so had this acoustic treatment from an old editing suite sitting at the back of a cupboard. He very kindly donated them to my on-going studio project.

So I got them back to my studio and my first thought was to put them in the top edges of my room (not shown in pic as I don't have any mounting glue!)



However, I remembered what you said about corners and placed them behind the speakers in the forward part of my room.





Without doing any measurements yet with RPlusD, it seems the ringing bass notes are significantly lessened and the bass seems tighter across the whole octave. I'll need to test more and will hopefully set up a reading to produce a waterfall later today, but I'm sure this is the best place for my newly acquired foam corner traps.

I'm sure by treating the top edges and remaining corners it would be better all round, but in the meantime this seems to have solved my audible problems.

Any thoughts or suggestions as ever, greatly appreciated.

Kind regards

Geoff

> Any thoughts or suggestions <

I still see a lot of bare corners.

Ethan,

Your photo of your room on the "Build A Better Bass Trap Site" appears not to have the corners covered either, what's up with that?

Mark,

> Your photo of your room on the "Build A Better Bass Trap Site" appears not to have the corners covered either, what's up with that? <

There are traps in the corners. But with that type of trap, two are placed in each corner flat on the walls. The front left corner has a window so that's not treated. All other corners are, except some of the ceiling corners. This is a very large room, so it doesn't need the same kind of "extreme" trapping that smaller rooms need. I have also added 13 more traps since those photos were taken.

--Ethan

Interesting, Ethan what do you consider a "very large room" ? My studio is 5,800 cubic feet, 3,100 of that is with a slanted ceiling from 11.5' to 9.75'. The remainding volume is 2,700 cubic feet with a 7'-10" ceiling. Its all one volume however.

Right now I am installing 2" of 705FRK on top of 2" of 705 plain in all corners in the high area (3,100). I was going to let all these have the foil facing towards the room. I haven't addressed first reflection points yet. I do have all hard wood flooring, so I know there will be a lot of ceiling treatment. Thought I would see what the corners did first.

What do think about all of that?

Mark,

> what do you consider a "very large room" ? My studio is 5,800 cubic feet <

Yes, that's very large for a home studio, and is almost exactly the same size as mine.

> Right now I am installing 2" of 705FRK on top of 2" of 705 plain in all corners in the high area (3,100). I was going to let all these have the foil facing towards the room. <

That all sounds great. Because you have so many large areas of wall, once the corner trapping is done you could consider wood panel traps on those walls.

--Ethan

Thanks Ethan!!!

I will get this done in a week or so and see what the graphs look like, but more so what my ears say.

I just got on the forum, and found this post... Holly smokes dude... these are amazing pics, suggestions instructions and everything! I'm waiting for my fiber and fabric and getting on this quest hopefully this weekend, and this post is what I'm following.

I love the cutouts, but I don't know if I will have the patience to do them on 8 2'x4' bass traps and 22 more various other traps and absorbers... that's a lot of holes to cut

Bummer that EFT demo/software is windows only, they seem to indicate it may or may not work on a Mac with emulation software. I guess I have nothing to lose to try it out, either that or since I have an Intel-based Mac I can certainly install bootcamp and dual boot the puppy. I think I would greatly benefit from taking a reading before I do anything so I know precicely what ails me, and much like you, take my finger out of the air and look at my screen.

R

Take a look at this

http://www.hometheatershack.com/roomeq/

It's a Java based application. Should run fine on the Mac. It's also free.

It's not as refined as ETF but it will get you started.

Bryan

Hi Robert,

Thankyou, I'm glad the post will help you. The drilling out the sides bit was the most time consuming and I think someone else suggested a milling machine rather than a jigsaw if you have access to one. The other thing is the holes you make with a jigsaw will not be as clean as those with a milling machine. You start off with best intentions, but once you're onto your third panel and you have another 40 or so to go, you start to take the quicker route to get the job finished before you reach retirement!! ;D

Cheers
Geoff

Geoff,

I have a plunging router which will do the same thing, I just need to get the right bit. Good idea thanks!

R

ps. too young for it to take that long

In fact is there a reason I can't make the wood as part of the decor of the panel? Like if I buy some oak and stain it, is there this much of a risk for reflection and audio anomalies?

R