My Room (need a little help)

This is my first post here. Great forum! Not so coincidentally, the attached image is my first attempt at sketchup. It's a finished attic space that I use for tracking, mixing and rehearsal (3 piece and a tight fit). Drums live in the middle of the back wall. So, it's an odd room. Back wall (LH side) is 13', larger side wall (front) is 12' and the little cove is 5'11" wide by 3'4" deep (leaving the shorter side wall at 8'8"). The cove is where my desk and monitors are. As the image shows, there's an angled part where the back wall meets the ceiling (ceiling's 7'4"). It's kind of hard to tell, but the entry door is the closed one with a window in it on the right wall. The 2 doors in that corner are both closets and the door in front of the image goes to unfinished attic space. A couple of questions: -How would I go about using a calculator for a room like this? That being said, I've never used a room calc even for a regular rectangular room. -I've got three 4" rockwool panels that I was planning to fit into the cove for some bass trapping. Should I put something reflective on the fronts of these so they don't absorb too much of the higher frequencies along with the bass? -I was given some raw Johns Manville panels. There's a 2.5", 2", 1.5" and 1". As far as I can tell, the 2" and 1" are 6lb density and the others are 3lb. Where would be the best place to put these for now? Eventually, I figure I'll need at least 1 or 2 clouds over the mix position and drums. And I'll need something on the wall behind mix position as well as other walls and corners. Since I don't have the material to get all that done right now, where would the ones I DO have be best served? I hope all of this isn't too confusing. It seems kinda garbled, but I can't really come up with a better way to describe my situation. Thanks very much. -AE

phantom power wrote:

-How would I go about using a calculator for a room like this?

You don't use a calculator for a room like that. And mode calculators are meant for designing new spaces, not to know how to treat an existing room.

Should I put something reflective on the fronts of these so they don't absorb too much of the higher frequencies along with the bass?

It depends where the panels are placed. If they're in corners, and out of the way of direct sound from the speakers, and not at reflection points, then a reflective facing is a good idea. As for density, either of those is fine. What matters much more is the panel thickness. --Ethan

Thanks for the reply Ethan. It cleared some things up for me. I forgot to mention that all of the panels are 2'x4'. I'm going to start by putting two of the 4" thick rockwool panels in the the corners of the cove area. The desk and speakers will sit just a little out in front of them. So what's good to put on the face of these? Also, where would the last of my 4" panels be best served (since the next thickest panel I have is 2.5")? Wall behind listening position, cloud above listening position, wall/ceiling corner in the cove, drum cloud, etc.? I was also wondering about the angled part of the back wall where it meets the ceiling. It's kind of aimed right into the middle of the room as well as right at my listening position. How should I approach this? Thanks again. -AE

Here's another quick reference. -AE

phantom power wrote:

where would the last of my 4" panels be best served

Corners, and on the wall behind you, including the wall-ceiling corner behind you. --Ethan

Ethan Winer wrote:

And mode calculators are meant for designing new spaces, not to know how to treat an existing room.

Sorry, that's not true at all. Cheers, Jean

Big8, Can you elaborate? Thanks -AE

Sure, first, let me say that room calculators are meant for rectangular rooms. yours is not (neither is mine) but the Height axial modes and the width (the longest dimension in the horizontal plane, in your case) will show. The length ones will be a little tricky, though, since you have two different lengths, one of which your thinking of using for monitoring>> needs complicated modelling which I don't know how to do. Assuming you had a rectangular existing room of sufficient volume, you could use a good mode calculators that would show you the axial, tangential and oblique modes like this one to: 1) modify one of the dimensions of your room, if space permits, that will get you to a preferred room ratio, for instance, the length. 2) do sine sweep tests in your untreated room, so that you can identify from the frequency response which of the peaks/dips can be attributable to room modes (results from mode calculator), and which may be due to other things (first reflections, resonance...), and then 3) decide if the effect of the modes on the response is acceptable for your needs (in which case you would only need to deal with first reflection and reverberation time), if not, 4) is broadband treatment suitable to deal with it (peaks & dips of a few dBs), or would you need narrow band tuned treatment. 5) if broadband can deal with it, it be good to know which dimension (L,W,H) is responsible for the modes you want to treat, so that you can emphasize treatment in the concerned corners (eg:if length, you could emphasize the broadband trapping on the horizontal wall to ceiling corners across the width, besides treating the 4 vertical wall to wall corners) ************ if you first treat/add treatment to your room, and later test it out, you may find out that some/most of the treatment was redundant and you may need to take some of it down to make way for tuned treatment. It may also be that your room was already good, to start with, that you didn't need most of the treatment you added. :lol: Best to have an idea of where you going before going there. Cheers, Jean

Cool! Thanks Big8. I'm sure that the room is in need of some help. I'm just not sure how much or where. I monitor with some old AR bookshelf speakers and an old Mitsubishi hifi amp. The setup has always sounded pretty good in other rooms. However, in this room, I've definately got some muddy bass build-up as well as some flutter echo (at least that's what I think it is). That, and it's pretty fatiguing (sp?) to rehearse up there after awhile, even when keeping it at a moderate level. Like I said before, I've got three 4" thick 2'x4' rockwool panels made and 4 fiberglass panels (un-covered as of yet) in 4 different thicknesses (1", 1.5", 2", and 2.5"). It seems like the only real way to figure this out is by putting them up and listening. However, a little forethought never killed anyone either. So, that's where I'm at. Any initial ideas? Thanks again. -AE

phantom power wrote:

Any initial ideas?

Here's one... http://www.johnlsayers.com/phpBB2/viewtopic.php?t=7572

BIG8 wrote:

Assuming you had a rectangular existing room of sufficient volume, you could use a good mode calculators that would show you the axial, tangential and oblique modes

Jean, mode calculators are not a substitute for measuring a room! When the goal is to treat a room you measure it. Anything else is just guessing. I assume you missed that thread a few years ago at Recording.org where I showed some measured versus predicted mode frequencies disagreeing by 20 percent? Hence my correct advice that mode calculators are meant for designing new rooms. Even measuring isn't needed for rooms like the one in this thread. In this case the goal is to treat as much corner surface as possible, and the wall behind the mix position, and the side wall and ceiling reflection points. Once that's done the room will be about as good as it's going to get. The main reason to measure a room like this is simply to confirm the improvement that your ears tell you anyway. --Ethan

Email notifications seems intermittent? didn't see this thread was replied to :roll:

Ethan Winer wrote:

Jean, mode calculators are not a substitute for measuring a room!

Dear Ethan, who claimed the opposite? :D

When the goal is to treat a room you measure it. Anything else is just guessing

. Room mode calculation is not guessing, it is science, physics. Without room mode calculation, you have to do an infinite number of measurements to determine which of the trouble modes is what type of mode (axial, tangential, oblique), to which dimensions (axis) it is due, so as to be able to focus appropriate treatment in proper locations.

I assume you missed that thread a few years ago at Recording.org where I showed some measured versus predicted mode frequencies disagreeing by 20 percent?

Yes, I missed that thread. 20 percent of what? of the predicted mode frequencies? Did you consider tangential and oblique modes in the prediction, or just axial modes? :roll:

Hence my correct advice that mode calculators are meant for designing new rooms.

Your original statement with the contested incorrect part in bold was:

Ethan Winer wrote:

And mode calculators are meant for designing new spaces, not to know how to treat an existing room.

Even measuring isn't needed for rooms like the one in this thread. In this case the goal is to treat as much corner surface as possible, and the wall behind the mix position, and the side wall and ceiling reflection points. Once that's done the room will be about as good as it's going to get. The main reason to measure a room like this is simply to confirm the improvement that your ears tell you anyway.

Hearing an improvement in a room doesn't say much about how suitable the room has become. If the room is to be used for leisure listening, it doesn't matter that much. If he wants to mix in there (as is the case), he should measure the room at least after applying treatment, if anything, to know the trouble frequencies (if any). Cheers, Jean

Jean, I'm not sure what your point is in this thread, other than maybe to overstate the importance of non-axial modes? :roll:

Room mode calculation is not guessing, it is science, physics.

Only if all of the room boundaries are infinitely massive and stiff! Which is never the case unless one builds a control room in an in-ground swimming pool or bomb shelter etc.

Without room mode calculation, you have to do an infinite number of measurements ... to focus appropriate treatment in proper locations

Yes, you have to measure, because predictions are often wrong. A room like the one described here should never have "targeted" absorption anyway. Broadband, baby, broadband all the way. 8)

20 percent of what? of the predicted mode frequencies?

Yes, that's exactly what I said. So now we're back to my original correct statement that a mode calculator is useful for designing a new room, but not for knowing how to treat an existing room like this. :) Look here, but try to pay attention to the facts, and ignore all the off-topic blather and insults: http://www.recording.org/modules.php?na ... ic&t=26568 --Ethan

Ethan Winer wrote:

Yes, you have to measure, because predictions are often wrong. A room like the one described here should never have "targeted" absorption anyway. Broadband, baby, broadband all the way. 8)

OK ... but looks like this corner stuff is not really broadband... Peaks band is more correct to say ... And it can sound good or bad depend on the room. I'm not sure jet if it's true that towing stuff in all the corners ( more corners as is possible) will improve any room. Also can you please explain why leaving air on top and bottom and behind the corner panels it's better than floor to ceiling? I guess you explained this somewhere but I don't remember well and where.... thank you in advance.

timogiodeson wrote:

looks like this corner stuff is not really broadband.

Yes, the material absorbs broadband. The seeming peak is due simply to placement because bass tends to collect in corners.

I'm not sure jet if it's true that towing stuff in all the corners ( more corners as is possible) will improve any room.

Heh, I have yet to see a room that is not improved that way.

Also can you please explain why leaving air on top and bottom and behind the corner panels it's better than floor to ceiling?

It's not better than filling totally, but it uses half as much material so it costs less. --Ethan

Ethan Winer wrote:

Yes, the material absorbs broadband. The seeming peak is due simply to placement because bass tends to collect in corners. Heh, I have yet to see a room that is not improved that way. It's not better than filling totally, but it uses half as much material so it costs less. --Ethan

yes correct the material absorb broadband, but when you put it in the corners it become peaky to about 100hz and depend on the room.. you end up with NEW nulls or peaks at different frequencies ..and it doesn't sound always better in any room correct?

timogiodeson wrote:

you end up with NEW nulls or peaks at different frequencies

That's news to me.

and it doesn't sound always better in any room correct?

Again, that has not been my experience. Since you're obviously into this stuff and want to learn more, I suggest you use ETF or REW or Fuzzmeasure and try some experiments on your own. --Ethan

Ethan Winer wrote:

timogiodeson wrote:

you end up with NEW nulls or peaks at different frequencies

That's news to me.

and it doesn't sound always better in any room correct?

Again, that has not been my experience. Since you're obviously into this stuff and want to learn more, I suggest you use ETF or REW or Fuzzmeasure and try some experiments on your own. --Ethan

yea that's what I'm doing now already... yes I'm trying to learn more some of my measurements are page 4 to page 8... my threads it's a little overwhelming but maybe interesting :oops:

Didn't have enough going on in your other thread timo so decided to hijack this one for a spell?

Ethan Winer wrote:

Room mode calculation is not guessing, it is science, physics.

Only if all of the room boundaries are infinitely massive and stiff! Which is never the case unless one builds a control room in an in-ground swimming pool or bomb shelter etc.

Rooms made from concrete walls and ceiling, or of 2 sheets of 12mm gypsum boards is all that is needed, you don’t need bomb shelters. :D

Yes, that's exactly what I said. So now we're back to my original correct statement that a mode calculator is useful for designing a new room, but not for knowing how to treat an existing room like this. :)

No No No, you won't get away with this :twisted:, the bold red part was not part of your original incorrect statement!! :twisted: :lol:

Look here, but try to pay attention to the facts, and ignore all the off-topic blather and insults: http://www.recording.org/modules.php?na ... ic&t=26568

I am very grateful to you for this link (I really mean this), I've learned a lot from it :D Nice long read. The ‘facts’ do back my thoughts about mode calculators, their utility etc...

Jean, I'm not sure what your point is in this thread, other than maybe to overstate the importance of non-axial modes? :roll:

Funny you should say that :lol:, from that long 13 pages thread, you were the odd one out understating the importance of non-axial modes and mode calculators, and they were a bunch of real qualified acousticians in there :D About that test room of yours and the tests which show modes 20% off.: Very interesting indeed :D, but……….the tests are just that: tests, and they are far too inconclusive to prove or demonstrate anything of the nature of what you made out from it. :D Cheers, Jean

Jean, you're still a beginner student with this stuff so I'm not going to debate the science of acoustics with you further. At some point you'll understand that axial modes matter the most, and why they matter the most, and maybe then we can continue the discussion. Hopefully the OP got the information he needs, which is to ignore mode calculators entirely and just treat his room as I described. --Ethan

Ethan Winer wrote:

Jean, you're still a beginner student with this stuff

Yes, I am, a proud beginner student of Acoustics :D And you? Please tell :lol: .

so I'm not going to debate the science of acoustics with you further.

mmmm….sounds pretentious! :lol: Ethan, I admire your mastery at the science of debating and twisting. You could even debate topics on genetic engineering with the best of ‘em :lol:

At some point you'll understand that axial modes matter the most, and why they matter the most, and maybe then we can continue the discussion.

Axial modes do have more energy than non-axial modes, how that equates they “matter the most” baffles me :roll: . Anyway, the best out there couldn’t convince you of the contrary, so with my beginner student’s level, I humbly step down from trying :D

Hopefully the OP got the information he needs, which is to ………… just treat his room as I described.

Which is my original point that all rooms need broadband in most corners and all first reflection points. :shot: Cheers, Jean

This is too much fun to resist. :twisted:

BIG8 wrote:

Axial modes do have more energy than non-axial modes, how that equates they “matter the most” baffles me

Exactly. :wink:

And you?

I'd list all of my articles published in pro magazines but it would fill the page. Start here: http://www.realtraps.com/articles.htm More here: http://www.ethanwiner.com/articles.html Of course, having dozens of published articles doesn't prove anything in and of itself. But I'll be glad to read yours if you care to link to them.

Which is my original point that all rooms need broadband in most corners and all first reflection points.

Actually that was my point. You came in guns a-blazin' trying to be a big man. The lamest thing anyone can post in a forum is to call someone else wrong, but offer no further explanation, as you did here:

Sorry, that's not true at all.

But since you like to argue, let's do that. I said a mode calculator will not help the guy assess his odd shaped room. You said I was wrong, and then said this proving my point:

room calculators are meant for rectangular rooms. yours is not

So that's Strike One. Then I came back with this:

In this case the goal is to treat as much corner surface as possible, and the wall behind the mix position, and the side wall and ceiling reflection points.

And now you're claiming that was your original point? You're kidding, right? Strike Two. Jean, I know it's a popular forum sport for children (you) to try to look smart by showing up the big guy (me). But in this case you just look like a fool. But just to be sure I'm not misunderstanding your, uh, "viewpoint" - you acknowledge that axial modes have "more energy" than non-axials but then can't understand why axials matter more? Amazing. More amazing is that axials versus non-axials has nothing to do with this thread! You brought that up solely to berate me because my ModeCalc program intentionally shows axials only. Strike Three. Had enough yet or do you need even more? :? --Ethan

I thought I was done, but this is too much fun to stop now. :oops:

BIG8 wrote:

Ethan, I admire your mastery at the science of debating and twisting.

This is what people say when they have nothing of substance to counter with. I've seen others use this tactic - ignore every point that's made, and instead change the subject to debating skills. Can't actually fault what I say? Then claim I twist words while offering no evidence of twisting. How pathetic. And transparent. If I'm a good debater (some might call me a master debater :)) - it's because I have the subject matter down cold, and because I'm skilled in explaining complex technical subjects clearly enough for non-technical types to understand. Versus you who has only insults and a bad attitude. You showed up here only a few months ago and have a grand total of 26 posts. And you come out swinging at the regulars? Sheesh. :roll: Earth to Jean - the "Acoustics War" is history. Get over it. It's no longer cool to insult Ethan Winer. Nobody gives a crap if Ethan Winer's ModeCalc program intentionally omits non-axial modes. Everyone in every single web forum is totally sick of the bickering, and even more sick of jerks like you who want it to continue. My apologies to the OP for having to wade through Jean's bullshit. --Ethan

Being a newbie at ANYTHING sucks. Given the voodoo/ high-level math nature of acoustics makes it even worse. This thread stopped being about my question a long time ago and I realize now that it's kinda my fault. It seems that I've posted one of those newbie questions that can be a little annoying. On the TapeOp messagebaoard, it would be something like, "which $100 mic sounds like a U87?". Anyway, I went through and read a lot of stuff on this forum before I posted. Some of it was just too hard for me to follow. Normally, if I'm this new to something, I'll just keep on reading up until some of the slang starts to make sense and eventually I know a little about it. THEN, I'll join in the conversation. Unfortunately, I don't have that luxury in this case. I don't want to have to get that deep yet. Too many other things on my plate. Really I just wanted to know where the stuff I DO have is best suited in my room; just as a starting point. I'm on a slim-to-none budget and my house is a rental. So, I kinda need to get it close to right without a hundred holes in the wall from moving things around too much. I know that I can't make my tiny little odd-shaped room sound like a 'real studio', but I could sure use some help with what I've got. Neighbors aren't much of an issue. I want to track drums, vocals and some amps. Probably DI bass. None of this is really loud either. I'm not real big on adding much reverb after the fact, so I'd rather not have a completely dead room. I'd like to mix in there as well. Are these goals attainable in my room? Thanks for the help so far. -AE Thanks for the help so far