thoughts on my room setup.

[deejfro]

I'd like to get some thoughts from the others in the community.

room is 11x11x9. as you can see I have a large null at the 70hz range and a huge peak at about 120.

I have GIK 244s floor to ceiling in the front corners, a 4x4 cloud of GIK 244's , Gik 244s on Sides, GIk tri traps in the rear corners. And one centered on the back wall.

My monitors (bm5a) are less than halfway the distance from floor to Ceiling.(not sure the exact measurement, but the top of the cabinet is right about halfway. And are as close to the front wall as I can get, the heat sinks are nearly touching the wall.

I have wood floors. I also notice a bit of comb filtering in the upper mids too. I suspect from the floors and not enough trapping along my 2nd reflection points.

I tried bringing my monitors further into the room and the peak remains. (same with the null)

is the peak just due to the size of my room? And the only solution is to put more bass traps??

[ciro]

There´s nothing wrong with your 70hz - i´d worry about the 120peak (height related) ,even worst/narrow in the R side (how´s the symetry cloud- L/R speakers?)

My room has a similar size, I had troubles years ago with a serious peak in the 130 region, I solved it:

lowering speakers placement (woofer center now at 34% of height instead 43% I had before- it helped a lot)
Adding a very thick front wall/ceiling corner trap (I also have a 6" cloud" over mix position - beside this trap).

Ciro

[bpape]

Why are the monitors so close to the front wall? Can you pull them forward a bit? While it doesn't appear that the peak is boundary related, it will certainly help smoothness and imaging to give them some room to breathe.

The first thing I would do is remeasure with your mic back say 6-8" from where your ears are right now and prove whether or not it's positional.

Bryan

[DanDan]

Scary dimensions. Put them into a Mode Calculator and you will see. www.bobgolds.com
Lots of stuff collaborating to cause the 120 ish bump.
Seems like you have done your best with trapping. So position tweaks are your next best friend. I presume you arrived close to the wall because that's where your bass loss is least. I differ from Bryan, with respect, on this one. I often end up with such a position, particularly in square difficult rooms.
So up for grabs are width, height, listen position. Speakers may be turned sideways or upside down to the get the woofer to a better place. Adjustable stands are great, with Mopads etc. to angle the tweeter as necessary.
Keep tweaking and measuring. Turn up the Bass and/or down the tweeter.
Try to get a warm slope like in Understanding RTA at studiotips - tips on studio design, acoustics, and wiring
Thomas Barefoot's Wall Bounce Calculator 2 D can be very informative, particularly regarding width, listening position, angle. Don't forget the ceiling and floor bounce too...
I notice a reflection in that Impulse Response. What is it? Maybe a work surface, mixing desk?
Edit, if you wish, save that measurement as Version 2 and send it to me, so that mystic DD can see into it.......

DD

[deejfro]

Thanks for the input, I'm going to upload some pics of the room so its easier to see what I'm dealing with...

I did end up mashing the speakers up to the front wall cause the bass roll off wasn't as bad as if I was out in the room more. there is a window in front of me, but I hung a an old 4x4 panel of no name foam, same with the 2nd reflection on the right(I know not ideal, but i have proper panels coming in soon.

I'll be sure to check out those links too.

on my speakers I have them set flat with the treble at +1.
I also uploaded the fuzzmeasure session. its the old measurements, same as the pics I attached earlier.

Thanks again fellas!

[deejfro]

ahhh files too big... lets try that again..

[ciro]

Without separated stands for the speakers you are very limited ; response changes (sometimes a lot) moving even 2" or 3" (any dimension) - at least in a room that size.

Ciro

[deejfro]

Yeah im not to happy with my current desk. I was thinking of getting stands for the speakers. and taking the shelf off the desk.

[DanDan]

+1 speaker stands, adjustable height. There is a reflection in the measurement, 1.5mS later than the direct sound from the speaker. Probably the desk, and probably causing some midrange cancellation.
Can you lose the desk altogether, looks nice, sell it? I have a kids desk here. A small surface just big enough for computer keyboard and trackball. I intend shortening two legs to cause and angle to prevent the small remaining bounce.
All bets are off in such a small room. Close to the wall/window is valid IMHO. However, what is that in the window? If it's absorption, hmmm. A solid panel there would give some bass reinforcement. Windows absorb.
The speakers look small, probably the main reason for not much action below 100. You will probably get more bass with less bumps if you are lucky by going wider. This may make your imaging very wide but people have worked successfully in 90 degree studios. I would give bass the priority.
Try slowly sweeping a sine generator around that 120. Things will shake when you hit resonance exactly. Find the loudest spots. That's where the bass traps should be, if not there already. Conversely you will now know where the hotspots and nulls are. Try to find a listening position that avoids them. Keep an open mind it could be anywhere, particularly if you are not tied to that desk.
DD

[deejfro]

Thanks Dan for your input,

Yes in the window I have cheap foam wrapped in black fabric. I'm the last building on my street so out my window is a gas station then a very busy road. I put that up in an attempt to cut down the outside noise.

My monitors are Dynaudio bm5a.

What are your thoughts on my cloud? I was thinking I could rotate it and corner hang one of the panels.

And for the rear corners I plan on getting another se of tri traps, and I have 4 2in panels that are going to go up on my back side walls and replace my 4in that I have on my sides, so I can put those in the ceiling/wall corners.

[tonio]

DD wrote :Close to the wall/window is valid IMHO.

I agree, I have BM6a's in a 12x12x8 room, and had to jam them up close to the front wall, to lessen the nulls (read_so I can hear some low end).

Ciro wrote:My room has a similar size, I had troubles years ago with a serious peak in the 130 region, I solved it:

Adding a very thick front wall/ceiling corner trap (I also have a 6" cloud" over mix position - beside this trap).

Ciro, how thick? I still to add a panel in the same spot.

T

[ciro]

Tonio:
It´s a 4" corner panel filled with more rockwool

Only the 4" trap would works ok, but the extra material is much better from decay/waterfalls below 120hz.

*this is my experience, my room,you know...
*speakers and engineer position matters a lot.

Need advices, acoustic treatment positioning, please help!

(link for the pictures post#9)

[tonio]

Originally Posted by ciro

Tonio:
It´s a 4" corner panel filled with more rockwool

Only the 4" trap would works ok, but the extra material is much better from decay/waterfalls below 120hz.

*this is my experience, my room,you know...
*speakers and engineer position matters a lot.

Need advices, acoustic treatment positioning, please help!

(link for the pictures post#9)

Thanks Ciro,

yeah that is thick thumbsup I made a superchunk for the rear ceiling wall junction-man what a PITA. I'll give your method a try-seems easier to make-function over asthetics

T

[ciro]

I´m sure you can do much better (mine is weird/ugly) , but it works.

(this one is 4" + 4"+mini chunks)

Ciro

[bpape]

Originally Posted by deejfro

Thanks for the input, I'm going to upload some pics of the room so its easier to see what I'm dealing with...

I did end up mashing the speakers up to the front wall cause the bass roll off wasn't as bad as if I was out in the room more. there is a window in front of me, but I hung a an old 4x4 panel of no name foam, same with the 2nd reflection on the right(I know not ideal, but i have proper panels coming in soon.

I'll be sure to check out those links too.

on my speakers I have them set flat with the treble at +1.
I also uploaded the fuzzmeasure session. its the old measurements, same as the pics I attached earlier.

Thanks again fellas!

You're trading one set of problems for another. While having separate speaker stands will help somewhat with the desk interface and the height related issues, it's still not going to help with the SBIR issues of the monitors so close to the wall.

If you're having rolloff problems with them anywhere but up against the wall, the problems are actually:

- need for a sub if you're going lower than the monitors will do

- sitting in a place where bass nulls are causing problems

Sorry - but IMO, you're trying to fix one problem by masking it and creating another one rather than addressing the root cause.


Bryan

[deejfro]

I see, Thanks Bryan, I'll experiment more and take some more measurements with the speakers off of the wall.

Im not too sure its that the speakers have less roll off at the wall, but it seems more as to how I am situated in the room. there isnt much space behind me before I'm sitting in the dead center of the room. I was trying to minimize that by going as far forward as I can.

I should add (if it makes any difference) I ran a 120hz tone and walked the room... It's much louder in the front half of the room. not nearly as bad from the middle to the back of the room. hmmm

Thanks again for all the help!!

[DanDan]

A Sub is probably a very good idea in this situation.
The optimum listening position could easily be in the middle or further back. Test would tell. That Barefoot Calc takes account for front wall, side wall, and listener position. Worth a look.
I doubt that the window is capable of reflecting bass well, thus I doubt if SBIR from the window is playing a strong part here. I would suggest that SBIR from the side walls may be significant, and may be useful to get a bit more bottom end. I have been looking at SBIR for some time now. I have tried Bass Traps behind speakers to see if things would improve. Slight change, 1-2dB, and my front wall is concrete. In BareFoot's Calculator the SBIR wobbles are typically 2dB or so. Yet Genelec claim such boundary effects can be 6-20dB. I am puzzled by these seeming contradictions.
DD

[bpape]

SBIR can definitely be more than 1-2 db. I'm not familiar with the Barefoot calculator. However, their speakers have opposing, side firing woofers which tend to create a natural null in the bass in the rear of the speaker where the boundary interaction would occur so I can see why theirs would be less if that's the design they're basing the calculator off of.

Bryan

[DanDan]

Hi Bryan, thanks for replying. I have seen situations where a floor reflection was given 9-10dB by Lupo. When I repeated the test here, I got 1-2dB. The difference was mainly due to bandwidth. I use third octave, the other used no smoothing.
I would of course argue that the narrow number gives a false impression, in terms of how audible.
As we are at it..
Rod suggested that SBIR could be effectively killed by a panel placed near the speaker rather than the wall. High particle velocity out there and all that.
Tried it. Nope. The panel worked better back at the wall. Odd, I thought that was a great idea. I strongly recommend getting hold of that Wall Bounce Calculator 2D. Google will find it, probably at John Sayers site.
It is generic, will work with any speaker. It can even accept wall absorption coefficients. It's fun too.
Best Regards, DD

[deejfro]

I punched in my dimensions for you to take a look at. nothing looks crazy to me, if im reading it correctly..

[DanDan]

Unless I am missing something, the peak is about +1dB, and the dip -2dB.
That is one of the reasons I suspect SBIR is not playing a large part in your room.
DD

[deejfro]

What are your thoughts on my cloud? I was thinking I could rotate it, then that way one of the 2 panels could be covering a corner. hmmm

Is it worth it for me to go through the hassle of re-hanging?

Also that way, It would get the cloud away from my ceiling fan so I could get it lower... I do have a 4in gap already.

[bpape]

How thick are the panels in the cloud? Generally, you don't get much more after your gap equals the thickness of the absorption.

Bryan

[deejfro]

Hi, Bryan... they are 244's

But I was curious if I'd see better results by straddling the corner with one of the 2, then the 2nd would still give me plenty of coverage for my RFZ.

[bpape]

It would certainly extend the reach of that 244 and minimize the horn effect out of the corner.

Bryan

[Mulmany]

I was struggling with a bad case of SBIR at the 120hz range in my room. Looks to be similar in size, mine might be a bit bigger. Instead of a peak I was getting a big dip, by big I mean -12db.

I played around with my traps, putting up two new ones at the back of the room, and increasing my RFZ panel thickness. These helped, but only smoothed out 3db of the dip.

I then doubled my first cloud thickness and double the width across the room, so now its a 2'x8'x2" panel hanging 8" off the ceiling. This hangs over my desk and the front edges of my monitors. This actually helped a ton since I realized that I was almost equidistant from the floor to ceiling. I also tried moving the speakers up but that had no significant effect.

I then started moving my monitors out toward the side walls. Every move was tested and the trace stored. So I found that bringing my monitors almost into the corners of the room brought my lows under control. No more peaks and dips just nice and smooth.

It does take stands though.

Hope this helps.

[DanDan]

Nice one mulmany.
deejfro, the Mirror Trick is great for determining where and how much surface area of cloud and RFZ.
DD