John Sayers' Recording Studio Design Forum Archive

gullfo wrote:hmmm ok, but if you step outside of the 5' circle, say 2' off the back wall, same?

Yes, 2' from back wall is where I had the mic for test #12 on the graph attached, the null widens to almost 250hz.

Test #14 & 15 are left and right 6' of listening position, showing an improvement in the 125hz range.

the improvement moving to one side or another is likely the side wall mode given no change in response with an altitude change. doesn't mean there is no SBIR (which is proven when you move the monitor positions around, like up again the wall left-right, etc) etc but i'd look into more modal response from the sides. you might not change it for the entire room easily (cheaply?) but at the listening position, you may need some pressure or resonant traps to shift that. one test is if you have 4" (or thicker) absorbers) which you can move out from the wall about 3"-4" (75mm-100mm) and see if you have a shift. it should be minimal but there.

Thanks for your help Glenn.

I tried the 4" panels on the sides away from the wall, but couldn't see a change, or hear a change.
I'm going to build out some slot resonators for the for the sides and see if there's some improvement.

I feel like even after the side treatment, the speakers will need to be pushed to the front wall completely. Then I'll be left with bulking up the low end treatment.

Really wish I could just get some different speakers and soffit mount them.. sometime in the future.

Pink Noise PN Spectrum Zoom to the area of interest. You will have to play with it hoping to get a stable image.
Move the mic inquisitively. I would start by moving it towards a spot on the floor half way between LP and speaker line.
Let's see if the frequency of the null changes.

DanDan wrote:Pink Noise PN Spectrum Zoom to the area of interest. You will have to play with it hoping to get a stable image.
Move the mic inquisitively. I would start by moving it towards a spot on the floor half way between LP and speaker line.
Let's see if the frequency of the null changes.

For some reason my Noise test in greyed out in the measure tool on REW.

I ran some standard sweeps instead, moving from Listening Position towards speaker in 6" increments:

The current speaker position is right up against the front wall.

https://www.dropbox.com/s/wtsnn7gds89av ... .mdat?dl=0

hmmmm...
21 126.6 Hz B2 2-2-1 obl
22 127.15 Hz C3 1-3-0 tan
23 128.38 Hz C3 3-1-1 obl
24 128.68 Hz C3 3-2-0 tan
there are 4 modes within 2hz. and the bonello distribution is not a good one. i was originally thinking maybe something in the 65-67hz range was actually the main culprit..
4 66.2 Hz C2 2-0-0 ax
but it might be the main one still @ 33hz
1 33.1 Hz C1 1-0-0 ax
the Barefoot monitors are pretty good down to that range.

if you run the sweep from say 90hz and up are you getting the same result? just trying to determine if this is due to a LF excitation (possibly something resonating) or these modes are truly and fully excited at those frequencies.

gullfo wrote:hmmmm...
21 126.6 Hz B2 2-2-1 obl
22 127.15 Hz C3 1-3-0 tan
23 128.38 Hz C3 3-1-1 obl
24 128.68 Hz C3 3-2-0 tan
there are 4 modes within 2hz. and the bonello distribution is not a good one. i was originally thinking maybe something in the 65-67hz range was actually the main culprit..
4 66.2 Hz C2 2-0-0 ax
but it might be the main one still @ 33hz
1 33.1 Hz C1 1-0-0 ax
the Barefoot monitors are pretty good down to that range.

if you run the sweep from say 90hz and up are you getting the same result? just trying to determine if this is due to a LF excitation (possibly something resonating) or these modes are truly and fully excited at those frequencies.

I thought the same thing, but I ran some tests previously starting at 100hz and I still have the same null.

just a quick question then - since i must confess to not having read every post on this - are you doing this test with a single speaker at a time? and did you run a full room test - one speaker in lower front corner, omni mic up in far opposite corner, then swap corners?

gullfo wrote:just a quick question then - since i must confess to not having read every post on this - are you doing this test with a single speaker at a time? and did you run a full room test - one speaker in lower front corner, omni mic up in far opposite corner, then swap corners?

Yes, I'm running a single speaker at a time, both L and R are showing the same nulls.

I have not run a full room test as you've mentioned... I'm assuming I would do so in an empty room without treatment?

ideally the full room without treatments but it depends on how hard it would be to move them out for the testing.

Update: Stopped working on the studio as I ordered some ATC scm100asl's!

I thought I'd be able to move the treatment out of the room, but it would be really difficult.

I'm just going to wait until I get the new speakers and go from there.
Depending on the results, if I end up wanting to soffit mount, it may be time to hire a local professional to come build it out for me.

I've read the guides on here for soffit mounting, but I'm not 100% confident and don't want to screw it up.
I'm open to any suggestions/recommendations.