[nickd]

Sebrof,
I looked at the pics in your gallery. looks like you sit near field? If there is room boundary behind your seat, my guess is you may have to adjust your listening position to compinsate for the suckout. if those single driver full range beauties are your primary speaker I might wonder if floor bounce is a problem? in my expierence woofers mounted closer to the floor tend to be bothered less by "floor bounce" cancellation and peaks (Roy Allison did a lot of work in that area). One possible weakness with single driver designs I'm afraid. The best place for a midrange and tweeter is not always the best place for smooth bass response from a woofer.

However, I'll bet the imaging from that design is very good

[Danny Richie]

Sebrof,
I looked at the pics in your gallery. looks like you sit near field? If there is room boundary behind your seat, my guess is you may have to adjust your listening position to compinsate for the suckout. if those single driver full range beauties are your primary speaker I might wonder if floor bounce is a problem? in my expierence woofers mounted closer to the floor tend to be bothered less by "floor bounce" cancellation and peaks (Roy Allison did a lot of work in that area). One possible weakness with single driver designs I'm afraid. The best place for a midrange and tweeter is not always the best place for smooth bass response from a woofer.

However, I'll bet the imaging from that design is very good

This is all excellent advise.

[Jeffrey Hedback]

On topic of LF acoustical measurements, the in-room LF response is a complex system.  Acoustically measuring the response can be equally complex (not as much to perform but to interpret).  The destructive interference example noted by Danny is one that would show in the 2-spkr measurement and is also likely to occur on certain program material.  Also as Danny previously mentioned, the LF content of program material is not a static "dual-mono" situation.  It could range from orchestral recordings with the Bass Section hard right to a country ballad with "doughnuts" (sustained whole notes) panned center in a static key center.  These two examples would excite a single room differently and may expose discrete issues.  No single measurement would fully relate to the full picture.

I've had measurements where the L & R channel vary greatly from each other and the 2-spkr data.  I've had measurements where all three are spot-on the same.

For basic purposes, I fully support the use of 2-spkr LF data and single speaker above ~250Hz.

To Sebrof, from the new insights brought forth by nickd...is your driver located at the 25% mark vertically?

[sebrof]

To Sebrof, from the new insights brought forth by nickd...is your driver located at the 25% mark vertically?

I really appreciate all the responses, guys. The info and suggestions are coming a bit faster than I can react to them (you know, work job kids wife...not necessarily in that order).

My speakers are Tekton Katz Meow V1 with a 8" Fostex FF225 and a bullet tweeter, no crossover. The 8" driver is 24.5" above the floor.
Amp is a 2A3 SET.
My recliner is at the back of the room. Room is 12' 3" front to back, 13' side to side, 9' high.
1 GIK Corner Trap in each front wall corner, 2 GIK 244s hanging behind the listener.
Speakers (main driver fronts) are about 3.5' from the side wall and 4.5' from the front wall. Me and the speakers are in an EQ triangle give or take a few inches, pointing just a few degrees out from directly at me.

Floor bounce - Should I try putting a GIK 244 on the floor in front of each speaker just to see what happens?

Doug S. - I have had the corner arrangement (i.e.: Diagonal configuration ala Steve Deckert) in the past with other speakers in there. I liked it for a while but I dunno...I always went back to the traditional setup. I'll give it a try with these guys, who knows maybe it will work.

I'll consider this a work in progress because I'm interested to see the correlation between best measuring and best sounding room. I'm not sure they'll be the same but the engineer in me really wants to find out.

And thanks again!

[roscoeiii]

Have you played around with the listening position. A few feet forward and back can swing my bass suckout by 5 dB or so

[sebrof]

Have you played around with the listening position. A few feet forward and back can swing my bass suckout by 5 dB or so

Yes I have. It changes the frequency more than anything, IOW the dip stays close to -10 to -13db, but the freq of the dip changes from 125Hz to 160Hz(?) (I forget exactly, and it changes the more or less I move into the room).

[Jeffrey Hedback]

Sebrof,

If the mic was ~21" from rear wall when the center freq of null was 160Hz...that is the cancellation off rear wall.

My likely cause of 125Hz is the vertical placement.  if you try with speaker ~30-40% above floor and the dip changes or smooths, then the speaker excitation of vertical mode is a prime culprit.  Your speaker type actually helps narrow down the range of offenders.

[sebrof]

Sebrof,

If the mic was ~21" from rear wall when the center freq of null was 160Hz...that is the cancellation off rear wall.

My likely cause of 125Hz is the vertical placement.  if you try with speaker ~30-40% above floor and the dip changes or smooths, then the speaker excitation of vertical mode is a prime culprit.  Your speaker type actually helps narrow down the range of offenders.

The mic was about a foot from the wall (actually the GIK 244 hanging on the wall) when I measured the posted graph.

If I read you right you're saying 30 - 40% of 9' room height, correct. So between ~ 32" and 43"
I moved the speakers in and out, fore and aft but not up and down. I did move the mic a few times higher and lower though.
I have stands that are about 8" maybe 10", which would put the main driver middles @ 34" or so above the floor.
I'll give it a try for science, but I had them on the stands about a year ago and didn't like the sound. But I didn't measure. I'll measure this time and report back on both measurements and how it sounds.

[Jeffrey Hedback]

Sebrof,

Could you post a plan view of your room with basic features noted (doors, windows, clg height...etc).  basic construction types of walls, floor and ceiling...also note where your speakers and ears are located.  I will be glad to do some predictive analysis that might help better understand the 125Hz zone without you going on endless measurement searches.

I would also suggest that you cross the bridge toward a measurement software platform such as REW, ARTA, etc...Being that you're an engineer I really think you'll enjoy the ability to look at the time domain as well as better resolution of the frequency domain.

[sebrof]

Sebrof,

Could you post a plan view of your room with basic features noted (doors, windows, clg height...etc).  basic construction types of walls, floor and ceiling...also note where your speakers and ears are located.  I will be glad to do some predictive analysis that might help better understand the 125Hz zone without you going on endless measurement searches.

I would also suggest that you cross the bridge toward a measurement software platform such as REW, ARTA, etc...Being that you're an engineer I really think you'll enjoy the ability to look at the time domain as well as better resolution of the frequency domain.

Thanks Jeffrey.
The sketch is attached. My ears are about 33" above the floor, same height as tweeters.
Speakers are the Tekton Katz in my gallery. Speakers (main driver fronts) are about 3.5' from the side wall and 4.5' from the front wall. Me and the speakers are in an EQ triangle give or take a few inches, pointing just a few degrees out from directly at me.
Carpeted 2nd story room, drywall, 9' high ceiling.
My head is at the back wall minus the thickness of the recliner headrest, with GIK 244s hanging behind me (not shown on the sketch). The GIK corner traps are the ones in the front corners.
The truncated wall over my right shoulder...I guess there's electrical duct or something. I have a heavy blanket covering that wall.
The measurements in my first post are with the meter in the chair where my head is.

[bpape]

While not related to the null, sitting next to a boundary like that is putting you in a pretty bad place due to bass build up near the boundary. I think you'll find that moving forward and listening more nearfield will give you a much better presentation, better imaging, less masking of imaging cues and harmonic structure/micro-details, etc.

Bryan

[sebrof]

While not related to the null, sitting next to a boundary like that is putting you in a pretty bad place due to bass build up near the boundary. I think you'll find that moving forward and listening more nearfield will give you a much better presentation, better imaging, less masking of imaging cues and harmonic structure/micro-details, etc.

Bryan

I've tried it a while ago, but I'll give it another shot with a fresh set of ears. Small room, so I'm trying to maximize the space.
btw: You helped me select the GIK stuff I have in the room based on another version of the sketch, Bryan. Thanks, again.

[doug s.]

per my earlier comments, these are the two set-up's i'd definitely be trying, if it were my room:







doug s.

[sebrof]

per my earlier comments, these are the two set-up's i'd definitely be trying, if it were my room:

doug s.

I'm with ya' Doug. It's just that...man that's a lot of work.
Are you suggesting this for sound/presentation, or specifically to address the suckout?

Actually - The 2nd drawing doesn't look like a major overhaul so I might try it today.

[doug s.]

I'm with ya' Doug. It's just that...man that's a lot of work.
Are you suggesting this for sound/presentation, or specifically to address the suckout?

Actually - The 2nd drawing doesn't look like a major overhaul so I might try it today.

from the prewious dialog, it seems suckout is more related to floor/ceiling issues.  sound absorption at 1st reflection points on the ceiling might help.  but regardless of suck-out issues, i would still be doing one of these options.  getting more room behind you, as mentioned by bryan, is a good thing, and smoothing room nodes is good, as well - my second layout will definitely do this better than the first, unless you slightly skew the speakers/listening chair, as i did in the 2nd layout...

regarding difficulty in moving stuff around, the 1st layout really isn't that difficult - you awreddy moved your gear - now you yust need to center it on the short-angle wall, and move the speakers.     and, you likely won't need long speaker cable.   

doug s.

[sebrof]

Actually - The 2nd drawing doesn't look like a major overhaul so I might try it today.

OK, yesterday I moved the speakers and chair and I'm pretty close to what's shown in the 1ST drawing in Doug's post (not the 2nd like I said).
Measures close to the same as before, I need to take a little more time and do it properly, but suffice to say there is a big dip at somewhere near 125Hz.

I've listened to it like that for about 3 hours. I don't hate it, actually has a lot of potential. Seems like the musicians have more room to play in, they're not bunched together as much as before. It does seem that the bass is slightly reduced, but I'm not sure yet. It may be closer to the way it's supposed to sound and it's just my getting used to it. It does sound different, with some things highlighted more than others. I'll give it a few days to see if it stays.

[neekomax]

Did you try with different speakers?

[sebrof]

Did you try with different speakers?

No I haven't had the energy.
I do Plan to do a baseline frequency test right at the speaker with only 1 playing to double check and make sure it's not something inherent in the speaker design. Because it seems that no matter where I move the speakers or meter I still vet a big dip.

[doug s.]

Did you try with different speakers?

yes, i am wondering this, too.  because, tho not as extreme, you still measured a suck-out when measuring them from 2' away...

doug s.

[sebrof]

yes, i am wondering this, too.  because, tho not as extreme, you still measured a suck-out when measuring them from 2' away...

doug s.

OK, so I set the meter 1' from, and level with, the main driver and measured. All frequencies I measured between 50 Hz and I think I got as high as 1,000 Hz were within 1db on the meter. Although as I got higher in frequency, where I stood affected the reading a bit. IOW it doesn't appear to me to be the speakers.

I'm still tweaking the speaker placement in the diagonal setup. It's actually pretty tricky to get the speakers set in the right spot because my room is not square so I can't really measure off the walls. I need to measure off the imaginary center line that crosses in front of the listener. My head right now is over 4' from the back corner and the speakers are out into the room more than shown in Doug's sketch #1.

Doug s - Did you just drop the 2 speaker blocks randomly on the drawing to show a general idea for placement, or is there some formula/guideline? To give you an idea where I'm at - My left speaker is pretty close to where the "R" speaker is on the Sketch #1, and my chair is farther back towards the corner (about where the "L" is for the Left speaker).
Thanks for sticking with me guys.

neeko - I'll get the big speakers up there soon.