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jim1961
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2nd March 2013
Old 2nd March 2013
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My Listening Room

Ive been working on this for a while now. I wanted to both share, thank you all for helping me over the months getting my ideas together and also collect any ideas, insights or comments anyone might have.

Room dimensions: 25.75L x 15.4W x 8H (vaulted, variable height from 7.5" to 8.75')

My Listening Room-my-room-03-02-arrows.gif

This illustrates basically how the sound is bounced around the room.

Black = Bass traps / Absorption panels
White = Reflection panels
Orange = Diffusers

My Listening Room-2013-03-02-04.jpg

My Listening Room-2013-03-02-03.jpg

My Listening Room-2013-03-02-02.jpg

My Listening Room-2013-03-02-01.jpg

My Listening Room-03-02-etc-both-no-smoothing.jpg

ETC, no smoothing, full bandwidth. Red = Right channel, Grey = Left.
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2nd March 2013
Old 2nd March 2013
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Quote:
Originally Posted by jim1961 View Post
Ive been working on this for a while now. I wanted to both share, thank you all for helping me over the months getting my ideas together and also collect any ideas, insights or comments anyone might have.

Views: Size: ">Attachment-IRJDSUNE9932123321222xxeww-332981

This illustrates basically how the sound is bounced around the room.

Black = Bass traps / Absorption panels
White = Reflection panels
Orange = Diffusers

Views: Size: ">Attachment-IRJDSUNE9932123321222xxeww-332982

Views: Size: ">Attachment-IRJDSUNE9932123321222xxeww-332983

Views: Size: ">Attachment-IRJDSUNE9932123321222xxeww-332984

Views: Size: ">Attachment-IRJDSUNE9932123321222xxeww-332985

Attachment 332980

ETC, no smoothing, full bandwidth. Red = Right channel, Grey = Left.
Looks like your speakers are pulled a lot off the front-wall (like mine). Looks about 9ft or so..
You have kept the speakers inverted because they have been elevated a lot higher?
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2nd March 2013
Old 2nd March 2013
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Quote:
Originally Posted by Jolida View Post
Looks like your speakers are pulled a lot off the front-wall (like mine). Looks about 9ft or so..
You have kept the speakers inverted because they have been elevated a lot higher?
The speakers are just under 8' from the front wall. Pretty good guess though

Not sure what you mean by "inverted" ?
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3rd March 2013
Old 3rd March 2013
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Quote:
Originally Posted by jim1961 View Post
Ive been working on this for a while now. I wanted to both share, thank you all for helping me over the months getting my ideas together and also collect any ideas, insights or comments anyone might have.

Attachment 332981

This illustrates basically how the sound is bounced around the room.

Black = Bass traps / Absorption panels
White = Reflection panels
Orange = Diffusers

Attachment 332982

Attachment 332983

Attachment 332984

Attachment 332985

Attachment 332980

ETC, no smoothing, full bandwidth. Red = Right channel, Grey = Left.
You have a very strong reflection around 25ms in your ETC, is this good.

Can you show the waterfallplot and the freq response?
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3rd March 2013
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Thanks for sharing your build with us over the last year. I'm sure your work has paid off well and you are enjoying the listening. It takes lots of creativity to make a non-ideal space into a great listening environment.
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3rd March 2013
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Quote:
Originally Posted by Mctwins View Post
You have a very strong reflection around 25ms in your ETC, is this good. Can you show the waterfallplot and the freq response?
This post may be indicative of why you continue to have confrontations with other GS'. In the world of acoustics, ignorance is definitely not bliss. You may find some of Jim's other threads helpful to finding an answer. He's been very generous with his documentation.
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3rd March 2013
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Quote:
Originally Posted by Mctwins View Post
You have a very strong reflection around 25ms in your ETC, is this good.

Can you show the waterfall plot and the freq response?
The 25ms peak is there on purpose, in case thats not obvious. To my ears and given the constraints of my knowledge and budget, this is the best way ive found to emulate what LEDE / RFZ rooms describe as the an ISD termination.

Without it, things are a bit lifeless and dead. Not all together terrible, but with the termination, things seems more animated. You feel more enveloped in the soundfield as opposed to it all happening across the room.

I may provide more measurement data at some future point.

For now, what I am aiming to share and invite comment about is the approach and theory for small room acoustics.
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3rd March 2013
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Quote:
Originally Posted by John White View Post
Thanks for sharing your build with us over the last year. I'm sure your work has paid off well and you are enjoying the listening. It takes lots of creativity to make a non-ideal space into a great listening environment.
Thanks John. It has been a lot of work. But I am willing to work some more on it if I was to become convinced that a modification to what ive done would be better is some way.
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3rd March 2013
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My Listening Room-etc-03-02-bands.jpg

Here is a sliced ETC.

Red = 668hz
Orange = 1k
Yellow = 1.6k
Green = 2.6k
Blue = 4.2k

All 1 octave bandwidth, 200us smoothing.

I have brought this up before, but still remain a bit unsure what is adequate here. Ideally, each band would be at the same level. But others have brought up how the ETC favors the higher range when slicing, so I am not sure that this is really an accurate measure.
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3rd March 2013
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Great work Jim, thanks for sharing.
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3rd March 2013
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Quote:
Originally Posted by jim1961 View Post
The speakers are just under 8' from the front wall. Pretty good guess though

Not sure what you mean by "inverted" ?
I must have mistook the picture. Thought u had kept the speakers upside down to compensate for the woofer height.
My speakers are about 7.2ft off the front wall & 4.4ft off the sides..
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3rd March 2013
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Quote:
Originally Posted by Jolida View Post
I must have mistook the picture. Thought u had kept the speakers upside down to compensate for the woofer height.
My speakers are about 7.2ft off the front wall & 4.4ft off the sides..
Ah, yes the speaker are upside down

Wanted to emulate the configuration of my soon to come new speakers.

My Listening Room-jenzen-seas-rtr-t25-02-13-2.jpg
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3rd March 2013
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Jim, that's some serious DIY treatment porn. You should be proud!
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3rd March 2013
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Great work getting all the little particles to line up and do something useful! But no FR chart?
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3rd March 2013
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My Listening Room-03-04-left-fr.jpg

(1/24th oct smoothing applied)

As one can see, I have an integration problem from the sub to the satellite and/or a reflection. Looking at the ETC, cant see any early strong reflection to account for the null though. A 2.38ms delay floor bounce corresponds to 180 degrees out of phase at 210hz, but the floor bounce is >-20db down.

I didnt post it cause its nothing to be proud of at this point :(

But as I said a couple posts above, new main speakers are on the way, and the sub will get new duty working only below 40hz. I hope to deal with that 210hz null then.
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4th March 2013
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Uh oh, sounds like the hunt is on. Grab your mineral wool and DB meter!
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4th March 2013
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great work Jim.
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4th March 2013
Old 4th March 2013
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Quote:
Originally Posted by jim1961 View Post
Attachment 333173

(1/24th oct smoothing applied)

As one can see, I have an integration problem from the sub to the satellite and/or a reflection. Looking at the ETC, cant see any early strong reflection to account for the null though. A 2.38ms delay floor bounce corresponds to 180 degrees out of phase at 210hz, but the floor bounce is >-20db down.

I didnt post it cause its nothing to be proud of at this point :(

But as I said a couple posts above, new main speakers are on the way, and the sub will get new duty working only below 40hz. I hope to deal with that 210hz null then.
Above 300Hz and 60-150Hz looks good but you have a peak at 40Hz and under this a null around 28-40Hz, I still would like to see the waterfallplot.

I don't think new speakers will solve that null at 210Hz.
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4th March 2013
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Quote:
Originally Posted by Mctwins View Post
Above 300Hz and 60-150Hz looks good but you have a peak at 40Hz and under this a null around 28-40Hz, I still would like to see the waterfallplot.

I don't think new speakers will solve that null at 210Hz.
You could be right. But there is are two factors that will definitely change that might help.

1) The sub is crossed over at 180hz (I know, a bit high), so some of the dropout will be filled in since the soon to arrive speaker will not have this constraint.

2) The woofer location in the new speaker is a good deal lower in proximity to the floor than the satellite woofer. If a floor bounce is the cause, this could definitely change things.

My Listening Room-03-04-waterfall.jpg

The sub is ported and tuned to 27hz, so take that into account when looking at the extreme low end.

And yes, I see the 210hz ringing. Cant figure out where its coming from :(
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4th March 2013
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Quote:
Originally Posted by jim1961 View Post
You could be right. But there is are two factors that will definitely change that might help.

1) The sub is crossed over at 180hz (I know, a bit high), so some of the dropout will be filled in since the soon to arrive speaker will not have this constraint.

2) The woofer location in the new speaker is a good deal lower in proximity to the floor than the satellite woofer. If a floor bounce is the cause, this could definitely change things.

Attachment 333257

The sub is ported and tuned to 27hz, so take that into account when looking at the extreme low end.

And yes, I see the 210hz ringing. Cant figure out where its coming from :(
Thanks for posting.
Good question about the 210Hz resonance.

Can you measure with your program in higher sequence lenght? I see that it does not measure good below 40Hz in the waterfall, you have some green lines, what does this mean?

In my speakers system and x-over settings I don't see that the effect is getting better or worse in the freq response by changing the x-over settings.

In your case, I belive it is room related about the problem you have at 210Hz and not your x-over settings.

Laborate with the x-over setting and measure and see what happens.

Last edited by Mctwins; 4th March 2013 at 05:39 PM.. Reason: adding text
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4th March 2013
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Quote:
Originally Posted by Mctwins View Post
Thanks for posting.
Good question about the 210Hz resonance.

Can you measure with your program in higher sequence lenght? I see that it does not measure good below 40Hz in the waterfall, you have some green lines, what does this mean?

In my speakers system and x-over settings I don't see that the effect is getting better or worse in the freq response by changing the x-over settings.

In your case, I belive it is room related about the problem you have at 210Hz and not your x-over settings.

Laborate with the x-over setting and measure and see what happens.
The crossover reference is to explain why the FR graph starts dipping sharply after 160-180hz. This is where the sub crosses over (18db/octave)

Agree the room is primarily responsible. Just saying that the problem is exaggerated by the sub crossover point.
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4th March 2013
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Quote:
Originally Posted by jim1961 View Post
The crossover reference is to explain why the FR graph starts dipping sharply after 160-180hz. This is where the sub crosses over (18db/octave)

Agree the room is primarily responsible. Just saying that the problem is exaggerated by the sub crossover point.
Ok,

But, do you have any highpass setting from your main speakers?
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4th March 2013
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Quote:
Originally Posted by Mctwins View Post
Ok,

But, do you have any highpass setting from your main speakers?
The satellite speakers are crossed over at 180hz at 6db/octave, so this should not effect things at 210hz much, if at all.

Anyway, as said before, I am not going to make a full effort to solve the null until my new speakers are in place. I wont know exactly what I am dealing with until then. In a week or two I think.

Then, if the null is still there, I will probably start a new thread asking advice to deal with that problem specifically if I can not figure it out on my own.

This thread was intending to get responses to my overall room approach.

Appreciate you trying to help
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4th March 2013
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Quote:
Originally Posted by jim1961 View Post
The satellite speakers are crossed over at 180hz at 6db/octave, so this should not effect things at 210hz much, if at all.

Anyway, as said before, I am not going to make a full effort to solve the null until my new speakers are in place. I wont know exactly what I am dealing with until then. In a week or two I think.

Then, if the null is still there, I will probably start a new thread asking advice to deal with that problem specifically if I can not figure it out on my own.

This thread was intending to get responses to my overall room approach.

Appreciate you trying to help
Ok, I understand. I thought so of my system as well about x-over setting was causing my null at 90-150Hz. But it wasen't.

My room

after the tuned HH resonators you see a flat response and x-over settings is the same.

I am running in bi-amp mode with JBL PRX600 series.
The subs freq response according to specs is:
(+/-3dB) 39-93Hz
(-10dB) 30-105Hz
and highpass to main from 118Hz Butterworth 18dB/oct.

Just some thought.
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4th March 2013
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Quote:
Originally Posted by Mctwins View Post
Ok, I understand. I thought so of my system as well about x-over setting was causing my null at 90-150Hz. But it wasen't.

My room

after the tuned HH resonators you see a flat response and x-over settings is the same.

I am running in bi-amp mode with JBL PRX600 series.
The subs freq response according to specs is:
(+/-3dB) 39-93Hz
(-10dB) 30-105Hz
and highpass to main from 118Hz Butterworth 18dB/oct.

Just some thought.
Impressive results
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5th March 2013
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It might sound academic, but did you check the ceiling? If it is 8ft, ~210hz is the third axial mode.

It could be coming from the area behind the speakers as well. I do notice the panels on the ceiling in front of them. Use your mic at the ceiling in front of and behind the speakers to look for a resonant peak. Also check the front wall in between the speakers.

A HH resonator might actually work well for this, but if it cannot be placed in the correct area then you should look at other options.
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5th March 2013
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Quote:
Originally Posted by OpusOfTrolls View Post
It might sound academic, but did you check the ceiling? If it is 8ft, ~210hz is the third axial mode.

It could be coming from the area behind the speakers as well. I do notice the panels on the ceiling in front of them. Use your mic at the ceiling in front of and behind the speakers to look for a resonant peak. Also check the front wall in between the speakers.

A HH resonator might actually work well for this, but if it cannot be placed in the correct area then you should look at other options.
I wasnt going to go into this now, but since offers of help seem to be coming for this, I will plunge into it, at least a little.

Here is what i have done. I got out a sine wave CD and played the 200hz tone (the closest one to 210hz that I could find) and walked around the room with a RS digital meter. I did indeed discover a heightened reading at a place between each speaker at a location just in front of where you see the equipment (CD player / amp).

The spot I am describing happens to be where the ceiling is 93" tall (the ceiling is vaulted, so therefore is a different height at different places in the room), and 93" from each side wall (the room is 186" wide). This spot also corresponds to just after the ceiling cloud stops and where those large side wall aborbers end (except at floor level). The front wall is 72" away from this point.

What I havent worked out yet is whats special about 93" other than its a point where the height of the room is exactly half its width. While there is certainly something going on there, I havent figured out what approach to take with it. I did take (2) large pieces (2'x4') of 2" OC703 and spaced them 16" away from each side wall (1/4 the wavelength of 210hz = 64") and took before and after FR reading with seemingly no difference. I HAVE noticed that blocking the front wall (2-3' away) with the same OC703 panels DID make some difference, but only 4db or so.

Like said before, I havent given this my full attention yet. There maybe something obvious that ive just missed. I havent even thought it through far enough to say if its a modal or reflection problem. To this point, ive been working on the ETC almost exclusively. Thats why I only included that graph in my initial post. The ETC part of the room equation is the only part I feel ive pretty well mastered for the room.
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5th March 2013
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Quote:
Originally Posted by jim1961 View Post
I HAVE noticed that blocking the front wall (2-3' away) with the same OC703 panels DID make some difference, but only 4db or so.
4dB is a very large improvement. Take a stab at the back wall also, since they are parallel surfaces. But my best guess is the ceiling above the sub, is causing the resonance.
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5th March 2013
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Originally Posted by OpusOfTrolls View Post
It might sound academic, but did you check the ceiling? If it is 8ft, ~210hz is the third axial mode.

It could be coming from the area behind the speakers as well. I do notice the panels on the ceiling in front of them. Use your mic at the ceiling in front of and behind the speakers to look for a resonant peak. Also check the front wall in between the speakers.

A HH resonator might actually work well for this, but if it cannot be placed in the correct area then you should look at other options.
I totally agree here

But, I think it is around 80Hz or something behind speakers.

Last edited by Mctwins; 5th March 2013 at 02:42 PM.. Reason: adding text
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5th March 2013
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Jim...
Could you measure behind speakers floor/wall and wall/ceiling corners, left middle and right.
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