[Housteau]

I just got back from AXPONA in Chicago.  I enjoyed the show.  When I came home I was a bit concerned about what my system would sound like after experiencing quite a few really fine sounding rooms.  I am always impressed the most by the smaller speaker systems that appear to do so much more than their size should allow.  But, when I had a listen to mine I was reminded that physics sometimes does matter and larger systems often tend to produce a more realistic weight and scale behind the notes.

The new Gayle Sanders system is very impressive in concept and performance.  The Kii Three has a similar concept in that they both actively work by utilizing their adjustable parameters to help eliminate the wall behind and just to the sides of the speakers, as far as bass is involved.  In other words they actively work to remove those boundaries preventing the bass reflecting back into the room.  They are creating a directional bass response.  This greatly helps to reduce the peak and null issues.  However, the rest of us without this sort of active control count on decent room design and acoustic controls.

That is where my questions come in.  Being inspired by how well those active systems actually work (a friend has the Kii Three's), I would like to build upon my existing front corner treatments to help absorb and reduce even more what is being reflected back into my room.  Currently I have the corners with solid triangular fill of 703.  They are large triangles about 3 feet across with a depth of around 16 inches to the corner.  But, that depth quickly reduces as you move down each wall away from the corner.  Here is a photo.  It is an older one and things have changed a bit, but the speakers are within 8 inches of what this shows.  The room is 21 x 25 ft.



What I am thinking about doing is extending the treatments down the wall behind and just above the bass towers about 16-18 inches.  I am not sure of the depth, maybe 10 inches?  I am thinking that would bracket those towers more and help reduce more of the reflection where I could reduce my necessary room corrections at certain points.  Does this sound reasonable?

I have read different places that simple R30 rolled insulation can work quite well when used in thicknesses around 12 inches.  Does anyone have any experience with this?  It would be a much cheaper and more available way to go.  Is it worth trying, or should I just bit the bullet and go for a solid fill of a more ridged material like the 703, or rock wool?

[JLM]

Looks like acoustically a nice space.  What exactly is/are your compliant(s)?  My experience with shows is that nearly all rooms have crappy setups, so I normally come home a proud papa.  Have you run a frequency sweep?  Have you tried DSP/EQ?  How far back do you listen?  Have you tried moving speakers/listening position?

First, recommend reading Floyd Toole's "Sound Reproduction" as a good starting point to understand in-room acoustics.  Second, open fiberglass is not safe (don't breathe in the fibers). 

I have a dedicated room that follows the Cardas Golden Cuboid (8ft x 13ft x 21ft) and use six GIK 244 panels to almost zero affect (however they have been very useful in other settings).  So room shape is critical, not that your's is bad but rectangular shapes have been studied more and are simpler to predict.  Not sure that adding more treatments would be all that helpful.  Note that I listen near-field (ala Cardas) and am very satisfied. 

[Housteau]

Looks like acoustically a nice space.  What exactly is/are your compliant(s)?  My experience with shows is that nearly all rooms have crappy setups, so I normally come home a proud papa.  Have you run a frequency sweep?  Have you tried DSP/EQ?  How far back do you listen?   

Complaints?  I would not say that I have complaints, quite the opposite really.  I just feel that I have room for improvement and a desire to give it a shot.  For me that is part of the hobby.  As I mentioned I am impressed by the new technologies of manipulation of the acoustic space through DSP. 

My system / room was set up using DSP for the best locations and the removal of peaks in bass response.  The new methods of DSP reduce those peaks and dips utilizing muli-driver phase manipulation creating a more directional bass, that aids in removing room boundaries from creating those issues to begin with.  Without creating a room from scratch, that just seems to be the way to go. 

Already having a room and system that I am happy with, I think The best path forward for me is to continue to improve upon the room itself by attempting to reduce bass reflections back into it.  My current treatments do that to a point, just not far enough.

[youngho]

See the third post here by Floyd Toole: http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2945266-bass-trap-reflective-surface-behind-subwoofer.html

If you're interested in upgrading your bass absorption technology, you might consider tuned/diaphragmatic bass absorption or VPRs like RPG's Modex Plate for passive, otherwise bass arrays (like DBA or double bass array) or PSI AVAA C20 for active options.

[Housteau]

See the third post here by Floyd Toole: http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2945266-bass-trap-reflective-surface-behind-subwoofer.html

If you're interested in upgrading your bass absorption technology, you might consider tuned/diaphragmatic bass absorption or VPRs like RPG's Modex Plate for passive, otherwise bass arrays (like DBA or double bass array) or PSI AVAA C20 for active options.

Thank you.  I will read up on that other technology.  In the past I fell into the broadband approach camp. 

The main pressure zones in my room are the two front corners.  My room used to be 21 x 15 ft with the same speaker arrangement, although then, that would have been a long wall set-up.  In that room the pressure zones were strong in the centers of the front and back walls.  Extending the room back 10 ft behind the listening position made them less apparent than the corners.  That and the arrangement of my back wall.  The cathedral peak is also worth mentioning, but I believe it is now under control regarding both bass and imaging issues.

However, with my current treatments in place there may now be other areas that now would be the higher zones.  That is certainly worth looking into.  I will look at the frequencies that I have done the most correction on (peaks and dips) and see where they peak in the room.  I have found that you can help fill a dip by absorbing that frequency where it peaks as well.  It should be interesting.

[Housteau]

I was able to do a quick check on my room.  I had two CD's which had the correct test tones for the frequencies needed.  The frequencies having the most correction in my room are 27, 40, 52, 63 and 116 Hz.  These are the ones I have I have cuts set for.  The build-up within the room was different for each frequency.  The 27 Hz was strongest in the left rear and by a good margin.  63 Hz was both left rear and right front corners.  52 Hz has the highest correction applied and it still measured to be strong along the front wall, corners and center.  The others bounced back and forth between the two front corners.

[Housteau]

  1

[JLM]

Careful not to overdue the treatments.  Having a proper room size/shape is far more critical.  Consider that the western ear has been conditioned to listening in a rectangular rooms something like 8ft x 14ft x 20ft (made up of the classic 5/8 Greek Golden rectangles that minimize echo and look 'right'), so those rooms are what sounds "right", not spaces that look like a psychiatric 'rubber room'.  Note that Toole's own listening room at home is a quite ordinary shared living room.

[Letitroll98]

There are very, very few of us with the ability to determine the room dimensions we listen in.  I learn much more from reading the solutions arrived at taming less than ideal rooms.

[JLM]

There are very, very few of us with the ability to determine the room dimensions we listen in.  I learn much more from reading the solutions arrived at taming less than ideal rooms.

Sadly room acoustics/treatments/DSP-EQ are poorly understood and the effects under appreciated.  While treatments/DSP-EQ can help, they aren't cure alls. So most in-room audiophiles way over-buy gear for the given poor performing room.  And nobody wants to hear that (pun intended). 

Honestly I'd rather have a well sized/shaped room with a $2000 system than a poor room with a $100,000 system.

[rollo]

Sadly room acoustics/treatments/DSP-EQ are poorly understood and the effects under appreciated.  While treatments/DSP-EQ can help, they aren't cure alls. So most in-room audiophiles way over-buy gear for the given poor performing room.  And nobody wants to hear that (pun intended). 

Honestly I'd rather have a well sized/shaped room with a $2000 system than a poor room with a $100,000 system.

   Well said. Unfortunately most are limited with space for a dedicated room. IMHO it is worth hiring an Acoustic expert to measure your space to get the best out of it before wasting money on gear you cannot truly appreciate. Just makes sense. Spectrum analyzer anybody ?

charles

[Housteau]

Sadly room acoustics/treatments/DSP-EQ are poorly understood and the effects under appreciated.  While treatments/DSP-EQ can help, they aren't cure alls. So most in-room audiophiles way over-buy gear for the given poor performing room.  And nobody wants to hear that (pun intended). 

Honestly I'd rather have a well sized/shaped room with a $2000 system than a poor room with a $100,000 system.

I fully agree that the room / listener interface is critical, as well as the proper set-up to optimize the various parts.  If the weakest link in that chain is the room, which is often the case, ignoring that and purchasing more expensive gear certainly could be a waste of resource dollars.  I see it similar to someone living far off the grid surrounded by many miles of dirt and gravel roads buying a hyper expensive sports car.  Yes it will look great sitting there and you can have a certain pride in ownership, but you will never be able to realize the performance you paid for without taking it somewhere else.

But, as was mentioned just above:  "There are very, very few of us with the ability to determine the room dimensions we listen in."  So, what is broken, or not quite right needs to be fixed.  Now, my room was designed and built from scratch, but I had limits and did not know enough about acoustics at the time.  The original dimensions were actually a good ratio at 21 x 15.5 x 10 ft average.  With the speakers along the long wall that placed my seat too close to the back wall.  I have always had larger 4 piece systems that enjoy this width.  Years later I had the opportunity to extend my rear wall back another 10 feet. Now that made all the difference in the world.  Sill, it is now an existing room that needs to be treated as any other.

As I mentioned in a previous post I have noted the main pressure zones in the room and at what frequency.  I had two portable panels 2' x 4' x 4 inches thick that were in locations they did not need to be.  I placed them together to reinforce what I already had in the right front corner.  Sure enough I made an improvement.  I am sure that part of it was also due to removing them from where they did not need to be.  Broadband bass control isn't about the square feet of coverage, it is about the total thickness in the right areas.  So, I feel I can thicken things up if needed and not negatively change the upper spectral balance in my room. 

[Tyson]

You might try to fix the source of the problem - the fact that box bass radiates like a pulsing sphere in-room.  An elegant solution to this is to use open baffle bass (OB).  This reduces room overload and unevenly pressurized zones a LOT.  The need for EQ and even room treatments drops considerably. 

[Hipper]

Hello Housteau.

If I understand correctly you are trying to reduce the work your EQ/DSP does by employing additional room treatment. I would be interested to know if the result is a better sound overall - in theory it should be I would guess.

I went a bit mad with room treatments last year (I had used some before), now employing a total of twenty-one bass traps (GIK Soffit traps) in all the corners except the floor wall ones, that in a 14' x 13' x 8' room. I took measurements as I added these bass traps using REW (I can post them if anyone's interested). I also noticed that there was a major improvement in decay times, down to between 120 to 180ms. That's probably too low for some but the result is really nice percussion, piano and plucked guitar for example. The decay times are something DSP/EQ cannot really change as I understand it and would guess these new active speakers can't do either?

[Mike-48]

I went a bit mad with room treatments last year (I had used some before), now employing a total of twenty-one bass traps (GIK Soffit traps) in all the corners except the floor wall ones, that in a 14' x 13' x 8' room. I took measurements as I added these bass traps using REW (I can post them if anyone's interested). I also noticed that there was a major improvement in decay times, down to between 120 to 180ms. That's probably too low for some but the result is really nice percussion, piano and plucked guitar for example. The decay times are something DSP/EQ cannot really change as I understand it and would guess these new active speakers can't do either?

Great work, Hipper!  In my opinion, one of the most important things room treatment can do is reduce decay time, especially in the bass. As you say, this is not accomplished easily any other way, and it can make huge improvements in clarity.

I also agree with your thought that room treatment -- and placement of the speakers and the listener, I'd add -- can reduce what's needed through EQ/DRC, and I think one winds up with a better result.

My view is, room treatment and room EQ are complementary. Each can do important things that it's difficult to accomplish with the other.