[Glady86]

Here’s a cheap tweak I just tried, I have a dip between 200 to 350hz. Sticking a thick carpet between the speakers that was just bare concrete helped. From what I understand, floor bounce reaction between woofers and floor can cause this. Plus the ceiling is not very high, though it’s insulated and have acoustic panels for the  drop ceiling.

[Glady86]

After reading more about floor bounce, apparently carpet does nothing to address it. And some say it’s not that detrimental to sound quality anyway. Although the extra carpet piece did change the sound, maybe the room was a little to “live” and the change added a little more “flesh” to the midrange. It’s crazy how much the room and what’s in it affects the sound.

[Tyson]

Room is the 2nd most important component, after speakers.

[jmimac351]

After reading more about floor bounce, apparently carpet does nothing to address it. And some say it’s not that detrimental to sound quality anyway. Although the extra carpet piece did change the sound, maybe the room was a little to “live” and the change added a little more “flesh” to the midrange. It’s crazy how much the room and what’s in it affects the sound.

Good idea.  I'll ask my wife to stand in different spots and see if it improves the sound.  If it does, I'll see if she can stand there while I want to listen.  Tomorrow will be 25 years, I bet she will... roll her eyes at me again.

Waiting to hear back about PIAudio foam treatments. I may try a few different things / looks. 

[Glady86]

I got stuff all over the place, sometimes I rearrange it and see how I like it. This is my most recent experiment.
 Next I need to paint the floor. 

 The diffusers do nice things, IMO.


 This is my man cave, ladies think I’m nuts and it’s ugly, I don’t care though.

 Here’s the arrangement I settled on after a bit of experimenting. Moving the QRD panels behind the bass traps and alongside the GIK Polyfusers made a nice all around bump up in sound quality.
 I was working with what I have, so if this arrangement isn’t something GIK or a room acoustics specialist would recommend, so be it, it’s working. Also, I think those MIflex capacitors finally settled down.

[jmimac351]

Thanks for sharing.  I'm in touch with Dave about the "Mr T" treatments, like what Danny has in his room.  I'm going to send Dave a video of the room so he can recommend what's best.

[Glady86]

Sounds like a good plan, hope you can update the thread and let everyone know how it goes with the MR T treatments.

[jmimac351]

I think I've figured out what I'm going to do and I think I've learned a few things.   

I think I already have a pretty good room.  Feedback from friends agrees.  I have tall ceilings and "no side walls".  I don't want the room to be any deader than it already is... I think I just need to see what happens with more diffusion on the front wall.  After I get OB subs, I will see how they like the room and whether I need to put some sort of absorption somewhere for bass.

I'll have wood diffusers on the front wall at the reflection points, then maybe foam diffusion of some sort that I can lightly hang on the TV, as needed.  I came across this place below on Amazon, but they are out of Colorado.  Quite a few different designs. 

I've noticed that quite a few others are doing the standard QRD diffuser design... i.e., horizontal diffusion, and not as much vertical. It's interesting to compare what they show for diffusion coefficient between the Triangle design and the Quadratic Residue Well. I would have guessed the Triangle design would scatter more than the "channel" design of the QRD Well design. Whatever the case, I wonder how big a difference exists when you actually listen to the variations.

https://www.soundassured.com/products/wood-acoustic-diffuser-wood-acoustic-diffusion-panel-60-x-60-cm?variant=41782131589278

[Jaytor]

The problem with these is that they aren't very deep. You're not getting appreciable diffusion below about 1500Hz and hardly any diffusion below 500 Hz. Here's a useful chart showing the frequency range of different instruments. You really want diffusion an octave or so below what these diffusors provide, which means they need to be 2-3 times as deep to provide much diffusion of the fundamental.

This chart shows the fundamental frequency range, so the harmonics will be an octave or more higher. So these diffusors will provide some help, but not nearly as much as if they provide some diffusion of the fundamental frequencies.

[jmimac351]

Jay, thank you very much for pointing that out.  I went and looked again at the ATS stuff.  She likes this layout, and I'm going to order a pile of these ATS diffusers.  I may provide enough space in the middle to accommodate a projector screen that is framed in.  There are ultra short throw projectors out that are remarkable.  I considered making a nice acrylic stand that will be over the KX-R Twenty preamp in the middle, which I don't mind being protected from something stupid anyway. I can set the projector on that, and can then also put custom sized diffusion in that cavity in front of the screen that makes it look somewhat seamless, or at least planned for... if I feel like putting it in. 

I think that may be pretty slick.

https://www.atsacoustics.com/square-acoustic-diffuser-qrd.html

[corndog71]

If you haven’t seen it, Ron of New Record Day posted a great video on diffusion.

https://youtu.be/iTgW2hZYn08?si=zMXHuoWmU1ZrejQc

The arrangement of QRD diffusers are important. 
https://youtu.be/iTgW2hZYn08?t=751&si=zMXHuoWmU1ZrejQc

[jmimac351]

Thanks for the feedback everyone.  I came across these... and they are deeper than the ATS, made in Indiana, and the price is nice.

Is it assumed that a deeper well to scatter more frequencies down lower is always desired with OB?  For instance, these come in 8.75" well depth, and they made a version over 10"deep. 

Is a deeper well always better for this application?

[toocool4]

The deeper the wells the lower the frequency it will diffuse.
You need to find out from them as to what frequency does it go down to? Use the lowers frequency it goes down to, to calculate the distance you need to be a way from it for it to work.
You need to allow the diffused sound to fully form before it reaches your location, else it will not do it’s job. You need the formula λ = v/f
where λ = wavelength
v = speed of sound in air (343 m/s)
f = frequency  (Hz)
 
In this case you say the deepest well diffuses 443Hz
So v (343) \ f (443) = 0.7743 meters or 2.54 feet. I would also add 50% to the distance to be sure.
 
I would recommend only using 1 dimension diffusers on the front wall, never mix it for your situation.
 
I am using 1 dimension quadratic diffusers on my front and rear walls.
On the front wall I am using QD-11 which are 9½ inch deep, it goes down to about 350Hz

On the back wall I am using QD 7 which are about4½
I calculated the distance from me before having them made, needed to know it’s going to work before spending money.

[Tyson]

toocool, your room looks great!

[jmimac351]

Thanks guys.  So, I am currently doing something very stoooopid... "Selling Past The Close."  Huge mistake.

"She" has already signed off on this one... my wife... she's amazingly patient with me; however, she does have an opinion about this particular project.  It looks ugly like stickers on a picture, but visualizing this... it will be pretty cool once spaced out properly - if it happens.

The wood QRD stuff on Amazon looks similar and is cheaper, but it's not as deep - so it doesn't perform the same as deeper well QRD options from ATS and others (thanks for pointing this out).

I have a quote from ATS for this layout, and the number made me want to keep looking... and now I'm reaching out to a guy in Indiana.

Is QRD what I even want?  Doesn't QRD create phase issues with angles?  It makes areas of the room "less ideal"... if you have to give space to them, yes? 

I have a hunch this is why AV Room Service says... "everyone is doing it wrong" and opts for rounded curves.  I picture that as allowing the sound to splatter on the rounded object and diffuse, rather than be captured in an angled corner. 

That's what my eyes tell me. Still lookin'... 

[toocool4]

Thanks Tyson, ideally I would have liked to do floor to ceiling on both front and rear walls. As you can see on my front wall the left and right side are different, I would not be able to treat both sides the same.
Since the middle makes more difference to the central image and I could treat it the same so I treated the middle of the front wall. What a huge difference it made, I have a deeper wider image, the sound goes a lot wider than the speakers are apart. I can hear more subtle things which were masked before, I am hearing more into the mix.

I would have like to use deeper panels on the front, but that would mean they would hang well over the mantel piece and that would not look good. Did not have much choice about the back wall since I am only sitting about 4½ feet from it, anything deeper would be a waste of money as it would not work properly.

Still work in progress, I need to get proper absorbers for the first reflection points. I also need to do cloud cover, to minimise the floor to ceiling bounce.

[toocool4]

Jmimac351 the Amazon stuff is cheaper as they are using less wood, it would not go low enough.

Quadratic is what you need on the front wall of a listening room, it’s the most powerful of the diffusers as you can made them as deep as you like to cover lower frequencies.
Not sure why anyone would want a 2D panels on the front wall of a listening room, 1D is all you need as you only want it to diffuse in 1 direction. On the back is a different matter, but for me I would still stick to 1D on the back.

I am not so sure about the image you posted, forget what your eye see you need what is going to work. At the moment sounds like you are guessing, it’s a lot of money to spend on a guess. When I was in my flat before I moved to this new house. I guessed and bought GIK, got it way wrong the GIK stuff was not very effective. I will not be making that mistake again.

If you don’t want to spend too much money, you can do like I did. I bought build plans from Acoustic Fields and make my own, Acoustic Fields are silly money, but they work. Here is a link to Acoustic Fields site. www.acousticfields.com/

[HAL]

Have been using various PI Audio Group styrofoam style diffusor panels for years.  The Mr T's and 2D panel styles.

Even built two portable 4ft x 6ft walls with them for shows.

[jmimac351]

Jmimac351
Quadratic is what you need on the front wall of a listening room, it’s the most powerful of the diffusers as you can made them as deep as you like to cover lower frequencies. Not sure why anyone would want a 2D panels on the front wall of a listening room, 1D is all you need as you only want it to diffuse in 1 direction. On the back is a different matter, but for me I would still stick to 1D on the back.

Why?  What about my room means I need QRD? 

If I look left, there is partial half wall'ish "thing" 10' away, and the main wall for the area after that thing is 22' away.  If I look to my right, the wall is 15'-ish away.  If I use the eyes in the back of my head... that's into the kitchen another 20' away.  If I look up... there's another 12' to the ceiling.  It's a "space" as much as a "room". 

Why do I need to focus on horizontal diffusion in a room with hardly any side walls to speak of?  My room... it already sounds good.  I want to hear what I'm missing from the front wall.

What I think I want is for the sound to go "SPLAT!" against that front wall... not be "Directed" one way, but "Diffused" in another, via a thing that gets grumpy if it's too close to something else - like a QRD.  Or, maybe that IS exactly what I need.   

I want to make it BLOOM - with Zero Absorption.  The room does not beed to be anymore "dead" (for now).

Why not have a bloom of diffusion from the front wall?  Why is having horizontal diffusion and no vertical diffusion on the front wall desired... why not have both?  Why is QRD better than the Cylindrical polys from AV Room Service or the "Mr T" from PI-Audio?

I have advice from the designer of the Mr T who says they reason they designed it was because of Open Baffle.  I have info from AV Room Service, with a picture of a tall diffuser behind an electrostatic speaker, who says "everyone is doing it wrong (re: QRD).

If there's guessing, it's also rhetorical... and effective at smoking out experience like yours so I can connect the dots.   Lots of people made different choices... who is right / wrong? 

I wish my wife would go for the Acoustic Fields stuff you did.  It really does look cool. 

Why ask why?  "Why" unlocks stuff.  I have a reminder in my phone that pops up monthly "Ask 5 Why's for Why You're Doing Something". 

Jmimac351
I am not so sure about the image you posted, forget what your eye see you need what is going to work. At the moment sounds like you are guessing, it’s a lot of money to spend on a guess. When I was in my flat before I moved to this new house. I guessed and bought GIK, got it way wrong the GIK stuff was not very effective. I will not be making that mistake again.

If you don’t want to spend too much money, you can do like I did. I bought build plans from Acoustic Fields and make my own, Acoustic Fields are silly money, but they work. Here is a link to Acoustic Fields site. www.acousticfields.com/

I saw that stuff too - thank you!  Unfortunately, I would like to do that, but I don't have time for that, I have to pay for stuff to get done right now.  Also, part of the challenge with this look is keeping it in smaller (24x24) pieces... rather than the longer pieces that "look like an unfinished wall" to her.  I'm trying to balance performance with the aesthetics she will go for.  She has already told me once... "I already told you what I like."

Besides, I'm trying to educate myself... and little by little, my guesses seem to get better.  My public conversation about this, and my "guessing", may be helping others think and learn too.  Many read, few participate.

And then... there's this... guessing... the good news is, apparently I know more than people who get paid for it.

This is a real response I received when I asked for some application advice after receiving a $3k quote.  Some say "Audio is a big fake"... could be, "Trust, but Verify".  And some stuff you just can't make up.  This person is actively soliciting questions from me about my inquiry, multiple responses... is on-point for this.  A complete waste of time / frustrating.  This made me think of "The Bobs". 

You've had trouble with GIK. This response is not from GIK, but the uniformed person who responded from another vendor has hearsay about my design, which my wife likes, thinks this is the ideal layout.  Hey, a clock is right twice a day - maybe it is!

Sometimes finding Truth in audio is a real life Detective story.

Whiskey Tango Foxtrot, Batman.

========

Hi Jim,

I'm the furthest from an expert when it comes to diffusion.
I've heard the configuration shown in your image is most ideal. In my opinion, it's most aesthetically pleasing as well.

[toocool4]

I don’t have the technical knowledge to explain to you why 1D quadratic is better for you on your front wall, you need to do some research on the internet. Or you can just stick to your design.

Talking about distance from the panels, I mean distance from the panels to your listening position not distance to anything else. The design you have chosen in the image you posted needs distance too.