[Don_S]

Has anyone tried either of of these or similar products? I do not care about their aesthetics and I know one won't do much if anything. If I got any I would get 4. I would fasten two together and cover with acoustic cloth.

I have OB-style speakers. Would these be good for behind them? Another option is either side of my listening chair. There are two windows behind the chair so they would not work there.

https://www.amazon.com/dp/B0B4PNL343/?coliid=I23K8K10ML2F3H&colid=3BQGYG8VLEG1W&ref_=list_c_wl_lv_ov_lig_dp_it&th=1



https://www.amazon.com/dp/B0BJTYP2Y2/?coliid=I2ZXVM9F7D6TF1&colid=3BQGYG8VLEG1W&ref_=list_c_wl_lv_ov_lig_dp_it&th=1

[AllanS]

I have no experience using them but received this comment from a reputable manufacturer when discussing the use of front wall quadratic diffusers in addition to absorption:
“ our take on QRD is no thanks.  They scramble phase information which tends to
obscure sound stage detail and their energy storage can color the tone.  The
practical effect of this is usually a more blurry sound stage, but with great
continuity across the room.  But I must admit they look cool, and it's not all
bad, just a little more like an omni-speaker experience…”

Since I have Spatial Audio M4 Sapphires this comment was also offered:
“ as much absorption on the front wall as possible below about 300 Hz for
dipoles gives a glorious presentation.  But you always want to be mindful of
keeping the treble range lively in the same area…”

It probably comes as no surprise that this mfg doesn’t offer such diffusers and we weren’t discussing rear wall treatments.
 
I also found it interesting that Real Traps offers far and near versions for rear wall applications depending on listening position proximity to the rear wall.  https://realtraps.com/diffusor.htm

[Don_S]

Thanks Allan. Useful information. I am thinking any "experiment" is going to be expensive. I think the Amazon units might be too shallow. Real Traps would probably cost close to $300 to ship a pair to the opposite coast.

[AllanS]

I am thinking any "experiment" is going to be expensive.

I’m learning this the hard way.  Some accept it as part of the hobby while figuring out how to minimize losses.
Knowing I’d have a low tolerance for the cost of experimenting, and given the chance to do it over again, I’d consider treatments second (after speakers) and invest time with REW before the first round of treatments.  I’d understand what my room needed first and take improvements in steps.  As it is, I threw treatments at it and hoped for the best.
Fortunately I think it’s fixable by adding to rather than replacing, but I’m being a lot more careful and selective with the second round of treatments.

[Early B.]

Whatever you try is a crap shoot -- those panels will either sound better, worse, or do nothing at all. I recently contacted an acoustics manufacturer to inquire about what I needed for my front wall and the response was nearly every product they offer. Some people say absorption is best, while others claim diffusion is better up front. Then there's the first reflection crowd, the no-treatment crew, and let's not forget the "get as much as you can" clan. I suppose the answer is: "there's no right answer." Seems like you gotta spend a lot of time and money to experiment.

I've always wondered what would happen if an audiophile hired an acoustics professional to analyze their room and recommend the number, type, and placement of treatments. Might be cheaper in the long run assuming the pro knows best (which isn't a certainty).

   

[Glady86]

  At least for GR Research open baffle speakers, my understanding is the general consensus is diffusion behind the speakers or front wall. Bass traps in corners, and absorption for the first side wall reflection point as the main starting points. Going further than that may or may not be worth it.

 Too bad companies like ATC don't offer try before you buy to promote their products. Though shipping costs are what kills that idea. I think the cheap Amazon diffusers may be returned if you don't alter or drill holes in them. Juat stack a pair on the floor in the area behind the speakers and experiment with the location a little and see what it does.

 Also, I'd try the cheapest type, the basic QRD not the 2QRD. More expensive versions from GIK etc. are deeper and diffuse a broader range of frequencies. Ive seen some as deep as 8 inches on eBay.

[Don_S]

I had two similar experiences. I sent room dimensions and pictures to one well-known acoustic treatment company. They pretty much recommended every product they make.

At an audio show I attended a demonstration from another company that shall remain nameless to spare their shame. The room had an outside patio or balcony filled with treatments. The manufacturer brought in a couple of devices at a time proudly smiling while they were installed. After a while I could not hear any improvement with added treatment. Eventually every free space was covered save for the door and light switch.

A young woman asked what was most important and what to treat/add first. She asked the question 3 times with mounting frustration because the answer was always the same "everything is important". The woman was dressed well above average for an audio show. I could envision her living space also being tastefully done and not overburdened with acoustic treatment devices. I am not as well put together personally but I still value an attractive listening space.

I remember the episode vividly because my question was the same as her question. What do do first? I bet most of the attendees had the same question. At the end of the presentation I walked out dejected, feeling like I had no useful information and had wasted my time. Talk about a tone-deaf company. 

[Glady86]

  At least for GR Research open baffle speakers, my understanding is the general consensus is diffusion behind the speakers or front wall. Bass traps in corners, and absorption for the first side wall reflection point as the main starting points. Going further than that may or may not be worth it.

 Too bad companies like ATC don't offer try before you buy to promote their products. Though shipping costs are what kills that idea. I think the cheap Amazon diffusers may be returned if you don't alter or drill holes in them. Just stack a pair on the floor in the area behind the speakers and experiment with the location a little and see what it does.

 Also, I'd try the cheapest type, the basic QRD not the 2QRD. More expensive versions from GIK etc. are deeper and diffuse a broader range of frequencies. Ive seen some as deep as 8 inches on eBay.

Woops, I tried to modify my response not qoute it.

[Glady86]

 I bought the BXI QRD diffusers from Amazon, they only cost 70 dollars a piece. I've seen similar diffusers to these for over 300 dollars. 

[Big Red Machine]

https://www.subwoofer-builder.com/qrdude.htm

Kinda need to know what you have and what you need to target a solution.

[AllanS]

I remember the episode vividly because my question was the same as her question. What do do first? I bet most of the attendees had the same question. At the end of the presentation I walked out dejected, feeling like I had no useful information and had wasted my time.

I hear ya.  More than once I've seriously wondered if I wouldn't be better off bagging the whole thing and just buying a nice headphone system instead.  The wife would certainly be a lot happier.
But instead I've been binging on acoustics/treatments related video and such.  Most are informative and I think mostly noncontroversial.  I suppose they're all intended to guide you to their products but if you follow them their natural conclusions 75% of your room surfaces will have some contraptions hung on them.
This vid from acoustic geometry is a pretty good starting point https://youtu.be/akiWq97dSBA
This ASC page shows you their progression https://www.acousticsciences.com/hifi/

It adds up very quickly.  But I have to admit that I hear very little difference in the gear that I swap in an out of the system.  Some of that is probably my inexperience but I'm also banking on some of that being room limitation.  I'll put a few more $$ into the room.  But if I don't hear differences - mainly in sound stage - I'll save a bunch in future gear buys that I won't make.