Hi Thomas, my length firing proportion was also to allow bass waves to roll out into the length of your space and become less modal. You clearly need a project 
I have glued panels up on my walls with Gorilla glue and tbh honest making good isn’t to bad, filler/sandpaper and paint is all you need. In fact I’ve made good on my ceiling 4 times 
Good luck with it Peter
Hi Thomas, are those quadratic based diffusers (?) in which case you might need to move your listening position slightly forward. I know you yourself state 2 metres, although literature also states no less than 1.5 metres, but this could of course be frequency dependant I guess, ie the further down the spectrum the more distance is needed…. Best Peter
I have to check if the current system position is really a problem. Especially considering the ~13 m3 of OW-703 fiberglass boards I’ll add.
You’re right diffusion isn’t the best thing to do in “small” rooms. I believe the distance depends on the type and amount of diffusion. 1 or 2 meters… it’s very subjective and based on psychoacoustics. The more the better.
→ https://www.ezacoustics.com/ez-pro/diffusion/ez-1d-clear-diffuser/
Very clever idea in clear perspex though Thomas 
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Wow, that was quick Mark. What have you put inside and what difference are you hearing?ATB Peter
Sorry Peter, that was a bad attempt at humour
There’s nothing in them at the moment, but I think I’ll go with foam … not sure yet what density I’ll need.
Cheers,
Mark
Check advanacoustics out Mark, they do different foam thicknesses 1, 2inches and so forth and are UK based. The white is very easy to cut to size with a knife
Good luck Peter
PS. You can find measurements for the various products on their website also.
I will forward those pictures to the wife and suggest it for the windows of our extension and run a mile awaiting a response 
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Excellent, thanks Peter … did you mean advanced acoustics?!
Cheers,
Mark
Yes sorry Mark
No problem
I like that they give the measurements and graphs, the lower density Acousti-Slab gives higher absorption in the midranges, looks like the one I’ll go for.
Thanks again,
Mark
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Mark. This is what I had in mind although I haven’t used it
https://www.efoam.co.uk/index2.php?shape=Frectangle
Love your idea. The amount of paint is likely to determine how reflective the canvas is so be great to experiment with and with canvases removed just for the interest of we observers Best of luck with it and look forward to seeing the artwork from your daughter
Thomas this entire thread is very interesting and helpful. I have to admire your single-mindedness. Just wondering why you are using the fibreglass rather than the denser Rockwool or are you looking to allow some of the bass to pass through.
Although an American site and therefore in pounds per square foot the relativities are nevertheless valid: have you seen this
https://www.atsacoustics.com/page--Selecting-the-Right-Acoustic-Material--ac.html
Hello John, thanks, I did look at that site and a couple of others. In the end I went with the Advanced Acoustics foam … which was due to be delivered today but looks like it’ll be tomorrow now.
I’ll try to get REW setup at the weekend and measure before and after. It’s been almost a year since I last did it and the room has changed a bit since then.
Should really have done it before ordering the foam … not being very scientific 
Edit: 5 minutes after posting this it turned up 
Cheers,
Mark
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Well Mark, there is no doubt that cladding your back wall with those filled in canvasses, will reduce overall reverberation time in your listening space in mid to high frequencies ATB Peter
PS. Tell your daughter to thin her paints please 
Haha, will do I doubt she’ll do the painting until the new year when she’ll have more time.
I’m looking forward to seeing what difference they do make … hopefully a positive one! 
Cheers,
Mark
Have you got the Roger Waters “Us and Them” Blu-ray to play on that projector?
I was fortunate enough to be able to build my own room from scratch (with the help of an architect buddy who is also an audiophile). For those in a position to do so, I heartily recommend it as the most significant upgrade you can make.
Basics of the room. 1) Minimum of absorption, focus on refraction/reflection. Angled panels behind speakers and on listening wall to bounce High and mid frequencies up to the ceiling and eventually trapped in hanging acoustic panels 2) built in bass trap/ Helmhotz resonators in front corners behind speakers. 3)Vaulting ceiling rising 2 floors behind the listening position. That gives 2 planes out of 3 non parallel. Side walls are parallel but on the first reflection point are the shelves that house the record collection (approx 6000 albums do their own reflecting/refracting and absorbtion). 4) dedicated power circuit
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