Sound diffusion panels--do they reduce brightness?

My listening room is still a little too bright
The doors behind the seating area have 2 absorbing panels. It has been suggested that adding 2 diffusion panels in this area of first reflections will cure the brightness. Does anyone have experience with these diffusion panels ?
IME no. Looking at your room, your speakers and seating position are well away from room boundaries. I would look to a change in amp or cables.
Doors are closed behind sofa now. Amp and cables just upgraded
If your room is bright, changing amps and/or cables is not a solution. Although you have bass traps and an open space behind the listening position (all help), your room still has a huge amount of reflective hard surfaces, especially at ear level and above. Adding wide-band absorbers at the first reflection points is a great first step. If that step is subjectively effective, consider more.

IME, yes. I have used both the rear panels and those at the first reflection points. Speakers are well away from the room boundaries. I have also used the free standing Furutech panels. The latter can be moved around and give you some idea of what improvement can be made at different locations. I use one directly behind each speaker and in the center between the speakers. I use many different speakers and amps and have found the improvement using the panels not matter what the 'chain' is. Getting room treatment right takes time and effort. I've use EQ wizard software to do room analysis and that helped me 'see' what I was hearing.
Adding absorptions and diffusion at the first reflection points will help reduce image smearing, better anchor images, increase sound stage, and detail ... but do little to reduce the brightness

The cause of the brightness is ... Long RT60 (decay/reverb) times ... when a note is sustained too long ... it's extended ringing will be irritating and fatiguing and be precieved as brightness

In addition to Long Decay times (RT60s) ... Echo Slap and Comb filtering can also add additonal high frequency ringing to the problem

The easist thing to do is visit Ethan Winer's "Real Trap" site and spend the weekend reading and watching some of the videos on the subject ... this will give you the complete picture

Ethan has made it very simple in plain language any one can understand
Two other issues are the equipment and the recordings. You didn't mention the make and model of speakers or the other equipment involved. The reality is the current fashion for a lot of audiophile gear is to sound bright. That's not meant to imply everything out there is bright, but the odds are not unfavorable.

I imagine you intentionally chose the gear you have now so I presume it sounded correct to you at some prior point. You might want to compare that previous environment to the one you're in now.

Recordings are also often bright. Close miking and the generous use of EQ and other effects are very common. Even classical recordings are not immune to this issue. Does your brightness problem occur with all recordings or just some?

The tonal balance of my system is just where I like it on an overall basis, but my biggest frustration these days is the variability in recordings. It never ceases to amaze me how many releases are poor and artificial sounding.
Before you do anything try toeing the speakers in so they are firing at a point in front of your head, say 2', this will reduce side wall reflections and give you a good idea if the speakers are positioned well. You may find you need to be closer to the back and/or side walls for low and mid reinforcement/balance. In the pictures of your room the speakers look far from the back wall this might be accentuating the highs. Try turning off the back firing tweeters first and after listening turn down the level of the main tweeters. I'd start with speaker position before spending more money.
Lovely audio room!

FWIW, your room is very similar to mine, size wise and set up wise, as were your problems for years until I got venturesome. Along the lines of Samhar's suggestions but going further, I relocated my speakers which both increased the size and specificity of the soundstage and minimized the first reflection problem from the side walls.

Try moving your speakers toward the side walls until you have a nearly triangular set up (mine are 9ft apart, chair is 10 ft back). Then toe in your speakers until the axis of the speakers cross well in front of the listening chair. Adjust to taste from there. BTW, I use a test record and a SPL meter to help find the best speaker/chair positions to smooth out bass response if I detect a problem.

Invest a couple of hours in trying it. You might be surprised. BTW, location of the chair and speakers from the walls behind them can be critical to the overall tone in both the bass and the highs, especially the chairs location. And, FWIW, I have found no need to introduce audio oriented diffusers or absorbers to obtain a very credible result.
What Samhar said.
Davehrab's advice is perfect...I treated my room after visiting this site and made the acoustic panels to Winer's specs...really works well...BTW I have on panel ceiling mounted just in front and above the speakers. You also might want to consider tube amplification. Happy Holidays! You have a beautiful looking house.
Beautiful looking room! Are you still using the same APC power conditioner for all your gear? I might suggest running your amp direct to the wall first, then if the brightness persists, try doing without the APC or replacing it.
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Have you tried playing test tones to see which frequencies are the most offending? Sound quality and timbre are usually affected at about 2kHz and higher.

Try moving the ottoman that sits between your chairs and the speakers out of the room or off to one side. It looks like it could be leather which may be a hard enough surface to reflect high frequencies to your ears thereby adding to the bright sound.

Pictures on walls are typically hung such that they reflect sounds downward because the top of the picture is farther from the wall than the bottom of the picture. Try placing a tennis ball or block of wood at the bottom of the pictures to angle the picture upwards to reflect sound away from your ears.

Speakers have too much treble, or too little bass – a hot tweeter and/or too little bass will create an exaggerated HF thereby throwing the timbre balance off. Try listening to your system using different speakers to see if the speaker’s sonic balance, cross-over or speaker resonances are at fault.

Direction of reflections – front and rear wall reflections are less advantageous than lateral side wall reflections, so absorption on the front wall improves image localization and reduces colouration whereas diffusion on the back wall helps create listener envelopment. You might consider closing the drapes across the front wall window and adding thick absorption (6” thick minimum) and add diffusion above the back wall absorption panels. Also interesting to note is that ceiling reflections affect timbre while side wall reflections affect spaciousness; looks like your ceiling is bare and therefore could stand some 1st reflection point treatment.

Longer low frequency reverberations help add ‘warmth’ to a room or hall. I guess in theory you could remove your bass traps to lengthen the bass RT60, or better yet keep the bass traps and add higher frequency absorption (e.g. at ceiling 1st reflection points and/or scattered along the side walls) to shorten the RT60 of the higher frequencies.

Let us know how you make out . . .

Wow lots of good ideas. Will get working on the suggestions this weekend
I did try some other speakers with the same brightness issue. The midtones and bass are good.
Here is something you can try to determined if you have an equipment issue or the brightness is being generated by the room

Warm your system up and give a quick listen to one of your reference CDs that you are very familiar with at your regular listening position (sweat spot)

Now replay the same tracks but go into the room in back of your listening room/chairs and give another listen

If my guess is right when you go into the room in back of your listen room ... the brightness will be greatly diminished because you are not sitting in the direct reverberant field that is aggravating the problem in the main listening position

By going into the other room and listening you remove yourself from the extended/sustained ringing in your main listening room that is being caused by the long RT60 times, Echo Slap, and Comb filtering

If your system still sounds overly bright when listening from the back room ... then you have an equipment issue because you are no longer being effected by the room's anomalies when you are listening from the back room ... it is the equipment that is generating the brightness ... metal dome tweeters ... tube in the pre amp fading or poor match ... etc etc etc

If when you listen from the back room the brightness is greatly reduced then

1 I know What the problem is
2 I know What's causing the problem
3 I know Where the problem is occurring
4 I know how to fix it and your significant other will never realize the you've applied some new room acoustics

Please let us know the results of your listening tests
Get that ottoman out'a there for starters!
Davehrab wrote: By going into the other room and listening you remove yourself from the extended/sustained ringing in your main listening room that is being caused by the long RT60 times, Echo Slap, and Comb filtering...

Not true. You are still hearing all that but with a very different perspective that affects the timing of those elements and, in fact, superimposes the filtering of the transition to the other room as well as the acoustics of the other room. May be informative but it is not unbiased.

I agree with 4est. Your ottoman is leather which is a reflective surface in close proximity to the listening position.

Before treating your room you may want to take a close look at your system components. You may have one or more components bordering on lean or thin sounding.
remove the ottoman? so where would I put my feet? where do you set the drinks? couldn't I just wrap it with a fur blanket? sound diffusion panels installed this weekend but not enough time to test results. Speakers have been moved back to be flush with rack and turned in some. will drag out the test cd and spl meter to plot a new graph of room response. more drapery panels added. Doing all this and trying to keep the WAF in check is a huge task.
Keep in mind the point of listening to music is enjoyment. For most of us, it should not be an exercise in deprivation. Leave the self-flagellation to those working on the fast track to sainthood.

What can be useful is to simply experiment a bit. A few inches this way or that, or the addition of a throw or other covering may offer the improvement you want without major decorating surgery.
Beautiful looking room! Are you still using the same APC power conditioner for all your gear? I might suggest running your amp direct to the wall first, then if the brightness persists, try doing without the APC or replacing it.

Are you suggesting that the power conditioner amp connection could be causing the brightness???
I would first try to identify the source of your problem--is it the room, or is it equipment related? Try setting up the system temporarily with the speakers somewhat away from the walls and your sitting position fairly close to the speakers (say 5-6 feet from the speakers). Experiment with the exact position to get the best sound possible. In this position, you are listening in the "near field" (position where the direct sound from the speaker is predominant so the room's contribution is diminished). You are now listening to your equipment moreso than the room. If the system sounds worse this way, you probably have equipment issues. If it sounds much better in the near field, you have issues with the contribution from the room.

I have generally found that it is too easy to go overboard with room treatments, and very few treatments, apart from major room rebuilds, look decent. That means you should take things slowly. First, experiment with correct placement of the speakers. You can make huge changes in the sound just by using different placement (distance from back and side walls, toe-in angle, backwards rake of the speaker, etc.). If you want some kind of systematic approach to finding the rough placement spot (experimentation is ALWAYS required to find the best spot), google the Sumiko method or Wilson method for two decent approaches.

Next, I would try very modest "treatments" that won't send your significant other running from the room. Look for nice tapestries to hang on the back wall (behind the listener) and for the side walls. This is usually enough to significantly reduce slap echo brightness without dampening the life out of the room. Experiment with a blanket or comforter, etc. Again, go slow and give yourself time to adjust and experiment with each addition/placement choice. Bookcases/cd rack/record racks along the side walls can also help to act as diffusers and rooms with such lining the sides usually sound pretty good.

If you can, either remove or cover the big ottoman to reduce its impact on the sound. A big reflective surface between the speaker and the listener is usually a major detriment to proper imaging, and if it is highly reflective, it can also contribute to bright sound.

Good idea on the near field setup first. Will try that tonight. Will also play around with the ottoman dampening test. thanks
Get rid of that chandelier !!!! Seriously, will that make a difference? I too have some glass fixtures almost directly over my top firing OHM I's Ive always wanted to ask this. thanks. Mike
Ranger..... are you trying to get me killed? WAF alert !
Tell her you think its possessed!
Hi Blueskies,

Have you solved, or at leat diagnosed, the problem with excessive brightness?
I have added 2 diffusion panels and the doors behind the seating area. They have helped but I continue to move my speakers around and am still testing various positions. This is difficult to do by oneself. My music club will be here next week so 4 other pairs of ears is always helpful.
It looks like you are discovering one of the most annoying "secrets" about audio. It can literally take years to discover the ideal placement of speakers. Results are quite unpredictable, and shockingly small movement can have BIG sonic consequences.

When using the "Sumiko Method," sometimes moving the speaker an inch in one direction will significantly alter the bass balance of the speaker. This is both frustrating and positive (gives one hope of finding a really good location).

just keep plugging away.
Upgrade your components.
I just did
Blueskiespbd - have you an update on your "brightness" problem?

I added a QRD diffuser to the side wall to treat the 1st reflection from the main speaker on the opposite side of the room which reduced a bit of HF glare while improving musical details. So, using a miror I found the spot on the left wall that is the 1st reflective spot of the right main speaker and vice versa for the other side wall, and placed a 2ft wide diffuser there at ear level. Worked well as would a thick absorbing panel. You might try it.
I added 2 RPG Diffusers behind the listening area and 2 absorption panels there also. The room is now tame and sounding most excellent.