Absorption, Diffusion or a combination of it all?

@ozzy that’s regular tri traps. Ones I was referring to and what I bought were with range limiter…Based on my listening tests, the description on GIK site is accurate

• RANGE LIMITER – with a membrane, bass traps absorb even lower frequencies while the membrane has less effect absorbing upper frequencies

The range limiter is an option you can select when ordering.

audphile1.

Here is what is described on the GIK website about the GIK Tri Traps.

"Effectively designed to absorb more low end, but also does an excellent job of absorbing the high end, creating smooth sound absorption from 50 Hz to 5000 Hz."

Based on this description and what the dealer claims, these would also not work well with the Planar speakers.

ozzy

I like these GIK Tri Traps with range limiter so far. Didn’t suck up the bass. Just improved its definition. Ozzy may be these will work with the planars. Worth looking into. 

JL makes great subs, in particular the room correction is outstanding. 

Anytime you work with bass traps or any absorber you are changing the tonal balance somewhat.  Excess bass trapping makes speakers sound lean, while an excess of reflections make the system sound bright.  Tuning a room is a balancing act. 

Also, check out the AM Acoustics room mode simulator.  Try to keep your speakers and listening location away from the lowest room modes if possible. That is a great first pass at tuning your room.

erik, jaytor,

Thank you for the help. The planar speakers that I am thinking of getting claims they go very deep and do not require subs. But I question that..

And the dealer recommends not using the ASC tube traps. He claims they will absorb too much. 

I do have (4) JL F-113 subs in the room.

ozzy

@ozzy - are you planning to use subwoofers with your planars? The bass generated by dipole speakers is a lot different than a typical box speaker since it doesn't pressurize the room like a box speaker. In my opinion, this results in more natural sounding, and very nuanced bass. 

A dipole speaker will have nulls in the low bass response to the sides of the panels since the front and rear waves cancel at that point, so the side to side and floor to ceiling room modes are not excited the way they are with box speakers.

I am using DIY bass traps that are similar in construction to the Tube Traps and I have found the bass to be very articulate and natural sounding. But in my room with my system (dipole woofers that reach down to below 20Hz), I haven't found that the bass traps make all that much difference. They do smooth out the bass a touch, but it's a fairly subtle effect. Using REW to measure the room response, I don't see a huge difference (although the response is a bit smoother with the bass traps).

It's possible (maybe even likely) that the ASC tube traps work a bit differently than my DIY solution, but I'd give them a try before making any decisions to change things. 

Hi OP,

I think bass traps aare great. My concern is specific to ASC tube traps that when I heard them they seemed to impart a very specific character to the bass, which traps should not do.

As I went from room to room, the rooms treated by ASC with tube traps all sounded the same, in a bad way. Like no matter what music played the drums sounded EXACTLY the same.

Imagine Duran Duran and a symphony orchestra sounding like they played the same drums.  Hopefully you don’t suffer this issue.

erik_squires,

I just have always had them in the corners of my room. It's a basement system so I thought they would be appropriate.

So, you don't think they would be good then with Planar speakers?

ozzy

I’ve heard a lot of ASC tube traps at shows, many of which set up by ASC, and while effective, at least in my experience they have a kind of "sound" to them. They turn a room into 1 note bass. Like all the music sounds the same in the bass.

I’ve not had that issue with other bass traps, and your mileage may vary. 

jaytor,

Thank you, you have been very helpful.

ozzy

@ozzy - I'd leave the tube traps in the corners. I like the ATS QRDs. I wrapped these with Guilford of Maine cloth and they look quite nice, but you might prefer the wood look. See my virtual system page to see how they look with cloth wrap. I have 4ft wide floor to ceiling diffusors behind the speakers. 

I think the Vicoustic Multifusors are also pretty nice if you prefer the look. These are deep enough to provide fairly wide band diffusion. 

jaytor,

Thanks, some good advice. Should I also remove the ASC tube traps?

What type of diffusors do you recommend?

ozzy

@ozzy - I'd recommend trying the planar speakers with your current room acoustics setup to start with and see what you think. I've found that I prefer diffusors behind my dipole speakers without any absorption, but every room is different and some people have found they prefer absorbing the much of the backwave. 

After getting them set up, I'd try removing the Stillpoint panels behind the speakers and seeing if you like the sound better. If so, this probably points to switching to pure diffusors.

I’m considering Planar speakers. Any recommendations as to room treatment? Right now, with my Focal Sopra 2's I have ASC bass tube traps in the corners and Stillpoints Aperture ll’s in the center, 1st and 2nd reflection points.

I know Planars will have different room acoustic requirements, any help in that regard would be appreciated.

ozzy

So the best combo seems to be the corner tri traps(range limited) and the 244 panels behind the speakers with 242 treating first reflections on the sides.
Cloud/ceiling panels on the way. Will post an update once installed.
Updated system photos. 

Going back to the original discussion…a follow up…

Got the first pair of Range Limiter TriTraps. Replaced a pair of 244s that were used as bass traps with Tri Traps. Moved the 244s to the first reflection points on side walls. There’s a very nice improvement in bass definition, texture and details. I’m also hearing better clarity in the mids and highs and I suspect it is due to the way the tri traps mitigate standing waves.

GIK ships out as they manufacture the panels. Still pending - two more range limited tri traps for the upper half if the wall, two more 244s that will cover the first reflections on the sides and allow me to hang the existing pair of 244s on the ceiling. 

I’ll post more updates as I introduce additional panels. 

@tsushima1  Good point.  It's difficult to tell what was "intended" b/c so many recordings are in the studio and then what was 'intended" is up to the engineer--and if the band/artist doesn't like it then you get later remasters if the artist becomes important enough.  But @pedroeb has a point with live music and when i approached room treatment it was from that perspective--tame some room issues b/c our rooms are never as big as even a small venue and there are reflections and mostly bass issues that have to be dealt with.

@pedroeb 

“ Perhaps I'm a purist. I want to hear the recording the way it was produced and intended to be heard.“

In a recording / production studio invariably packed with wall to ceiling room correction treatments you mean ?

@wyoboy

Those diffusors are $500 for a pair. I bound them together with zip ties and then got the hanging hardware on amazon. The engineers at sonitus give free consults, just call them, np. 

https://www.sweetwater.com/store/detail/PSSC22--partscience-spacecoupler-2-pack

@kota1 That window of mine behind my speakers has been my biggest worry in the room but i went the other route--electing to absorb the sound b/c i was afraid of the highs being emphasized--never occurred to me to go the diffusion route--how much did that "cloud" diffuser cost?  I might have to try that as it looks about as big as my window.  

Found it interesting that Sonitus feels a mixing room is the same as a 2 channel listening room--might have to ponder that -- seems plausible unless the mixing room is also where the player(s) are and then you would think they would generally go for diffusion to mix into the recording rather than absorption to tame reflections.

@wyoboy

Yes, the acoustic lens is the squarish thing. I had the vertical blinds long before I had the acoustic lens diffusor, they don’t do anything. I got the idea to hang it from a recording studio that had the same issue and had the acoustic lens hanging and it did the trick. You'll see in the pics I also have a "cloud" of acoustic lens hanging at the rear of the room below my PJ. All I did was follow Anthony Grimani's acoustic recipe. Here is a link to the various diffusors I use in my setup:

https://www.oeler.com/pdfs/Sustain-Data-Sheet.pdf

@kota1  I'll check out their site-thanks.  Interesting that acoustic lens over the window--is that the squarish thing that seems to be hung over vertical blinds?  If so, can't help but wonder if the verticals all by themselves could have acted as an "acoustic lens" similar to the way i played with the blinds on the window behind my speakers.  Have you ever removed it and heard the difference ? 

Although i only spent a few hours on room treatments i will admit that i started down the rabbit hole by reading Jim Smith's book,  "Get Better Sound" and then booked an hourlong phone session with him b/c i had several questions on material in the book as well as idiosyncrasies in my room with doors--he was quite helpful but also urged me not to obsess beyond dealing with a few important things pertaining to my room.

@wyoboy 

The setup is the same for both 2 channel and HT, Look at the room kits at is website and you can compare both setups. I have a large windo to the right side of my MLP and I hung a diffusor called an acoustic lens which allows the light to pass through. You can see a pic in my profile system. You will see that the room kits are determined by the size of your room

Here is the layout for 2 channel (they also have HT):

https://www.sonitususa.com/product/studio-acoustical-systems

@kota1 -- thanks for the video--i only watched starting at :49 but it seemed to me the discussion was more pertinent to home theater setup (which you have) rather than 2 channel setup (or 2.1).  Can't help but wonder if his "formula" is based on having center and side/back surround speakers in the mix and thus maybe overdone?

As for diffusion v absorption behind speakers as w anything it depends--in my room i have a large window behind my speakers and, therefore, opted for absorption (of high/mids) behind the speakers with a curtain rod and heavy drape and it worked well.  When i slide the drape out of the way and play with the the wood venetian blinds of the window (as a diffuser of sorts?) it produces an interesting effect that is not displeasing but seems to de-focus the soundstage.  

Someone above said smaller rooms have different challenges than those addressed in the video and are more challenging. I fall into the wolf garcia crowd of just doing a few things (bass trapping), first reflection and aforementioned absorption and then just enjoy the music (although admittedly i measured frequency response in every part of my room first, mainly for speaker placement and knowing where the bass was emphasized--which, surprise, the usual corners)--i only spent three or four hours total and I'm happy.  As someone else said above, unless your room is really problematic don't obsess over treatment tweaking.

Taking time to research. I’m using the panels that I already have to experiment. I’ll play with REW soon. We’ll see what it does. 

85 decibels is a sound level equivalent to that of a food blender. Uncomfortable and only tolerable for a short time. Most listening levels might not even be that loud.

Having said that, peaks can still get fairly high above the general listening level, so treatment is still wise.

Maybe not as important, but crucial.

If most listening is below, say 85 db, are room treatments still as important?

Having a good mix of absorption and diffusion is certainly essential. Also consider DSP based room correction technologies which operate in the time domain. Dirac Live helps listeners correct for one of the weakest components in the audio chain, the listening room. Dirac Live not only corrects the frequency response, but also the impulse response of the loudspeakers in a room, yielding improved imaging and timbre, better clarity, tighter bass, and less early reflections, as well as reduced resonances and room modes.

Please check out our Tech Blogs at Deer Creek Audio

Deer Creek Audio is an authorized miniDSP dealer

Love this topic as it’s not as common but extremely important.  Working with the folks at GIK (or other acoustic expert) is key.  REW has been a very helpful tool along with my ears, and the USB mic was a worthwhile investment as I’ve used it multiple times over my three year journey in treating my room.  I cannot recommend it enough. And the GIK folks will use those REW measurements to help diagnose your room and suggest treatments.  My listening chair is only 2’ off the back wall so pure diffusion wasn’t recommended.  I’ve read elsewhere that pure diffusion on the back wall isn’t beneficial unless your listening chair is 6’ or more away from it.  GIK  instead suggested their combination diffusion/absorption Alpha series panels, as I had low frequencies that needed to be tamed along with me trying to make my room sound bigger,  My last and final addition was adding 3 x Q7D diffusers to the front wall and a pair of wall hung monster bass traps directly behind the speakers.  My small square room has never sounded better.

I see advice all over the map here yet nobody condsiders the size of the room? It's not one size fits all!

OP, diffusion is great but unfortunately not of much use in a small room simply because you need to be seated a minimum distance away for the effect. Situated close to your ear will just not do.

My suggestion is to at least heed the advice to measure the room yourself. That way you can ignore the noise being made about creating a room that is dead.  It has been mentioned to get GIK to 'analyse your room' and then buy their products. Well they are in business to sell stuff and will, as has happened to some I know, oversell if you keep buying. 

To measure: Install REW, it's free

Buy a microphone: for the cost of a dinner.

This will provide the tools to achieve the ideal response in your particular room. Tables online will supply the target time required for the sound to decay, across the spectrum by a certain amount, this amount also found in the tables.

What I can assure you is that with the confidence you gain with understanding the requirements for treatment, and can measure any changes from adding traps or panels, will be the biggest step towards an immersive and realistic sound. Ideally the treatment will essentially largely remove your room's sonic imprint and transport you to the venue.

No electronic component exists that could correct the acoustics of a room regardless of cost. The recommendation to 'just get DSP" to sort out the problems can not sort out the damage that strong early reflections cause. How can any electronic gizmo know how much decay to apply and at which frequencies to apply it?

Should you hire 'professionals' to do an installation you can of course measure the results to ensure they do not reduce the decay time beyond the recommended time, which is generally 300 to 400ms. Overdoing the absorption is what renders the room being too dead. You newfound skills will allow you to prevent this.  It will also help you find the best position for the speakers and a sub or three.    😀

The subject is fascinating, understandable and most importantly, essential for great sound. I repeat:  No $5000 cable nor $10000 amp can do anything to tame the elephant.   But you can  😎

Experimented today with all the panels (GIK 242) except bass traps leaned against side wall at first reflection points. It helped with better focus, imaging was more precise and the soundstage deeper and wider. Front wall was bare. 
I think it depends on the room size. Diffusion may work combined with absorption in my small room. If the room was larger it’s possible the diffusion alone would be fine. Not sure. I’ll need to try. So far I think Mike Major is on point with absorption. 

Floyd Toole did listening tests to determine if listeners preferred absorption, diffusion, or bare wall at the first sidewall reflection point. 

Diffusion and bare wall were the most preferred....with absorption by far the least preferred for sidewall first reflection. Going off memory only like 14% preferred to absorb sidewall. 

Why do so many people recommend absorbing sidewall first reflections? It has to do with pro-audio rules of thumb and advice given by acoustic product companies such as GIK.

Pro-audio wants as much direct sound as possible, to take the room out of the equation....basically a headphone type experience with speakers so their mixes with translate. 

Hi-fi uses the room to enhance the experience. That's why we don't listen at a desk or shove our speakers up against the wall. 

Having said that, very close sidewall or close behind our head reflections can be very destructive and smear the sound...as long as we have some space though, our genius brains can sort out the direct sound from the indirect sound and we get this really nice ambiance or reverb without the smearing.  

@jpan , @audphile1 Thanks for your feedback.

I got an email chain going with Mike Major of GIK. His recommendation based on information and pictures I provided is to fill the side walls up with at least 5” thick absorption panels all the way to the level of listening chair and go as thick as possible with bass traps on the front wall. 
 

I’m evaluating all suggestions at this point as I continue the researching. 

As with everything else in this hobby, it takes a lot of experimentation to get the best results. You can get a head start by hiring an experienced acoustician to come an evaluate your room and provide recommendations, but your personal tastes need to dictate the final solution. 

It's relatively easy and inexpensive to experiment with absorption since low cost fiberglass or rock wool panels can be purchased from your local home-improvement store (Lowes, Home Depot, etc.), or you can just use spare blankets, pillows, quilts, etc. 

Diffusion is a bit more challenging since good diffusors are somewhat costly. I haven't found the cheap diffusor panels to be that effective.

But once you get it reasonably dialed in, acoustic treatments provide a LOT of bang for the buck. 

@Gordon

Yes, that was my experience. Mike Major was the guy that helped me. I submitted all my stuff. He replied right away that he was stacked up and would need some time to review. (I liked that b/c he set the expectation up front.) He wrote a fairly lengthy set of recommendations and comments. I was impressed.

I wouldn't have posted if I wasn't so pleased.

Maybe you could try again and/or call them.

Does GIK really do an assessment of your listening environment?  I modeled my room on their site, uploaded photos of my room, and uploaded REW measurements.  All I got was a generic response that did not include anything related to the specifics of my room.

You can reach out to GIK directly and they will do an assessment of your listening environment. GIK has an online form that you fill out and you can include photos of your room. I had tried doing it on my own, by tackling first reflection points. But when the analysis came back one of their techs came back with a detailed analysis and set of recommendations that included some of the things I had and then went further, like a pair of 4A Alphas Series Bass Trap Diffusor/Absorber -- which are amazing! -- that go "on" the front wall, behind the speakers (though not directly behind.)

Anyhow, to me, that is the way to go. Reach out to them and see what an expert says.

The peg board proves my point.  😀

....meanwhile...  may as well dance....

All or nothing, all the time.  Twas' always thus.

One finds the balance one wants, some luckier than others. *S*

Enjoying the hunt is what counts....

You will need absorbers and diffusers for certain. Just look at my house of stereo. Too much work involved to put it in a post and it's all room dependent anyway. Keep at it, you will make mistakes, persevere and you will be glad you did.

@erik_squires 

Hi Erik. That is mostly correct. My room is right on the edge of small to medium so my acoustician designed it to sound bigger than it is. There is no drywall in the room. The walls behind the speakers have Rockwool in between the studs and 1/4 inch pegboard over the studs so there is probably some reflection there. All the other walls have Rockwool then pegboard then a layer of 2 inch rigid fiberglass over the pegboard. The ceiling has Rockwool in the joists and two layers of pegboard and 2 inch rigid fiberglass. The outside of the room is 1/2 inch drywall then a layer of mass loaded vinyl then  another layer of 5/8 inch drywall. All cracks have been caulked. I put some pictures on my systems page. I have been very happy with the result. I enjoy having people over with more listening experience than I do to critique my system. 

i beg to differ on an all absorptive room sounding terrible.

Really?  You have a room that has no reflections, and is 100% covered in absorption materials?  @ronboco 

Perhaps I'm a purist. I want to hear the recording the way it was produced and intended to be heard.

Compressed and with a sizzling treble for ear buds/car radio playback? I think a lot of recordings are engineered with the lowest common denominator in mind.

@audphile1 

I would suggest a consultation from an acoustician. Jeff at hdacoustics is very good. Duke LeJeune recommend him to me. He can analyze your room for you. He designed my room and it turned out amazing. Good luck !

@erik_squires 

i beg to differ on an all absorptive room sounding terrible. I think it depends on the room. My room was designed by an acoustician and I built it. I would love to have you over for a listen. I think it will really surprise you. If you are ever in Colorado and would like to check it out let me know. 
 

Ron 

@jaytor

Yes, I tried many combinations, including nothing at all. I found that absorption (and bass traps) behind the speakers along the full length of the front wall presented a most realistic presentation: most detail and clarity with realism. Without as much absorption, the sound was more robust, but unrealistically robust, and slightly muddled. Depending on your amplifiers, etc, less absorption may be better in your system.

@redlenses03 I spent quiet a bit of time dialing in speaker placement. I’m sure I can squeeze some more out of it when the room acoustics are dealt with. 
Need to look into REW. Haven’t had the time yet. 

If you want to hear a recording in the most ideal conditions

go outside when it is quiet-for some impossible- and set up

your speakers and required gear. 

Your eyes will pop out !!!

You may move to a warmer climate too!!