I’m looking for some diffusors to put behind my big Maggies. Anyone have any suggestions for best option?
The best bar none are the GIK Acoustics Polyfusors. They are designed specifically for dipole speakers like the Maggie‘s.
Four of them are required and the cost is quite reasonable. They’re placed at the acoustic corner stacked one on another each side of the back wall behind the speaker. The acoustic corner is about 6ish inches from the physical corner. This depends on the overall with of the room as to where the acoustic corner precisely sits.
I bought mine with up-rated beige fabric and they disappear into the wall.
Since the speaker box is the room for a dipole speaker… look at acquiring two 2‘ x 4‘ bass traps for the ceiling. This made a very significant improvement in overall bass response. The long bass waves bounce in return towards the speaker canceling out bass in the 70Hz region for an 8’ ceiling.
Not strictly diffusors but I used the GIK Tri-Traps linked below with the “Range Limiter” feature to reflect some high frequencies from the back wave of my Sanders 'stats. These work great as bass traps and provide some reflection. For diffusion I used GIK’s diffuser/absorber panels also linked below.
There’s another topic that discusses diffusors over here:
This is of interest to me.
Would you mind clarifying what you meant by stacked “one on another”…?
Maybe you can indulge me with a picture of one side of your front wall?
I have been looking to “treat” my front wall and these might be just the ticket.
Couple of notes here. My room is 17x30. Carpet over cement w heavy suspended ceiling tile about 8’. The room is very dead. Very quiet. Would the polyfusors add to that as I’m trying to avoid more absorption and create a more lively sound. I do have 4 GIK 244s right now. None behind the speaker as I believe Maggies love diffusion
I can take a picture when I’m back home. The polyfusors come 2 to a box with each one about 3’ 11”. One stacked on the other is nearly 8’ high to fill the acoustic corner. One additional stack of 2 is needed on the other side as well.
The full room treatment recommended by GIK cost $1450 about nine months ago.
The room was sheet rock walls with carpeted floor and a sliding mirrored closet in the back. Performing the slap echo test by clapping your hands, the sound was ear splitting. Now the room is beautifully acoustically balanced and still has a liveliness to it, and not overcompensated. The whole family now likes to hang out in that room for doing whatever they like such as reading or watching TV because of the acoustics.
Also everybody wants to listen to the hifi more than they did before.
Ah, that makes sense.
@scotte1 Here’s a pic of the polyfusors in one of the corners. Also along the side wall is one of the single axis diffuser/absorbers. It’s twin is on the other side.
I get in now, thanks.
It looks like the polyfusors could more or less “disappear” if I choose the right color and place them carefully.
Food for thought…
[PS: is the placement based on the where the corner of the room is or does the speakers’ orientation to the room’s corners and the polyfusors matter as well?]
A summary of my journey with treating a 32x18x8 room with 20.7s and Rel carbon subs Acoustic Treatments for Magnepans/Dipoles - Diffusion not Absorption - #26 by MTB_Vince
Speaker placement makes little difference to where the Polyfusors are placed, given the Maggies are canted-in slightly. The sound wave radiating from the back will land in the corner and scatter creating unfocused sound energy blurring the image.
Forgot I posted a pic in another thread already. Room Treatments
My set up has my speakers (not dipoles or planers) much further out into the room and much further away from the side walls (with no toe-in). I am curious as to whether I would get the proper diffusive effect/deepening of the sound stage if I placed the GIKs more or less in the corners as recommended/shown.
Is this particular model designed to deal with lower frequencies more so than breaking up the reflection of relatively higher frequencies?
Hope I am not being too lazy here with this dialogue – suppose I could just spend some quality time over at “GIKDOTCOM”.
You would really only get effective bass absorption with a corner placement and the relative position of your dynamic speakers. Diffusion at the first order reflections on the ceiling would be more beneficial if your side walls are a distance away from your speakers. If you want bass treatment you are better off with a tube trap like product in the corners than the polyfusers or half traps.
An example of bass traps and front wall diffusion, ceiling 1st reflection diffusion and side1st reflection diffusion. There are additional mid-hf absorption panels further along the side walls.
The speakers are Quad 2905 ESL. I have great depth and wide soundstage.
If you want <100Hz absorbtion you have to have large (surface) and thick (deep) units. They have to straddle a large chunk of the corner. It is the distance away from the reflecting surfaces of the corners & wall/ceiling and wall/floor interfaces that make it work. The GikAcoustic Polyfuser chart shows it does very little below 100Hz. They say it operates from 80Hz, builds to most effective attenuation at 100Hz and then tapers off.
If you have a particular room node (narrow frequency band that is excited by speaker placement, listening position or room dimensions and you cannot change one or more of those 3 items you could design a Helmotz resonator absorbing panel targeted at the problematic frequency band.
This type of effort is best assessed using Laptop/REW & USB-mic - you can then better understand what’s going on.
Another idea that will work is to build floor to ceilings bookcases. You can pull the books in/out on the shelves to simulate the wells of a diffuser.
I make my own (mostly qrd type) because I’m cheap, with some absorbers usually made from Armstrong high density fiberglass panels (the type that would normally go in ceilings. There’s a poly film backing, which when used with an air gap, also acts as lower frequency resonant absorption to a limited extent. There’s a lot of free calculators online to calculate the necessary depths, widths, sequences, and periods.
They’re all stashed right now because I’ve been doing the basement for awhile though…
Draw your room out using GIK free tool. They will provide an analysis and recommended treatments in rank order of impact. All no-charge.
I’m a über DIY guy. Half my electronics is DIY. It was difficult to make a finished product at the cost of GIK components. Most people have no clue about what treatments go where and then make effective treatments. Few even own a calibrated mic for room measurements.
You can also get the Dayton Audio iMM-6 measurement microphone from the likes of Parts Express for about $30 including shipping.
You can then download the calibration file specific to your particular microphone from Dayton’s website to load in apps such as AudioTool, which has a decent spectrum analyzer.
The app, plus the mic, plus the calibration file makes for a pretty awesome setup on the cheap. It’s not uber fancy, but it will allow you to get the response peaks/valleys in your audio environment that would have easily cost in excess of $5000 in the days before apps and people making cheap stuff.
So I’m trying these tubes from Lowe’s. They are used as forms for for cement - 12”x48”. I just plopped them behind my Maggies - and I’m not sure I like them there. This is to get a ‘sound direction’ as to what it might do.
Well putting them behind mags did produce a slightly more diffuse sound. Everything seemed a little more ‘floaty’. But vocals did take on a sharper tone and it seemed like I lost some ‘weight’ to the presentation.
Tomorrow I’m going to put them on the back wall. See what that does.