Auralex T-fuser & Metrofuser... and diffusion questions

[Lights]

Hey folks:

Quick Summary of my Question: I'm looking for opinions on the inexpensive Auralex T'fusor, Q'fusor, and Metrofusor products as well as any general recommendations on how and when to use diffusion in my small basement studio, where absorption is my general priority.

Background:

I'm midway through treating basement home studio with a combination of...

- 10 "DIY" (friend-made) 2'x4'x4" Knauf Ecose 3PCF fiberboard bass traps spaced 4" off the wall or mounted at wall-to-wall or wall-to-ceiling corners (one under the desk as well).

- 4 or 5 (haven't decided) large soffits ranging from 1'x2'x8' to 2'x'2'8' filled with OC Ecotouch R-30 insulation to fill corners floor-to-ceiling.

- An Auralex room kit with 24 2'x'2x2" wedgie tiles and 8 LENRD corner traps to treat the mid-to-high reflections.

Mostly I've been focused on dealing with the bass issues in the rather odd-shaped room and I haven't really thought about how and where to use diffusion. I've seen what a good diffusor goes for and don't have the stomach to build one or shell out big bucks for one. So these inexpensive plastic and styrofoam panels seem like a good way to get some natural sounding reflection back into the room once it's fully treated without hemmoraging cash.

However, none of these are QRD-model diffusors so I don't know if anybody has discovered that they're effective.

My biggest placement concern would be the proper use of diffusion on the walls behind me, the largest of which is angled.

Thoughts?

[Lights]

For the second half of the question I thought I'd attach the studio. Only 3 of the bass traps and some of the tiles are installed. It will be a few weeks before everything is in place so I can modify placement to add diffusion.

The logical places for diffusion are on the 2 back walls directly behind the listening area (one flat and one diagonal) and perhaps on the back of the door.

[kasmira]

Is the Auralex really that necessary with all those traps in place? You would barely hear any flutter echo at all with like 4 of those traps up, let alone the 10+ that you're putting in there. I say space on the Auralex. Would more than likely deaden the room..even if you put diffusors in

Also, why not just 17" soffits? Can anyone account that making these even bigger would help anything? 17" soffits would require half the amount of insulation than 24" soffits would, and I'm not sure if spending twice the amount of money would be worth your while (although, who knows, it might be!)

Also:
Seriously, its a piece of plastic.

[amishsixstringe]

Originally Posted by kasmira

Is the Auralex really that necessary with all those traps in place? You would barely hear any flutter echo at all with like 4 of those traps up, let alone the 10+ that you're putting in there. I say space on the Auralex. Would more than likely deaden the room..even if you put diffusors in

Also, why not just 17" soffits? Can anyone account that making these even bigger would help anything? 17" soffits would require half the amount of insulation than 24" soffits would, and I'm not sure if spending twice the amount of money would be worth your while (although, who knows, it might be!)

Also:
Seriously, its a piece of plastic.

I agree that the auralex stuff is probably not necessary and may just start sucking the life out of the space, however your statement seems to infer that diffusion would somehow brighten (opposite of deaden?) the room. That is false. Diffusors absorb sound. You can't add energy into a room. That's what speakers do.

24" soffits are twice the volume of 17". Yes, this is true. Twice the volume equals twice the cost. Good job. But, duh. Of course they will perform better and lower than 17". If you have the stuff, 24" would be the idear.

The auralex T fusors suck, but claiming that they suck because they are a piece of plastic is stupid. There are lots of the things that are "just a piece of plastic" that are quite valuable. I think their suckyness has more to do with them being thin and only functional at really high frequencies.

I wouldn't use the diffusors at all, personally. I would treat corners with the fattest traps you can, and the ceiling/side walls with 2 or 4" rock fiber stuff, and lose all the auralex.


I know you have REW right? Just keep an eye on that stuff as you stack shit up in there. You'll be ok.


Neil

[amishsixstringe]

P.S. The other thread stated the OP has an issue in the 50-60Hz range which is getting close to the really hard to treat zone. Most of the responses over there nudged Lights into building the deepest corner traps he could afford (reel estate as well as financially). I feel we could easily relive that thread if everyone doesn't check out the other one.

Neil

[Lights]

Thanks for the thoughts guys. I did some reading on diffusors and watched Ethan Winer's video. A few things I took away from that:

Diffusors, according to my research, can be made from any material--styrofoam, wood, plastic, it shouldn't matter. I understand that packing the T'fusor with material may make it diffuse at lower frequencies. But I'm not sure about how effective the particular shape is.

Ethan said that a diffusor needs to be at least 3" deep and the T'fusor is 5. The Q'fusor is 3 but based on the QRD mathematical model.

Ethan also suggested diffusors on the back wall can make a room feel much bigger and can be combined with bass trapping so I was wondering if I could kill 2 birds with one stone by mounting bass traps to my back walls with diffusion panels attached. The realtraps diffusors are also bass traps, but I can't afford those

I'd like to keep this thread to the subject of diffusion to keep it simple so I won't say more about the use of the foam in conjunction with the knauf ecose

Let's talk about if I need diffusion (Neil says no) and if so where, what kind, and how much.

Right now I have a lot of flutter echo, but only 3 traps in place and the front wall treated with 2" foam.

[kasmira]

Originally Posted by amishsixstringe

I agree that the auralex stuff is probably not necessary and may just start sucking the life out of the space, however your statement seems to infer that diffusion would somehow brighten (opposite of deaden?) the room. That is false. Diffusors absorb sound. You can't add energy into a room. That's what speakers do.

24" soffits are twice the volume of 17". Yes, this is true. Twice the volume equals twice the cost. Good job. But, duh. Of course they will perform better and lower than 17". If you have the stuff, 24" would be the idear.

The auralex T fusors suck, but claiming that they suck because they are a piece of plastic is stupid. There are lots of the things that are "just a piece of plastic" that are quite valuable. I think their suckyness has more to do with them being thin and only functional at really high frequencies.

Re-reading my statements I realize I came off like OP hadn't done research on the matter, and thats not what I meant. Also, I know that diffusors wouldn't add "brightness" to the room - moreso meant that his auralex is in front of him, which would absorb all the highs the back wall would bounce back towards the mix position. Diffusors in the room would scatter those reflections on the back wall, meaning even though the diffusor scatters sound away from the mix position, the auralex would still probably absorb more than necessary after all those traps are in place. I should have been more clear.

To the OP, yes T-fusors are 5" deep, but it doesn't even make use of the entire 5" - they just protrude 5". The triangular cuts into it barely will do anything other than very high end diffusion, and there's no way these are effective down to 800hz without a wall filled with them. If you notice, they have the big "T" shape protruded out - which, when putting multiple pieces together, would use that large deep space for low end diffusion, but wouldn't do much at all with just 2 of them next to each other. If these are 60$ each, you would probably have to spend 250$ before they were even effective. You might as well buy a pre-made diffusor in this price range.

Truth is, if you want great diffusion for your dollar, you'll more than likely have to build your own.

Originally Posted by amishsixstringe

P.S. The other thread stated the OP has an issue in the 50-60Hz range which is getting close to the really hard to treat zone. Most of the responses over there nudged Lights into building the deepest corner traps he could afford (reel estate as well as financially). I feel we could easily relive that thread if everyone doesn't check out the other one.

Neil

Definitely missed that thread, and I'm usually pretty good at checking that type of stuff!

Originally Posted by Lights

Ethan also suggested diffusors on the back wall can make a room feel much bigger and can be combined with bass trapping so I was wondering if I could kill 2 birds with one stone by mounting bass traps to my back walls with diffusion panels attached.

You definitely could do this, but I still think the range of diffusion the tfusor will give you is very limited, even if mounted on front of a bass trap.

Originally Posted by Lights

Let's talk about if I need diffusion (Neil says no) and if so where, what kind, and how much.

Right now I have a lot of flutter echo, but only 3 traps in place and the front wall treated with 2" foam.

I would say your first primary goal is to get the rest of those traps built before you worry about diffusion. Get all of those in place and measure around, finding the best places to put your absorption. Diffusion can help spaces, but sometimes in a smaller room isn't even worth your while. I believe your money & time is better spent on the absorption you need (especially with a 50hz ring!) - oh and speaking of, sorry I didn't see the other thread, 24" soffit with pink fluffy could do quite a bit of damage to that!

[Lights]

Cool thanks for the info. BTW: the T'fusor is ~$60 for 4 of them. The Q'fusor and metrofusor seem to come in boxes of 10 or 12.

I'll follow the advice and wait and think about diffusion when the absorption is in place. Perhaps my best bet is to add a bit of reflectivity on the front of the bass traps mounted in the rear. I don't have the tools to accurately build my own diffusor.

[kasmira]

Hmm! This is interesting..

Before I posted about the cost, I looked online and saw that ONE piece of the t'fusor is $60, while a 4-pack is ~250$ (as seen here: https://www.google.com/search?rlz=1C...w=1280&bih=856)

BUT, the musicians' friend site lists the description for the $60 unit: ...Includes pack of 4.
However, in the specs on the same product, it says 4 square feet, and doesn't say it includes multiple pieces.

Auralex Studiofoam T'Fusor Sound Diffuser: Shop Accessories & Other Musical Instruments | Musician's Friend

Bit confusing. It doesn't say pack of 4 on any other site for anything less than ~200$ something. I think Musician's Friend may have messed up on that one..
If it were 60$ for a 4-pack, I would say it wouldn't hurt to try. That evens out to about $4 per square foot of diffusion.

[Lights]

Yea maybe musician's friend is wrong. Hmmm.

[Lights]

So what about the Q'fusor?

[kasmira]

Originally Posted by Lights

So what about the Q'fusor?

The Q'fusor does seem a little more practical, but its still very abysmal in the effectiveness of it. Lower frequencies are affected by diffusors with larger depths and wider cavities. Auralex's Q'fusor has different sized widths and depths of the cavities to try to kind of extend the frequency range upon which it works. But since diffusion is normally needed to be very broad, you want the widths of the cavities to be larger, and the q'fusor still doesn't have very many large cavities.

I too wanted to build a diffusor for my room, because they do look challenging to build and I think it would be fun to learn how to make one. However, in my thread regarding solutions for my room, most people told me to steer clear of diffusors since my room is small, and only spend my budget on traps, as it would be much more effective to spend my money on traps.

I do think your angled wall would be a nice place to put the diffusors if you did get them, since the angle will make for echoes at all sorts of varying times coming back at you in the mix position, and it seems it would be hard to even out the left and right reflections without something like diffusion.

The q-fusor is definitely more practical price wise. If you do decide to do it I don't think it would be a bad thing, and if you mount them on top of your bass traps then you aren't really losing the point of the traps, either.

GIK's QRD diffusor is honestly pretty affordable. 250$ for two of them, and they are 20" x 48", so you're covering almost a total 16 square feet with them. Link: GIK Acoustics. Acoustic Panels and Bass Traps.

Also, GIK makes the GridFusors which would be practical if you didn't want to mount those bigger ones on your wall, or wanted to do them in a different array other than two 4' long pieces.. Those are 200$ for a box of four 2x2' panels. Also convenient for mounting since they are very lightweight..
GIK GridFusor. GIK Acoustics. Acoustic Panels and Bass Traps.

[Lights]

Interesting. Those GIK diffusors look like a better value.

[kasmira]

Hey Lights,

I just happened to read this thread from a couple years ago: Sonotube Diffusor

Talks quite a bit about diffusion. Great read with tons of insight, and has quite a bit of points on the reasons diffusors don't work great in smaller rooms. I heard on other threads and my own threads that diffusors wouldn't be useful for a small room but I never understood the science behind it. This thread helped explain it to me quite a bit. I love this damn forum..

[Lights]

It seemed like that thread indicated that QRD diffusors are more effective than polys because polys don't prevent comb filtering like QRDs do in small spaces and I should use a relatively shallow one as you need to be about 1ft per inch of depth.

Did I miss something?

[localhost127]

Originally Posted by Lights

Diffusors, according to my research, can be made from any material--styrofoam, wood, plastic, it shouldn't matter.

material does matter - the diffuser's construction material (acoustical impedance) needs to be as reflective as possible throughout the diffuser's bandwidth range.

dense extruded polystyrene foam will work - but you can see from user Jens' experimentation that even 2 layers of latex paint can really have an effect on reflectivity:

Originally Posted by Lights

I understand that packing the T'fusor with material may make it diffuse at lower frequencies. But I'm not sure about how effective the particular shape is.

are there published measured docs regarding this product? if not, why on earth would you buy anything blindly without objective measured performance? especially something like that of a diffuser - where the complexity of the subject demands such data?

Originally Posted by Lights

Ethan said that a diffusor needs to be at least 3" deep and the T'fusor is 5. The Q'fusor is 3 but based on the QRD mathematical model.

one generally determines what the bandwidth or surface area of the diffuser they need for their particular situation needs to be, and then builds or buys accordingly.

it's not just the depth that is important but the overall size of the diffuser as well - as the diffuser needs to be relatively large with respect to wavelength size or the wave will diffract around the diffuser and not be seen. (this error code is programmed into QRDude and it will inform you if period size is smaller than design frequency).

it's another factor with small diffusers as generally we need to cover large surface areas, and with small diffusers means you will be using many many repeating periods.

Originally Posted by Lights

Ethan also suggested diffusors on the back wall can make a room feel much bigger and can be combined with bass trapping so I was wondering if I could kill 2 birds with one stone by mounting bass traps to my back walls with diffusion panels attached. The realtraps diffusors are also bass traps, but I can't afford those

diffusers and bass traps are treatments for entirely separate problems - specular and modal region respectively. yes, you can mount diffusers to the outer face of your bass traps, which is much more ideal than a simple reflective surface on the bass traps (such that the porous bass traps do not inadvertently over-absorb specular energy and create a dead room)...but if a control room, then it depends on the size of the room whether you can place diffusers there or not (dependent upon how you want to introduce indirect specular energy to the listening position with respect to the time-domain).

[localhost127]

Originally Posted by amishsixstringe

however your statement seems to infer that diffusion would somehow brighten (opposite of deaden?) the room. That is false.

large, repeated arrays of small diffusers (incorrectly but so often do we see examples of being deployed in such a fashion) can induce significant lobing or glaring at certain frequencies which could exhibit such 'brightness'.

Originally Posted by amishsixstringe

The auralex T fusors suck, but claiming that they suck because they are a piece of plastic is stupid. There are lots of the things that are "just a piece of plastic" that are quite valuable. I think their suckyness has more to do with them being thin and only functional at really high frequencies.

do you have any published data on the product?

Originally Posted by amishsixstringe

I wouldn't use the diffusors at all, personally. I would treat corners with the fattest traps you can, and the ceiling/side walls with 2 or 4" rock fiber stuff,

not everyone prefers a dead/fully damped room in the specular region. to adhere to certain psycho-acoustic triggers, you really have to fight to keep as much energy in the room as possible and manage how it is reintroduced to the listening position accordingly. if you don't understand the reason for diffusers in small acoustical spaces, then it is unfortunate.

[Lights]

Well I have to say I don't fully understand diffusion yet--but based on looking at the info I found and watching Ethan Winer's video on the subject it seemed like I wanted to treat the back walls with some to prevent comb filtering effects while keeping the room sounding natural.

Note the image in the second post. It has all of the dimensions of the room. Any recommendations of what to put where would be greatly appreciated. Only a few things are in place now and I haven't purchased any diffusion products yet.

[davecfraser]

Lights,

Very interested in your situation as I'm in a smiliar one (albeit a few months ahead) I've already got my bass traps installed (incredible difference) and now I'm working on the idea of Diffusion.

I think QRD seems to be the diffusion needed (IF needed) for a small room, Poly's (like the sonotube) diffusors seem to be more practical for larger rooms.

I'll keep checking in and see what the genuises here have to say.

[Kubilay]

Generally, you want plenty of diffusion behind you and plenty of absorption in front of you (behind the monitors.) I can't say enough good things about these diffusors in a small room:

Steven Klein's Sound Control Room

The Saturn diffusors work great when they are fairly close to the listening position, in situations where more complex diffusors can introduce pretty nasty comb filtering. So they're awesome for small studios - and which studio isn't small these days? Stuff them with varying amounts of absorptive material for some added absorption and better diffusion.

For all treatments I've found that left/right symmetry is important for a good stereo image (which of course is hard to do in an asymmetrical room - but with some playing around with general layout you can get close.)

Also, don't forget the ceiling (it's usually damn low in modern small rooms.) I ended up with about 60-70 percent of the ceiling covered, by about 66% absorption/33% diffusion. Again, arranged symmetrically from the mixing positions's point of view.

Diffusion is all saturn diffusors in my room (plus a number of bookshelves, since I need the books and some small instruments and gear around - I made sure they are arranged as symmetrically as possible, relative to my listening position.)

I've also found that using various different absorbers helps prevent the introduction of comb-filtering through absorption (too many of the same depth and density will end up absorbing too much of a single freq. range.) Again, each variation on the left is mirror-image of the same on the right, when viewed from my mixing position.

I've also found that bass traps for me work best in the two corners in front of me, but that may differ from room to room, not sure.

[Lights]

Hmmm. Seems very similar to the poly/sonotube solution. Any threads on the Saturn where acousticians have weighed in?

[Lights]

Also on the same site as the Saturn is this: Steven Klein's Sound Control Room

Maybe also good for tight spaces as the tile is a mixture of absorption and diffusion?