[DTB300]

I have seen Root 7 and Root 13 Diffusers primarily discussed and sold - both in wood and EPS. 

For instance GIK has their GridFusor which is a 13 and then the QRD which is 7, but they are both 2' wide.

What dictates or determines which root to use in your setup? 

[InfernoSTi]

There are also higher prime QRDs you can purchase such as Prime 37.  My understanding is that when used in pairs (or more), QRDs tend to produce lobes of sound...the smoother the lobes, the better (no lobes would be the best), so I've been told the higher the root, the better particularly if used in pairs.  So in theory, it would be better to get one large Prime 37 than an equivalent set of three Prime 7 diffusors put together. Perhaps someone else will jump in with more info.  Here is an illustration of the concept:



I really like my Prime 37 diffusor from SRL Acoustics http://www.srlacoustics.com/cgi-bin/cart.cgi but it is 6 feet wide and nearly a foot deep, so it isn't for everyone! 

John

[Big Red Machine]

That is why I built my own Prime 53's.  It would have been easier, but more expensive, to hang multiple Primes from a manufacturer on the walls.  I wanted the smoothest I could get in the space I had to offer.

[bpape]

Actually, our 7 roots are 19" wide including outside. The 13 is actually 2 mirror imaged 13's in a 24" form factor.

There is  a range over which a diffuser will function. Depth controlling how low, width controlling how high. If you want a wider range then you need a higher root sequence.  Higher sequences also tend to diffuse a little smoother.

The drawback from a commercial standpoint is the complexity of building the higher roots.  A good 7 root in a form factor of 2x4 or less and 6" thickness or less will function from the 300's into the 4kHz ish range.  That's really covering a large portion of the musical range in a reasonable size and reasonable cost package.  Getting something that's going to perform down into the low 100's requires a very thick diffuser if going the QRD type route. Another option (which I'm still bugging Glenn about) is to do a Polycylindrical diffuser. 

There is a lot of misinformation about poly's out there.  Done properly and mounted properly, they can cover a very wide range of frequencies and have the advantage of not really having a top end.  The drawback is that they are relatively large and heavy.  Once you get up into the 300's, the density of the material required isn't nearly as great. 

Anyway, enough rambling on theory...  To answer more specifically, your answer would depend on the range you want to cover, the space you have to work with, and the ability to build something of the given complexity.

Bryan

[cheap-Jack]

Hi.

That is why I built my own Prime 53's.  It would have been easier, but more expensive, to hang multiple Primes from a manufacturer on the walls.  I wanted the smoothest I could get in the space I had to offer.


[

Hopefully this is a dedicted place for yr OWN use only. Or you should be living alone. How can anybody living with you can live with such messy things hanging on the wall even if those panels really worked per their specs.

As I posted in the forum earlier, I have none such backwall reflective issue at all with my seat right against the untreated wooden backwall, & my ears only 15" from the backwall. My ears can't hear anyting wrong, verified by my realtime acoustiscal measurement.

I am still awaiting Ethan Winer's "sweep using his Room Wizard" to prove I am wrong.

c-J

[Ethan Winer]

I am still awaiting Ethan Winer's "sweep using his Room Wizard" to prove I am wrong.

I was still waiting for you to tell me your room dimensions and approximate placement of things (speakers) in the room. That's the way I recall that thread was left. If your room is 35 by 25 and I measure in a 10 by 12 room, "proof" of comb filtering will be less convincing to you.

--Ethan

[InfernoSTi]

Let's NOT hijack THIS thread, please?  The previous discussion can be handled in the previous thread.  It has NOTHING to do with this thread.  Here is the link:  http://www.audiocircle.com/index.php?topic=104929.40

Best,
John

P.S. I like the look of functional equipment.  Not everybody is limited to a standard living room, a standard spouse, or standard tastes.   But I guess some folks are better at criticizing than being supportive.  Their value is seen in the help they give others....

[PDR]

Hi.
Hopefully this is a dedicted place for yr OWN use only. Or you should be living alone. How can anybody living with you can live with such messy things hanging on the wall even if those panels really worked per their specs.
c-J

Beauty is in the eye of the beholder....
If you are so inclined you can make them blend quite nicely into your decor.
I dont live alone....but I do have a room I call my own, there I am the only one that has to be pleased.
And yes, they work.

[tasar]

PDR......if I might ask here......what absorption material/build technique did you use at front corners with the Super V OBs ? Better said, based on QRD depth/build/materials, what part of the LF range were you striving to tame with absorption ? Sorry, we can start another thread if this is off topic.

[Don_S]

PDR,

Great looking room.  Proves your statement.  I am jealous. 

Beauty is in the eye of the beholder....
If you are so inclined you can make them blend quite nicely into your decor.
I dont live alone....but I do have a room I call my own, there I am the only one that has to be pleased.
And yes, they work.

[Austin08]

Beauty is in the eye of the beholder....
If you are so inclined you can make them blend quite nicely into your decor.
I dont live alone....but I do have a room I call my own, there I am the only one that has to be pleased.
And yes, they work.

PDR,

It seems like your diffuser panel was made out of eps so what kind of paint do you used?  Water base paint? Thanks.

[DTB300]

Water based.   Other paint will "melt" the EPS

[Austin08]

Water based.   Other paint will "melt" the EPS

Thanks, You guy are always great.

[PDR]

Was made of EPS, the white popcorn kind with a thin layer of acrylic stucco base
brushed on smooth, then painted.
Put together in my living room, just to make my wife happy...

[InfernoSTi]

Brave (foolish?) man!  Nice work, that....

Best,
John