QRD Diffuser

Has anyone tried to build QRD Diffuse? If so did you copy a design, did you buy a instructional book, What materials did you use, what tools required?

Thanks in advance
 

tomlinmgt

Moderator
Yes...I've built several different types of diffusers and a few different QRD'S. I've built them from wood and styrofoam, and built from plans and from the QRDude freeware. The easiest to build were the stepped leanfusers from Arquen acoustics...seen here on my front wall (the diffusers on the floor are poly diffusers...they were fairly easy, too).
QRD'S are definitely the most time consuming and labor intensive. I've built both 2D and 3D ("skyline"), and I would classify both as a "labor of love"...because I truly did love the process. For me it was rather therapeutic...if not slightly addictive.

MichaelIMG_0018.JPG
 
I have been wanting try make some from foam board. The 4x8 sheets of insulation from Home Depot.
What type of styrofoam did you use?.
I like the look of the wood, but they have to weigh in pretty hefty.
 
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DIY diffusors have been on my To-Do list for years, but each time I look over the design details they just seem like too much work, not to mention too big and too heavy. I am convinced, however, that diffusors do a better job than absorbers, just as a broad brush generalization. Absorbers always deaden the sound too much whereas my makeshift diffusors are more neutral. They just add some more “goodness” to the music.

Here’s a pic of one of my so-called diffusors which is simply a walnut grill I removed from my speakers. I have one hanging on each side wall at the first reflection points.
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Those look like they were pretty easy to make.... 😁
I want to try difusion at point on the ceiling of room, hence the interest in the foam board idea.
I also am revisiting the idea of too much absorption.
 
I should have been more balanced in my absorber vs diffusor comment. I actually have several absorbers in my room—a Tube Trap in each corner behind the speakers, a Real Trap in the back corners, and a small Real Trap on each side wall. Each of my absorbers is either missing a defective strip (Real Traps) or has the reflective strip hidden (Tube Traps).

My problem with absorbers being too dead arises when you have too many or have one at the first reflection points.
 
I should have been more balanced in my absorber vs diffusor comment. I actually have several absorbers in my room—a Tube Trap in each corner behind the speakers, a Real Trap in the back corners, and a small Real Trap on each side wall. Each of my absorbers is either missing a defective strip (Real Traps) or has the reflective strip hidden (Tube Traps).

My problem with absorbers being too dead arises when you have too many or have one at the first reflection points.
Thanks,
I have floor to ceiling traps 4" rockwool in each corner plus 3 other 2x4 panels of it up.
Plus difusion at 1st reflection and on the wall behind speakers.
Things sound pretty darn good here, but the tweaker in me keeps taunting .
 

Wntrmute2

Not So Mediocre Member
I've done nothing to my room other than use records and books at the first reflection points so I'm
:popcorn
 
Books and papers can do good things. Heck a really poor mans bass trap can be a stack of news papers or magazines in corners.
I rearrange my music room in a previous home once, I took out a book shelf full of books and a desk, plus some other things because I had been using it for oan ffice when I started by business.
I was shocked how it changed the sound.
 

tomlinmgt

Moderator
I have been wanting try make some from foam board. The 4x8 sheets of insulation from Home Depot.
What type of styrofoam did you use?.
I like the look of the wood, but they have to weigh in pretty hefty.

I built my first 2D QRD from the blue dense foam 4x8 insulation boards. The frame was pine and the well dividers were thin craft ply, but the well faces were done with the foam. The next 2D QRD build used cedar 1"x2" for the well faces. Yes, it was heavier, but not by much, and I preferred the end result quite a bit more. For quick diffusers, the foam is a good option and you don't have to frame them in wood...and omitting wood in the build cuts down the weight significantly. However, getting good square cuts with the foam is not as easy as you'd think. That's a big reason why I prefer the all wood build...they could be constructed with a greater degree of precision. And foam dust is a big damn mess if your cutting with any type of electric saw or meat carving knife. And I also tried the hot knife and it didn't work out for me, either (messy edges to the cuts).
The first pic is the foam QRD which I pained black with truck bed liner paint. The second shows the cedar QRD (four in all...two 11-well units flanking the leanfuser in the center). These were later removed and replaced with additional leanfuser modules to complete the 7-module stepped diffuser array (seen in the first picture I posted up in this thread).

MichaelIMG_3498.JPGIMG_0005.JPG
 

MWalt

Active Member
Like a perfectly broke in pair of boots.

As long as I have room for 'em, my A25's are stayin' put.
I upgraded the caps, internal wiring, put quality 5 way binding posts on them and fresh linen grills. The walnut veneer was perfect. I vowed I would never sell them. But, we just moved 3 states away and had to liquidate a lot of our belongings to cut down on weight and space for the move. I sold 6 pairs of speakers and a litany of other audio gear. It was painful.
 

tomlinmgt

Moderator
This is the leanfuser stepped diffuser configured in the 7-module array mocked up on the floor before I mounted it. That's seven individual units, so mounting it wasn't as daunting a task as it may seem.

Worth noting is that I stood the diffuser array four inches off the wall so I could get a layer of rockwool behind it...making almost the entire front wall absorptive (mid and upper bass frequencies only) and diffuse.

This design would be very easy to make from the dense styrofoam insulation that comes in 4'x8' sheets and could be painted the wall color (or whatever color) with latex paint as an alternative to the wood construction, and is a much less labor intensive and time consuming build than a QRD.
IMG_0570.JPG
 
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