I have a bunch of diffusion and abfussor room acoustics products on their way. The goal being to enhance the sense of spaciousness in my room without buggering up the audibly pleasing frequency balance my current room treatment are providing.
The rear wall of my room will soon grace a modulated 5 unit array of these N7X7 Fractal 1D QRD diffusors from Seven Audio (in Poland!). The two pictured units are stock size but in custom colors. The remaining three units are in two different custom 2" and 4" greater frame depths with the resulting air gap behind the EPS diffusor filled with rigid polyester wool absorption panels. Below 500Hz the three deeper central panels of the array will transition from diffusion to absorption.
I also scored a good price on six 2’x2’x4" RPG BAD ARC panels on A’gon. They are in the wrong GoM fabric covering but that is easily remedied. This Binary Amplitude Diffusor variant features a poly-cylindrical version of the normally flat BAD scatter plate and thus improved diffusion performance. These aren’t firmly earmarked for any particular application yet. I do intend to begin experimenting by stacking the open backed BAD ARC panels over the fronts of the first three primary reflection broadband panel traps along each side wall though. We’ll see what happens when I diffusively return half the higher frequency energy from the primary sidewall reflections back into the room instead of entirely absorbing it.
Probably the best next upgrade would be to lose the piano in the listening room. I did a sound check, clap test and claves, after being away for months to find the room decay predominately piano overtones.
My friend just received his last week. Another friend has one one (both KTE edition’s). I heard the second friends system and brought over my Sony UBP-X1000ES with the HDMI Video - I2S adapters. He’d never heard SACD’s/DSD files played back correctly (i.e no PCM 176.4/24 Bit downconversion).
These latest R2R DAC’s are surely giving the PS Audio DSSr. a run for their money but I’ll always prefer DSSr. over the newest “Johnny come lately” DAC’s that have flooded the market.
You have eagle eyes @weedeewop- LOL! The pic of the two fractal QRD diffusors was taken by the manufacturer in his studio space just prior to boxing them up for the trip across the Atlantic. No piano in our dedicated music and cinema room. I sure wouldn’t mind having the additional space to accommodate one though! Years ago when my use of this room transitioned from strictly two-channel to multi-channel as well, it got a little cramped. A couple extra feet in width and depth would be nice.
I’ve been looking into these and have no idea where to start. It seems there are different theories and math for how to build and segment diffusors. How did you figure out these are the right kind for your space?
Best practice minimum listening distance from 1d or 2d phase grating diffusors (like the the QRD and BAD diffusors in my post) is for the MLP to be at a minimum distance from the diffusor of 3x the length of the lowest (longest) wavelength which the diffusor is designed to operate at. In my case, with an MLP only 5’ from the rear wall, and a multi-panel modulation which requires several of the panels to be offset up to 4" further off the wall, I stuck with a relatively shallow 5" deep QRD diffuser design. It’s lowest effective diffusion frequency is 983Hz with a wavelength of 1.1ft. So for this diffusor minimum listener distance would be 3.3’ + the 4" maximum offset from the rear wall of two of the modules. At a distance of 5’ from the rear wall I’m good.
Did that info and practical example make sense to you @vee? Whether you intend to DIY or buy, Arqen.com provides some great best-practice primers and diffusor designs which are relatively simple to DIY.
@MTB_Vince Thanks for explaining and sharing the site. I’ll have a look. The short of it seems that diffusers won’t work for me since my listening space is small and my seating position is nearly up against the back wall.
I’ve been looking to improve the spaciousness of my room sound. I’ve been removing more and more trapping / absorption to re-introduce room reflections. My entire back wall used to have absorptive bass traps, but is now bare – and I’ll likely try putting something up that breaks up direct reflections instead of absorption like staggered shelving for books.
Hey @vee, you are totally correct. Diffusion doesn’t lend itself well to really close quarters. If your MLP is pushed up against the rear wall, best practice would be a 4-6" deep broadband trap on the rear wall immediately behind you to entirely suck up the mid and high frequency component of that strong reflection.
I wouldn’t be so quick to install shelves full of books in place of broadband absorptive treatments for primary reflections. The mistake many well meaning audiophiles make when applying absorptive room treatments is to use under-performing products which only offer meaningful absorption at high frequencies. They treat their rooms with these products and inadvertently skew their rooms frequency balance. “Where did the highs go? WTF? My room sounds dead now!” 99% of “acoustic foam bass traps” would fall into this under-performing category as do essentially all fibrous fiberglass/mineral wool/polyester wool/recycled cotton wool rigid panel traps of less than 4" depth.
Either a 4" trap spaced several inches off the wall or a 6" full depth fiber trap will offer near-complete absorption from 200Hz on upwards. If your broadband traps efficiently swallow the entirety of the primary reflections instead of just the high frequencies, it will leave a moderately furnished and carpeted room’s neutral frequency balance intact.
And if you are still interested in mid and high frequency diffusion, a suitable place for that in smallish rooms is in front of your corner bass trapping. Room corners tend to be far enough away from the MLP for diffusion to be effective. I use expensive floor-to-ceiling columns of ASC Tube Traps in the four corners of my room and they offer a built-in mid and high frequency poly-cylindrical diffusor down one side of the cylinder. Alternatively GIK Acoustics offers optional scatter plates for the fronts of their reasonably priced corner bass traps and panels.
Until today, I had a 4" 3’x4’ rock wool trap directly behind the seat. I pulled it down to hear what that would do and noticed an increase in mid high response. It’s different and seems better, so I’ll do some sweeps and some listening.
Edit: Here’s the sweep. It reinforces what I heard – removing the back wall traps reduced some excess FR variances and served to flatten the FR. In this case, more definition on the mid/top end.
@Elk Hmmm i may need to check out the felt. My wife’s grand piano is coming this week but will be setup in a living area that opens to my audio room about 30 foot away separated only by kitchen/dining area with large open doorway I wonder if the affect will be noticeable? I will rerun my DSP as we changed dining area table too. Funny thing I found if my laundry room door is not closed my bass suffers as my last DSP was run with it closed despite laundry being in a hall off the listening room.
Unless you play your system loud the piano will likely not be an issues. The undamped strings are all in the upper register and take a good amount of energy to excite. If you can hear them in a clap test standing near your speakers it would be worth placing a towel in the piano to make certain it is not adversely affecting he sound.
I will try The clap test before and after the piano arrives and cover the strings to see if any noticeable changes. I wonder if having the top cover on the grand closed will make a difference if I hear issues. Expecting the wife to take cover on or off her strings could be a YGTBSM moment to explain that. Lol. I already have one mortal sin with two sets of surround speakers in the same room when I listen in 2 channel mode on my reference system. I have heard that that can also change your sound since pressurized air can excite the cones and domes. Luckily I am not obsessed enough yet to go to that extreme. Or have enough space that I could transfer to HT to another room.
Closing the lid might make a difference in hearing the strings vibrate, but would likely not impact the movement of the strings themselves. The soundboard of a piano is massive and is what is vibrating, causing the strings to move.
I would make it a simple ritual to place a towel or the like on the strings before listening, removing it again once I am finished. A gentle bother.
The too heavy to lift amp is still in the garage. I get someone to say they will come and help me with it, and then they bow out. I think I may have to call piano movers…
I bought one of those audiophile ethernet switches. My concern was noise coming along the ethernet data line from my modem. They are all made by a Chinese company run by an American-educated network systems engineer, branded as Bonn N8, English Electric (Chord) and presumably others.
It was on sale or return, either my brain is playing tricks or it does improve things a notch. Call it my Christmas gift to the audiophile industry and impending Chinese world dominance.
I have found every bit of thee digital chain
DS matters. Who cares if todays science doesn’t explain it. If your system is revealing enogh and ears and brain can hear it and it is better sounding. Then it is worth it. Now for that 2000 dollar ethernet cable. Lol
