Diffusing 1st reflections of speakers that measure great on and off-axis - instead of absorbing

[j_j]

if you'd like to refute Schroeder, Ted Schultz, or any other well-understood acoustical concept that is accepted within the community, by all means please simply state that such that we can learn and understand since it was implied by another in this thread that this is your area of expertise.

the onus is not on me to answer this for you. i am not contesting what has been quoted above.

i am starting to think the problem is with me because after your replies i am simply unable to actually parse what you are trying to say, or what specifically you are attempting to refute (if anything)? each reply leaves me more and more confused on your position since there isn't sufficient follow-up to better explain the cryptic responses prior.

i'd like to gain an understanding of what you mean when you state you don't support LEDE (physics & perception) - surely it should be straight-forward to clarify your statement so we can all as a community gain a better understanding of the subject matter and any legitimate points of contention.

In other words, you're not going to answer my question.

If you want an "understanding" here, first you need to start with the assumptions. And those rest on LTI assumptions, which directly get to "Schroeder Frequency" definitions.

So either discuss, or continue trying to bully other people. Your choice. First, LTI (sorry, for the other people in this thread, that means Linear Time Invariant) is "interesting" even in small spaces, to say the least. (Not talking about air nonlinearity at high levels, though, that's another can of worms, in general assume we're staying at levels where air is decently linear.)

 

[localhost128]

In other words, you're not going to answer my question.

If you want an "understanding" here, first you need to start with the assumptions. And those rest on LTI assumptions, which directly get to "Schroeder Frequency" definitions.

So either discuss, or continue trying to bully other people. Your choice. First, LTI (sorry, for the other people in this thread, that means Linear Time Invariant) is "interesting" even in small spaces, to say the least. (Not talking about air nonlinearity at high levels, though, that's another can of worms, in general assume we're staying at levels where air is decently linear.)

what acoustical-based textbook would you recommend to better understand LTI and how it is applicable to aid my understanding of small room acoustics?

is it a requirement to have an in-depth awareness of LTI in order to understand LEDE principles and/or other matters related to this thread?

 

[Thomas savage]

what acoustical-based textbook would you recommend to better understand LTI and how it is applicable to aid my understanding of small room acoustics?

is it a requirement to have an in-depth awareness of LTI in order to understand LEDE principles and/or other matters related to this thread?

You need to stop harassing @j_j and trying to catch him out .

One minute it seems you want more detail then you want less , I expect he's trying to work out what you know so he can chose to carry on this engagement or not .

So far you just seem to answer questions with questions, it's starting to look a lot like trolling.

 

[j_j]

what acoustical-based textbook would you recommend to better understand LTI and how it is applicable to aid my understanding of small room acoustics?

is it a requirement to have an in-depth awareness of LTI in order to understand LEDE principles and/or other matters related to this thread?

I would suggest a signal processing book rather than an acoustics book for the mathematical roots. I'd specify one, but I'm at work, and my intro books are all loaned out to various employees at the minute. The basic principle is simple, but from there then the degree to which things are not, for instance, time invariant, comes into play. I'm not trying to be mysterious.

 

[nerdoldnerdith]

What would people recommend I use for diffusion in a nearfield Genelec Ones setup? The speakers are ~6ft away and the side wall first reflections are ~4ft away from the speakers and ~7.5ft away from the listening position. The ceiling bounce is ~5.5ft away.

 

[Bjorn]

What would people recommend I use for diffusion in a nearfield Genelec Ones setup? The speakers are ~6ft away and the side wall first reflections are ~4ft away from the speakers and ~7.5ft away from the listening position. The ceiling bounce is ~5.5ft away.

If the goal is accuracy, you're better off by using broadband absorption with such close surfaces. If accuracy isn't a goal and you prefer a more spacious presentation with more liveliness, I would recommend thick (6" or 8") BAD Arcs.

 

[nerdoldnerdith]

If the goal is accuracy, you're better off by using broadband absorption with such close surfaces. If accuracy isn't a goal and you prefer a more spacious presentation with more liveliness, I would recommend thick (6" or 8") BAD Arcs.

Thank you. Should I use those even if the room is already treated with absorption panels?

 

[Bjorn]

Thank you. Should I use those even if the room is already treated with absorption panels?

Type of treatment depends on areas like the design goal, directivity of the speakers, room size and seating position in regards to surfaces, where treatment can be placed, etc. There isn't a simple answer.

 

[Tangband]

Type of treatment depends on areas like the design goal, directivity of the speakers, room size and seating position in regards to surfaces, where treatment can be placed, etc. There isn't a simple answer.

Very good advice Bjorn .
I might add : Because 2 channel recording and listening with 2 loudspeakers are so flawed, and theres only an illusion of the real event happening , using diffusion can be a real help to make the illusion better .
In a big room reflections from the walls bouncing 3,5 - 5 metres away ( 20-30 ms delayed at listeningposition ) can be beneficial for the illusion of orchestra recordings .

 

[nerdoldnerdith]

This is a 4.1.4 setup with eight Genelec SAM Monitors, GLM, and subwoofers crossed over with a MiniDSP. It ain't no wimpy two-channel setup. I'm just trying to figure out how I should go about diffusion or if I need any at all. I've already taken care of absorption.

 

[Tangband]

This is a 4.1.4 setup with eight Genelec SAM Monitors, GLM, and subwoofers crossed over with a MiniDSP. It ain't no wimpy two-channel setup. I'm just trying to figure out how I should go about diffusion or if I need any at all. I've already taken care of Absorption.

Aha - With multichannel its mostly beneficial with a lot of absorption , and a thick, big carpet on the floor .
If you miss fine details or space in the sound - try different loudspeaker position and make sure that you feed your SAM monitors with a good digital signal .

 

[nerdoldnerdith]

Aha - With multichannel its mostly beneficial with a lot of absorption , and a thick, big carpet on the floor .

Does this change when the speakers have good vertical directivity?

 

[Tangband]

Does this change when the speakers have good vertical directivity?

You dont need any help from reflections to get the recording illusion greater with multichannel . Its much better than stereo . So absorption on the walls and the floor is a good thing . Even if the directivity are perfect from the loudspeakers , using a hard floor without a carpet gonna bring delayed reflextions within 5 ms blurring the multichannel sound .

 

[Frgirard]

In studio multi or stereo, the absorption on the floor is not recommended.
My own experience is opposite. I use Japanese tatami and a rug (to protect the tatami).

 

[j_j]

Hm. With multichannel and a dead-ish room it is possible to recreate the acoustic of choice, be it artificially or by capture (obviously not 2-channel capture, and obvious not by "sound field mike". An array of soundfield mikes, or hypercardiods, is a good start.

 

[nerdoldnerdith]

Would it be a good idea to put BAD ARC panels on the ceiling where the ceiling bounce occurs (5.5 feet away) if I am going for spaciousness, or is there a better panel for the ceiling?

 

[kthulhutu]

What type of diffusion would be recommended for a small room nearfield setup where the goal is to re-introduce some of the energy incident to the back and rear sidewalls as a diffuse field?
Currently, I attenuate the most troublesome specular reflections at the listening position (the 'dead end') and would like to experiment with increasing the perceived psychoacoustic size of my room.
My supplier of choice is Gik as I live in the UK, and they sell two diffusers that have caught my interest. One is their N23 2 dimensional diffuser. The size and price are definitely appealing to me.
The other is the Q7D 1 dimensional vertical well diffuser. This one is a little large and heavy which makes me more hesitant to try it in my room, but from what I've read in this thread, 1D diffusion with the diffraction lobes oriented horizontally is much more efficient at providing lateral envelopment than 2D.
So should I even bother with QRD? Also, my distance to the diffusers will vary from 6-9ft depending on the placement I choose so from my understanding I do not want diffusers that scatter too low or I will have problems.

 

[dasdoing]

1D diffusion with the diffraction lobes oriented horizontally is much more efficient at providing lateral envelopment than 2D

no clue why 2D has so many fans, as there shure is no benefit in throwing sound up and down in a studio

 

[Bjorn]

With 6-9 feet distance RPG's Modffractal would be great and much better than a standard and narrower QRD.

 

[kthulhutu]

With 6-9 feet distance RPG's Modffractal would be great and much better than a standard and narrower QRD.

View attachment 206484

I see your own website sells these, do you offer delivery to the UK? And if not, do you know of any other sellers with RPG products?