My diffusor design - is it ok?

[pitchfork]

Opps..didn't see this.

btw, because of the small creatures calling Oregon pine their home, the pine you get is probably imported from GA or Canada at greater cost

You hit it on the nailhead. Hey Glenn, ever priced CLEAR HEART FIR??
I love that stuff, and you'd think plain ole Fir would be cheap. Ha!!! Unbelievably priced. Especially for Oregon. I mean, theres a GAZILLION f__king acres of it here.

and btw Glenn, thanks for chiming in. Sometimes this stuff really bothers me and it helps even if one person trys to shed some light on it.

[gullfo]

us skeptics have to stick together

[jayfrigo]

Originally Posted by Jens Eklund

If RFZ then, yes: You do want the Haas kicker.

Not quite in the way it is thought of with the original LEDE designs. RFZ rooms will often have some kind of diffuse termination of the ISD gap, but not a Haas Kicker in the original sense. Those were too strong, and early on, not nearly diffuse enough. These days a more diffuse and less conspicuous termination is generally preferred.

By the way Jens, the diffusers look great! Can't wait to check 'em out when they're available. Could you tell us a bit about the measurement setup and technique?

[pitchfork]

Quote:
Originally Posted by Jens Eklund View Post
If RFZ then, yes: You do want the Haas kicker.
Not quite in the way it is thought of with the original LEDE designs.

Hi. Could you expand on that a bit. I'm just a home recording enthusiast who's interested in this stuff, but I just found this at Wiki, which seems at odds with some of the statements here.

Many older LEDE ("live end, dead end") control room designs featured so-called "Haas kickers" - reflective panels placed at the rear to create specular reflections which were thought to provide a wider stereo listening area or raise intelligibility.[3] However, what is beneficial for one type of sound is detrimental to others, so Haas kickers just like compression ceilings are no longer commonly found in control rooms.[4]

and Did I mention contradictions?

I did own Everests 1st edition, but never saw any of these Hass Kicker thingys IN a LEDE environment. There was one picture of these things, but in a really old CR environment. Over the years I've asked various questions about them, but was usually told something like ..."like QRD's these have been superseded by modern schools of thought"...or something to that effect. Anyway, still curious about modern use of them and how they relate to the RFZ thing. Again..only an enthusiast trying to learn.

[pitchfork]

us skeptics have to stick together

Wow. Didn't know you had the same healthy affliction. Unfortunately, in my case, coming from a poor DIY HR enthusiast point of reference doesn't help. Always looking for a way to DIY interpret this stuff into a cheap way around it.(kinda like how Woo/Holder interpret the Constitution)Sorry...couldn't resist.

[Jens Eklund]

Originally Posted by jayfrigo

Not quite in the way it is thought of with the original LEDE designs. RFZ rooms will often have some kind of diffuse termination of the ISD gap, but not a Haas Kicker in the original sense. Those were too strong, and early on, not nearly diffuse enough. These days a more diffuse and less conspicuous termination is generally preferred.

By the way Jens, the diffusers look great! Can't wait to check 'em out when they're available. Could you tell us a bit about the measurement setup and technique?

Hi Jay


To me, a ”Haas kicker” simply refers to the termination of the ISD-gap assuming it has sufficient gain to actually trigger the Hass effect, the “Hass trigger” if you will. It does not necessarily need to be a single strong specular reflection at the beginning of the (semi)-diffused field following the ISD-gap termination. Perhaps I´m using the word “kicker” incorrectly. I´ll try to use “Haas trigger” instead from now on to avoid confusion. So, If LEDE/RFZ: you do need the “Haas trigger” (a termination of the ISD –gap of sufficient gain to trigger the Haas effect i o w).


The Optiffuser is available and has been implemented in some designs already, here´s one of them:
GIK or Realtraps?

For information (measurements, BEM-simulations etc), check out the manual:
http://www.resonatorstockholm.com/Op...ser_Manual.pdf

The measurements are standard boundary plane measurements:
Acoustic Absorbers and Diffusers: Theory, Design and Application - Trevor J. Cox, Peter D'Antonio - Google Böcker
but since I didn´t have the time or energy to do all 1369 (37*37) combinations of speaker/microphone positions needed (I don´t have access to a 37 mic setup …yet) to produce full random incident coefficients and also, the total panel width used when measuring was only 2,4 meter wide (not wide enough to fulfill the requirements outlined by the current standards), I only use them to confirm temporal diffusion since the BEM model in Reflex cannot simulate this. BEM modeling is on the other hand very good at predicting spatial diffusion and compares well against real world measurements and is considered accurate enough to be used as a performance measure:
diffusers


Sincerely Jens Eklund

[Mctwins]

Originally Posted by pitchfork

Hi. Could you expand on that a bit. I'm just a home recording enthusiast who's interested in this stuff, but I just found this at Wiki, which seems at odds with some of the statements here.



and Did I mention contradictions?

I did own Everests 1st edition, but never saw any of these Hass Kicker thingys IN a LEDE environment. There was one picture of these things, but in a really old CR environment. Over the years I've asked various questions about them, but was usually told something like ..."like QRD's these have been superseded by modern schools of thought"...or something to that effect. Anyway, still curious about modern use of them and how they relate to the RFZ thing. Again..only an enthusiast trying to learn.

Very interesting observation here. I have the same thinking here.

I would also have that to be expanded a little bit further.

[johndykstra]

Originally Posted by Mctwins

Very interesting observation here. I have the same thinking here.

I would also have that to be expanded a little bit further.

Originally Posted by jayfrigo

Not quite in the way it is thought of with the original LEDE designs. RFZ rooms will often have some kind of diffuse termination of the ISD gap, but not a Haas Kicker in the original sense. Those were too strong, and early on, not nearly diffuse enough. These days a more diffuse and less conspicuous termination is generally preferred.

By the way Jens, the diffusers look great! Can't wait to check 'em out when they're available. Could you tell us a bit about the measurement setup and technique?

Originally Posted by Jens Eklund

Hi Jay


To me, a ”Haas kicker” simply refers to the termination of the ISD-gap assuming it has sufficient gain to actually trigger the Hass effect, the “Hass trigger” if you will. It does not necessarily need to be a single strong specular reflection at the beginning of the (semi)-diffused field following the ISD-gap termination. Perhaps I´m using the word “kicker” incorrectly. I´ll try to use “Haas trigger” instead from now on to avoid confusion. So, If LEDE/RFZ: you do need the “Haas trigger” (a termination of the ISD –gap of sufficient gain to trigger the Haas effect i o w).

[Mctwins]

Yes, I do understand that.

So, if RFZ is used then a Hass trigger/kicker is needed, but if one don't follow the RFZ then the trigger is not needed. Is the trigger only suited for RFZ???

[DanDan]

I think it might be worth considering some historical perspective.
In 1974 USA, the Record Industry was worth more than HollyWood and Sport combined.
Studios were expensive and profitable, as were recordings.
So much of the acoustic work of that time was written up and copyrighted.
Thus we see plenty of LEDE, RFZ, and such in the text books.

And little enough patented or written about since.

However development has continued, and one would hope that current thinking has improved on the previous good work.

I am open to surprise but I am not aware of any LEDE certified rooms built in recent history.

DD

[Jens Eklund]

Unless NE (including FTB and other variants of it) or possibly Ambechoic (more or less, intentionally or not), most rooms built today are LEDE/RFZ (yes; LEDE = RFZ in terms of the acoustic response criteria) but naturally not necessarily “certified” and unfortunately, not always good implementations of the concept.

LEDE Control Rooms

[bwo]

Haas trigger is important if one wants accuracy and liveliness. The Haas trigger/kicker hasn't really changed in LEDE designs, but has evolved from the use of reflectors to the use of diffusors to obtain it. Getting a high termination from diffusors is obviously better with less coloration. That simply wasn't possible in the beginning when one didn't have QRD diffusors.
And to get a strong termination from diffusors, they should be in a hard surface like for instance wood or glass.

[DanDan]

Unless NE (including FTB and other variants of it) or possibly Ambechoic (more or less, intentionally or not), most rooms built today are LEDE/RFZ (yes; LEDE = RFZ in terms of the acoustic response criteria) but naturally not necessarily “certified” and unfortunately, not always good implementations of the concept.

Agreed, not a certified one built in recent memory that I am aware of.

And it seems entirely possible that some of the designers are deliberately not sticking to the old rules in order to build a variant which they consider an improvement. Evolution.

I am implying that rigorous application of the certification rules and criteria is a bit passé. Furthermore, the laborious discussions we see on the matter, look to me like people comparing their (mis)readings of the same text book.

I would love to see a substantive discussion on say RFZ. Is it really a given?
I see many designs these days with diffusion at the sides and overhead.

DD

[hsal]

I see many designs these days with diffusion at the sides

One benefit of placing diffusor on sidewalls can be seen in figure 7.8 page 114 in "master handbook of acoustics" 5 edition (page 210, in 3rd edition).

Sound from a posteriour angle and oblique (posteriour/lateral), can be seriously attenuated at higher frequensies due to head diffraction/shape of pinnea.

In LEDE rooms the sound comes from an oblique posteriour/lateral angle.

This attenuation of higher frequensies does not show in measurements with a normal measurement mic, unless recording binaural with a dummy head.

As for settling "what is best" on the net, the analogy "it`s like dancing about architecture" seems fitting.

And yes I have been dancing about architecture before, with others on this forum

[DanDan]

Good points hsal.

I have a topic under discussion with a client at the moment.
He has achieved quite a remarkable Zone Without Reflections.

More than 20dB down. Quite a lot of it 30dB. I am checking the data!

Except for a spike at 23mS.
Now it was/is at -15 or so, perhaps of little consequence.
It appears to be a multiple bounce. Two carefully placed diffusors completely eliminated it.
So a fairly weak 'Hass Kicker' ish, has been replaced with pretty much nothing. Nothing on the ETC that is.

I am wondering is this a waste of diffusors. I suspect to get a decent termination would require quite a lot of them.

Would there be better chance of possible benefit placing these diffusors at the sides, (boggy), or overhead (Northward)?

Would welcome thoughts on this.

DD

[johndykstra]

People come to this site multiple times a day and ask 'where should my diffusion go... how much?... I think the skylines look the best I want those...'.

Should we all just start saying 'where ever you want... there's not specific 'science' or anything to the idea of incorporating diffusion into a control room'.

If there's anyone dancing about diffusion (great analogy) in here, it's because diffusion was brought into the control room for a specific purpose.

From what I gather, the addition of diffusion in a "trigger-less" control room needn't be considered a total failure. But if you're going to all the trouble to add 'life' to your control room, does it not make sense to at least attempt to hit the trigger? I mean there is only one concept that utilizes diffusion to any significant degree correct? (barring the small % in FTB, the unobtainable degree of ambichoic and those wacky early diffuse hifi designs) So when people come in here asking about diffusion, isn't it the proper thing to do to explain to them what it is they are trying to achieve when using it? Fall short and you've got what you would of had if we all stop dancing and toss crap on the walls where it looks good. But at least an effort was made.

I'll admit the RFZ/lede preachers can be over barring at times if you as a question asker want something quick and attractive. But no more annoying than the complacency and status quo that continues to encourage 2'x4' 'objects' as recommended treatment plans. At least the RFZers are preaching a strategy and not an acoustics angle created by retailers.

Retail acoustics are fabulous. There are an entire league of bedroom producers who owe them oodles of gratitude for the services and products they provide. No question. Hats off... this isn't about that. When an individual is willing and able to pick up a saw and a staple gun let's all try to think a little more creatively outside the 2'x4' "box" no?

And when someone asks about the strategy and process behind diffusion, let's let the diffusorers do their thing.

Sorry. I'm crabby this morning

[Jens Eklund]

+1 John!

A different way of treating a room

[DanDan]

Que?

[pitchfork]

That simply wasn't possible in the beginning when one didn't have QRD diffusors.

Huh? I THOUGHT one of the primary concepts of LEDE certified rooms was the use of QRD's on the rear wall?
Although, I only have my first introduction to LEDE in Everest's first edition to refer to, of which he provided a plan view drawing of the concept, which indeed showed a QRD rear wall . So, in the "beginning", from your observation, there WERE LEDE rooms built without rear wall diffusion, no? If so, it would seem that the LE part of the equation must have been spectral.

Which seems rational, as I found something this morning some of you may be interested in . While searching the net for the aforementioned drawing in Everest's Handbook(mine disintegrated from overuse) I came across these little tidbits of enlightenment.

It is the importance of Richard C. Heyser‘s invention of Time Delay Spectrometry (TDS), that allowed manufacturers to implement a computer that measures Time, Energy, and Frequency (Techron TEF). TECnology Hall of Fame 2006 Using such a computer and software allows you to measure sound in 3 dimensions. This enabled Don and Chips Davis to invent the LEDE critical listening room. It enabled Dr. Peter D'Antonio to commercialize Diffuser panels. It enabled speaker designers to "time align" multiple speakers I feel this comment is insightful of the importance of these inventions in modern day acoustics, especially, "90% plus of serious professional control rooms in operation reflect this design type."

And this...

This is the Chips Davis designed and built LEDE control room I worked in. I was very fortunate to have been one of the house engineers and got to observe Chips designing and building this facility from scratch to its finished state.

(see them below)

Ok, he goes on to say..

Nowadays the “dead end” is referred to as Reflection Free Zone (RFZ) and some like it more live (like me) than dead. I.e. more diffuser panels are used versus absorbent panels in the front of the control room.

Holy shit.
Here is the link. Quite interesting.
Hear music the way it was intended to be reproduced ? part 5 - Blogs - Computer Audiophile

So, from the authors statement, it appears PRIOR to using QRD's, the front of the room WAS dead by virtue of absorption. See the pictures of the control rooms he is referring to below: Are the panels the "absorption"???

It also appears a certain amount of "discretion" was allowed, in as much that various owners had their OWN input into how much absorption was used in the front, and or the use of QRD's at the rear. This begs the question..when did the actual CERTIFICATION STANDARDS get defined, as well the first time this Certification criteria was implemented(as well as tested and approved), as it seems there was a period of trial and error..or something to that effect. Furthermore, IF some of these rooms during this period did not meet a later implemented Certification, then how could they be called LEDE rooms, as I believe you couldn't call a room LEDE UNLESS it was certified..no? Moreover, now that I see "how" the term
RFZ came into vogue, then something tells me an RFZ is actually...a DEAD FRONT END...right? Which then begs the question..what is all the SIBR stuff about in relationship to DE/RFZ. Doesn't this mean you simply absorb the whole front end and be done with it?(just kidding!)

Anyway, thanks for roadsigns so far. Just sorting stuff out.

[Mctwins]

Originally Posted by bwo

Haas trigger is important if one wants accuracy and liveliness.

You really mean that in LEDE/RFZ it is important with the Hass trigger to get accuracy and liveliness, but in other concepts/designs one can do without it.

[DanDan]

RFZ came into vogue, then something tells me an RFZ is actually...a DEAD FRONT END...right?

Reflections at the Listening Position can be very effectively eliminated by angling the side walls. Some even use hard clouds. These reflections are directed towards the back of the room where they can be absorbed or diffused and returned to the LP.

It might be worth noting here that the Front End of a FTB room is also lively.

DD

[pitchfork]

and those wacky early diffuse hifi designs

Holy cow. Speaking of "wacky", is your name really Scott?

From Scott

" The world of studio design abounds with anti-scientific ideas. Clients want cool looking structures that express in physical form a wide range of wacky esoteric ideas. Corrugated diffusers are only one example. Designers and builders serve these emotional needs to the extent their clients have the money to fund its realization, and that's OK with me even if the Pope is a bit miffed. We might as well start bitching about fancy automobiles having little statutes of naked women on the hood because they don't make the car go faster. I say - let the boys have their fun.

But if you want to understand how well a curved plate works as a diffuser, versus how poorly all these silly corrugated surfaces work you can start reading some scientific papers on the subject [a couple of suggested papers are listed below to start you off]. You can also use standard speaker directivity measurement techniques [ground plane measurement method] to explore the matter yourself - it aint rocket surgery.

You will soon find that the corrugated stuff, to the extent it works at all, only works at certain frequency bands. Between these bands are lobes of utter ineffectiveness. Also you will find that at anything other than normal incidence, such diffusive performance as the device do obtain at normal incidence quickly collapses at other angles.

This is why when a professional is serious about needing diffusion [as opposed to just messing with the clients head and providing some eye-candy] they use a curved plate. If you look in a reverb chamber where maximizing diffusion is critical to measurement accuracy, you will not find corrugated diffusers in the corners, you will instead find curved plates. There is a very good reason for that "

Did you get that..." wacky esoteric ideas. Corrugated diffusers are only one example" part??? Did I mention "schools of opinion"?

[Mctwins]

Originally Posted by Jens Eklund

+1 John!

A different way of treating a room

And your point is..????

[Jens Eklund]

Originally Posted by pitchfork

Did you get that..." wacky esoteric ideas. Corrugated diffusers are only one example" part??? Did I mention "schools of opinion"?

Diffuser Idea. Looking For Opinions

[johndykstra]

Originally Posted by pitchfork

Holy cow. Speaking of "wacky", is your name really Scott?

From Scott



Did you get that..." wacky esoteric ideas. Corrugated diffusers are only one example" part??? Did I mention "schools of opinion"?

Sorry, I don't understand your point. Early diffuse or Moulton rooms are controversial at best. My choice of 'wacky' as an adjective is bothersome?

I do subscribe to the usage of poly diffusors for certain response, but who's this Scott chap?

[Jens Eklund]

Originally Posted by Mctwins

And your point is..????

The “solution” is often not more diffusion, it´s knowing how to use the tools (absorption, diffusion & reflection) effectively. All too often people think that simply adding diffusers to the walls will solve their problem (whatever the problem might be ...).

[bwo]

Originally Posted by Mctwins

You really mean that in LEDE/RFZ it is important with the Hass trigger to get accuracy and liveliness, but in other concepts/designs one can do without it.

Not really. Other designs aren't as accurate as LEDE/RFZ. It has to do with psycoacoustics. Ambechoic might be an exception (I'm not sure though), but no one can build it anyway for practical reasons. A Haas trigger and lateral exponential decaying diffuse field is important wherever critical listening and accuracy is a requirement.

The fact that someone does something else, doesn't change what we know from studies. A NER room lacks important psycoacoustic cues and other designs are basically a contradiction to knowledge and research.

[DanDan]

Strong opinions bwo!
Perhaps there is research on the more modern concepts which has not been published for commercially sensitive reasons?
If that is true, surely relying on only 'the knowledge' will ensure incorrect conclusions.

Some of the modern innovative designers do publish.
http://www.bozoel.com/hosted/myroom-...hite_paper.pdf

Short of publishing, Thomas does explain a lot of the FTB in his PRW forum
PRW The Great Sounding Room! hosted by Thomas Jouanjean

Hedback's projects gallery shows plenty of examples of early diffusion.

If the LEDE/RFZ concept were the best available, surely the best studios would be built in this manner?
This is not and has not been happening.
I know of not one example built within recent history.

DD

[Jens Eklund]

Originally Posted by DanDan

If the LEDE/RFZ concept were the best available, surely the best studios would be built in this manner?
This is not and has not been happening.
I know of not one example built within recent history.

DD

The Control Room | Manifold Recording and the Miraverse

[bwo]

Originally Posted by pitchfork

Huh? I THOUGHT one of the primary concepts of LEDE certified rooms was the use of QRD's on the rear wall?
Although, I only have my first introduction to LEDE in Everest's first edition to refer to, of which he provided a plan view drawing of the concept, which indeed showed a QRD rear wall . So, in the "beginning", from your observation, there WERE LEDE rooms built without rear wall diffusion, no? If so, it would seem that the LE part of the equation must have been spectral.

LEDE started out with a total absorptive front end and a reflective rear end with no diffusors. There were no measuring tools those days. The introduction of TEF changed and evolved LEDE. Then, it was possible to create a RFZ by measuring and only absorping the spots that were needed. And later also by redirecting the energy with reflectors or non-parallel surfaces to the rear of the room.

I believe it was Peter D'Antonia that introduced advanced QRD diffusors to LEDE and then that became another development and a reflective rear wall was abondended. And so was eventually reflectors to create a Haas kicker and replaced by diffusors with hard surface.

An interesting sidenote is that the first diffusors (built by masonry) were much deeper then the commercial diffusors from RPG are today. Peter D'Antionia doesn't actually use his own commercial diffusors in his designs. Their depth (and also width) is a compromise.