Above the Schroeder Frequency. Diffraction.

[johndykstra]

Originally Posted by dykstraster@gmai
Is this practical in say an 8' x 10' room? To bounce it enough times to get it to your ears at an acceptable delay, but still maintain a usable gain?

SAC Quote:
Yes.

This is where you choose to be succinct? No, you're right... you've been incredibly helpful.

[SAC]

Damned right!

As the subject of the Haas effect and the the particular special instance defined by a Haas kicker is derivative from a larger topic - which is far beyond the scope of a thread where we have spend 5 pages arguing over whether the ETC response is of any use!

Yup, another who "just wants the answer"!!!
Well you have "the answer". Its called a "Haas kicker". What's wrong? Does it require a bit more understanding to know where and how to use it? And what its "for"? After all, a colleague who has no use for an ETC and already knows all about this stuff just asked where they were positioned after the post that stated where they are typically positioned. Ironically, you will want to use the ETC to position it properly!

Heaven forbid that we would have spent how many weeks/months discussing applications where the use of the ETC would be beneficial instead of arguing over whether or what a graph of time versus gain meant!

But give yourselves more credit. You are the ones who chose to argue and challenge a topic as SIMPLE as the utility of the ETC. And now you petulantly demand "the answer".

Well, my lunch time is just about over. May I suggest you check out the books mentioned in the meantime?

And too small...
How about as small as the width of a sound board in a Swedish television production truck.

[Seamus TM]

Well, I think that one thing is clear.
Someone has to trademark "Haas Kicker" immediately.

[johndykstra]

This thread started out plenty useful. For the first time I saw you actually interpreting the knowledge on a reasonable level. Beyond that, you've done little more than point us in the direction of text. Something that Amazon.com is quite good at. As someone who clearly has read and can understand the text, I guess I thought you could help a bit to explain it. A big part of explanations is through examples. Something you are clearly not fond of using. It's cool. Stop accusing me of not putting in the effort. I've read every link posted. Non of them tell me how to interpret an ETC. For example, at what gain or delay of a reflection should we begin using diffusion instead of absorption? If the "real" answer requires a degree in physics, may I suggest you provide us with a "generally speaking" type answer. Pretty please with sugar on top?

[johndykstra]

Originally Posted by Mumblesound

Well, I think that one thing is clear.
Someone has to trademark "Haas Kicker" immediately.

I googled it. There must be a lot of kickers named Haas, as it turned up nothing but sports related topics.

[SAC]

Copyright the term? 30 some years too late.

Nonsense you have read all of the sources I have cited! And ALL of the basics are in SSE! And NO math is required.
And I never cited Google as a source.

Yeah, and what does Google return in the first 4 substantive links? Gee, two references! And even a PICTURE of a LF QRD used as a Haas kicker! You might also want to Google "Hooked on Phonics"

1. Haas denkt über Davis-Cup nach - Tennis - kicker online
   
   Kicker - Haas denkt über Davis-Cup nach - Vor knapp zwei Jahrezehnten ist Thomas Haas über den Großen Teich gefloge... Haas denkt über Davis-Cup nach - Tennis - kicker online.
   tweetmeme.com/.../haas-denkt-uber-davis-cup-nach-tennis-kicker-online - Cached
2. Einzig Haas überlebt den Tag - Tennis - kicker online
   
   Einzig Haas "überlebt" den Tag: War Tag drei für die deutschen Tennisprofis noch ein erfreulicher, endete Tag vier... Einzig Haas überlebt den Tag - Tennis - kicker online.
   tweetmeme.com/.../einzig-haas-uberlebt-den-tag-tennis-kicker-online - Cached
   
   
3. Sound system engineering - Google Books Result
   
   Don Davis, Carolyn Davis - 1997 - Technology & Engineering - 665 pages
   50 100 TIME— MILLISECONDS 100 200 TIME— MILLISECONDS A Haas kicker— This is a ... A Haas kicker is any energy return from either a specular reflective ...
   books.google.com/books?isbn=0240803051...
4. Video results for Haas kicker
   
   
   
   YouTube - red front offenbach
   4 min 32 sec - Dec 18, 2008
   YouTube - Broadcast Yourself.
   
   
   Steffen Haas (Kickers Offenbach 2008/09)
   3 min 46 sec - Dec 22, 2008
   YouTube - Broadcast Yourself.
5. AES E-Library: Some Aspects of Control Room Acoustics
   
   by É Arató-Borsi
   They say that so called Haas kicker msst be placed to the side rear wall of the listener at the console. At the rear wall behind the mixer's position ...
   Audio Engineering Society (AES) › Publications › E-Library

Bye for now!

[johndykstra]

Quoted from reference #3 above:

"b. Diffusion-Our very definite preference is for Schroeder quadratic residue diffusors (QRD) or primitive root diffusors (PRD). We believe that the optimum placement of these is behind the mixer's position (at the rear wall - a good distance from the mixer is from 7 to 15ft.). The diffusors should not be in the on axis path of the monitors since the undesired specular reflections at frequencies above the diffusion frequencies can occur."

Seems this may be difficult in a SMALL room.

[Nordenstam]

Head over to the bass trap/treatment section, start a thread detailing the framework and what sort of diffuser you'll like. Collo will serve it on a plate if you ask for QRD's, 1D or 2D. I'll give you the lowdown and some of that cryptic technobabble if you want to do PRD.

Diffusers can be made to suit just about any practical setting. A 4" deep 2D diffuser have a minimum distance of about 3 feet. Shallow enough for your room?

[johndykstra]

Originally Posted by Lupo

Head over to the bass trap/treatment section, start a thread detailing the framework and what sort of diffuser you'll like. Collo will serve it on a plate if you ask for QRD's, 1D or 2D. I'll give you the lowdown and some of that cryptic technobabble if you want to do PRD.

Diffusers can be made to suit just about any practical setting. A 4" deep 2D diffuser have a minimum distance of about 3 feet. Shallow enough for your room?

Thanks Lupo, that's plenty shallow. To be honest, I'm not really looking to do anything to my room, I just want to learn. My live room is great, and will be better when I finally get the polys built. My control room is a 9'x9'x9' box... it'd take a miracle to save that nightmare.

Perhaps I'm at a wall where diving into the math is the next logical step. sigh.

[Brainchild]

OK home at last. So here is the front and side view of the "cells" I have made according to the various different formulas for Helmholtz resonance that use different variables but all converge on the same result: resonant frequency. They're just boxes made of 3/4" white pine fastened with screws, caulk and glue (I'm no craftsman, so I just try to make sure they have a solid seal). I use 1" inner-diameter black PVC plumbing pipe for the ports and a "hole drilling" bit or whatever they're called to drill the holes in the front face. A 1"-thick square of OC 701 abuts the backs of the ports and is held in place in the back with hanging brackets nailed into the sides of the cells. Anyway:




So I have 20 of these things stacked in five rows of four columns each in the closet at the back of my bedroom studio. This is where I measured the most serious glob of 37Hz buildup during my initial measurements way back when.

This is the FFT analysis of 20 seconds of pink noise being fed from my subwoofers only, without the arrays in place, measured with a Nady SCM 960 in omni mode, two feet from the back wall of the closet (and room).



And this is the same measurement with all the cells in place.



So, not an enormous difference, but significant, and most especially important to me is the way the formulas actually do match up amazingly well with the frequency dip in the measurements. For a DIY thing that I find enjoyable in its own right, this is a good approach. Not for everybody.

[PaulP]

Thanks Brainchild, that is fantastic. I realize the dimensions are relative to
your target frequency but, just for clarification, your boxes are roughly
10" x 10" x 10" ? So the entire array is about 40"h x 50"w x 10" deep ?
Very simple construction.

If you went directly from the formulas to the finished array that is accurate
indeed. You've given me great hope.

Paul P

[DanDan]

I note a persistent refusal to answer the following two questions.

Originally Posted by dykstraster@gmai
Is this practical in say an 8' x 10' room? To bounce it enough times to get it to your ears at an acceptable delay, but still maintain a usable gain?

SAC Quote:
Yes.

How would that happen in an 10 x8 room?

In the same room, where can we place Haas Kicker?

I am sure this will merely provoke another classic SAC/foxyr rant about how it was all done three decades ago by the usual suspects, blah blah blah.
He will continue to suggest that there is another way, if only us plebs had minds as superiour or education as expensive as himself. There will be constant references to well known phenomena which are valid only in large room situations. When it comes to small rooms we just get the mysterious 'Yes' and 'everyone ought to know where to place Haas Kickers'

Pathetic.



DD

[johndykstra]

I'm eating my words Dan.


Brainchild, for the construction of the frequency of your HH, is the internal volume for your box that of 4 seperate devices? But all sharing one air space?

[DanDan]

dyk,

I'm eating my words Dan.

?
I agree with your questions and your comments expressing frustration about SAC's thing.

e.g.

This is where you become frustrating, if it's so well understood, it should also be well documented. Since you seem to be an encyclopedia of references, clearly you should be able to produce "a" picture of a small room treated to your specifications.

It seems to take quite a while for many to see through foxfyr's freudian slip.
Ultimately it becomes obvious though, he's got nothing.

DD

[johndykstra]

No, I know. Earlier in the thread I pleaded that you give him the opportunity to show some worth. I asked you to leave him alone and said I'd "eat my words" if this thread didn't pan out.

The acoustic leprechaun strikes again.

[Brainchild]

PaulP,

Pretty much; the inner dimensions are 12"x12"x12" and the ports are actually 5" long (the picture I posted is from when I had them at 4").

dykstraster,

Yeah, the four ports on the front face of each cell feed into one common volume.

[johndykstra]

Originally Posted by Brainchild

PaulP,

Pretty much; the inner dimensions are 12"x12"x12" and the ports are actually 5" long (the picture I posted is from when I had them at 4").

dykstraster,

Yeah, the four ports on the front face of each cell feed into one common volume.

Just to clarify, the one common volume is the amount you would have for 4 seperate traps right?

[Brainchild]

I'm sorry, yes. Looking back at the front-view picture I posted, I see my answer was annoyingly vague. The picture makes it look like maybe the cell is divided into four separate chambers (one per port), but those were just guide lines for making the drawing. It is four ports on the face of each 12" cube, and each cube is just one open volume.

[johndykstra]

Originally Posted by Brainchild

I'm sorry, yes. Looking back at the front-view picture I posted, I see my answer was annoyingly vague. The picture makes it look like maybe the cell is divided into four separate chambers (one per port), but those were just guide lines for making the drawing. It is four ports on the face of each 12" cube, and each cube is just one open volume.

I've read that putting absorption inside will widen the Q but lessen the effectiveness at the target frequency. Did you perhaps try it both ways?

[Seamus TM]

Please correct me if I'm wrong, but...

Sound travels at 1130 ft/sec
That's 1.13 ft/millisecond.

So for sound to go from the listening position, to the back wall and then back to the listening position in no less than 20 ms, you would need a minimum of 11.3 feet or so between the listening position and the back wall.

... right?

[Nordenstam]

If the room is too small to use the rear wall directly, send the sound off to the sides (splayed rear wall) and let them bounce from there to the sweetspot.

[Nordenstam]

Originally Posted by DanDan

It seems to take quite a while for many to see through foxfyr's freudian slip.
Ultimately it becomes obvious though, he's got nothing.

It's funny how different the world looks when avoiding conflicts.

The way I've seen this is that he's got lots. More than most in here. Been learning some crucially important things lately!

[Seamus TM]

Originally Posted by Lupo

If the room is too small to use the rear wall directly, send the sound off to the sides (splayed rear wall) and let them bounce from there to the sweetspot.

Right, but if you were absolutely stuck with a rectangular room, and could only use the back wall to try and achieve a true-ish LEDE/Haas effect... thing...
Would 12 feet be the magic-ish length between the listening position and the back wall?

[DanDan]

Lupo we may agree to differ on that topic. I suggest that a little research on your part will convince you of the truth. Search for posts by SAC or foxfyr. You will find repeated examples very similar to this thread. All end up with confusion and unanswered simple questions.
As regards conflicts, I don't see it like that. I believe this guy has diminished the forum and continues to do so. Why else has foxfyr vanished? I have had PM's from six very frequent posters, of quality contributions, who have agreed with and encouraged my stance on this. I would be happier of they would simply post their own opinions, but I feel strongly enough to pursue my own view in any case.

DD

[DanDan]

It is widely written how some absorption will broaden the bandwidth/lessen the Q, at the expense of narrow band performance. I have read that ash was used in the Helmholtz units in ancient Greece. I have tried a particular experiment myself. It did show exactly the behaviour described. It did also indicate that just one unit had nothing like the claimed performance in the MHOA. I can guess that a wall of those may work well though.
Acoustics Forum • View topic - Helmholtz formula, is this incorrect?

One detail. Some time afterwards I noticed a post which suggested that the absorption needed to be in the port of the device. Didn't see that anywhere else, so I can's say if that is the reason why my one did not work. Common sense though, suggests that one little unit could not affect a 47Hz mode as described in the MHOA.
DD

[PaulP]

Originally Posted by Lupo

If the room is too small to use the rear wall directly, send the sound off to the sides (splayed rear wall) and let them bounce from there to the sweetspot.

A large horizontal poly would be good for this, perhaps with an absorptive band
in the middle to take care of the small amount that would be reflected straight
back.

Paul P

[PaulP]

There are a lot of conversations going on here...

Originally Posted by Mumblesound

Right, but if you were absolutely stuck with a rectangular room, and could only use the back wall to try and achieve a true-ish LEDE/Haas effect... thing...
Would 12 feet be the magic-ish length between the listening position and the back wall?

What I don't like about using the rear wall in a minimum distance situation is
that all the 'large room' information will come only from the rear of the room.
It seems to me it would be better if we could find a way so that it would come
at us from different directions, like it would in a real large room.

What we want is to have some come off the rear wall (if it's far enough
back, otherwise it has to be sent elsewhere), some from the sides
and some from the front.

I have this crazy idea of a small room with a lowered ceiling in which the
reflections off the rear wall are directed up into the space between the
two ceilings where they travel to the front of the room before being let
back down into the room. This way delay info would also come from the
front.

Paul P

[DanDan]

Just being Devil's advocate here, or the Devil
We have been over this already.
But, 10 feet, 38%, six feet to the back wall. Slightly longer to splayed side walls.
On a rough estimate it would take at least 3 bounces to get beyond 20mS. Thus the level would be diminished. Furthermore, most paths are interrupted at first bounce. We are talking about very little stray energy back there, and if it triggers a flutter, it is on death row immediately.
Sure some of us have noticed that there is a sometimes a slight bloom knocking around in the back of the room, but I will add that it is generally detrimental to listeners on the couch or even in the back 38% sweet zone.
It seems to me, like there is an attempt to stretch the realities of the common small room to squeeze in elements of larger room, more desirable behaviour. IMHO it doesn't happen. We need to deal with the real world questions. e.g. Are Diffusors desirable at short distances or not?
DD

[Nordenstam]

Originally Posted by PaulP

What I don't like about using the rear wall in a minimum distance situation is
that all the 'large room' information will come only from the rear of the room.
It seems to me it would be better if we could find a way so that it would come
at us from different directions, like it would in a real large room.

What we want is to have some come off the rear wall (if it's far enough
back, otherwise it has to be sent elsewhere), some from the sides
and some from the front.

This seems rather easy to me. Take an empty room, add first reflection point treatment, make sure bass traps reflect some stuff back and it should be solved by itself! The reflecting surfaces on side walls and in front will send some of the energy that came from the rear wall back towards the listeners. Angling the reflectors appropriately may aid in the goal. An obvious place to do it would be to add some splayed surfaces to the sides. Would send the first reflections backwards and send some of the rear wall returns back to the sweetspot.

Originally Posted by PaulP

I have this crazy idea of a small room with a lowered ceiling in which the
reflections off the rear wall are directed up into the space between the
two ceilings where they travel to the front of the room before being let
back down into the room. This way delay info would also come from the
front.

Doesn't seem crazy at all. Unless I'm too crazy to see what's wrong with it. Have been thinking/doing the same.

Am having the rear part of the cloud reflect some sounds back to the rear wall. The path is speaker->rear wall-> up into cloud-> back at rear -> sweetspot. It does of course presume a bit of depth to cloud, to make it worth the effort frequency wise. My cloud is about 50cm down from the celing, which should reflect sound down to about 700Hz. Sending the sound across the upper part of the cloud, as you're thinking about, doesn't work in my particular setup. It's only a halfdone idea at the moment, haven't making all of it reflecting yet. Will get back to this when I get to test some more..

[SAC]

Originally Posted by PaulP

A large horizontal poly would be good for this, perhaps with an absorptive band
in the middle to take care of the small amount that would be reflected straight
back.

Paul P

A poly would not be a good choice, as not only is it an 'uncontrolled' scatterer, but it is an extremely 'frequency limited' scatterer.

It does NOT provide a broadband reflection, but rather a very bandwidth limited frequency spectrum based upon its curvature.

For so many with concerns about the frequency response of reflections, this method has severe restrictions - especially in the critical band from 250 Hz to 5000 Hz.

Originally Posted by DanDan

I note a persistent refusal to answer the following two questions.

Originally Posted by dykstraster@gmai
Is this practical in say an 8' x 10' room? To bounce it enough times to get it to your ears at an acceptable delay, but still maintain a usable gain?

SAC Quote:
Yes.

How would that happen in an 10 x8 room?

In the same room, where can we place Haas Kicker?

I am sure this will merely provoke another classic SAC/foxyr rant about how it was all done three decades ago by the usual suspects, blah blah blah.
He will continue to suggest that there is another way, if only us plebs had minds as superiour or education as expensive as himself. There will be constant references to well known phenomena which are valid only in large room situations. When it comes to small rooms we just get the mysterious 'Yes' and 'everyone ought to know where to place Haas Kickers'

Pathetic.

DD

Pathetic Indeed!

Originally Posted by SAC

Additionally, it is a rather easy process - assuming you can see what is going on (hence the use of the ETC) - to install a rear laterally mounted reflective Haas 'kicker' (often a low frequency QRD does 'double duty' and works wonderfully for this) to create a 'strong' reflection at a point greater that the room's natural Initial Signal Delay gap to stimulate the Haas response, effectively ending the ISD; and to then use the remaining sound field to augment the sense of space in a SMALL room.

And not only was a source provided where you could SEE one in practice; a truly sentient being might wonder just where a "a rear laterally mounted reflective Haas kicker" might be located???

Let’s take a stab…it just might be in the rear of the space and "lateral" to the orientation of the room and speaker axis – as in

lat-er-al adj.

1. Of, relating to, or situated at or on the side.

Words mean things, and as you have repeated the same question twice now that was answered before you asked it the first time, you would know if you would try actually reading for meaning and not simply dreaming of your next nonsensical complaint.
“Pathetic” is right!

But then the erudite scholar requires a cookbook answer as to “where” to place it, rather than how the position is determined relative to specific response criteria. Ironic, as the ETC response is a fundamental tool for such evaluation. Especially as we have listened to the constant whining that ETCs are of no consequence from the same limited functioning ‘reflections are evil and to be removed at all costs’ brain trust.

The real problem here is that this fiasco has gone from a multi-page argument over whether ETCs even have merit (which you have lost), to now the complaint that the entire acoustical room model, complete with a cookbook solution to obtaining it has not been posted! In other words, we have progressed from "a wrench is not a viable tool" to "so why have you not posted a complete blueprint for the construction of the space shuttle complete with all of the derivative discussions adequate to understand all of the underlying principles upon which each subsystem is based"! LOL!

But since you DD refuse to acknowledge that the ETC has value, why not just stick to your advanced technique of wandering about clapping – as if that has anything to do of value with evaluating individual reflections in context to each other and with regards to the Haas Effect. Perhaps your 'partner' can run behind hurriedly applying beau coup absorption to kill all of the evil reflections?

But where to place it? It is generally mounted in a rear lateral location where the reflection can be introduced generating the specific timed arrival of the Haas kicker. And I say generally as it may not be placed in that location if one has a Z shaped bathroom with their primary mix position located in the shower stall as seems to be your primary niche and focus of concern.

You can’t figure out how to get a direct signal to reflect with sufficient energy? LOL! You mean you can't tell by using your 'hand clapping' technique???

But then you and your 'partner' just keep demanding a cookbook solutions!

To determine the timing and gain of the required reflection, as well as to verify the proper application of a Haas kicker, in each room as appropriate, we use, …wait for it folks…. the ETC response!!!!!! And the Haas kicker is placed specific to your individual room response! Hence the purpose for the measurements!!!!

And if he knew as much as he claims to know, he would know that while an 18-20 ms delay between the direct signal and the first reflections ending the ISD gap, he would know that the ISD can be effectively ended as soon (but no less) than 10 ms (and not more than 60 ms) and with an amplitude not more than 15 dB below the direct signal in order to stimulate the Haas Effect! Of course, that knowledge might be useful in a smaller space to implement the technique, but ole' DD is too busy arguing to research or learn more about that which he already claims to know all.

It sure is amazing that one such as yourself who already knows all, can’t figure out the answer to your own insipid questions. But that would be to mistake your REAL purpose here, which is simply to argue any alternative to your limited “absorption, absorption, and more absorption” “solution”.

And it drives DD crazier that others who so many are quick to quote HAVE developed exactly such a preferable alternative!

And then you claim that I only cite Large Acoustical Space room scenarios? LOL! You have utterly lost it. Name one!

I have consistently complained AGAINST the myriad large acoustical space tools inappropriately used in small acoustic spaces - like your persistent and inappropriate references to RT60s! Even the graphical source of response controllers cited (originally from Beranek, et. al.) that was the focus of this thread is based upon a large acoustic space model which needs to be modified for small acoustic spaces! But you didn’t know that either…

And if you will note, a picture of a SMALL certified compliant Swedish television production truck was posted with an effective width narrower than 8 foot! So, as a space as small or smaller than your proverbial room can be completed, why would anyone think a larger small acoustical space could be done had they actually reads the posts'!

But quite frankly, I personally do not consider a space any smaller a legitimate environment to do much of anything in audio. And I don’t care what you think about it... Regardless of how much absorption you put in it. At some point, if someone is serious, they make the decision to commit and utilize resources adequate to the task. And if they do not, then there should be no surprise that they will encounter problems.

Including the FACT that the best imaging does NOT necessarily occur in an anechoic space (unless what's being listened to is also in an anechoic chamber). Reproduction minus a reflected field will contain false directional cues. Establishing a strong Haas trigger (either naturally or with a Haas kicker) and energy from all directions can once again 'trick' the ear-brain into accepting cues that do arrive from the monitors as part of the generated ambiance of the control room, but perceived, due to the first reflection of the studio, as a logical extension of the studio's late sound field. As all of this is effectively an exercise in generating an engineered psycho-acoustical response.

But keep attacking me as if the ideas you reject were developed by such folks as P.D’Antonio, R. Berger, D.Davis. Bob Todrank, C. Davis, Hellmuth Kolbe, R. Heyser and so many more. As it’s humorous to watch you declare every concept they developed based upon objective analysis correlated with subjective experience false.

The fact is, there is much to the concept - one that has been in practical application but the best in the field for over 25 years. But there seems to be little opportunity to simply present it piece by piece in a general discussion format without so many flies in green tights buzzing about simply determined to denounce any approach which threatens their limited understanding of current room models and analytical techniques.

And for those who have received some of the additional material, I would suggest reading through it slowly in chronological order in order to get a succinct 'Cliff's Notes' summary of the many various concepts and techniques involved, as well as the techniques used to evaluate each concept and application.

Oh, and on p. 10 in the 15.1 doc, please take note of the comments regarding requests for a "cookbook" solution and specs. I think you will get a chuckle out of it, especially with respect to the demands several keep repeatedly making here!