Live and Die in LA - The "Sonic Interuptor"

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John Casler

Live and Die in LA - The "Sonic Interuptor"
« on: 5 Jul 2004, 09:30 pm »
Well, that is actually the title of a movie made years ago with one of my favorite soundtracks. (OK I know it is Wang Chung, but it was their best)

Anyhow the title is in reference to LEDE or Live End/Dead End acoustical space, and how to approach it, without having a "dedicated" listening room.

First off, a real LEDE room will blow you away as to the soundstage, depth, and quality of sound.

Only problem is that aesthetically it doesn't fit most peoples decors and there lies the rub.

Well there are a couple little things you can do to "approach" this sound without miles of foam and all ont the wall.

First, the goal is to limit as much as possible anything coming from the front and sides of the room, except for the speaker's sound

So here are acouple things that will help:

1) Sit extremely nearfield.  I mean the speakers should be no more than 6-7 feet from your ears

Sitting nearfeild will cause the most immediate sound you hear to be from the speakers and this will cause the ear/brain to disregard reflected sound that is of a lower db level.

2) Move the speakers at least 3-4 feet out from the front wall

This will significantly reduce reflections on the front wall to a major degree.  

3) Do not sit close to the rear wall.

Be at least 1/3 to 1/2 of the way into the room and as mentioned, in a nearfeild position.


4) Listen on axis


This doesn't work in all cases, but with most drivers the greatest, clearest and most accurate sonic energy is directly on axis.

5) make sure you have carpet or a nice thick rug on the floor between you and the speakers.

Hopefully you have some nice carpet, and even an extra rug in front of the speakers is helpful.

6) Set the room up with the speakers against the "LONG" wall. :notworthy:

Here we go now.  By doing this w/nearfeild you effectively eliminate most all "major" sidewall reflections and reduce the ones left over by a huge amount.

7) Pick up 2 pieces of 48" x 24" x 4" acoustic WEDGE foam.

Pick up "at least" 2 (4 is better) of these.  To use them you place the first one on its side 24" x 4" edge on the floor.  Curve it slightly so that it easily "stands on its side".

Then take the 2nd sheet and place it on top of the first so that you now have a slightly curved 48" x 48" "acoustical interupter".

This Interupter should be placed 2-4 feet in front of your listening position.  Now if you got 4 sheets place the 3rd and 4th in the exact same position but behind sheets 1 and 2.

This will yeild a "acoustic foam wall" 4 feet by 4 feet to block, absorb and interupt most all of your front wall reflection. :wink:

This will effectvely block much of the reflected sound from the front of the room

So lets review:

You are sitting close to reduce effects of reflected sound.

You have eliminated most of the side wall reflections

You have eliminated most reflections from the front of the room

All we have left out is the ceiling bounce and the nearfeild will help that a bit.

After setting up in this fashion, you will absolutley not beleive the "pinpoint" imaging, the incredible 3-D depth, and the quality of the soundstage.

You will also marvel at the improvement in "air", resolution and detail, this uncovers.

You know when someone tells you they can now "hear INTO the recording"?  This will take you there.

Now obviously the sheets of acoutic foam will likely be placed in the closet between serious listening sessions, but they only take two seconds to place and they are the final key to a Faux LEDE I suggest here.

To achieve this affect you have either two choices.

1) block and absorb the sound to keep it from reflecting off a wall, ceiling or floor surface,

or

2) Block it or over power it before it gets to you.  :mrgreen:

I have my front wall "VERY" treated and still use these stacked, curved foam panels because I have my equipment in between my speakers and this blocks all reflection of the sound of off the components.

The depth of soundstage and instrument and vocal placement is "freaky" good. :rock:

Russtafarian

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Live and Die in LA - The "Sonic Interuptor"
« Reply #1 on: 6 Jul 2004, 06:15 pm »
Very interesting John.  True LEDE is nearly impossible to implement in the home environment, and even in a studio environment it has its critics.  Check out the lastest RIVES audio article posted on Positive Feedback:

http://www.positive-feedback.com/Issue14/rives.htm

But as you said, you were describing a modified LEDE approach.  Actually I find your approach to a good synthesis of various speaker setup theories that are floating around out there.  

I have my room set up almost exactly as you've described except that I rely on a combination of diffusion (bookcases and blinds)and speaker dispersion control rather than absorption for sidewall and front wall reflections.  The Gallo CDT has a virtual 360 dispersion pattern that puts a lot of HF energy into the room.  I've found that by wrapping a washcloth part-way around the outside of the cylinder, I can kill side and rear reflections before they start.  

Also, I do sit against the back wall.  Based on the Haas effect, the brain ignores the arrival difference between the direct and reflected sound when the distance from the reflection to the ear is no greater than the circumference of one’s head, which is roughly 18 inches to two feet.  This gives me the added option of "tuning" the perceived ambient soundfield by putting a pillow behind my head.

If you plan on cruising down to OC for the Audio Society meeting in a few weeks, you're welcome to drop by and give my room a test drive.  I'm going to post a general invitation to any other local ACers who want to stop by Sunday afternoon on their way to the meeting.  I've heard Tweeter CMs surround sound rooms and I think I do it better!  Tell me what you think.

Russ

Carlman

Live and Die in LA - The "Sonic Interuptor"
« Reply #2 on: 6 Jul 2004, 06:38 pm »
I don't think putting all your gear in the center of the room is going to win any more WAF than putting foam on the wall.  :lol:

Seriously, I have moved to a nearfield environment for my setup.  It was the last hope for good imaging... and it worked!  I'm using monitors on stands and this method works well for that.  It would not have worked with my last pair of 3-way floor-standing speakers.  The drivers just wouldn't gel together... I could hear sounds from the individual drivers at 6 feet.

Thanks for the nice write-up.  You'd need a room at least 14 x 17 to get it to work out... If I were to try that setup in my room, the speakers would be on either side of my head... like a large pair of headphones.

BrunoB

Re: Live and Die in LA - The "Sonic Interuptor"
« Reply #3 on: 6 Jul 2004, 09:01 pm »
To move to a nearfield environment and/or to adsorb or block  sound coming from between the two front speakers has another advantage. You can increase the relative distance between the two front speakers without weakening the center imaging. It is often recommended to set the distance between the two speakers smaller than the distance between the listener and the speaker. IMHO, this rule does not apply to a nearfield environment with sound adsorption.  Presently, I am sitting 5 feet from the speakers which are 7 feet apart.  I also have a lot of foam between the front speakers. The center image is very strong, actually much stronger than the three other ACers setup I have listen to. The wider separation gives symphonic orchestra a more realistic size. In my previous setup, the speakers were closer and I had the impression of a miniature orchestra in front me.

Bruno

John Casler

Live and Die in LA - The "Sonic Interuptor"
« Reply #4 on: 6 Jul 2004, 10:12 pm »
Quote from: Russtafarian
Very interesting John.  True LEDE is nearly impossible to implement in the home environment, and even in a studio environment it has its critics.  Check out the lastest RIVES audio article posted on Positive Feedback:

http://www.positive-feedback.com/Issue14/rives.htm

 ...


Hi Russ,

I just read the Rives article (the section on LEDE) and am somewhat surprised at his assessment.

Not that I am an expert or anything (and of course he is) but in a professionally set up LEDE there are no direct reflections that have to reach the listener.  They are "all" diffuse.  That is instead of a wave, they are a "spray" of sonic particles, not a ripple or stream of a direct refelction.  So his example of the sound reaching him doesn't make sense, since it is a light sonic mist and not something that is heard or has a reverberant quality.

I guess an example image would be two candles in one end of a room painted with black "light absorbing paint" on one end (Dark End), and somewhat reflective, but totally diffuse material in the other (Light End)

Standing in the Light End the light from the candles would cause it to be faintly light, but you would not be able to make out a direct reflected source (as you would if the surface was all mirrors, for example)

Standing in the Dark End, you would see no light except that of the candles

The total concept of the LEDE is that the stereo image is sent to your ears "without" any reflected room sound, and that the Live End creates an "air" or spatial ambience.

This gives you the purist signal straight from the microphone to your brain, but does not deprive your brain of the spatial perceptions it needs.

Since the brain is used to "diffuse" sound to give it the perception of "space", the LE (live end) is "all diffusing" surfaces which offer no direct reflection of any type.  No echo, no decay, no sonic attribute except "spatial presence and awarness" created by diffuse sonic particles (again for lack of a better term)

Hope that makes sense.


 
Quote
I've found that by wrapping a washcloth part-way around the outside of the cylinder, I can kill side and rear reflections before they start.


Great tweak!  A lot of people don't realize there are many approaches to reducing unwanted reflections other than absorbing them at the room boundary.  Many times directing them, interupting them or blocking them on their way (as you have) will work well too.

Just depends on the frequency, the speaker characteristics, and the room.

Quote
Also, I do sit against the back wall. Based on the Haas effect, the brain ignores the arrival difference between the direct and reflected sound when the distance from the reflection to the ear is no greater than the circumference of one’s head, which is roughly 18 inches to two feet. This gives me the added option of "tuning" the perceived ambient soundfield by putting a pillow behind my head.


I like the pillow.  :mrgreen:

Also a couple sheets of quality acoustic foam will help those who have to listen close to the back wall.

Quote
If you plan on cruising down to OC for the Audio Society meeting in a few weeks, you're welcome to drop by and give my room a test drive. I'm going to post a general invitation to any other local ACers who want to stop by Sunday afternoon on their way to the meeting. I've heard Tweeter CMs surround sound rooms and I think I do it better! Tell me what you think.


That would be great, if I can work it into the schedule.  I haven't heard the Gallo's in a long time, and it sounds like you have yours set up well.

Cool!

John Casler

Live and Die in LA - The "Sonic Interuptor"
« Reply #5 on: 6 Jul 2004, 11:18 pm »
Quote from: Carlman
 I don't think putting all your gear in the center of the room is going to win any more WAF than putting foam on the wall.  :lol:

Thanks for the nice write-up. You'd need a room at least 14 x 17 to get it to work out... If I were to try that setup in my room, the speakers would be on either side of my head... like a large pair of headphones.
...


Hi Carl,

Actually, you can go as small as 12 feet.  The distance the speaker is from the front wall can be changed based on couple criteria.  

I mentioned 3 feet based on a totally reflective front wall and using the sonic director, but if you are able to treat the walls behind and between the speakers a bit, you can put them very close.

And if you use the "interuptor" or thoroughly treat your front wall, you "can" have the speakers very wide, which is almost like headphones and still get an incredible center image and complete soundstage.

My 626Rs are over 9 feet wide, and I sit around 5 feet from the center of their "frontal plane".  And I can sit forward to the front of my listening couch and get fabulous soundstage up to 3-4 feet from the frontal plane.

It is like headphone detail, but with a real soundstage that is in front of, and all around you and not "inside the middle of your head".

This works better with a limited dispersion driver compliment since toeing the speakers in on high dispersion speakers, will splash the front wall with more sound to reflect.

John Casler

Re: Live and Die in LA - The "Sonic Interuptor"
« Reply #6 on: 6 Jul 2004, 11:26 pm »
Quote from: BrunoB
To move to a nearfield environment and/or to adsorb or block  sound coming from between the two front speakers has another advantage. You can increase the relative distance between the two front speakers without weakening the center imaging. It is often recommended to set the distance between the two speakers smaller than the distance between the listener and the speaker. IMHO, this rule does not apply to a nearfield environment with sound adsorption.  Presently, I am sitting 5 feet from the speakers which  ...


Yes Bruno, that is what I am talking about, but "we" both have 626Rs which have a limited dispersion in the mids/highs.

With a wide spacing, and extreme toe in, regular "high dispersion" drivers will need much more "treatment" for this to work, since they have greater "off axis" response, and at these convergence angles will be side firing on the front wall pretty hard.

This acoustics thing is a little tricky for most.

Reflection, direction, interuption, absorbsion, diffusion, and all the rest of the "tion's" all need to be considered to harvest the best sound from your room/speaker/components combo. :mrgreen:

zybar

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Live and Die in LA - The "Sonic Interuptor"
« Reply #7 on: 7 Jul 2004, 12:40 am »
John,

What I might try is putting foam "behind" the screen to help tame things.

As you can see from the pic below, I have wood mounted to the wall to bump out the screen so it is a tad farther out than the soffit.  This gives me 5+ inches of clearance between the wall and the back of the screen.



So the question is, will putting foam behind the screen have any impact?  Is it worth it?

George

John Casler

Live and Die in LA - The "Sonic Interuptor"
« Reply #8 on: 7 Jul 2004, 01:34 am »
Quote from: zybar
John,

What I might try is putting foam "behind" the screen to help tame things.

As you can see from the pic below, I have wood mounted to the wall to bump out the screen so it is a tad farther out than the soffit.  This gives me 5+ inches of clearance between the wall and the back of the screen.



So the question is, will putting foam behind the screen have any impact?  Is it worth it?

George


Hi George,

Good Question.  I would think it certainly should help for some frequencies.  Much would also depend on the "sonic reflection qualities" of your screen. :scratch:

I would also wonder if it would be very expensive to cover the blacked out area in "black felt, velvet or velor" (you know like a big curtain at the movies) and place a layer of foam behind that.

If you really wanted to DEAD END the front wall, you could run a curtain rod the length of the wall, (extending out at the soffet, enough to be in front of the screen) and "really" mount a black or dark blue curtain on it.  Then for movies you could slide it open, and for two channel you could slide it shut to block the screen bounce.

The the whole front wall could be treated with foam and you would be listening to one big black hole in front of you with music coming out of the nothingness

Look at me "spending" your money :mrgreen:

But George, that would be "VERY COOL"  :rock:

zybar

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« Reply #9 on: 7 Jul 2004, 01:48 am »
John,

I have sent an e-mail to Stewart and will see what they say about the screen and its properties when it comes to audio.

At one time I was going to do velvet or velour curtains, but in the end I decided not to.

Have to think about my next steps...

George

John Casler

Live and Die in LA - The "Sonic Interuptor"
« Reply #10 on: 7 Jul 2004, 02:35 am »
Quote from: zybar
John,

I have sent an e-mail to Stewart and will see what they say about the screen and its properties when it comes to audio.

At one time I was going to do velvet or velour curtains, but in the end I decided not to.

Have to think about my next steps...

George


Well lets see.....

I think you need some AMPzillas, with Sons of Ampzilla, and either a S/N P-965 or a Krell Showcase Pre pro, and then some Velvet Curtains :lol:  :lol:

That should take care of a few steps 8)  :mrgreen:

JLM

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Live and Die in LA - The "Sonic Interuptor"
« Reply #11 on: 7 Jul 2004, 10:51 am »
George,

Have you considered horizontally sliding screens across the entire front wall made of rigid fiberglass with wooden frame.  The fiberglass could be covered in fabric and the screens opened for viewing.  (Ala Real Traps.)  Patterns could be painted onto the fabric.

Personally I just don't like the idea of velvet and gorillas (ampzillas).   :o  :nono:  :lol:

Russtafarian

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« Reply #12 on: 9 Jul 2004, 11:29 pm »
Here's an AA link to various speaker setup procedures.  More than enough info to keep us busy this weekend.

http://www.audioasylum.com/cgi/d.pl?audio/faq.html#speakers