[*Scotty*]

Rclark, it is fairly obvious, you can have too much absorptive type of acoustic treatment in a room as any acoustic technician will tell you. Once again you can suck all of the life right out of the music. This is why almost all dedicated audiophile listening rooms need a balance of diffusion and critically placed absorption. Most of the those proudly posted pictures of audiophile listening rooms are missing diffusion and frequently absorption treatment as well. The diffusion problem is the hardest nut to crack because it is just plain expensive and you need a fair amount of it if you are going to start with a bare room with just your stereo equipment and a chair in the sweet spot.
 It is much easier to get good sound out of an average living room with a mix of acoustically absorptive stuffed furniture and diffusion from bookshelves and irregularly shaped reflective furnishings such as end tables and plant stands,etc.
I don't know if I would call too much absorptive treatment in a room a source of distortion as MGA does. This implies that a condition can exist whereby the impact of the rooms acoustics on the recovered acoustic waveform does not alter it from that of what might be heard from headphones with a flat frequency response curve.
Scotty

[michael green MGA]

Well, you could start with an explanation of your method, and some measurements would be nice. Actually, start by explaining your "tuning" versus "distorting" picture above.

Ok, do you know what a pressure zone is?

[michael green MGA]

Rclark, it is fairly obvious, you can have too much absorptive type of acoustic treatment in a room as any acoustic technician will tell you. Once again you can suck all of the life right out of the music. This is why almost all dedicated audiophile listening rooms need a balance of diffusion and critically placed absorption. Most of the those proudly posted pictures of audiophile listening rooms are missing diffusion and frequently absorption treatment as well. The diffusion problem is the hardest nut to crack because it is just plain expensive and you need a fair amount of it if you are going to start with a bare room with just your stereo equipment and a chair in the sweet spot.
 It is much easier to get good sound out of an average living room with a mix of acoustically absorptive stuffed furniture and diffusion from bookshelves and irregularly shaped reflective furnishings such as end tables and plant stands,etc.
I don't know if I would call too much absorptive treatment in a room a source of distortion as MGA does. This implies that a condition can exist whereby the impact of the rooms acoustics on the recovered acoustic waveform does not alter it from that of what might be heard from headphones with a flat frequency response curve.
Scotty

Boy, at the beginning of this thread I was  really starting to hate coming here. I'm so glad to see some listeners kick in.

[Rclark]

Ok, do you know what a pressure zone is?

... Would that be a zone, with a lot of pressure?

[*Scotty*]

Michael here is an effective way to deal problems associated with a rooms resonant modes below the Schroeder frequency that you may be unaware of. See pdf doc at this link. The server can be a little slow but patience is rewarded.
http://vbn.aau.dk/files/12831869/AC-phd.pdf
You may also find various discussions on this circle interesting and perhaps informative. The Bass Place
http://www.audiocircle.com/index.php?board=198.0   
Scotty

[michael green MGA]

hi Scotty I'll check it out. checked it, cool

I've always thought that the way audio people talked about the soundwave in a room was weird. Some talked about it like it was outside but a room is completely different. Some talked about it like it's traveling in a straight line, and that didn't make sense. When I started measuring rooms in the late seventies I found things that made a lot of sense to me and as years went on I started to build a meaningful model that worked every time. I never got a chance to see it spelled out with my testing tools but in the early 90's I got an oppertunity to see a laminar proto room. This was basically an area where they tested air moving over the wings of airplanes and at this particular one they were showing very light air movement in a room and then putting things in this room and seeing how the air formed around it. Fascinating! The first warm up they did of this test I shouted "that's my model". It was exacting what I was testing in my rooms. Now get out your mics guys, and start in the corner of your room about a foot out and about half way up your corner. Start measuring the pressure. Now for you guys wanting the quick test version, walk up to that same corner and start talking and both of you listen to how the sound builds then starts to die off, then it will be quiet then start to grow again. Call this any audio term you want. Make up your own name who cares. Walk around this (empty room) and listen to the sound build and fall, build and fall. Now find the shape of that build by walking around or take your fancy gismo and you are going to see something interesting those rises and falls are spherical. Now go put a speaker in that room and test this out. Your going to find all of these pressure build ups, and they act differently in different types of rooms but always fallow a pattern of spherical balls of pressure that I gave the name "Pressure Zones'. But what about the sound waves coming from the speakers? I'll get to that. My interest was what happens to waves when they hit the wall. The more I fired waves at the wall the more I realized something was happening that was much bigger than any reflection. When you test the middle of the room with your voice, music or mic and start walking toward the wall you will find a point where the waves heading toward the wall are hitting the waves coming off of the wall, and just like that laminar flow test place when this happens the sound fires along the wall just like air over a wing. The acoustical energy in your room comes out of the source heads toward the walls spreads across the wall hits the corners and loads your room.

Holy smokies batman do you mean it is not a bunch of reflecting waves. What I'm saying is you have a combo of activated reflecting waves but the laminar flow and the pressures zones are a far bigger deal in shaping the sound and keeping things in pitch and in the creation of the harmonic balances. This is heresy, burn him at the stake. Well while your making your fire lets play some music. Do you hear the reflective waves more or do you hear the pressure zones more? Do you hear the reflections more or do you hear the laminar flow more? Put your hands down, I created the clapping hand test to find echoslap. I'm talking about what you hear the most of. That's right the laminar flow and the pressure zones are the two biggest factors in your room. Now put barricade products up in those build up areas and listen to how much you just controlled your room. BIG! At this point you can go and fix or tune the other things like the reflections. They will be much easier to fined because you have controlled all the sources that are causing the major build up of waves in the room and have organized the wave flow. If you want to come in and do you testing you are going to get much better and more consistant responses.

We're not done, I have to get flamed for this part first.

[werd]

Thanks Scotty for the post on dampening, I will use it when I am ready to venture into my speakers which will realistically not be until the new year.

Getting the torque wrench tomorrow for exact tension. I think I am going to tighten up my speaker screws a bit. Not tight like I had it but a couple notches before.  But not yet, right now I am just going to keep everything unwound till after Xmas to get used to it.

[Russell Dawkins]

We're not done, I have to get flamed for this part first.

O.K. 

Please continue.

[michael green MGA]

Michael here is an effective way to deal problems associated with a rooms resonant modes below the Schroeder frequency that you may be unaware of. See pdf doc at this link. The server can be a little slow but patience is rewarded.
http://vbn.aau.dk/files/12831869/AC-phd.pdf
You may also find various discussions on this circle interesting and perhaps informative. The Bass Place
http://www.audiocircle.com/index.php?board=198.0   
Scotty

Hi Scotty

yep, this is cool stuff

Sometimes I get visitors that do testing in my Tunable rooms. Yale even had me build one for them for testing. Spec guys can be a trip!

[Rclark]

Rclark, it is fairly obvious, you can have too much absorptive type of acoustic treatment in a room as any acoustic technician will tell you. Once again you can suck all of the life right out of the music. This is why almost all dedicated audiophile listening rooms need a balance of diffusion and critically placed absorption. Most of the those proudly posted pictures of audiophile listening rooms are missing diffusion and frequently absorption treatment as well. The diffusion problem is the hardest nut to crack because it is just plain expensive and you need a fair amount of it if you are going to start with a bare room with just your stereo equipment and a chair in the sweet spot.
 It is much easier to get good sound out of an average living room with a mix of acoustically absorptive stuffed furniture and diffusion from bookshelves and irregularly shaped reflective furnishings such as end tables and plant stands,etc.
I don't know if I would call too much absorptive treatment in a room a source of distortion as MGA does. This implies that a condition can exist whereby the impact of the rooms acoustics on the recovered acoustic waveform does not alter it from that of what might be heard from headphones with a flat frequency response curve.
Scotty

blah blah blah. You know, I don't see any diffusers in play here, from "MGA" products, now that you mention those. And you saying bookshelves are useful as diffusion is highly suspect.

Something fishy going on here.

[michael green MGA]

Actually R

We do have diffusive systems.

http://tuneland.techno-zone.net/t76-mga-sound-shutters-acoustical-defuse-aeroplanes

[Guy 13]

Actually R

We do have diffusive systems.

http://tuneland.techno-zone.net/t76-mga-sound-shutters-acoustical-defuse-aeroplanes

Hi Michael and all AudioCircle members.

I have been reading everything you write and I keep reading,
even if it's laborious,
and I am still not convinced your approach works....
Well, it might work, but I don't think it change dramatically the sound,
To me, testimony from satisfied customers, mean nothing,
of course you will post comments from satisfied customers, it makes your products and approach look good.
Customers reviews from Parts Express is where I can see
if a product is good or not, because parts Express let unsatisfied customers express themselves and negative posts let you judge.

Well, keep writing, who knows, maybe one day before I die, I will change my audio religion...

Guy 13 

[bpape]

I've deliberately been keeping my nose out of this for a variety of reasons but I can only take it so long....

Sorry. Those are not diffusers or anything like diffusers. A single angled hard flat surface is anything but diffusion.  Diffusion by definition scatters evenly and randomly both in the time and spatial domains. This does nothing but reflect at a different angle.

'nuff said....  carry on.

Bryan

[Guy 13]

I've deliberately been keeping my nose out of this for a variety of reasons but I can only take it so long....

Sorry. Those are not diffusers or anything like diffusers. A single angled hard flat surface is anything but diffusion.  Diffusion by definition scatters evenly and randomly both in the time and spatial domains. This does nothing but reflect at a different angle.

'nuff said....  carry on.



Bryan

Hi bpape and all Audio Circle memebrs.

 

Guy 13

[werd]

blah blah blah. You know, I don't see any diffusers in play here, from "MGA" products, now that you mention those. And you saying bookshelves are useful as diffusion is highly suspect.

Something fishy going on here.

How about dropping the combative nature like its a -must have - to be in this thread.


Aligning books on a book shelf are well known to have diffusive properties due to the mass of the books and the random size and shape of the books on the shelf. These will break up any sound that comes in contact With  it? The problem is  they are not considered full bandwidth and may distort the sound also.. But they are better than nothing.  It's pretty basic acoustic knowledge... Nothing fishy.

[michael green MGA]

I've deliberately been keeping my nose out of this for a variety of reasons but I can only take it so long....

Sorry. Those are not diffusers or anything like diffusers. A single angled hard flat surface is anything but diffusion.  Diffusion by definition scatters evenly and randomly both in the time and spatial domains. This does nothing but reflect at a different angle.

'nuff said....  carry on.

Bryan

Hi Bryan

Actually, people do use Sound Shutters as diffusers by putting the different sizes in various patterns and angles, and tensions. I however do not use them that way. I use Sound Shutters as organizers. I'm not too crazy about disorganizing waves. In fact as far as the book shelf thing goes, I can understand if someone wants to play with the differences that this can make, but most of my clients either turn around the cases to make resonators out of them or get rid of them altogether. being a designer in acoustics forever I've seem people go through all types of stages and what I tell folks is you have to keep in mind what recordings do and what they are for. I say this because people get locked into thinking of recording in general as an absolute and unfortunately the more anyone moves toward a fixed sound it starts to limit their ability to adjust per recording. Which gets into the plug and play thing vs the adjustable thing.

When I'm sitting down to listen at first because the room was set for a different recording, along with the electronics and speaker I listen a couple of minutes to see if I like the presentation well enough to keep it where it is or do I wish to change it. Most of the time I will make a small adjustment and continue on. I'm not thinking about what technology is being use, I'm thinking about patterns I wish to create that make the sound to my liking. Unless someone is actually tuning like werd is starting to do it's hard to visualize what I'm saying. Tuneland can help a lot in this area, but basically what I'm saying I try to keep away from fixed anything. i have always let the fights between theories play themselves out in that arena, but for me I'm purley thinking recording code, flexible system, now how do I get there.

This isn't fair but let me give a case and point. Pick out a recording at home and take it to an audio trade show with you and start taking it room to room. You will never hear the recording sound the same in any of the rooms. many times the press and the clients make decisions based on this. well in all honesty none of these systems have been tuned into that recording any the system you chose was the one that was the closest for the recording. the next day go in with a recording with a completely different code, different studio, label, engineer, style. You will choose a different system. At the end of the show your walking around saying this play it well and that played that well. Unless you are going to have 20 or so different rooms in your home it might be a good idea to figure out what is going on in the process of playback and how do you want to attack it on a per recording basis or do you only want to listen to a few pieces of music that you call your references.

Outside of my world I see people talking about dampening vs trapping vs diffusion a lot and I look at it like this. For myself the sound of materials in a room stick out like a sore thumb if you don't find a balance of how much of what. No matter what the designers say they do, you can hear what they are made out of. acoustical theories never make the sound of the materials the product is made out of disappear.

[michael green MGA]

How about dropping the combative nature like its a -must have - to be in this thread.


Aligning books on a book shelf are well known to have diffusive properties due to the mass of the books and the random size and shape of the books on the shelf. These will break up any sound that comes in contact With  it? The problem is  they are not considered full bandwidth and may distort the sound also.. But they are better than nothing.  It's pretty basic acoustic knowledge... Nothing fishy.

Yep, the combative thing has kind of ran it's course, and people are moving on to listening and seeing if myths can be debunked by doing so.

How about dropping the combative nature like its a -must have - to be in this thread.


Aligning books on a book shelf are well known to have diffusive properties due to the mass of the books and the random size and shape of the books on the shelf. These will break up any sound that comes in contact With  it? The problem is  they are not considered full bandwidth and may distort the sound also.. But they are better than nothing.  It's pretty basic acoustic knowledge... Nothing fishy.

Hi werd, I would have to agree. I'm not a huge diffusion fan personally but if this is the route of choice I have found the flexibility of a book case and books to be far more flexible than a fixed diffuser. With a book case you have the ability to make a lot of variable sounds that you can't get out of a fixed object. Again it's not quite my flavor but a lot better than fixed in my book. Get it, in my book.

[bummrush]

Sorry. Those are not diffusers or anything like diffusers. A single angled hard flat surface is anything but diffusion.  Diffusion by definition scatters evenly and randomly both in the time and spatial domains. This does nothing but reflect at a different angle.
   That part helped me right there,,, the above paragraph

[*Scotty*]

Basically a bookshelf full of books and other items might be found in a ordinary living room and has some useful diffusive qualities when compared to a bare wall. Certainly I would prefer a few real diffusion panels but I don't have that option and I do have a lot books.
Scotty

[werd]

I've been using the PZCs (both wall mount and floor standing) just like those in the picture above for the last few years. The bare room has lots of reverb and echo, and sounds terrible untreated. It would give anyone a headache listening there for any length of time. The devices control the sound energy well enough to make the room a place where I can listen for hours (ok, sometimes I fall asleep with a cd on repeat  ). The floorstanding PZCs also help me create the kind of center imaging I like, and adjust it if I want.

Other tweaks Michael Green has suggested over the years have produced significant improvements. For example, removing the cover of my 75-lb 220wpc solid state amp and cracking the internal and external screws 90 degrees, which simply relieves some of the mechanical tension in the amp, opened up my amp and allowed for a more natural sound. I also removed the transformer from the amp (the wires were plenty long), and the bass improved in quality.

All I can say is try one or two tweaks (one at a time though), give your system a week or better two to settle in (it actually may sound worse to your ears initially as your system's equilibrium has been disturbed), and then hear if you like the difference. Not sure what all the fussing here is about. If you try it and it works for you, it works; if it doesn't, it doesn't.   

I am beginning to hear that mechanical tension is directly related to soundstage tension.  For me soundstage tension has always been an issue at higher volumes on my pre amp.  Listening to music in high tension mode usually made me keep the volume down.  As I tune the tension it reduces a listening fatigue compared with everything  tightened right up. There is a definite  audible  release in the soundstage, it's quite noticeable and you get it off axis too.