Room Treatments

[Hauger92]

I don't know much about acoustic panels/room treatments. I was hoping you guys could give me some pointers on what to purchase and from whom.

I'm only doing 2ch with Puritys and a Dynamo up front. My Puritys are about 2ft from the front wall, 9ft from side walls, the Dynamo is on the right side of my right front Purity, and my listening position is about 8ft from the back wall.

Thanks!

 

[JonFo]

Hi Brian,

I did a fairly comprehensive thread on this topic, please read the 200+ posts and then we can cover how it applies to your system and situation.

There are many links out to vendors and other information in that thread. You'll be busy reading

We'll wait

 

[kach22i]

You could try this, and it might be easier than reading all those posts and trying to figure out how it applies to your situation.

1. Draw a floor plan (I like to use grid paper) and give a few dimensions including speakers distances you already mentioned.

2. Post floor plan along with photos of your room so we can see the floor and wall finishes. You could just lable the plan.

In general:

A: Some corner treatment including intersection at wall/ceiling is a good idea.

B: Reflective or diffractive surface directly behind the speaker, and absorbtive surface between the speakers.

................................................................

Poke around the "Members System" section and see what people are doing and why. If you don't see "a why" then post a question to them and hope they see it.

 

[Hauger92]

Thanks fellas. I'll do some reading on that thread and also draw up a floor plan with some photos so you can give me some ideas.

Hey kach22i, good to have a local Michigander on the board! I'm located downriver, near Southgate/Trenton area. I was just out at Overture Audio about a month ago and bought a pair of Grado headphones and love 'em.

Anyways, thanks again!

 

[Rich]

Also, check out the Acoustics Circle forum over at Audio Circle. Lots of good information there. Here is the link:

Acoustics Circle

 

[kach22i]

Hau........see this thread, might be room for one more.

Link:
http://www.martinloganowners.com/forum/showthread.php?t=5819

 

[JohnA]

...B: Reflective or diffractive surface directly behind the speaker, and absorbtive surface between the speakers.
...

Not sure about the 'reflective' bit
In my experience it's absorb or diffract more likely

 

[kach22i]

Not sure about the 'reflective' bit
In my experience it's absorb or diffract more likely

The rear wave is what helps give a stat a sense of space by adding a second wave out of time with the first.

If you take away that rear wave it sounds a little flat or dead and you might as well own a pair of boxes at that point.

Everyone has their own room and their own ears, I do not mean to dictate to anyone.

Please take the time to experiment with your set up.

 

[Rich]

The rear wave is what helps give a stat a sense of space by adding a second wave out of time with the first.

If you take away that rear wave it sounds a little flat or dead and you might as well own a pair of boxes at that point.

I have to disagree with this point. I think the additional "ambiance" from the rear wave is not only unnecessary to achieve great sound from your ML's but more often than not hurts imaging, clarity, and soundstaging. Using absorption panels to absorb the rear wave allows you to hear the music as it is meant to be heard, in my opinion. It doesn't sound flat or dead at all, just not unnecessarily "live." And believe me, it sounds nothing like a box speaker.

Everyone has their own room and their own ears, I do not mean to dictate to anyone.

Please take the time to experiment with your set up.

Now that I can agree with 100%.

 

[Hauger92]

Kach - Thanks for the invite! Sounds great and I'll definitely try to make it. I'm actually going to start working around the Ann Arbor area in the next couple weeks so if for some reason I'm working maybe I can still stop by.

And thanks for the discussion of room treatments, these all help!

 

[kach22i]

Using absorption panels to absorb the rear wave allows you to hear the music as it is meant to be heard, in my opinion.

I went back to that big thread and read most of it, I plan to go back and read again, good stuff. I know know where you are coming from, and why.

My opinion is based on my room and my experiments, all kind of "seat of the pants" and not as scientific as in that other thread.

The last thing I tried was placing five inch diameter round sponge rubber tube from a place in Ann Arbor called the "Scrap Box" directly behind each speaker. The tubes were as tall as the speakers, and I just laid them behind the speakers on the front wall with clear tape tacking them in place. They just seemed to suck all the air out of the music so I went no further.

The tubes are all cut up for a large hovercraft model I'm building but the Scrap Box has more tubes for about $3.00 each so I mignt re-try the experiment one more time.

 

[JohnA]

I, too, bought the Logans expecting the benefits in 'ambience' and 'presence' of the rear wave.

Alas, experimentation and research showed me the evilness of the rear side.

Should I now ignore the new evidence and stick to my former theory? Of course not, we live and learn...

 

[Rich]

My opinion is based on my room and my experiments, all kind of "seat of the pants" and not as scientific as in that other thread.

I understand, kach. All we can really judge by is the listening experiments we conduct in our own environments. I would never be one to say that absolutely rear wave absorption will be better for every person in every situation than reflection or diffusion. I hold the opinion that it probably will be, but I do understand that rooms, systems, and individual preferences all differ.

The last thing I tried was placing five inch diameter round sponge rubber tube from a place in Ann Arbor called the "Scrap Box" directly behind each speaker. They just seemed to suck all the air out of the music so I went no further.

What is really needed is a material that can absorb evenly from about 250 hz. on up. If you have a material that absorbs the highs, but not the mid-bass, then you get a deadening of the highs which sounds like it removes the life out of the speakers, with no corresponding increase in clarity, imaging and soundstaging because you still have mid-bass reflections muddying your sound. I think this is what you experienced with the sponge rubber tube. Also, because you used a five inch round rubber tube, the absorption was probably uneven not just in frequency, but across the diameter of the tube itself.

I did a similar experiment using a microtrap from realtraps (which really just absorbs the highs), a diffusion panel from RPG, the bare rear wall, and a HF mini trap. The microtrap sounded terrible behind the speakers, compared with the HF mini trap (which absorbs evenly through the whole spectrum of output from the ELS panels).

The diffusion panel and the flat rear wall sounded too bright, with poor clarity, imaging and soundstaging. I couldn't tell that the diffusion panel improved at all over the flat rear wall, which is why I am not a fan of diffusion behind ML speakers. The micro-trap removed the brightness, but not the muddiness. It sounded overly rolled off in the highs, with poor imaging and clarity.

The HF mini trap sounded like I had moved the system to a completely different, acoustically-perfect room. Everything snapped into place. All of the sudden, I had three-dimensional imaging and soundstaging, clarity was phenomenal, and the speakers disappeared. To me, it was a night-and-day difference from every other thing I had tried.

I highly recommend you try a couple of panels designed for even absorption from 250 hz. on up (rather than DIY foam rubber of unknown acoustic absorption qualities). I think you will find they make a huge difference for the better. And if you don't like the way they sound behind the speakers, you could always utilize them somewhere else in the room such as the first reflection points on the side walls, so the purchase won't be wasted. Also, remember that when you are using panels like this behind the speaker, you lower the SPL output of the speaker, so to hear the same level of sound you will have to turn up the volume a little.

 

[JonFo]

Well, Rich nailed it. Not much more to add :bowdown:

Hauger92, I'd suggest starting with two Minitraps HF behind your purities and see how that goes.

Being 8' from your rear wall, you could use a diffuser back there. RPG skyline is what I'd recommend.

Also, a pair of Mondo traps in the rear corners for the low bass would be advisable as well.

 

[Hauger92]

Ok, very good advice from all. I'll go ahead and try what you are all suggesting. Thanks again for the feedback.

 

[kach22i]

I did a similar experiment using a microtrap from realtraps

Based on reading a few books, taking college courses in acoustics and experiments I built a front wall/behind the speakers wall.

I may have a little luck thrown in and might already have in place the absorber you speak of.

See my Member System in my signature.

THE WALL (sits 2" off a stairway):
1-1/16 inch oak balaster rails at 16" o.c. holding an approx. 60% open perforated hole metal panel at 1-1/16 inch off the face of a 1/4" oak veneer plywood panel (might be 1/8" or 1/6") with 3/16" drilled holes in face at 16" grid pattern. I forget the stud of frame system inside of the 4' high x 6 feet wide movable wall, but there are at least three chambers inside filled with batt insulation. The outside is framed in oak trim and the back panel is 1/2" homasote. There is acoustic foam stuffed behind the wall at the bottom, as the whole wall sits on a few stacked bricks and the sound going under it was not good (foam solved this).

This is a fairly light weight low mass wall panel in which the front face diffuses and then another plane 1" beyond deflects from air pressure while creating a (mid) bass trap via small face holes in an insulated 3-1/2" deep cavity.

I have construction pictures from 15 years ago and will post them if I ever find them. No measurement were taken before or after on this wall and or room.

 

[Rich]

Very interesting, George. I would have loved to have seen before and after measurements, but from your description that sounds like a very effective setup. Leave it to an architect . . .

 

[kach22i]

Very interesting, George. I would have loved to have seen before and after measurements, but from your description that sounds like a very effective setup. Leave it to an architect . . .

Thanks, this is a great hobby for the obsessive isn't it?

 

[the-chauffeur]

Guys - can I beg your indulgence?

I've been reading the other thread on room treatments and spent most of the weekend watching Ethan's videos. I've always known that room acoustics played a big part in the listening experience, but I've never seen such a clear demonstration of how some relatively simple damping can make such a big difference.

Which got me thinking about my own set up. At the very least I'm in need of some bass treatments - I've got a number of high and low points around the room - and I already know there are some resonant frequencies that could really do with being tamed. But much as I like the look of Ethan's products, I have two very specific issues. The first is that I live in the UK and until he's got a UK distributor, shipping + customs costs = prohibitive.

The second problem is space. I've uploaded a floorplan (Lounge Layout) rather crudely drawn in excel, which should give you an idea of what I'm dealing with. The room is virtually square (350cm wide x 360cm long); ceiling is 230cm high. The diagram isn't completely to scale, but it's not far off - each square represents about 5cm.

As far as materials are concerned, the room is brick built, with carpet/underlay covered conventional concrete flooring; walls are papered; ceiling is artexed. Windows are covered with heavy drapes (closed when listening to music). Bookcases are MDF and reach floor to ceiling. The chairs are leather (arm height 65cm, back height 95cm). The TV and equipment rack stand about 130cm high.

So as the room stands, there isn't a whole lot of bass-absorbant material - and that's what I need some help with. I know I've got very little room to play with, so I'm wondering what's the best way to go. I've seen several places that sell stackable 3'x1'x1' triangular dense foam traps (designed for recording studios) and reckon I can squeeze 2 sets in each of the front corners of the room (one on top of the other) giving me 6' high triangles. And I've already thought about putting a trap accross the wall behind the left hand side of the sofa to equalise the effects of the missing wall on the right-hand side.

But that's as far as I've got. I think it's probably best at this stage to throw the question Whadd'ya think? open to the floor...

Thanks in advance

Neil

 

[JonFo]

Neil, an almost square room and with little space to add much. This is challenging indeed.

First off, do not skimp on the effectiveness of your sound management tools, you just don’t have enough space to make up for it in volume

That is, each acoustic treatment needs to do a great job, because you can only place so many in there. So, no Foam!

First question (mostly because people forget this is an option): Are you willing to put things on the ceiling?
Since you have very little floor (or even wall) space, that vast emptiness up there beckons. The sound waves sure are making use of it to create room modes.

Second, you do have some local options for room treatments in the UK. Please visit http://www.customaudiodesigns.co.uk/index.htm

One ceiling option is to use a product like the rounded bass trap for corners laid horizontally along each Left and Right side of the room at the ceiling/wall boundary.

Heck, consider putting a pair of them at the rear wall/ceiling boundary as well. You just don’t have enough space in the vertical corners to put anything effective there.

On the Rear wall, put some absorption just behind the sofa. That should balance out the opeing on the right, and reduce the reflection, which must be pretty noticeable, from that rear wall.
Likewise, treat the walls just behind the armchairs. For one, you want to mitigate reflection, for another you want to damp low frequencies in the middle of the room.

As for the front of the room, those curtains are damping some of the highs, but not the mids or lows. Consider adding some absorbent panels like a MiniTrap HF mounted such that you could swing them out of the way when the curtains are open. With your speakers so close to the wall, you absolutely need to absorb the rear wave in both highs and mids.

Finally, you will need to look to EQ’ing the sub, as there will be <60Hz room modes that no treatments can fix, so something like a velodyne SMS-1 is recommended as a cost-effective ‘fix’ for the low-bass.

Hope this helps. I’m sure others will chime in with their ideas and suggestions.