Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion Off Topic OT: What have you done to acoustically treat your listening room?

Ian - did you see on their site that Lego also appear to have a tie-up with Ferrari ( link )?

Gents,

I've read this with some interest because it's a (another) audio area I know little about.
Can someone explain why you can't achieve the dampening by just hanging heavy lined curtains on the walls? It's not of practical use to me at the moment as my listening/watching area has two walls of glass that I'm not allowed to cover but we'll be moving at some point and it would be good to know what can be achieved before MRC.
Thanks,

Ed.

Hi Ed,

I'm still learning as well, so take what I say with a grain of salt...

Drapes may or may not be effective, depending on the frequencies you are attempting to address. Drapes will have some affect if you are trying to address first reflections, primarily related to mid and high frequencies, but will have little affect as a bass trap for lower frequencies.

Dan

Ah, but this is exactly what you want to do (or, at least, try). You want the two subs to get the same signal and then use the volume and phase adjustments to maximize output and achieve smooth response. You need to begin with placement, then tweak the onboard controls. You need a low frequency test track sweep or a heavy bass recording with which you are familiar. You can do it by ear, but you're better off with a SPL meter or, better yet, an RTA program so you can see the full bass spectrum. You are essentially using your first sub (presumably, the one you place in a corner) to excite your room and the second sub is used for active cancellation of the most offensive room mode peak or peaks. You can only correct the nulls by moving the subs or the listening position.

Hmmm, an interesting comment about the role of the 2nd sub, I'll have to spend some time contemplating that.

Of course, my thinking about sub placement has also been shaken up by the Harmon research paper linked to in another thread, which advocates placing subs at the midpoint of walls, precisely in the null point.

Thanks,

Dan

In a medium size room like this intelligibility should not be an issue
Its page one for hifi to be able to clearly understand dialog even over music and fx.
Listen nearer to the front 3 speakers
Near field gives more detail
Up the centre levels and try some eq presets
Move all speakers away from boundaries and drape and carpet as much surface as possible.
If still bad, start room treatments and managements

I hear you. If you use one sub and place it at the midpoint of one wall, you are placing it at the null point of only one axis. Since it is unlikely that the other two axes are of equal length (width and height or length and height), you get the benefit of the boundary gain from two dimensions with different frequency modes. If the dimensions are the same or one is a multiple of the other, then you will be exciting sympathetic room modes anyway.

If you use two subs and place them front and back or side and side at the midpoint, you still are placing them at the null of the one axis. But, now you are actively cancelling the modes of the other axis because you have two sound sources firing at each other. The frequency response should be smoother, but, by placing the subs at the nulls, the output is likely to be lower.

As an alternative with two subs, try placing them at one-third and two-thirds points on the front wall. Now you have them symmetrically placed at the peaks on one axis. They should act the same as one sub at the midpoint and cancel the modes from that axis, but now you have two sources acting in the other two dimensions. It could help the output.

Exactly right. It's interesting that the title of this thread starts with OT - in my view, room acoustics are central to good sound, and thus about as on topic as anything else in a forum dedicated to high end audio gear.

The thread Vince links to, and the information linked off of it, are pretty good resources for understanding room acoustic issues. Some more resources:

- The series of articles and utilities on the RealTraps web site: http://realtraps.com/info.htm

- The Audio Asylum/Rives room acoustics forum: http://www.audioasylum.com/forums/rives/bbs.html

- Some examples of room treatment, from simple to elaborate, on Rives Audio:
http://www.rivesaudio.com/examples/frame.html

My room is currently treated, fairly extensively, based on a plan by Rives Audio. For those of you that can swing the investment, a Rives Level 1 or 2 plan is a huge return compared to almost anything else in an expensive system. Even though I have a pretty good working knowledge of room acoustics, Rives brought some insights to the table I would never have had by myself. There are quite a few other free-lance consultants out there who are probably similarly competent.

Without resort to a consultant, the basics are still pretty simple. In order:

1. Damp or diffuse first reflections off the side walls, ceiling, and floor. Sorry, hardwood floors must be covered in the first reflection area!

2. Treat bass modes, using effective corner absorbers like RealTraps, GIK acoustics panels, Tube Traps (not as cost effective as the first two), AV room service corner traps, etc. It's really remarkable how reducing a few bass resonance modes subjectively improves clarity and reduces congestion through the entire frequency range. And for Meridian G68 or 861 users, it goes without saying, make sure you use MRC effectively - see the Wiki for tips.

3. Treat strategic areas - ceiling and back wall - with diffusion, to reduce slap echo and enhance ambience, without making the room too dead. One of the real hazards with acoustic treatments is to go overboard with absorption, which can take the sense of ambience, space, and life out of the room.

Hi Guys,

I have had the same problem. As my appartment is a typical Danish one there is glass all arround and hard floor and a hard ceiling. When I first moved in It drove me MAD! The sound was terrible compared to what I was used to. It got to the point where I didn't even want to switch it on.

I then added heavy cushions and curtains all arround the large glass windows, added a heavy rug ect...... But then I wanted to do a little DIY for both acoustic reasons and aesthetic. See the link below to see what I did.

The differene in sound is AMAZING!!! now the sound is so solid. I can hear the quietest details in movie sound tracks in particular. I highly recommend it and although not to everyones taste I think it looks nice too. In real life the ambi light isn't that bright and I can control the output on a remote control dimmer.

http://www.avforums.com/forums/home-cinema-diy/900280-floating-acoustic-wall.html#post8490987

IAN: I bet you probably have a few of my products laying arround as I was a head designer at LEGO for 4 years. (Beware of the death bricks...... the ones you step on in the dark, there like little sharp landmines ; )

In case you are interested in what I have done see below. The ceiling, panels flat on side and rear walls are for first reflections. The panels on angles between ceiling/wall, wall/wall and wall/floor are to soak up bass. All the panels are from realtraps.com which, as someone noted, is a great source for no nonesense articles and information about acoustic treatment. It makes a huge difference in terms of clarity and clean low frequency.


Front



Right Front




Rear Wall

I'm sure that sounds fantastic, but even if I had the time, money and inclination there is no way my wife would let me.......

Also you should experiment with the sub distance setting. The sub and main speakers may be out of phase near the crossover frequency enough to be causing problems like this (phase cancellation) and if you are running full range with the main speakers and adding a sub that too can be a problem. I always get better more articulate bass crossing over the main speakers with the sub.

Ron