Adjusting Room sound using material damping methods (not DSP)

[loud_speak]

Would anyone like to share their experience with acoustic treatments?

I recently auditioned some of the Harbeth line of speakers in a dealer's listening room and subsequntly decided to try the SHL5s at home. My hi-fi is located in a small room (3.2m (L) x 3.2m (W) x 2.75m (H)), chosen because it is neighbour-friendly (my basement is larger but is adjoined to my immediate neighbour).

The problem is that the room is sparsely furnished and comprises drywall and two windows (no curtains, just venetian blinds) resulting in a bright sound and a fatiguing listening environment.

I am considering acoustic treatments, but nothing too expensive. My thoughts are as follows:

• Add more furniture, e.g. bookcase, soft furnishings

• Acoustic panels:

What materials? (foam/rockwool/OC 703 fibreglass/egg cartons?)

What percentage of the room needs to be covered? (ceiling?/corners? etc.)

• Room frequency response:

Should I have the room measured or is this overkill for such a small room

• Short term solution is headphones (another minefield )

Thanks in advance for your input,
Chris

[BAS-H]

Hello Chris,

Well, DIY rockwool panels about 10mm thick and a metre square in area make good reflection stoppers, placed on the points of first reflection. One per side wall, two behind each speaker (or one wide enough), two behind you (or one again), two on the ceiling if you can install them there, and a thick, heavy rug handles the floor.

Bookcases make fine substitutes and are nicer to look at.

Taming bass is the tricky part; you need traps of thickness measured in feet.

Your short term alternative is to buy little P3s instead, turn the volume down and don't bother treating your room at all; just decorate it the way you like to look at it. P3s are astonishingly forgiving (this is my approach. It's simple and free).

And of course, don't forget the G&T / glass of beer.

{Moderator's comment: don't forget that room treatment, esp. catching the side-wall reflections, is discussed in the current Harbeth User Guide included in the carton (and downloadbale too.}

[loud_speak]

Hi Ben,

Thanks for your input. I will probably start with a bookcase. I am also looking into what acoustic panel companies have to offer (e.g., GIK acoustics).

Cheers,
Chris

[BAS-H]

Here's a DIY panel made by the designer himself...

http://www.harbeth.co.uk/usergroup/s...not-DSP)/page6

[thurston]

Mr. Shaw mentioned Vicoustic some posts ago.

I tried their Cinema Round Premium in order to dampen the back wall because I sit relatively near to it.

I can now truly say that the room is an unbelievably big part of the listening experience.

It is my first step, but the effect/difference is so big that I feel the urge to encourage others to focus on the rooms acoustics.

[Reffc]

I'm in the process of designing and building acoustic absorbers and bass traps for my business. The idea came recently whilst preparing the living room for my SHL5's, soon the be delivered. Looking at the absorption coefficients, most rooms can be adequately treated with a broadband absorber behind each speaker and to the adjacent walls, with a bass trap in the corner. I had a look at the rather ugly foam options for bass traps, but unless they have a true density of 45kg/m3 they are all but useless below 500Hz. A far better approach is to use glass fibre wool (loft insulation is perfect) in at least 45kg/m3 density, preferably 60kg/m3 and make up some 1.2m by 300mm by 100mm thick pine panels. Fill these with the insulation and cover in acoustic fabric.

At 100mm thick, the wool has an acoustic absorption coefficient some 4 times greater than that of 50mm panels. Place across the corners of the room. Bass which isn't absorbed will pass through the panel into the air gap to the corner, and be reflected back through the panel, cutting down bass boom quite effectively. You can make larger panels using the same design and have them free standing 0.75m behind the speakers with a small air gap to the rear wall, for the same effect.

Making up 50mm panels using the same materials and placing on the points of first reflection plus another few along the rear wall is all the average under-damped room will need to make a significant improvement. These panels will be far more effective than the cheaper thin foam tiles commonly available and can be covered in FR acoustic cloth to a colour to closely match your own decor.

It's important not to overdo it though as overall SPL levels can be reduced considerably and the room made too "dead". A little at a time, then listen to the results is the key. You cannot overdo bass traps though. The more corners treated the better.

[HUG-1]

Attached a scan of the Vicoustic brochure. They specialise in surface treatment for absorption of room sonic reflections etc.. There are numerous examples of real-world rooms. The makers have done their best to offer a range of attractive styles and finishes, to suit all tastes?

[thurston]

Attached a scan of the Vicoustic brochure. They specialise in surface treatment for absorption of room sonic reflections etc.. There are numerous examples of real-world rooms. The makers have done their best to offer a range of attractive styles and finishes, to suit all tastes?

I used some more Vicoustic products to dampen my ceiling (adding to big bass absorbers in the corners and some Vicoustic Damping at the wall behing my listening position).

The picture shows my construction. It combines some damping and difusers (and some lamps). In my opinion it looks quite good. At least for a listening room. In a living room it might be a little over the top.

The acoustic result speaks for itself. The sonic improvement is quite obvious. Resulting in a pretty good sounding room. Something that you only realize when you know both versions. I doubt that many rooms sound good without any help in that area.

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