Damping & RF Shield Box:
There are 2 things that can effect the sound of your system components; cabinet resonance and RF interference. This project will help eliminate these 2 problem areas by constructing boxes filled with metal shavings, which are then placed on top of your components. The metal shavings provide RF rejection while the weight of the box provides damping.

Similar boxes are sold by a company that we cannot mention for $100.00 and more each. You can now build your own on the cheap and save.

You can use these on top of your CD player, DAC, preamplifier, phono preamplifier or any other source component you may have.

The first thing to do is to determine the sizes you would like and what components they will be used on.

Purchase some Masonite, 1/4 inch or thiner in thickness and some 1 inch by 1/4 inch wood strips. Make boxes out of these that are the width and depth of your components and 1 inch tall. Use the Masonite for the bottom and top and the 1 by 1/4 inch wood for the sides. Leave the top un-attached for now! Cigar boxes will also work well, supplied from a tobacco store, usually given away for free. You can come up with many other ideas for boxes by visiting your local hobby or craft store.

Now that your boxes are made, fill them with scrap metal shavings supplied from a metal shop. I used brass shavings. If none are available in your area, you can use old nuts and bolts or nails, just so they are tightly packed.

Secure the top on the boxes and place them on the components you designed them for. An improvement in sound will be heard.

Your Listening Room:

In many ways, the most important component in your system is your listening room. In this issue, we will cover the basics of wall treatments that I have personally found to offer a successful presentation of the music I listen to.

In all listening rooms, regardless of wall layout or angles, you will basically have a wall behind the speakers, behind your listening chair and walls to the left and right. I will be writing for the ideal situation, not giving into account your furniture, windows, etc. You can work around the ideal according to your room and other factors.

The wall behind the speakers: This wall should be as dead as possible, absorbing the rear wave from the speakers as well as the reflection bouncing from off the wall behind your listening chair. In my listening room, I place egg crate bed foam on the wall and then cover this with curtains.

The left and right side walls: The goal here is to kill the first reflection from the speakers using something soft and absorbent like egg crate bed foam, a piece of carpet, etc. Make two pieces 2 by 4 feet in size, one for the left wall and one for the right.

Now, where do they go? A simple way to find the first reflection point on your side walls are as follows...Obtain a mirror and sit in your listening chair. Have a friend hold the mirror flat against the left wall while moving it back and forth along the wall until you can see your left speaker in the mirror. When you can see the speaker in the mirror, mark that location. That is where your absorbent panel will go. Do the same for the right speaker and wall. You want the center of the panel to be at the same height as your head when seated.

If there is a bookcase or piece of furniture in the location where the absorbent panel should go, do not put one there...the shelf or piece of furniture will serve in its place.

If you want to get fancy, you can do the same for the reflection from the left speaker on the right wall and the reflection of the right speaker on the left wall, looking for the speaker in the mirror to know where to put the absorbent panels.

If this deadens your room too much, diffraction panels can be used in place of the absorbent ones. A book case for example is a good diffraction panel, anything that has a lot of angles, etc for the sound to bounce off of.

The rear wall: The wall behind your listening chair needs to be diffracted since the wall behind your speakers absorb the sound.

The rule for the front and rear walls in a listening room is to have one wall absorb and the other diffract. A book shelf or some other "many angled" surface can be used for diffraction.

I bought some 1/4 inch foam blue board from the hardware store and made 2 by 4 foot open boxes, 5 inches deep. I then took strips of the same blue board and attached them inside the box, up and down at different angles, creating several diffraction points. I then covered the whole thing in an attractive fabric.

The Floor: All listening rooms should have wall to wall carpeting, or at least throw rugs or area rugs.

Mike Morrow