Help w/ beginner s room treatment

Thanks: Yes, the fibers would be a major problem if released into our household. If I build one, I will place it in a plastic bag and rough it up a little to see how well the batting performs.

Thanks to all for your responses (especially Abstract). I do, however, have a couple of clarifying questions:

1) what's the difference between and absorber and a diffuser (both in purpose and in the actual item one would use)

2) what does it mean to say that the Radio Shack SPL meter is "not linear" and that I need to make corrections?

3) What do ASC and WAF stand for?

Thanks again!

Felthove:
1. An absorber does just that, it absorbs sound. The newspaper things I described, Sonex panels are examples of absorbers. Diffusers do that, rather than absorb the sound they reflect it, but not uniformly like a flat wall would. An example would be the RPG diffuser panels. You can make diffusers with wood or other material, you just make small sqares or triangles that are varying heights. Diffusers are frequently used behind the listener to break up the sound, but still have some sound reflected to create ambiance.
2. The readings on the SPL meter are not correct. The meter either needs to be modified or you just add the correction values. The values are as follows:
10Hz +20.5
12.5Hz +16.5
16Hz +11.5
20Hz +7.5
25Hz +5
31.5Hz +3
40Hz +2.5
50Hz +1.5
63Hz +1.5
80Hz +1.5
100Hz +2
125Hz +0.5
160Hz -0.5
200Hz -0.5
250Hz +0.5
315Hz -0.5
400Hz 0
In order to correct the low frequency roll-off, you can do the following modifications to your meter. This will make the meter FAR more sensitive to low frequencies and allow measurements with very good accuracy to well below 20 Hz. Due to the increased sensitivity at very low frequencies, it is possible for low frequency "thumps" to slam the meter if using a very low SPL setting. In order to prevent meter movement damage, take precaution not to peg the meter off scale on a regular basis. If this is occuring regularly, you either need to move up to a higher SPL range on the meter or take more caution as to how your performing your tests. All of the following capacitors must be rated for AT LEAST 15 volts or so. Size does matter, so try to use the smallest package possible.C1 & C2 are changed from 1 uF to 10 uFC3 & C4 are changed from 1 uF to 47 uFC7* is changed from 10 uF to 220 uFC8 is changed from 100 uF to 470 uFC9 is changed from 22 uF to 220 uFC15 is changed from 100 uF 220 uFWhile all of the above parts are spec'd as microfarads, the following is in picofarads. Do not confuse the two values or the meter will not work very well at all. This last change helps minimize high frequency roll-off that is inherit in the stock microphoneC12 is changed from 33 pF to 12 pF.Please note that all of the above parts can be soldered directly in place of the originals EXCEPT C7. Due to its location, a "normal sized" 220 uF cap will be too big to allow the case to close correctly. In order to get around this, simply solder it on the "solder side" of the board instead of on the "parts side" of the board. Pay special attention to the POLARITY of ALL of the caps as you pull them out to replace them. For this reason, i recommend pulling and replacing the caps one at a time to minimize confusion. Once all of these mods are done, the meter is more than accurate enough for anything that a home audio enthusiast would ever need use of. If you really want to "get crazy", you can remove the factory installed mic and either remotely mount it on a "wand" or make use of a calibrated mic like those available from Old Colony.

Note: I need to give Sean credit for providing us A-goners with this valuable information the first time.

3. ASC is a company name: Acoustic Science Corporation I believe. They make tube traps and other room acoustic devices. WAF= Wife Acceptance Factor. This is very important to many of us in the real world.