I don’t trust my Radio Shack 7-Range Analog Display Sound Level Meter. I know the device lies to me whenever I take an audio test signal reading because acoustics experts have told me so. Whenever I do take readings that I think will enhance the blend between my Vandersteen 1c front loudspeakers and Hsu Research VTF2 subwoofer, I have to do too much math in my head. If I want to measure a 63 Hz test tone at 75 db on the SPL meter (+1.5 db error), I actually want the needle to center on 73.5 db. Or, wait, is it 76.5 db? I can never remember. If only I were a polymath (read Scott Westerfeld’s Midnighters trilogy).
Rives Audio Test CD 2 solves the above problem. No longer will I have to do math under the aural stress of a 85 db test tone. The Test CD has a sequence of one third octave test tones adjusted for the inaccuracies of the affordable Radio Shack meter.
The only difference in this series of tracks is that it is not flat. It is precisely calibrated to compensate for the non-linearity (particularly in the lower octaves) of the Radio Shack analog SPL meter (sound meter). We have found this meter to be very reproducible, but not very accurate. It is also very inexpensive and easy to obtain. For this reason we made these tracks to compensate for this device.
Rives Audio also provides a few Excel spreadsheets to record your results, graphing any sonic anomalies in your listening room. The CD includes detailed instructions on how to properly take the measurements with the Radio Shack Meter.
The CD’s instructions end with a one third octave table with all the SPL meter decibel adjustments. I must admit I’ve tried to recreate Rives’ test CD with Amadeus II generated test tones that I adjusted the gain according to the table. Unfortunately, for the $21 left in my wallet, I don’t trust my own authoring. I would rather leave it up to the experts.
If you own the Radio Shack SPL Meter, the Rives Audio Test CD 2 will save you many arithmetic head aches. If you don’t own a Radio Shack SPL Meter to calibrate your relative loudspeaker levels, I’m not sure why you’re bothering to listen to movies or music at all.