Radio Shack 33-2050 SPL Meter
Radio Shack 33-2050 Sound Pressure Level (SPL) Meter
Photograph 1: Radio Shack 33-2050 Sound Pressure Level (SPL) Meter
The analogue Radio Shack 33-2050 Sound Pressure Level (SPL) meter is useful for measuring sound intensity, determining speaker sensitivity or developing quick frequency response plots for loudspeakers. Power analogue SPL meter is supplied by a single 9-volt battery, which make the meter very portable portable. At the bottom of the meter is a screw mount which cab be used to attached the SPL meter to a tripod.
To create quick audio frequency response plots, one can use the SPL meter in conjunction with an audio test CD (test tone CD) and read the sound pressure reading directly from the SPL meter. For more detailed audio frequency response plots, you can use the Radio Shack SPL meter with a wide variety of commercial and free software packages. With this meter the Frequency Response Plotter Software with built in corrections for the 33-2050 meter noted in the Resources section below works well.
Photograph 2: Radio Shack 33-2050 Sound Pressure Level (SPL) Meter
When Used in conjunction with a Dayton Audio Woofer Tester 3 (WT3), this simple meter comes in very handy for working on DIY Speakers.
Correction Table - Radio Shack 33-2050 Sound Pressure Level (SPL) Meter
For more accurate results while testing loudspeakers, it is best to do the measurements outdoors in a quiet and spacious area. The Radio Shack Analogue SPL meter is not very linear and will need to be corrected. Use the following correction table with the meter set to "C" weighting and "Slow" response.
Correction Table - Radio Shack 33-2050 Sound Pressure Level (SPL) Meter
|
Frequency
|
Correction
|
Frequency
|
Correction
|
|
|
10 Hz
|
+20 dB
|
500 Hz
|
-0.5 dB
|
|
|
12.5
|
+16.5
|
630
|
0
|
|
|
16
|
+11.5
|
800
|
0
|
|
|
20
|
+7.5
|
1.0k
|
0
|
|
|
26
|
+5
|
1.25k
|
0
|
|
|
31.5
|
+3
|
1.6k
|
-0.5
|
|
|
40
|
+2.5
|
2.0k
|
-1.5
|
|
|
50
|
+1.5
|
2.5k
|
-1.5
|
|
|
63
|
+1.5
|
3.15k
|
-1.5
|
|
|
80
|
+1.5
|
4.0k
|
-2
|
|
|
100
|
+2
|
5.0k
|
-2
|
|
|
125
|
+0.5
|
6.3k
|
-2
|
|
|
160
|
-0.5
|
8.0k
|
-2
|
|
|
200
|
-0.5
|
10k
|
-1
|
|
|
250
|
+0.5
|
12.5k
|
+0.5
|
|
|
315
|
-0.5
|
16k
|
0
|
|
|
400
|
0
|
20k
|
+1
|
Projects Measured with Radio Shack 33-2050 SPL Meter
- Tang Band D4-1 DIY Back Horn Speaker Kit
- DIY Fostex FX120 Bass Reflex Bookshelf Loudspeakers
- DIY Sealed Jordan JX92S Bookshelf Loudspeakers
Resources - Radio Shack 33-2050 SPL Meter
- Radio Shack 33-2050 Sound Pressure Level (SPL) Meter Manual - (PDF 525KB)
- Radio Shack Sound Level Meter Characteristics - (PDF 361KB)
- FREE Frequency Response Plotter Software
- Dayton Audio Woofer Tester 3 (WT3) for Impedance Measurements