Quest Engineering OB-100 User Manual

23
Figure 15. Meter Electrical Input (Direct)
Figure 16. Weighting Characteristics
F.
Weighting
Characteri
stics
The
weighting
characteri
stics
(frequency
response)
for A, B,
C, and
LINear are
shown in
Figure 16.
The "A"
weighting response emulates the response of the human ear and is used for
most industrial and community noise measurements. "B" weighting is seldom
used. "C" weighting is often used for measuring noise reduction in hearing
protectors and for other scientific purposes. The "LINear" weighting has a
flat frequency response over the range of human hearing and is useful in many
applications such as audiometric analysis. It is also used when taking
octave and 1/3 octave measurements.
24
G. Internal Electrical Noise
The maximum measurable SPL of the 1800 Meter is 140 dB with a sinusoidal
input. (120 dB if measuring a complex signal with a 20 dB crest factor.)
With optional microphones the upper range can be extended to 150 dB.
When used with either the OB-100 or OB-300 filter (octave mode), the specific
minimum measurable SPL's when using either the Model QE4170 or the Model
QE4146 microphone are as shown in Figure 17. The inherent noise level is
typically at least 5 dB below the RMS values shown in each table.
Model QE4170, 1 Inch Microphone:
Octave
Band
Weighting Scale
ABCLIN
All Pass
31.5 and 63
125 and 250
500 and 1K
2K and 4K
8K and 16K
23dB
<0dB
6dB
9dB
11dB
11dB
24dB
10dB
12dB
10dB
9dB
9dB
27dB
20dB
16dB
10dB
9dB
9dB
35dB
22dB
16dB
10dB
10dB
14dB
Model QE4146, One-Half Inch Microphone:
Octave
Band
Weighting Scale
ABCLIN
All Pass
31.5 and 63
125 and 250
500 and 1K
2K and 4K
8K and 16K
27dB
5dB
13dB
17dB
14dB
13dB
30dB
16dB
20dB
17dB
13dB
12dB
34dB
26dB
23dB
18dB
13dB
12dB
40dB
29dB
23dB
18dB
14dB
15dB
Figure 17. Minimum measurable SPL's for the Model 1800 using the Model
QE4170 and the Model QE4146 microphones.
Noise Floor values were determined by substituting an equivalent electrical
impedance in place of each microphone.
For the One Inch Microphone: 56 pF Capacitor
For the One-Half Inch Microphone: 18 pF Capacitor

Quest Engineering OB-100 Specifications

General

Brand	Quest Engineering
Model	OB-100
Category	Music Equipment
Language	English