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The Dorrough 40-B is a professional analog loudness meter, designed for modern stereo recording and broadcast requirements, and offering simultaneous average and peak program display, with separate ballistics and lightning-fast response. The 40-B is equipped with a 40-LED bar graph, showing 1dB of resolution per LED, with a scale ranging from -36 to +3dB, measuring percent of modulation, providing very reliable peak protection at transmission sites.
Rack or console mounted Analog Loudness Meter with dual dedicated ballistics for simultaneous peak and average readout
Microchip processor with accuracy of oscilloscope, ultra-fast response time of 600ms average, virtually instantaneous peak for seamless continuous display of peak/average relationship
Individual left and right XLR inputs for stereo mixing applications, +4 dB factory-calibrated
Display with 40 LED's providing 1dB resolution per LED
Proprietary "B" scale calibtared in percent modulation, from -36 to +3dB, providing accurate peak protection at transmission sites
XLR, 6 DIP switches for function assignments, mini 8-pin DIN port out for access to alarm relays, meter mode functions, and peak hold modes, standard with unit
In the Box
Dorrough 40-B - Horizontal Rackmount Analog Loudness Meter with "B" Scale
1 Year Warranty
Table of Contents
20 kOhm balanced 10 kOhm single-ended, +/- 2%
Common Mode Rejection Ratio
80 dB at 60 Hz 60 dB at 20 kHz (balanced mode)
-10 dB for full-scale display
Maximum Input Level
+24 dB before clipping
Signal Path Bandwidth
10 Hz - 25 kHz, +/- .25 dB
Signal Path Distortion
>1% THD at 1 kHz, +24 dB input
>0.1 dB at 1 kHz
>0.1 dB at 1 kHz
40 LEDs, 1 dB/LED
Step Size Error
+/- 0.25 dB
+/- 0.25 dB (Full Scale -39 dBu)
+/- 0.25 dB
Average Time Constant
600 mS, +/- 6%
Peak Acquisition Period
10 uS, to full-scale, sine input 25kHz
Peak Attack Period
Peak Decay Period
180 mS, from full-scale to all LEDs off
Display Update Rate
Approximately 10 mS
Display Duty Cycle
Display Time, AVERAGE, PEAK HOLD - 75% Display Time, PEAK - 100%
Power Supply Input Range
117/237 VAC RMS, -20% to +10%, 50-60 Hz
Left/Right input sensitivity Option DIP Switch: A) Peak Auto [ON] B) Difference Mode [ON/OFF] C) Over Level Alarm [ENABLE] D) Under Level Alarm [ENABLE] E) Auto ARMP
DB-9 Connector: A) Alarm relay closure contacts,1 form C, 1A, 30V AC or DC B) Mode control switch (user supplied) C) PEAK function switch (user supplied)