Dorrough Loudness Meter w/Percent Modulaton

Dorrough 20-B Loudness Meter w/Percent Modulation

Dorrough 20-B Loudness Meter w/Percent Modulation

B&H # DO20B MFR # 20-B
Dorrough Loudness Meter w/Percent Modulaton

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  • 1Description

The Dorrough 20-B Analog Loudness Meter is a single-channel version of Dorrough's standard 40 series loudness meter with a straight-line scale display calibrated in percent modulation, referenced at 100%. It has a lower scale in dB from -36 to +3dB for accurate peak protection at transmission sites.

This meter provides access phase correlation, peak hold, sum/diff, and reference mode allowing 0 reference setting to .1dB accuracy, directly or with the optional remote control. It has Phoenix (euroblock) connectors. Rack mounting is required.

Straight Line Display
The 20 Series is functionally identical to the 40 series, except that the 20s have a straight-line scale designed for applications with limited vertical space. These easy-to-read meters are made to install easily to a custom console or with optional rack mounts.
Peak and Average Percent Metering
The 20-B, like all Dorrough loudness meters, simultaneously displays peak and average, in this model in a straight-line scale display calibrated in percent modulation, referenced at 100% . The relative difference, in dB, between Peak and Average ballistics is derived from the integration time of the persistence scale.
Right and Left Inputs for Stereo Mixing
With one instrument, the operator can easily see the stereo mix and avoid classic in-phase/out-of-phase problems as well as center channel buildup that can cause a mix to seem louder. This is especially important in preparing stereo program material for broadcast, while still being able to maintain monaural compatibility.
In the Box
Dorrough 20-B Loudness Meter w/Percent Modulation
  • 2-Year Warranty
  • Table of Contents
    • 1Description
    Input Impedance 20k Ohm balanced, 10k Ohm single-ended, +/- 2%
    Common Mode Rejection Ratio 80 dB at 60 Hz, 60 dB at 20 kHz (balanced mode)
    Input Sensitivity -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 Less than 1% THD at 1 kHz, +24 dB input
    Sum Error Less than 0.1 dB at 1 kHz
    Difference Error Less than 0.1 dB at 1 kHz
    Display Resolution 40 LEDs, 1 dB/LED except model 60D, +/- 0.25 dB.
    Step Size Error +/- 0.25 dB
    Absolute Error Full Scale -39 dBu: +/- 0.25 dB model
    Drift +/- 0.25 dB
    Average Time Constant 600 mS, +/- 6%
    Peak Acquisition Period 10 uS, to full-scale, sine input 25kHz
    Peak Attack Period Virtually Instantaneous
    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
    Calibration Controls None needed
    User Controls 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

    User Port 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)
    Dimensions (WxDxH) 8.5 x 3.0 x 1.75" (in.) (3.3 x 1.2 x 0.7cm)
    Weight Not Specified by Manufacturer

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