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Dorrough 21B Vertical Analog Loudness Meter with Percent Modulation
- Price: $449.95
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Usually ships in 7-14 business days
Availability Details
CloseThis is a special order item and is non-cancelable and non-returnable. Est. arrival at B&H is 7-14 business days (subject to availability). Your order will be charged at time of shipment.
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- B&H # DO21B
- Mfr# 21-B
The Dorrough 21B Vertical Analog Loudness Meter with Percent Modulation is a straight line version of Dorrough's standard 40 series loudness monitor. The 21B requires rack mounting and needs an external power supply. It also comes in a handy vertical orientation.
Like the 40B, the 21B measures Relative Loudness to Peak Modulation. The meters are calibrated in percent modulation, referenced at 100%. Access phase correlation, peak hold, sum/diff, and reference mode allowing 0 reference setting to 0.1 dB accuracy, directly or with the optional remote control.
- Actual Energy Display
- Dorrough Loudness Meters display actual energy content of the program material, regardless of frequency, while still indicating the peak amplitude of the complex audio signal. This feature allows all program material to be adjusted for equal perceived loudness while protecting the peak of the waveform.
- Peak and Average Level Metering
- The 21B, 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 these two 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 causing a mix to seem louder. This is especially important in preparing stereo program material for broadcast, while still being able to maintain monaural compatibility.
| 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, +/- 0.25 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 |
| Step Size Error | +/- 0.25 dB |
| Absolute Error | +/- 0.25 dB |
| Drift | +/- 0.25 dB |
| Average Time Constant | 600 mS, +/- 6% |
| Peak Acquisition Period | 10 uS, to full-scale, sine input 25 kHz |
| 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) | 2.8 x 8.5 x 6.5" (7.11 x 21.59 x 16.51 cm) |
| Weight | Not Specified by Manufacturer |
Cables
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