Analog Monitor FAQs
Q : How are the various models of Dorrough Audio Meters different?
A: All Dorrough Loudness Meters feature the same Dorrough Practical
Standard (DPS) ballistics. The units are available in different
sizes for stand-alone, rack-mount, and console-mount applications.
There are also a variety of scale options. All meters feature high-resolution
40 LED displays.
Q: What are the different scale options?
A: Standard scale options include:
"A" Scale (14dB of headroom)
"B" Scale (Primary scale expressed in percent of modulation -- "0" referenced
to 100, with a secondary "A" scale)
"C" Scale (20dB of headroom)
Q : What is the input impedance of your analog meters?
A: All Dorrough Loudness Meters have an input impedance of 20k-ohms
balanced, and 10k-ohms single-ended.
Q : What are the display time-constants used in your meters?
A: The average signal level display uses a time constant of 600 mS,
while the peak display is virtually instantaneous. For background
information on these ballistic characteristics, refer to the Audio
Engineering Society's published Preprint 2567 (B-1).
Q : What is the display resolution of your meters?
A: The standard analog 40 dB scale provides a resolution of 1 dB
per LED. The optional 60 dB scale also provides a resolution of
1 DB per LED, except for the rightmost 10 LEDs, which are 3 dB
per LED. The digital meter with the 60 dB scale option is identical.
Q : To what reference level are your analog meters calibrated?
A: All Dorrough analog Loudness Meters are calibrated to a reference
level of +4 dB at the factory. This is adjustable to any reference
Q : What are the mounting options on the 40-A2 meter?
A: The Model 40-A2 can be used either stand-alone, rack mounted (using
our optional one or two-meter rack adapters), or console mounted.
Digital Monitor FAQs
Q : To what reference level are your digital meters calibrated?
A: All Dorrough digital Loudness Meters are calibrated to a reference
level of -20 dB. Other levels, such as -14 or -18, can be specified
at the time of ordering.
Q : What is the Over Indication level on your digital meters?
A: 1 count over is the factory default setting. The digital meters
conform to all formats defined in the AES/EBU Audio Specifications.
Included are 24-bit and 16-bit formats. Sampling frequencies are
32 kHz, 44.1 kHz, 48 kHz, and 96 kHz.
Q : How are the input connections made to the digital meters?
A: Electrical connections to the digital meters are made through
a standard BNC or XLR connector.