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 level.

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.