The Model 20-A is a straight line version of the standard 40-A. The loudness meter Model 20-A has a scale allowing 14 dB of headroom in 1 dB steps from +14 to -25. It also features a phase warning light with access to a full scale correlator via the 3 position switch. Supplied with power supply - rack mounting options are also available separately. Two XLRs for right and left audio.
The DORROUGH Loudness Monitor displays, in an easy-to-read format, the actual energy content of the program material, regardless of frequency, while still indicating the peak amplitude of the complex audio signal. It allows the operator to ride levels in a manner such that all program material can be adjusted for equal perceived loudness while protecting the peak of the waveform. Now, one meter gives you more complete and more usable information than any combination of peak hold, VU and PPM indicators.
The DORROUGH Loudness Monitor integrates on the same scale, two ballistics, showing the relationship between the average and the peak. It simultaneously displays peak and average, and the relative difference, in dB, between these two ballistics is derived from the integration time of the persistence scale.
The operator has only to adjust the level until either the peak or persistence reference is reached. This will result in the maximum level, regardless of program content. Material with or without compression can easily be matched for the same listening level.
Each DORROUGH Loudness Monitor features Right and Left inputs for use in stereo mixing applications. With one instrument, the operator can easily see the stereo mix and avoid the classic in-phase/out-of-phase problem. “Center channel build-up,” the addition of in-phase or monophonic material which causes the mix to be perceived as louder, will appear as a sudden increase in level. This is especially important in preparing stereo program material for broadcast, while still being able to maintain monaural compatibility.