Digital Stereo Processor & Leveler

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The 261 Utility Processor provides an all-inclusive system for general audio normalization, level management and FM-airchain use. It combines the functions of gated, gain-riding AGC, dynamic range compression and independent broadband and high-frequency program peak limiting. Processing functions may be selected from the front panel separately or combined for comprehensive program audio control.

The 261 features AES-digital and L/R analog inputs; digital and analog outputs are available simultaneously. Digital input sample rates are detected automatically, while multiple output sample rates can be easily selected from the front panel.

Extra features like alarms and a front panel lockout switch make the 261 a complete package for broadcasters looking for comprehensive level management. 100% digital DSP architecture ensures easy setup, transparent signal path, and unobtrusive menu-driven operation.


  • All-digital design using proven DSP technology with 32-bit architecture

  • Fast menu-driven setup with an easy-to-read LCD display

  • Accepts both analog and multiple sample-rate digital program inputs

  • Pre-emphasis protection limiting (with Rev. 2 firmware) ideal for LPFM

  • Gated-AGC (Automatic Gain Control)

  • Dynamic range compression

  • Wideband and high-frequency limiting

  • Remote alarms for audio loss, input overload and AGC out-of-limits operation

  • Front-panel lockout switch (located in back)



Frequency Response

  • ±0.25dB, 20Hz-20kHz at 44.1kHz and 48kHz sampling rates.

  • ±0.25dB, 20Hz-15kHz at 32kHz sampling rate.


  • Digital I/O: Better than 120dB below limiter ceiling, 20Hz-20kHz.

  • Analog I/O: Better than 75dB below limiter ceiling, 20Hz-20kHz.


  • <0.01%THD below limiting threshold

  • Limiter self-modulation distortion is an inverse function of frequency; <0.1%THD at 100Hz, <0.5%THD at 50Hz


  • Digital Digital I/O: Better than 120dB between channels

  • Analog I/O: Better than 65dB between channels

Program Line Inputs

  • Digital: AES/EBU (XLR) input accepts 16-, 20-, or 24-bit inputs at sampling rates of 32kHz, 44.1kHz and 48kHz

  • Analog: Active-balanced, bridging (XLR) inputs accept nominal program line levels between –15dBu and +15dBu

  • Input Gain: Menu-controlled over a 20dB range

Program Outputs

  • Digital: The AES/EBU (XLR) output syncs to the rate of the input program when the digital input is selected, or may be set to a 32kHz, 44.1kHz or 48kHz output rate when analog program inputs are used.

  • Analog: Active-balanced (XLR) outputs may be adjusted by menu selection for a nominal line level between –10dBm and +10dBm

  • Output Level: Menu-adjustable over a 20dB range

  • Latency: 4.5ms

AGC Capture Range

30dB nominal capture range (±15dB) with menu-programmed control over maximum (positive) AGC gain from +15dB to 0dB. AGC has selectable ‘slow’ and ‘fast’ correction rates.

Dynamic Compression

Compression of program dynamics is afforded by a timedomain “platform” function associated with the broadband peak controller. Additional circuit gain is imparted when this function is enabled, increasing the average value of the program by as much as 6dB, depending on the average/ peak ratio of the source material.

Broadband Peak Control

The look-ahead limiter has program-controlled attack and release timing that has been optimized for unobtrusive operation. Program peaks are held at an absolute ‘ceiling’ value without the need for flat-topped clipping.

High Frequency Limiter

Emphasized portion of the 50μs or 75μs FM transmission characteristic. In addition to menu selection of the appropriate curve, either a normal ‘flat’ output or a preemphasized output may be selected.


A front-panel flashing display and open-collector NPN transistor ‘tally’ outputs signal INPUT OVERLOAD, AGC OUT-OF-LIMITS or PROGRAM AUDIO LOSS conditions.

Power Requirements

105-130VAC and 210-260VAC; 50/60Hz; 20W.

Size and Weight

  • 23” x 16” x 2” (2U); 8 lbs

  • 584mm x 406mm x 51mm ; 3.6 kg