Audio Level Optimzer

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Inovonics' 220 is a definitive automatic level controller incorporating the functions previously necessitating a Compressor, a Peak Limiter and a "De-esser".


  • A fully gated Compression / Limiting function with choice of GAIN HOLD, HOLD AND RELEASE, or HOLD AND FADE modes

  • Selection of Peak or Peak+Average limiting characteristics.

  • Adjustable peak limiting symmetry for full AM carrier modulation

  • A separate frequency-selective limiting option to prevent high frequency overmodulation in FM and TV audio

  • A frequency-weighted gating threshold to discriminate against non-program input signals

  • Very low distortion, even at low frequencies, is assured by unique open-loop gain control and ripple-cancelling circuitry.



Frequency Response

±0.5 dB, 20Hz-20kHz

Noise Level

Better than 70dB below output program level


  • (50Hz - 200Hz) SLOW Release <0.5% /FAST Release <0.8% / Below Limiting Threshold: <0.15%, 20Hz - 20kHz at +23dBm

  • (200Hz - 20kHz) SLOW Release <0.3% /FAST Release <0.4% / Level Limiter 0.5% max/Frequency Selective Limiter <0.5%

  • Below Limiting Threshold: <0.15%, 20Hz - 20kHz at +23dBm

  • Output Clipping Level: .+24dBm

Limiter Timing

  • Peak Limiter - ATTACK < 1us/dB-limiting

  • Peak Limiter - RELEASE - continuously variable between 30ms/dB-limiting (SLOW) and 6ms/dB-limiting (FAST)

  • Averaging Function -ATTACK and RELEASE approx.50ms / dB-limiting.

  • Frequency Selective Limiter -ATTACK: <1us / dB-limiting

  • Frequency Selective Limiter -RELEASE: 50ms (max) for any degree of reduction.

Gating Circuit

  • Operation: Circuit serves to hold gain at level of prior compression when input signal falls below Gating Threshold. If input signal remains below threshold in excess of 10 seconds, at the user’s option the circuit will (1) continue to HOLD GAIN at the level of prior compression; (2) slowly increase gain reduction to a maximum of 20dB (DELAY & FADE); or (3) slowly restore gain to the uncompressed value (DELAY & RELEASE).

  • Threshold Level: continuously variable; adjusts to open Gate on input signals of -40dBm at maximum sensitivity.

  • Threshold Weighting: -3dB points at 300Hz and 3kHz to restict gating operation to legitimate program material.

Peak Line Symmetry

A series of straps on the circuit board permits setting the value of positive peaks to 100% (symmetrical), 105%, 110%, 115%, 120% or 125% of the negative peak value.

Stereo Coupling

Two or more units may be interconnected for ganged gain reduction.


  • Sensitivity - Adjusts to accomodate input levels between -20 and +15dBm.

  • Impedance - 20k - bridging, with transformaer isolation.


Transformer-coupled Line Output feeds 600ohm line or bridging input at program levels between 0 and +15dBm.

Frequency Selective Limiting Characteristic

  • Optional Plug-in insert compliments 75us (FM broadcast - TV Audio) pre-emphasis characteristics to prevent overmodulation from the high frequency program energy. Circuit provides independent limiting for high frequencies.

Power Requirements

105-130 VAC (230V available), 50/60Hz, 10 watts

Size and Weight

3 1/2” x 19” x 6”; 12 lbs.