You are involved on Radio Audio processing?
Must reed the following post.


When stations cannot produce product they try fancy technical Equipment. Do you really think the listener cares that you have OPTIMOD whatever? Of course, listeners will be turned off by obvious Defects in audio such as earburn highs, distortion and other Artifacts.

For any station, a basic level of processing is necessary to provide reasonably constant levels, and peak limiting to keep the signal within FCC modulation limits.  And on FM these days, since most everyone runs at least the equivalent of a first or second generation Optimod, if you DIDN'T limit peaks and control gain based on the the preemphasized signal, you would sound significantly less loud that most every other station on the dial. Many broadcasters have this fundamental belief that listeners will tune up and down the dial and listen to the loudest station that they hear.  I think this superstition dates from the AM days of 50 or so years ago when receivers had much less AGC, and signal strength really did make a big difference in how loud a station would sound. 
Now, with FM, signal strength does NOT determine how loud the audio coming out of the speaker will be, only how much noise is under it.  In any event, these broadcasters are still trying to get the last half db of loudness into their signals, and I claim it doesn't make one iota of difference to their share. It remains true (fortunately) that radio programming is still an art, not a science, and so it's hard to say for sure what makes the difference in growing or shrinking the audience.  However, the evidence strongly points to program content as the primary factor and processing differences as insignificant.
If you've never played with an Optimod, how do you know what it's capable of? Just because you've heard some stations that don't sound too good (and I admit there are some) doesn't mean the Optimod is a fault. Firstly, it needs setting up correctly, it's not just a case of plugging it in and running away. It takes effort, over a period of time, as well as knowledge.
Secondly, the source material needs looking at. It's no good sticking mp3s through an Optimod - that will sound awful. It's no good having your entire music library on Minidisk or PC. Voice processors on mic channels, overly compressed promos, new Hyper-processed & clipped CDís etc. are all good sources of distortion. The studio engineer is unlikely to know what type of processor a particular radio station uses and how it is set up for that station's preferred sound and target radio type. The choice of Optimod / IDT / Omnia or whatever and the settings applied varies a lot from station to station.
You will find multiband processors in recording studios because record producers like their CDs to sound loud. Some studios engineers will apply multiband limiting (or worse, clipping) to keep the producers happy even though this can destroy the waveform of the music and, in particular, the peaks that Optimods love to get their teeth into. The result of this double-processing is an unattractive distorted mush which is no louder than pure audio would be straight into the Optimod.
Radio stations are also finding they have to increase the processing on their studio voices to match the loudness of today's heavily compressed music. More distortion. All of this comes to a head with digital radio where the coders need some light and shade in the audio in order to know what to throw away.
A few independent record companies are starting to issue 'radio mixes' to major stations. These are not clipped and sound far better on air, but it will take a major stand from the radio industry to the big labels to end this horrible practice. Optimod is a trade name for a variety of signal processing widely used in broadcasting.
I have worked with Optimod-AM quite extensively and with products from competing companies, and can state that properly set up, Optimod seems to do a decent job.

The Optimod system consists of basically three sections: 

A wideband, gated AGC amplifier.
A multi-band compressor.
Peak limiting and (in the AM case) bandpass filtering; negative and positive peaks are adjustable separately for Optimod-AM. 

The "gating" of the AGC amplifier prevents the AGC from going to maximum gain during pauses in the program or otherwise quiet passages. The gating is adjustable to a specific RMS level; with the gating off, it's a wideband compressor. 
The multiband compressor is purported to have the time constants and bandwidths required for the most natural increase in loudness without audible effects.  THe advantage of the multiband compressor is that, judiciously used, it has the ability to equalise program material to a more "uniform" sound.  This isn't really a bad idea when you own an AM radio station, and have less-than-ideal sources, from CD's all the way down to your news reporter's cassette deck and Traffic Patrol.
Peak limiting is the time-honoured trick of increasing the RMS of the signal by, deliberately clipping the peaks.  The Optimod does this reasonably tastefully, and allows you to adjust the clipping thresholdfrom -3 dB to + 2 dB for negative peaks, and similarly for positive peaks. An elliptical output filter
allows this clipped audio to have reasonable overshoot characteristics when it leaves the Optimod. The Optimod does have a phase scrambler (all pass filter) which takes the assymetry out of normal speech and music programmes.  This helps prevent certain types of transmitters from grossly overmodulating during "difficult" recordings.  The phase scrambler might be in Optimod-FM as well. Finally, there is parametric EQ after the wideband AGC, with both bandwidth, center, and gain adjustable for bass and treble frequencies.
The Optimod-AM also has some adjustable single order filters for tilt and overshoot compensation of older transmitters. Orban do make other products, such as Optimod-FM (the Optimod 8000 is mostly a stereo generator with some compression, the 9000 being sort of the Optimod-AM with the stereo generator). When Optimod-FM was introduced, it was the benchmark of stereo generators, and it is still damn good. They also make a TV stereo sound system for BTSC.  Orban also manufactures a line of studio toys, such as parametric EQ, de-essers, compressors, etc.
I personally like the Optimod AM, but the chief engineer at our Boston radio station has pasted over the front panel so that it reads IM-AM (I guess for intermodulation...).
Compression and EQ is a matter of taste and virtually a black art.  In the US, there is more anxiety over audio processing and its supposed relationship to cumulative audiences than probably any other single thing in a major market station.

York David Anthony
WKTD Wilmington, NC