Is there really an advantage to using de-emphasis followed by outboard analog re-emphasis?
This is really a mixed bag… Our processing inevitably produces some amount of intermodulation distortion, or IMD. We go to great lengths to minimize this, but as we are frequently behaving as a nonlinear compressor in each of the Bark bands, it is inevitable. Using an outboard equalizer to re-emphasize our de-emphasized boosts affects not only the desired freqeuency boosts but also the inadvertant IMD products. IMD products are found both above and below the signal frequency of a strong carrier. The outboard equalization is generally a high-shelving boost, so those IMD products above the band will be boosted higher. If we did not perform de-emphasis and did not use outboard re-emphasis equalizers, then these IMD products would not receive any extra boost. That could be a good thing, especially if these IMD products are near audible thresholds. But, not performing de-emphasis inside the System 5000 means that in some cases of severe hearing corrections, we will have to use up as much
