Yesterday I bought Robin Trower live CD of a 1975 gig he did in Stockholm that I attended. Fantastic blues roch album but sadly it was compressed with a DR of 6 (
) and after a short while I must lower the listening level. To me, that is a sign of a lot of distorsion and I wonder if anyone know of any measurements of that? Only as a result of this silly compression/limiting going on.
Mike
The waveform view will give you an idea of how much dynamic range, compression, and loudness there is in a recording. And whether it has been"brick-walled" to the point of distortion. This article on Wikipedia explains it in more detail…
Once the damage is done, it’s difficult to undo. There is software that purports to undo some of the limiting and compression used to boost loudness. If a recording is badly compressed though, and clipped at the peaks, then there’s really no way to recover that. All you can really do is turn down the volume. Or try to get a better version of the recording with more of the dynamic range intact.
Another article on DRC…
If you’re using EQ with your audio gear, then you may want to use a preamp or pre-gain filter to ensure that your EQ filters do not also clip and distort your audio content by exceeding 0 dBFS.
Done this years ago.
Know about the loudness war (that we lost) but I was after actual distortion measurements so that I can put a figure on the level of destrction.
cheers, Mike
Now I have found some information about this and its not good news. According to this paper - Learn to dial in Perfect Compression on ANY Song! - compressors can easily generate 10% IMD distortion if fed a complex signal (i.e. music). That is not good . A smart engineer can by choosing the right settings on the compressor reduce that but as compression levels increase that will be harder and harder. IMD levels higher than 20% can be generated and we all have heard metal band and singers intentionally use this as an effect. While the harmonic dist is fairly low these nasty IM products is another matter, our ears dont like them at all.
This youtube video perform a simple test of recommend compressor settings for least audibility.
