The Danger of Over-Compression

17 07 2007

A few weeks ago I wrote about compressing pastors and others who speak from the platform. I really like to use compression (judiciously), and would use it on just about every input on the board if I had enough comps (one of the many reasons I want a digital board…). Compression can really help even out the spoken word, especially in smaller venues, and enhance clarity.

On the other hand, when over-used, compression makes things muddy and takes away all the dynamic and punch. I came across the video below on Dave’s Going to 11 blog. It does such a good job visually and audibly demonstrating the dangers of over compressing something I am posting it here. Check it out—it’s really interesting (make sure your speakers are turned up to a good listening level).

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2 responses

20 07 2007
mb

OHHHHH. Some of us need a picture – and frankly, up until now all i knew about compression was that it made bad things not happen when “certain” people spoke, sang or played. (pretty technical huh?)

So here’s a question that everyone but me knows the answer to – why would you compress an entire band rather than just the individuals who happen to need it? (non-“tech-speak” answer requested – preferrably one-two syllable words, please)

23 07 2007
Mike Sessler

Good question. Strictly speaking, you wouldn’t want to compress the whole band, at least not with a single compressor. The video example was good in that it showed the overall effect of a compressor on a signal. However, when a compressor is inserted on a mixed signal (like a whole band, or at a radio station), it can really take the life out of the music by destroying the dynamic range.

Because most (if not all) musicians playing in church worship teams are not professionals, they tend to have less control over their dynamic range. By using a little compression to even that out, one can keep individual instruments from “taking over” a mix should they hit a drum head a little too hard, or strike a key harder than usual, or strum more enthusiastically. Thus the short answer is, everyone needs a little compression.

Ideally, each input would be input limited, which is to say that there is a limiter before to the mic pre-amp that keeps the signal from ever getting so loud so as to overload the pre-amp. That takes a lot of wiring, however, and most sound consoles are compressed/limited via the use of insert jacks, which are almost always after the pre-amp in the signal chain.

Compression is really only bad when it is over used. Like on the music channels of Time Warner cable. They have the compressors set up with a short attack and long release which means a single loud drum hit drops the level of the song by 6-8 dB (a pretty noticeable amount), but it takes forever (2-3 seconds) to come back up. This type of compression is totally unnatural and sounds like, well, yucky. You can also do the same thing with the spoken word by dialing in too much ratio (which will knock down the level too much) with a too long of a release time (in the seconds range). Then every time they pop a “p” or “t”, their overall level drops noticeably, but for no reason.
Hopefully that was “non-tech speak” enough…’;-).

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