The Microphone Preamp As Part Of A Voice Processor
Thursday, April 1, 2010The microphone preamp is one of the most important parts of a voice processor because it sets the stage for your sound. To record with the best signal to noise ratio possible, you need to bring up the output level of the microphone 30 to 60 dBu needs to be brought up to line level 10 dBV or +4 dBu. Usually, this change in level will color the sound somewhat and in many cases that’s good. One of the joys of engineering is tone sculpting, and the mic preamp can have as much to do with this sculpting as the microphone. For example, a tube preamp will have a different character than a solid state unit. In addition, Class A circuitry solid state or tube will give you superior sound and performance but will often cost a little extra. Ultimately, the degree of transparency or coloration that you want the preamp to impart depends on your own personal taste and the needs of the music. Other considerations include the recording medium you’re using. Engineers with tape less studios may want a preamp that adds “tube warmth” or that can emulate the effects of tape saturation. On the other hand, analog tape users may want a transparent sound with as little coloration as possible. The call is completely subjective. What sounds harsh and buzzy to one engineer may sound warm and fuzzy to another. Another consideration is how your collection of mics will sound through the preamp invariably, some mics will sound better than others. There are no rules that say you can’t run a cheap mic through an expensive preamp or vice verse whatever works best for the style of music you’re recording should determine which preamp you choose. A mic preamp should include a couple of features to make life easier. First, it should have +48V phantom power so that you can power the mics that need it. A phase reversal polarity switch is also useful, to change the phase of the signal by 180 degrees. In addition, preamps often have a 10 or 20 dB pad to attenuate high output mics and a low cut filter to remove low frequency energy such as rumble. Most of the voice processors on the market include many or all of these features.
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