How to Use a Microphone Preamp
Successful use of a microphone preamp will undoubtedly entail some trial and error, not to mention a lot of level adjustments. Microphone preamps are used to boost the signal that comes from a microphone in order to process it via other devices. Mixing consoles or mixers as they are commonly known feature a built-in or internal mic preamp. This is for the sake of simplicity. An external microphone preamp, however, can add different qualities to vocal recordings not possible with internal preamps. Also, rather than purchase an expensive mixing console, consider spending less money on a lower-priced mixer along with a good mic preamp. It will cost less and likely deliver better results with more versatility.
Step 1: No Wrong Way
Provided a signal successfully travels from the instrument or microphone, through the mixer and to the recording console, there is virtually no wrong way to record music and sound. The recording levels must be set so they do not feedback, but producers have made waves for generations experimenting with different sounds. The first step is to organize the components for proper hookup. The basic order is microphone into the mic preamp into the mixer into the recording module.
Step 2: Connect Preamp to Mixer
Run a cable from the output jack of the external microphone preamp to the input jack on the mixer. This may be accomplished either with a shielded 1/4-inch instrument/component cable or an XLR microphone cable. Some mixers, however, won't bypass its internal preamp if an XLR cable is used. Check with the manual to be sure. While it won't ruin the components, there may a higher level of noise that is heard. This is because the external preamp is effectively being used to amplify the signal of the mixer's internal preamp. Make sure the phantom power on the mixing console is turned OFF.
Step 3: Connect Microphone to Preamp
With the external preamp connected to the mixer, now connect a microphone to the preamp. Connect an XLR cable to the microphone and connect the other end to the input jack on the external preamp. Test the microphone for a signal and set the levels on the mixer. The level signal indicator should barely, if at all, bounce into the red on the mixer for an optimal signal with no distortion.
Step 4: Connect to a Recording Module
The mixer is not the end destination for the signal. It simply mixes the signal. Even small mixers have several level adjustments, allowing to add gain, EQ, boost the high, mid or low frequencies, etc. The more expensive the board, the more features. From the mixer, the signal needs to travel to a recording module. For low-fi applications, this may be a cassette 4-track. Other options are A-DAT machines and digital recording modules. Most home engineers these days use a computer-based recording application such as ProTools or Apple's Garage Band. To run an external mixer to one of these applications, an audio interface is necessary.
It's also possible to include other sound processing and/or effects components between the mixer and the recording module. These are additional expenses, but most computer-based applications offer a multitude of digital plug-ins for precisely this purpose.