Adding a VCA, Mixer or Attenuator to your Eurorack modular synthesizer allows you to precisely adjust the individual levels of the synth. Without the addition of a mixer, all of the sounds produced from the synth will playback at the same level. With a mixer, you can send desired modular components to sections of the mixer to controller oscillator levels, sub frequency amount, pink noise level, ring modulation, and more.
More advanced mixers can allow for the adjustment of the panning position, similar to a large-format mixing console, or a mix window inside of a DAW. Others will have an additional auxiliary send, which allows a copy of the signal to be sent to another modular unit, or external effects processors such as delay, reverb, or modulation.
In the more advanced mixer setups, you will have the ability to adjust the bias of the signal being sent to the VCA, this will allow you to create more or less headroom desired, and the ability to oversaturate the tone without a huge jump in level. If the level becomes too high, most advanced mixers allow an attenuation before being sent to the CV output, allowing the optimal signal level to be transmitted from the modular unit. You then have the option to send individual sound out of the mixer to another modular destination or send the sum of everything out of the mixer to the desired source, or two bus processing.
For more information on finding the right mixer for your Eurorack modular synthesizer setup, be sure to contact your sales rep at Vintage King.