Now, before we get into what the DETECTOR LOOP and GATE KEY IN jacks do, let's explain what this "detector" is. At the heart of the compressor in the MDC is a VCA or voltage controlled amplifier which is responsible for controlling the gain or reduction of the input signal. Instead of using the audio input to control the VCA, the MDC uses an external DC voltage to control the VCA. This external DC voltage is derived from a circuit that reads the input signal then converts it to a DC "control" voltage. This circuit is called a "detector circuit."
With this in mind, consider now that the MDC-2001 has four of these detector circuits. One is shared by the compressor and expander. The other three belong to the noise gate, limiter, and the exciter. The MDC-2001 lets you access two of these detector circuits: the one for the compressor and expander and the one for the noise gate.
The detector circuit for the compressor and expander is accessed via the DETECTOR LOOP jacks. Being able to control the compressor from an external source probably has several applications, but we only played with one the manual suggests. Let's say you have a busy music track that you're mixing a voice track with. Let's say the voice is so soft that you need to "ride" the levels of the music during the mix, "ducking" the music when the voice is there and kicking the music back up when as the voice pauses. By sending the music through the inputs and outputs of the MDC and patching the voice track through the DETECTOR LOOP, the "ducking" can be done automatically. Proper adjust-ments of the compressor controls resulted in a very smooth control of the music level with respect to the voice track. We tried the DETECTOR LOOP with a live mike and some music with impressive results. This could be the big fix for stations with jocks that can't seem to ride their music levels properly when talking over intros.
The other detector circuit you have access to is the one belonging to the noise gate. Patch your mike into the GATE KEY INPUT and the MDC becomes a voice activated noise gate that opens when you talk. Now, think of the many sounds you can have going through the MDC's audio chain while your mike is controlling the gate. When you consider that any line level audio signal can trigger the gate, there are lots of creative possibilities here.
The impressive specs of the MDC-2001 include a frequency response of 16Hz to 28kHz, a signal to noise ratio of -110dB, dynamic range of 120dB, and THD at less than .04%. Some of these specs you might attribute to digital processing, but the MDC-2001 is doing all this clean work in the analog domain. A.R.T. even incorporated an audio mute circuit that engages and disengages the outputs of the unit after it has been turned on and off and mutes the output for two to six seconds after power up.
A compressor. An expander. A noise gate. A de-esser. An exciter. A peak limiter/clipper. A full stereo processor. Clean enough to put in your transmitter audio chain. All in one box and all for $499. A.R.T. is proud to say that their design staff put some thirty years of cumulative compressor expertise to work to come up with what they feel is their best effort yet on a dynamics processor. We think they hit the mark. A.R.T. gets our nod once again.