MXL 990/991 Condenser Microphone Package Large and Small Diaphragm Pair

MXL 990/991: Two Microphones, Two Jobs, One Case

The MXL 990/991 is a two-microphone recording package pairing a large-diaphragm cardioid condenser with a small-diaphragm cardioid pencil condenser. Most first studios buy one microphone and then discover that the thing which flatters a voice is rarely the thing that captures a hi-hat or the top string of an acoustic guitar. Supplying both formats at once removes that second purchase and, more importantly, removes the compromise of pointing the wrong tool at a source. For a songwriter who sings and plays, it is the difference between two separate overdubs and one performance captured properly.

Large Diaphragm Versus Small Diaphragm

Diaphragm size changes what a microphone is good at, and the two formats in this package sit at opposite ends of that trade-off. A large membrane like the 22 mm element in the 990 collects more acoustic energy, which gives a stronger output, a lower relative noise floor and the flattering low-mid weight that makes voices sound substantial. A small membrane like the one in the 991 has less mass to move, so it starts and stops faster and tracks sharp transients such as a pick attack or a stick hitting a cymbal more accurately, with more even off-axis response. Understanding that single distinction is the most useful thing a new engineer can learn about microphone choice.

What the 991 Brings to the Pair

Published figures for the 991 are a 30 Hz to 18 kHz response, 15 mV/Pa sensitivity, a 110 ohm output impedance, 18 dB A-weighted equivalent noise, a 78 dB signal-to-noise ratio and 137 dB maximum SPL, drawing less than 3.0 mA. That 137 dB ceiling is the number that matters on a drum kit, because a pencil condenser placed over a cymbal sees peak levels that would overload a less capable microphone. Its slim body also fits into positions a wide side-address microphone cannot reach, such as under a hi-hat or close to a guitar soundhole. Engineers recording a busy kit or a bright acoustic instrument reach for this format first.

Working the Pair Across a Single Source

Running both microphones at once on one performer is where the package pays for itself, with the large-diaphragm body on the voice and the pencil condenser aimed at the twelfth fret of a guitar. Keeping the two capsules at a sensible distance and checking the result in mono reveals whether they are reinforcing each other or thinning each other out, which is the practical form of the three-to-one placement guideline. Because both microphones are cardioid, each one rejects the source the other is capturing, and that rejection is what keeps the two tracks separable at mixdown. A singer-songwriter gets a performance with the interaction intact rather than two disconnected overdubs.

Powering Two Microphones at Once

Both bodies require 48V phantom power within a four-volt tolerance, delivered over standard balanced XLR cables. Recording the pair simultaneously therefore needs a two-input interface or mixer with phantom power available on both channels, which most two-channel interfaces provide from a single switch. Phantom supply travels up the same cable that carries audio back, so no batteries and no external supplies are involved on either microphone. Anyone planning to use the package as intended should confirm their interface has two microphone preamplifiers rather than one before the first session.

Who the Package Is Built For

Singer-songwriters, home recordists and small project studios are the natural owners, because all three regularly need to cover a voice and an instrument in the same afternoon. Podcasters use the large-diaphragm body on the host and the pencil condenser for a room or a second source. Drummers and rehearsal rooms get overheads and detail positions from the same two microphones the studio already owns. Arriving with stand adapters for both bodies inside a high-impact case, the pack travels between rooms as easily as it sits on a desk.