A Designs JM3001 Solid State Mic Pre with EQ

The JM-3001 from A-Designs Audio is equally ideal for both studio recording and live sound use.
Hand-built in the US, the new A-Designs JM30001 features three inputs: microphone, instrument and EQ/insert, which may be used together or independently. The product is also equipped with a highly musical three-band parametric EQ, high/low filters, and two independent transformer-balanced outputs (microphone and EQ).

The heart of the JM-3001 is its C12X discrete-transistor operational amplifier designed by Carl Johnson. Operating on ±30VDC rails, the C12X is a high-gain, fast-slew, stable audio block with virtually no DC offset over the audio spectrum, and is capable of driving a 50 ohm load at 50Hz with very little current draw. It is used in the microphone preamp, instrument input amp, and main output/EQ output stages of the product.

According to A Designs' Peter Montessi, œThe JM-3001s preamp is an original design with depth and detail for miles, while the EQ is a full parametric with its own transformer, so you can use it with or without the pre. The freq settings are highly reminiscent of classic console filters and musically complement any source you run through them. The instrument input is totally separate from the pre and EQ and sounds amazing on its own as well."

The JM-3001s microphone preamplifier is a single-stage, transformer-coupled and balanced I/O design benefitting from the C12X for ultra-transparent audio. This section feeds the EQ and preamp output mult simultaneously and includes phase reverse, a -20dB pad, +48V phantom power with LED indicator and a plastic conductive gain control pot.

The instrument input preamplifier is a single-stage, single-ended, high impedance input designed primarily with guitar and bass pickups in mind. Similarly utilizing a C12X discrete op amp, this section is separate from the mic pre and includes a 1/4-inch phone jack and gain pot on the front panel. Like the mic preamp, this section also feeds the EQ and preamp output mult simultaneously.

The equalizer input/insert return is a direct-coupled, balanced input that is post the mic pre and the instrument input. Inserting a TRS 1/4" phone jack into this connection allows for direct input to the equalizer, bypassing both the mic pre and instrument input.

The JM-3001s three-band parametric equalizer is a unique design featuring 33 frequencies with three bands of overlapping ranges covering from 50Hz to 15KHz. Both the frequency selection and the ±12 dB equalization controls are step-type switches for precise and repeatable settings. Each band has a Q switch with three fixed positions: sharp (S), wide (W) and narrow (N). The low and high bands are normally of a peak/dip type, but flipping the shelf switch to the up position on those bands changes the characteristic to shelf type. The shelving switch disables the Q feature on high and low bands only.

When in the up position, the high/low filters insert the fixed 12dB/octave high- and low-cut filters. These filters work whether the EQ is in or out.

As with all A-Designs Audio products, only the best possible components are used. Resistors are 1% metal film except the EQ, which is 0.1%. Capacitors are all quality polystyrene, polypropylene, COG and bi-polar. Furthermore, input/output XLR connectors and switches are gold/silver contact with no relays.