Aimed at both studio recording and live sound, the A-Designs Audio JM-3001 is a versatile preamplifier, equaliser and instrument input housed in a 1U-high rack frame.

JM-3001Hand-built in the US, the JM-3001 features three inputs – microphone, instrument and EQ/insert – which may be used together or independently. It is also equipped with a three-band parametric EQ and high/low filters, as well as two independent transformer-balanced outputs (microphone and EQ).

The heart of the JM-3001 is the C12X discrete transistor operational amplifier designed by Carl Johnson – a high-gain, fast-slew, stable audio block with virtually no DC offset over the audio spectrum that is capable of driving a 50Ω 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.

‘The JM-3001’s 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,’ says A-Designs’ Peter Montessi. ‘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. Needless to say, the JM-3001 is a very welcomed addition to our lineup here at A-Designs Audio.’


The JM-3001’s mic preamp is a single-stage, transformer-coupled and balanced I/O design. 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 pick-ups in mind. Similarly using a C12X discrete op-amp, this section is separate from the mic pre and includes a quarter-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 equaliser input/insert return is a direct-coupled, balanced input that is post the mic pre and the instrument input. Inserting a TRS quarter-inch phone jack into this connection allows for direct input to the equalizer, bypassing both the mic pre and instrument input.

The JM-3001’s three-band parametric equaliser features 33 frequencies with three bands of overlapping ranges covering from 50 Hz to 15kHz. Both the frequency selection and the ±12dB 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 12 dB/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.


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