The API 3124MB+ is a discrete, high quality, compact, 4-channel mic/line preamp with stereo mixer, plus D.I.
Both the 3124+ and the 3124mb+ are designed with the professional engineer in mind. Both units give the highest possible quality 4 channel mic preamp. However, the 3124mb+, provides an additional audio mixer with a transformer balanced output, keeping the unit size and price at a reasonable level. Both models are equally at home in the control room, studio, and recording truck or on stage.
The 3124mb+ utilizes the same microphone preamp circuit that is used in all API consoles. It uses the RE-115 K mic input transformer along with the same output transformer that is used in API equalizers. The unit has an internal 48-volt phantom power supply, which is front panel switchable for each channel. Also provided is a front panel -20 dB pad switch that affects both the mic and line in. A 1/4" phone jack is available on the rear panel for each channel as an insert tip-send/ ring-return placed between the mic pre amp output and the mixer input.
Like the 3124+, the 3124mb+ provides up to 65 dB of gain to an output clip level of +28 dBu. The Hi-Z front panel input goes directly to the op-amp, allowing a low level input such as a guitar or bass to be amplified without a matching transformer or direct box. This Hi-Z input can accept input levels as high as +20 dBu, making it perfect for keyboards and other high level devices. The rear output is an XLR connector.
Additionally, the 3124mb+ adds a stereo panner with a level control, and a post "fader" aux send. The stereo panners and the aux sends are bussed to master output controls and then to the rear panel jacks. A stereo AUX return is provided to return effects or cascade additional mixers for more inputs. The unique stereo aux return control acts to balance the left/right signal, yet staying stereo. It can also be used as a mono return.
Uses API 2520 Op-Amp
Classic Console Circuit
Four XLR Mic Inputs
Four 1/4" Un-Balanced Inputs
Front Panel Polarity Switch
Front Panel 20 dB PadSwitch
Front Panel Mic/Line Switch
Front Panel 48V Power Switch
Output Clips at +30 dBm
Input Impedance: 1500 Ohms Mic, 470 K Ohms Un-Balanced, HI-Z in
Output Impedance: Less than 75 Ohms Channel Outputs
Nominal Levels: XLR Channel Output +4 dBu
Stereo Output Level: Unbalanced: nominal -2
Clipping Level: XLR Channel Output better than +28 dBm
Frequency Response: +0, -5, 10 Hz to 20 kHz (-.5 at 10 Hz)
Noise EIN: -129 Mic, -125 Un-Bal. Actual
Measured Noise: Better than -91 dBm / below Nominal +4.
Distortion: All Outputs at +4 out, .03%, at +22, .09% Max
Gain Range: 150 Ohms Input 10 dB Min., 65 dB Max (inc. PAD).
Un-Bal. Input 14 dB Min., 50 dB Max
VU Meter: Calibrated for XLR Outputs, OVU=+4 dBu,
(-12, -6, -3, 0, +3, +6, +18)
Controls: GAIN, PAD (20 dB), 48Volts, POL (polarity),