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API Audio 3124+ 4-Channel Microphone Preamp - Used  From API

Used 4 channel API mic preamp coming from a small smoke-free private studio with it's original packaging. 


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API Audio

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What We Think

This preamp remains to be a favorite among rock engineers and as a preamp for drums kits and percussion. Nevertheless, it's somewhat subtle coloration makes it one of the great workhorse preamps still in production. Engineers have successfully utilized API-based preamps (on which the 3124+ is based) on projects from classical instruments on film scores all the way to indy-rock distorted electric guitars. It's the classic, unforgettable API-famed sonic texture keeps clients coming back to it. The 3124+ is particularly noted by it's compact 1 rack size, and affordable price. On a per-channel basis it is truly hard to beat. Request a quoteback and see for yourself.

Manufacturer's Description from API


  • Uses API 2520 Op Amps
  • Classic API console circuit
  • Four female XLR mic inputs
  • Four front panel 1/4" Hi Z instrument inputs
  • Front panel polarity switches
  • Front panel -20dB pad switches
  • Front panel mic/instrument switches
  • Front panel 48V power switches
  • Outputs clip at +28dBu

The API 3124+ is a high quality, compact, 4-channel mic preamp. It is equipped with the RE-115 K mic input transformer and the proprietary API output transformer found in the 512c single mic pre and throughout the API product line. The unit has an internal 48-volt phantom power supply, which is switchable for each channel, as well as -20dB pad switches that affect both the mic and Hi-Z instrument inputs, both located on the front panel.

Another feature of the 3124+ is that it can provide up to 65dB of gain to an output clip level of +28dBu. Additionally, the Hi-Z front panel inputs feed directly to the op amps, which allow a low level input such as a guitar or bass to be amplified without a matching transformer or direct box. These Hi-Z inputs can take input levels as high as +20dBu, making them perfect for keyboards and other high level devices. The mic preamp outputs are on rear panel male XLR connectors.

API Audio

About Manufacturer

API (Automated Processes, Inc.) is world famous for its all-discrete audio products: studio and broadcast mixing consoles, and a full line of rack mount mic preamps, equalizers and processors. It all began with a dream. It was 1968. The company: Automated Processes Inc., formed by men with a vision. Best known for their now legendary "2520 amplifier", this unique amp has been and will continue to be the heart of all API discrete products. It continues to provide reliability and sonic purity unmatched by the competition. The resulting console met the needs of the music, commercial and broadcast industry. API became the leading audio broadcast console manufacturer for radio and television networks and high profile stations. In addition, recording studios, large and small, began using API.....and receiving rave reviews from engineers and producers. There are over 700 API consoles across the nation and around the world, including the three major networks. Over thirty years later, many of these consoles are still in daily use in some of the most prestigious recording and broadcast facilities in the world because, to date, there are few, if any consoles of equal sound quality at a cost-effective price.



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, Balanced: +4

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.


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)


GAIN, PAD (20 dB), 48Volts, POL (polarity),

MIC (mic/un-ba;), VU, AC

Power Consumption, Quiescent:

.66 Watts


19" X 1.75" (1U) X 11" Deep

Size (Boxed for Shipping):

23.25" X 6.5" X 16.5"

Actual Weight:

10.38 lbs.

Shipping Weight:

14.06 lbs.