120B 1X4 Distribution Amplifier

List: $475.00


SKU: APH-120B Categories: , Tag:


120B 1X4 Distribution Amplifier


Transformerless High Performance Audio Distribution

Model 120B is a high performance audio distribution amplifier with a single high impedance input and four low impedance outputs, all electronically servo-balanced and designed to be as transparent as possible. The 120’s transformerless circuits are designed for wide, flat frequency response, free from ringing or overshoot, making it ideal for distribution of time code or audio. Each output has its own amplifier and level control for maximum versatility and isolation. The sturdy steel chassis may be used stand-alone or rackmounted, singly or in pairs.




High Quality Audio Distribution Amp

  • 1 input/4 output with output trim adjustments
  • Transformerless design for wide, flat frequency response
  • Works for audio or time code


The input circuit is adjusted for optimal common-mode rejection. Servo-balancing compensates for high common-mode voltages, so headroom isn't sacrificed. The high input impedance allows bridging of the input signal with minimum loading. This way several amplifiers can be easily driven from the source.


The individual output amplifiers are very low impedance so long lines and capacitive loads are easily driven with no loss of stability or high frequency response. Servo-balancing permits the outputs to be used single-ended at any time without a change in gain by simply grounding the unused pin. Individual output level controls are recessed for bump-proof operation, yet can be easily adjusted without tools. The front panel power LED also acts as a signal present and clip indicator for the input.


Rackmount Kit for 120B, 124B and 141B
Allows for the rack mounting of one or two "B" series products in one rack space. The new front panel design of the "B" series products and the new rack mount kit design makes installation 100% faster!

Part # 45-008B
NOTE: This kit is ONLY for "B" series units. Contact Aphex for info about rack mounting kits for legacy products.




  • Frequency Response: 5Hz - 100 kHz (+0, -0.5dB)
  • Dynamic Range: 94 dB
  • Hum and Noise: Better than -90 dBm at unity gain
  • THD: 0.002% @ +4dBm, 0.005% @ +20dBm
  • IMD: 0.002% @ +10dBm
  • Channel Isolation: 70dB
  • Slew Rate: 13 V/usec


  • Connector: XLR 3-pin Female
  • Type: Transformerless, differential servo balanced
  • Impedance: 100k ohms balanced
  • Maximum Level: +25 dBm
  • CMRR (typical): > 45 dB


  • Connector XLR 3-pin Male
  • Impedance 65 ohms
  • Maximum Level +25dBm into 600 ohms balanced, +21dBm unbalanced
  • Output Gain Range ±15 dB

Other Specifications

  • Power Requirements: 100, 120, 220, OR 240 VAC, 50-60Hz
  • Dimensions: 1.75"H x 8.25"W x 7.25" D (44.5mm x 209.5mm x 184.2mm)
  • Net Weight: 3.5 lbs (1.6 kg)