Dual Channel Transformer Input/Output Coupled 100% Discrete Fully Balanced Microphone --Currently out of production; not filling new orders at this time.


The Ingram Engineering MPA201 provides two channels of semiconductor based 100% discrete two-stage amplification of microphone signals. Amplification is provided by all-discrete JFET input / Class-A Output circuits. This unit has a fully balanced design from input transformer to output transformer and has the highest voltage rails that will likely ever be encountered for a semiconductor design. A combined variable-attenuator/gain stepped switch control at the input provides the ability, unique among most pre-amp designs, of optimizing signal to noise and dynamic range for any audio signal level. A high current Class A buffer drives the output transformer.


  • Transformer Coupled Input
  • Transformer Coupled Output
  • Combined Attenuator / Gain Stepped Switch for Optimal Noise Performance and Dynamic Range Utilization (No Input 20dB Pad)
  • 100% Discrete Design
  • Two Stage Gain Structure, Each Stage with JFET input / Class-A Output
  • High supply voltage for high headroom
  • High Current Class A Output Buffer Stage
  • Fully Balanced Signal Path, Input to Output
  • 80 Hz 2nd Order High Pass Filter
  • +48V phantom power
  • Polarity reversal switch
  • Clip Detector LED
  • Continuously Variable Output Level Control
  • External Power Supply
  • Custom ETI noiseless level control pot with 10 million rotation life expectancy
  • Long Life Panasonic Electrolytic Capacitors
  • Polypropylene and Metallized Polyester Non-Electrolytic Capacitors
  • 1% Metal Film resistors


  • Max Gain: 75 dB
  • Frequency Response: 45kHz, ±3.0 dB, with Gain Setting = 0
  • High Pass Filter -3 dB Cutoff Frequency: 80 Hz
  • THD = 0.02% at +4dBu, 100k Ohm Load
  • >+28dBu into 100 kOhms at 0.05% THD
  • Overload level LED indication @ THD = 1% nominal, both positive and negative peaks, Overload circuit bandwidth > 30kHz