MASS-Kobo Model 394II Balanced Headphone Amp

Based on the model 370, this is a completely balanced headphone amplifier from input to output. The model 394 II was created with the goal of driving headphones without adding or subtracting anything from the recording, so that it can also be used as a master monitor in a recording studio. (Unbalanced inputs are converted to balanced at the input section)

XLR has +4dBm/-10dBm reference balanced input selection. RCA has -10dBm reference unbalanced input, and is equipped with a worldwide power supply (AC100V-240V, 50/60Hz) for overseas use.

Model 394II is equipped with a switch that can switch the output between low and high. Low is usually for normal efficiency headphones and high for low efficiency headphones.

The Model 394II uses custom-made conductive plastic resistance faders (pictured below) used in high-end professional mixers.

Specifications

Model : Full Balanced Stereo headphone amp
Input : Electronically Balanced = XLR3-31 , Unbalance = RCA
Output : Balance = XLR4-31 x 1 or XLR3-31 x 2(L,R) , Unbalance = φ6.3 TRS x 2(High or Low)
Input Impedance : 3.7kΩ (XLR)/ 12kΩ (RCA)
Reference Input Level : +4dBm/-10dBm (XLR)/ -10dBm (RCA)
Maximum Input Level : +25dBm (XLR)/ +10dBm (RCA)
Maximum Output Level (P-P) : Balance = Hi 24V, Low 18V (with 32Ω loaded, 1kHz, THD+N 0.05%)Unbalance = Hi 12V, Low 9V (with 32Ω loaded, 1kHz, THD+N 0.05%)
(RMS): Balance = Hi 8.5V, Low 6V (with 32Ω loaded, 1kHz, THD+N 0.05%) Unbalance = Hi 4.2V, Low 3V (with 32Ω loaded, 1kHz, THD+N 0.05%)
Maximum Output without Distortion : Balance = 2.2W , Unbalance = 600mW (with 32 ohm load, 1kHz, THD+N 0.05%)
Frequency Characteristics : 13Hz - 100kHz (-0.5dB)
Power Supply : AC100 - 240V, 50/60Hz
Energy Consumption : 0.5A (with AC100V)
Size :
285mmW x 230mmD x 50mmH (except the rubber feet and projections)
285mmW x 230mmD x 52mmH (including the rubber feet and projections)
Weight : 2.9kg (without the power cable)