MASS-Kobo Model 475 Full-Balanced Portable Headphone Amp

MASS-Kobo Model 475 Full-Balanced Portable Headphone Amp

Updated the external DC power supply terminal of the full balanced headphone amplifier model 428, which has been popular since its release, from USB micro B to USB Type-C.

The input and output terminal of Balanced uses Pentaconn manufactured by Nippon Dicks Co., Ltd. with high reliability.

No cable is used between the internal substrates, and all the connecters are gold-plated.
The sound quality is clearly improved.

This amplifiers are equipped with a mode change-over switch that enables you to connect both balanced and unbalanced output players.

Both models are equipped with the same output gain-changing switch as the one used in model 406, our flagship model.
Now you can listen to all types of headphones and earphones, with both dynamic and balanced-armature drivers properly with a single amplifier.

It can be used for about 4 hours with alkaline AA batteries.
(It varies depending on battery condition and type)

It can also be powered by connecting a power bank to the USB Type-C terminal.
(There is no charge function, digital input / output function)

*Balanced output of model 475 is not compatible with unbalanced headphones and earphones.
Unbalanced headphones or earphones connected to the balanced output with or without adapters may cause the amplifier to malfunction.
NEVER connect them to the balanced output.
Please use 3.5 mm unbalanced output for unbalanced headphone or earphones.

Specifications (Batt. 6V or USB 5V)

Model: Full-Balanced Portable Stereo headphone amplifier
Input: φ4.4 TRRS x 1 (balanced or unbalanced)
Output: 4.4 TRRS (balanced) , φ3.5 TRS (unbalanced)
Maximum Input Level: +16dBm (balanced), +10dBm (unbalanced)
Maximum Output Level (P-P): 7 V (balanced), 3.5V (unbalanced) (with 32Ω loaded, 1kHz, THD+N 0.5%)
　　　　　　　　　　 (RMS): 2.3V (balanced) , 1.2 V (unbalanced) (with 32Ω loaded, 1kHz, THD+N 0.5%)
Maximum Output without Distortion: 165mW (balanced), 45mW (unbalanced) (with 32Ω load, 1kHz, THD+N 0.5%)
Frequency Characteristics: 20Hz - 20kHz (-1dB)
Noise Level: Less than 40μV (in the minimum volume position, 32Ω loaded) Less than 150μV (in the maximum volume position, 32Ω loaded)
Power Supply: AA Alkaline or rechargeable battery x 4
External Power Supply: Micro USB +5v
Consumption Current: 0.19A (battery 6V, No signal) 0.21A (rechargeable battery, 4.8V No signal) 0.21A (USB 5V, No signal)
　　　　　　　　　　 0.28A (battery 6V, 1/8 Output) 0.32 A(rechargeable battery, 4.8V, 1/8 output) 0.31A(USB 5V, 1/8 Output)
　　　　　　　　　　 0.49A (battery 6V, Maximum Output) 0.61A (rechargeable battery), 4.8V, Maximum Output) 0.58A (USB 5V, Maximum Output)
Size: 97mmW x 132mmD x 40mmH (not include protrusions)
Weight: 440g (with batteries), 382g (without batteries)