model 424 & model 428 Full-Balanced Portable Headphone Amp.
Currently, we have stopped accepting orders for the power supply unit used for portable amplifiers due to worldwide shortages.
model424 (Balanced Out XLR 4pin type) 220,000JPY - Taking orders has been suspended -
model428 (Balanced Out 4.4mm Pentaconn type) 220,000JPY - Taking orders has been suspended -
Mass-Kobo products are basically made to order, but some products are in stock. The new two models of amplifiers use the balanced circuit of model 404 which is one of the most popular models. The input terminal 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. These 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. It can be used for about 4 hours with alkaline AA batteries. It can also be powered by connecting a power bank to the micro USB terminal. *Balanced output of model 424, model 428 is not compatible with unbalanced headphones and earphones.
<Specifications> (Batt. 6V or USB 5V) Model: Full-Balanced Portable Stereo headphone amplifier
Please pay the price in advance by Paypal. (We will start production after payment is completed)
I will send bill by Paypal later.
Cancellation after you pay cannot be undertaken unless it is impossible to manufacture the product. Please be careful.
The balanced output terminal is XLR in model 424, and Pentaconn in model 428.
The size of the body is smaller than 404, for the number of power-supplying batteries is down to 4 instead of 6.
The sound quality is clearly improved.
Now you can listen to all types of headphones and earphones, with both dynamic and balanced-armature drivers properly with a single amplifier.
(It varies depending on battery condition and type)
(There is no charge function, digital input / output function)
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.
Input: φ4.4 TRRS x 1 (balanced or unbalanced)
Output: model424 XLR-4Pin model428 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: model424 445g (with batteries), 387g (without batteries)
model428 440g (with batteries), 382g (without batteries)