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Qualiton A50i Stereo Class-A Röhrenverstärker 2x50W

Class-A integrated vacuum tube amplifier with an output power of 2 x 50 W. The appliance can be connected to 4 Ω and 8 Ω nominal impedance speakers. The power outputs, based on output pentodes type Tung-Sol KT 120, were tuned to the before-mentioned nominal loads through our in-house manufactured, precision winding output transformers. The bias control circuit plays an important role in the operation of the power output too. This curcuit monitors the quiescent current of the output tubes and adjusts it to a preset value. Thus, all four output tubes are in perfectly equal operation states.

Out of three asymmetric and one symmetric inputs, one can choose the desired one using the front panel volume control and input selector rotary switch. The symmetric input features a mini XLR connector. In this case too, the entire volume control and input selector unit is in full harmony with the shiny polished casing of the appliance, bringing together functionality and aesthetics perfectly.

The clearly arranged, minimalistic remote control was designed with this philosophy as well: the unique and aesthetical exterior design was always kept in mind and the usability was improved. Finally, a couple of words on the set of tubes we use: the audio signal arriving on the selected input of the appliance is received by vacuum tubes type Tungsram ECC83. The driving voltage as well as its matching are produced by Tungsram E88CCs. In power output, the before-mentioned output pentodes Tung-Sol KT 120 are in action—strictly in Class-A.  


Rated output power                     2 x 50 W, stereo

Total harmonic distortion            < 0.75% (f = 1 kHz, rated output power)

Frequency response                     30 Hz - 100 kHz (-3 dB, rated output power)

Input sensitivity                             425 mV, unbalanced input

Number of input ports                 3 unbalanced input per channel, 1 balanced input per channel

Number of output ports              1 output terminal pair per channel, 1 line level output per channel

Gain                                                 +33.5 dB (8 Ohm); +25.5 dB (4 Ohm)

Input impedance                           10 kOhm

Nominal load impedance             4 Ohm and 8 Ohm

Output polarity                              non-inverting

Signal-to-noise ratio                      > 95 dB; output noise less, than 1 mV

Power requirements                     300 W

Tubes required                               4 x Tung-Sol KT120; 4 x Tungsram E88CC; 2 x Tungsram ECC83

Weight                                             25 kg

Dimensions                                     35 x 21 x 40 cm