Petr Žwak - tube amplifiers

Callisto - stage line tube preamplifier

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	Used tubes	1 and 1/2 ECC82 for each channel
	Optimal input	100 mV - 1 V / 10 kOhm
	Gain	16 dB / 20 Hz - 20 kHz / +/- 0.5 dB
	THD distortion	max. 0.05% / 0.775 V
	Output voltage nom.	0.775 V / 1 kOhm / 1kHz (max +20 dB overload)
	S/N ratio 0 dB (A)	min. 82 dB
	Power supply	230 VAC / 30 W (0.5 W standby)
	Size (h x w x d)	90 x 135 x 240 mm (one box)

The line stage preamplifier Callisto is designed from triode vacuum tubes with sound quality in mind and meets even very high demands. It is equipped with selected passive and active components of high quality with regard to the durability of the device and the desired sound expression. It can be controlled by IR remote control (volume, mute, 3 inputs) or manually.

The preamplifier uses one active stage and output current driver. The first stage is equipped with a half of legendary ECC82 (12AU7) tube in common cathode topology. The output uses a White Cathode Follower with ECC82, which thanks to the low output resistance allows optimal excitation of another amplifier even on longer lines. The preamplifier allows a choice of three inputs, volume control by motor potentiometer and MUTE function (only via IR). The preamplifier has no global negative feedback (NFB), the tubes are paired. The preamplifier is designed in two separate cabinets to suppress source interference. The cabinets can have a silver or black front panel just like Jupiter. Both the preamplifier and the power supply (PSU) are controlled by a microprocessor to provide the highest optimal sequence / shutdown and thus ensure the life of the tube.