Усилители мощности стерео — Fezz Audio Fezz Lybra 300B

The Lybra 300B is a stereo vacuum tube amplifier within the Fezz Audio Evolution family, the Polish company that shares its roots with Toroidy.pl. It uses a parallel single-ended (PSE) circuit with four 300B directly heated triodes, two per channel, which gives more output than a single 300B per side. Three RCA line inputs and a remote control are included, and the transformers are made by Toroidy to Fezz specifications for this model.

Key specs that matter

Rated output reaches 15 W for each of the two channels. Speaker outputs are selectable between 4 and 8 ohm, with separate terminal pairs for each impedance. The tube complement is four 300B output tubes, two 6SN7 and one 12AX7. Total harmonic distortion is below 0.25 percent, and frequency response extends from 12 Hz to 60 kHz at minus 3 dB. Power consumption is 180 W and the mains fuse is rated 3.15 A slow-blow. The amplifier measures 420 x 380 x 226 mm and weighs 23.5 kg. Finishes include black, white, burgundy and red.

Engineering and use context

Both the power transformer and the output transformers are toroidal, and the power supply also uses toroidal chokes from Toroidy. The power supply was redesigned with a stronger main transformer, and delayed anode voltage switching is used to extend tube life. An automatic bias module sets the operating point of the 300B tubes, which removes manual bias trimming when tubes age or are swapped. A signal ground switch helps remove hum when the amplifier is connected to other components. Anti-vibration feet support the chassis, and the logo is backlit. A protective cage covers the tubes, and cotton gloves are supplied for handling them. Each channel uses one 6SN7 and half of the 12AX7 in the driver stage, and the output tubes are Psvane 300B. The chassis panels are 3 mm powder-coated steel. Internal parts include metallised resistors, Nichicon, EPCOS and Miflex capacitors and an Alps volume potentiometer. Warranty cover is two years on parts and labour and 90 days on tubes.

Pairing

The two sets of speaker terminals let the owner match 4-ohm or 8-ohm loudspeakers to the correct transformer tap. With three line inputs, a CD player, a streamer and a phono preamplifier can stay connected, and a separate phono stage such as one of the Fezz Gratia models is needed for vinyl because there is no built-in phono section.

Alternatives

The Fezz Audio Titania Power Amplifier is a tube power amplifier of the same maker that runs in stereo at 2 x 45 W or bridged to mono.