Nobsound F2 Single-Ended Class A Tube Amplifier Review

The Nobsound F2 is a single-ended Class A tube amplifier priced at $349.99. It brings the rich, smooth tone of a single-ended vacuum tube design to a home setup, with lifelike detail and natural dynamics aimed at relaxed, immersive listening with matched speakers.

The tube complement is designed for rolling: all tubes are pluggable. The default set is a 5U4G rectifier, a 6SN7GT preamp tube and 6CA7 power tubes, with compatible alternatives including 274B, 5Z3P and 5Z3PA rectifiers, 6SN7, CV181, 6H8C and 6N8P preamp tubes, and EL34 power tubes - enough combinations to personalize tone and texture. Around the tubes sit audiophile-grade parts: a robust 160W transformer with a Japan Z11 steel core, an ALPS precision potentiometer and gold-plated terminals, chosen to reduce noise and elevate musical detail.

Power output is about 9W x 2 into 8 ohm in Class A operation, which Nobsound says can drive a wide range of bookshelf and floor-standing speakers - specifically passive models rated around 10-100W with sensitivity of 88dB or higher, in a desktop or living room setup. Compatible speaker impedance spans 4-8 ohm; 6-ohm speakers can connect to either the 4 or 8 ohm terminals, with the 8 ohm terminals usually recommended for better dynamics. Dual RCA inputs with a front selector let a DAC, network streamer or CD player stay connected for instant switching. Listed performance is THD under 1% at 1kHz, an 88dB SNR and a 20Hz-20kHz response, and the unit weighs 8.6kg.

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