F1J vs F2
The F2's power @ 8ω is 5W against the F1J's 10W, its power @ 4ω 10W against 6W, its thd 4.000% against 5.000%, and its output impedance 15Ω against 80Ω.
AI-generated product photo — not official manufacturer imagery.
AmplifiersPower Amplifiers
Estimated price (community-sourced)
$2,000
Around — community and catalog average, updates slowly
About the F1J
The First Watt F1J is an updated version of Nelson Pass's F1 current-source power amplifier, using state-of-the-art power JFET output devices in place of the original gain MOSFETs for improved high-frequency distortion performance, extended bandwidth, and about 1.5 dB more gain. Like the F1, it is a power transconductance amplifier (current-source amplifier) rather than a conventional voltage amplifier, optimized for sensitive full-range loudspeaker drivers and noted for its clarity, transparency, and precise control of voice coils. It operates in balanced single-ended Class A with no feedback, delivering roughly 10 watts per channel while each channel draws a constant 100 watts, and provides both balanced XLR and single-ended RCA inputs. Compared with the original F1, the F1J also has lower input impedance - approximately 30 kohm balanced and 15 kohm single-ended - and is recommended for use with preamps having ordinary to low output resistance for best high-frequency performance.
Specifications
Power Specifications
Amplification power output and characteristics
- Power @ 8Ω
- 10W @ 8Ω
- Power @ 4Ω
- 6W @ 4Ω
- Amplifier Class
- A
Analog Output
Analog signal output specifications
- THD
- 5.000%
- Output Voltage
- 20.0V RMS
- Output Impedance
- 80Ω
Connectivity
Input and output connections
- Digital Inputs
- XLR, RCA
Key Specifications
Power: 10W
Specifications are community-contributed and may not be accurate or complete. Verify all details with the manufacturer before making purchasing decisions. Terms & Conditions