First Watt F8 - Slutsteg

First Watt J2 är den konstruktion som blivit mest uppskattad och älskad av de som hört och köpt First Watt förstärkare. F8 är en vidareutveckling som Nelson Pass jobbat med i 8 års tid. Dämpfaktorn och högfrekvensåtergivningen är enligt Nelson Pass dubbelt så bra, distrortionen är lägre och detta har han lyckats med med 5 db lägre återkoppling. Såhär säger han själv om förstärkaren: "Still, this is not the primary thing - it's just what I can show you in print. The real merit to the amplifier is in the experience of listening. This is a matter of how compatible it is with the rest of the audio system and the taste of the listener. “This might not be the amplifier for you, but I think it deserves a listen. “You will have noticed, I enjoy amplifiers with a little personality. They don't have to measure perfectly, they just have to sound good. This is a simple little Class A amplifier with a very nice personality, and I hope you like it.” - Nelson Pass 2020-10-06 The F8 is a stereo two-stage single-ended Class A amplifier using the NOS Toshiba 2SJ74 P channel Jfets and SemiSouth R100 SiC power Jfets for signal gain, plus IRFP240 Mosfet mu-follower current sources, for a total of three devices per channel. It is similar to the J2 amplifier, but has only one front end transistor instead of six, operated as a current feedback amplifier (CFA) as opposed to the J2’s voltage feedback (VFA) differential input. This front end is more consistent with the single-ended approach to amplifier design and yields a purer second harmonic character, less distortion with lower negative feedback, greater bandwidth and higher damping factor. Nominal Specifications: Distortion @ 1 watt, 8 ohms: 0.02% Input Impedance: 100 Kohm Gain: 15 dB Input Sensitivity (1 watt): 0.5 V Input Sensitivity (max output): 2.7 V Damping Factor: 38 @ 8 OHMS Output power 8 ohms: 25 watts @ 1% THD, 1KHz Output power 4 ohms: 13 watts @ 1% THD, 1KHz Frequency response: -0.5 dB @ 10 Hz, 200 KHz Noise: <100 uV unweighted, 20-20 KHz Power consumption: 170 watts Fuse: 3AG slow blow type - 2.5 Amp for 120 VAC / 1.25 Amp for 240 VAC Warranty: Parts and labor for 3 years, not covering shipping costs or consequential damages.