First Watt F8 Power Amplifier

First Watt F8 Power Amplifier

The First Watt F8 is now end of production and will be available until UK stock and component parts are no longer available. F7 is still in production & new SIT4 available Q2/Q3 2024.

The FIRST WATT F8 is the second of two power amplifiers from the Nelson Pass limited availability range rather than the more commercially available PASS LABS.

Why do we prefer FIRST WATT? Well, there’s something personal in these designs which just floats our boat. Plus the limited availability makes them collectable and something to own, treasure and enjoy.

Each FIRST WATT amplifier has a limited run and then they are gone. This can be down to availability of parts or just Nelson experimenting and evolving previous designs.

Either way, like many other enthusiasts, we love what Nelson does and we’re very happy to share that experience with you.

Of the FIRST WATT F8 Nelson says:

“Originally created almost 6 years ago, 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: 0.015%

Input Impedance: 100 Kohm

Gain: 15 dB

Input Sensitivity (1 watt): 0.53 V

Input Sensitivity (max output): 2.6 V

Damping Factor: 40@8 OHMS

Output power 8 ohms: 25 watts @ 1% THD, 1KHz

Output power 4 ohms: 15 watts @ 1% THD, 1KHz

Frequency response:  -0.5 dB @ 200 KHz

Noise: 100 uV unweighted, 20-20 KHz

Power consumption: 170 watts

Fuse: 3AG slow blow type – 1.25 Amp for 240 VAC

Warranty: Parts and labour for 3 years, not covering shipping costs or consequential damages.

Finish: Black