First WattF4usedFirst Watt F4-(1) Stereo - Balanced -Pass Labs/ First Watt F4 Stereo or Mono blocksI have 2 of these. This sale is for 1. I am keeping one for stereo use but can be convinced of selling both. Relaxed ultra resolution and purity are indeed what this amp is about. The two I have we...2300.00

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First Watt F4-(1) Stereo - Balanced -Pass Labs/ First Watt F4 Stereo or Mono blocks [Expired]


no longer for sale

I have 2 of these. This sale is for 1. I am keeping one for stereo use but can be convinced of selling both. 

Relaxed ultra resolution and purity are indeed what this amp is about.

The two I have were Sold as a consecutive serial numbered Mono block. Designed as Single ended Stereo or mono.  This is one of my favorite FW amps. This is one of the most diverse First Watt designs  Still over 2 years warranty left. 

Buyer pays Shipping and Insurance; Paypal Fee's of 2.9% upon check out. 

ONLY FOR SALE IN USA; Lower 48 States

This simple amp offers the best sound in the F line up, up to the F4. Can be used as a Stereo or in Mono Balanced or Mono Parallel. Take a look at the 6moons review or read the manual. Purchased in Feb. 2019; both still have many years on the warranty. 

Like everything else from First Watt the F4 is a unique amplifier. It has no feedback and no voltage gain, only current gain. This design is sometimes called an “impedance converting amplifier”, but more commonly referred to as a buffer – in this case, a power buffer.

The F4 is Class A impedance converting amplifier, having no voltage gain or feedback. Its input impedance is 47,000 ohms, and its output impedance is about 0.2 ohms. It is suitable for driving a high sensitivity loudspeaker with the output voltage of a preamp or other line-level audio source. It is also useful with a less sensitive loudspeaker in a bi-amped configuration where it takes input from the output of a conventional amplifier.

As a stereo amplifier with single-ended inputs and outputs, it will deliver up to 25 watts into 8 ohms with a damping factor of 40. It will do 50 watts into 4 ohms, and as a mono-block amplifier with parallel inputs and outputs, it will do about 100 watts into 2 ohms. As a mono-block amplifier with balanced inputs and outputs the power output rating is 100 watts into 8 ohms at 1%.

The amplifier operates Class A to 25 watts (50 peak), and the distortion is 2nd and 3rd harmonic in character, rising or declining in proportion to the output power. The amplifier has a direct coupled input and output, with a -0.5 dB rolloff around .1 Hz and 200 KHz. It does a clean square wave at 100 Khz.


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