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First Watt SIT-3 Class A Amplifier - NEW IN BOX - 1 of 250 made!

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Pickup currently unavailable at SkyFi 479

First Watt Sit-3 Class A Amplifier - New In Box 1 Of 250 Made!

First Watt SIT-3 Class A Amplifier - NEW IN BOX - 1 of 250 made!

SkyFi 479

Pickup currently unavailable

479 South Broad Street
Glen Rock NJ 07452
United States


This is a First Watt SIT-3 class A amplifier, a superb sounding Nelson Pass amplifier. There were only 250 of these amps made by Nelson Pass and they are highly sought after. This one of the very few New In Box still available!

Herb Reichert from Stereophile stated that when matched with the right speaker, this is one of the 3 best amplifiers he's ever heard - regardless of price. That's really saying something considering Herb's experience!

Priced at near original MSRP... that's right! Pass only made a few of these, and the company that made the special transistors is now defunct. Which means no more will ever be produced. 

Link to Owner's Manual

Link to Photos from a different SIT-3

From Herb's review in Stereophile:

"Besides commissioning his own semiconductors, Nelson Pass is the only mainstream amp designer I know of who writes his own owner's manuals, and does so in an intimate conversational tone. The SIT-3's manual opens with this description:

"The SIT-3 is the very latest example of single-ended/single-stage class-A amplifiers using the SIT (aka VFET) power transistor exclusive to First Watt. It is preceded by the successful SIT-1 and SIT-2 and very much follows their technical philosophy and construction.

"There is a key difference in the new SIT-3, which is that the Static Induction Transistor (SIT) that forms the heart of the circuit is operated in an entirely different mode, what is known as Common Drain Mode. . . .

"The channels of the SIT-1 and SIT-2 consisted of a single SIT operated in Common Source Mode in which (conceptually) the signal comes into the Gate and appears amplified at the Drain pin, but phase inverted. The Source pin is grounded. The amplification with Common Source operation is both voltage and current, and the phase inversion is corrected by reversing the output terminals.

"The SIT-3 goes in another direction, using Common Drain operation, where the signal goes into the Gate pin and comes out the Source pin and the Drain of the FET is grounded (literally attached to ground). This mode only provides current gain—the voltage gain is provided by a high quality voltage step-up transformer which takes the input signal from a preamplifier (or other device) and boosts the voltage. It has no phase inversion.

"In both approaches, the SIT does a good job of amplifying the signal without feedback, but Common Drain operation delivers the amplification with much lower distortion and noise and also a much better damping factor for the loudspeaker.

"The trade-off is the addition of the input transformer, but I think you will find the compromise there is small with respect to the sound quality achieved.

"Common Drain has the same simple spectral distortion character that graced the SIT-1 and SIT-2, and allows similar control of the amplitude and phase of the second harmonic content, but at a much lower distortion figure.[footnote 1] . . .

"If like me you find 18 watts is enough power, then I think you will find that this is a really delightful amplifier . . .

"It has less gain than the amplifiers you are used to [11.5dB vs 25dB+ for most amps—HR], but you can clip the output with about 3 volts. . . .

"The SIT-3 has enough damping factor at 30 to work well with general loudspeakers, but it has been designed around relatively high efficiency speakers, those having 88dB sensitivity or greater."

What other mainstream amp designer would create something this original?"

Summary of the nominal specifications:
Maximum output
18 watts @ 8 ohms
30 watts @ 4 ohms

Input Impedance
200 Kohms

11.5 dB non-inverting phase

Damping Factor

Frequency Response
-.5 dB @ 10 Hz, – 3dB @ 50KHz

Output Noise
50 uV unweighted 20 - 20 Khz

Power consumption
150 watts

3AG slow blow type
2.5 Amp for 120VAC
1.25 Amp for 240 VAC

17” W 16” D 6.75” H

32 lbs

Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.



Original Box





Not Applicable


Yes - Power

Physical Condition


Working Condition


SKU: 102166