First Watt SIT 2 Stereo Amplifier Reviewed
By: Terry London,
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The greatest 20th Century inventor, Thomas Edison, had his New York-based Menlo Park Laboratory to experiment with all types of materials and designs to see what applications he could come up with to help improve the quality of living for the masses in his time era. Legendary Nelson Pass, one of the greatest creators of modern audio designs, has his own version of Edison's Menlo Park Laboratory called First Watt, which is located in Sea Ranch, California. In the First Watt "laboratory" is where Nelson explores a variety of Class A circuits with output power ratings of 25 watts or less in search of new and innovative designs to get closer to the sound of live music. Each amplifier is hand built by Nelson himself in very limited numbers, then he shares these new minimalist circuit designs with the DIY community so that they can build their own versions of his First Watt amplifiers. What Pass discovers in his First Watt explorations is brought to his team at Pass Labs to possibly be incorporated into the much more complex and powerful Pass Labs amplifiers.
The subject of this review is the unique First Watt SIT 2 amplifier, which retails for $5,000. The SIT 2 is based on a Silicon Carbide (SIC) power JFET known as a Static Induction Transistor. The SIT is the only solid-state gain device that behaves/measures like a Triode tube. Nelson invested a large sum of money to have a custom production run of power SITs made by SemiSouth in Mississippi. He predicted that he could use the SIT in a Class A single-ended circuit to produce a beautifully musical solid-state amplifier that would have some of the sonic characteristics of SET tube amplifiers without the shortcomings inherent in those tube designs. It took him over two years, followed by many prototypes, to finally get the SIT 2 (along with its mono-block sister amplifier, the SIT 1) to perform to the sonic level he had envisioned when he took the financial risk to obtain the SIT transistors. (FYI, the SIT 1 and 2 amplifiers were the first Silicon Carbide SIT-based SET solid-state amplifier manufactured in the world. A company in Japan called Maxonic makes a single-ended design using older Silicon-based SIT transistors.)
Unlike the Pass Labs amplifiers that always have some of the most attractive and expensive chassis work on today's market, the SIT 2 amplifier is housed in an extremely well built yet very plain dark-gray enclosure. The SIT 2 weighs 32 pounds and measures five inches high by 17 inches wide by 15 inches deep. On the front plate, there are two blue LED lights to indicate that the amplifier is on, along with white engraved lettering composed of the First Watt emblem and the name of the amp. On the back panel is where one pair of RCA inputs, an on/off toggle switch, an IEC input, and a pair of speaker-wire binding posts are located. The SIT 2 only uses one SIT transistor per channel and produces 10 watts into eight-ohm speakers. Because the SIT 2 only produces 10 watts, it should only be teamed up with speakers that are around 90-dB efficient with no dramatic dips into very low impedances. I auditioned the SIT 2 with five different speakers that fit those parameters and had no difficulties with volume levels or overall dynamics.
When I started to listen to Keith Jarrett's piano solo recording "The Melody at Night with You" (ECM), I immediately noticed how the SIT 2 was extremely detailed in its presentation of all the nuances of Jarrett's playing-- how he pressed into the keys and the decays that were directly coming from his piano. These direct decays from the body of his piano were very easy to differentiate from the decays coming from the room in which he was playing. The SIT 2 was one of the quietest amplifiers I have ever listened to, which allowed all the micro-details to be heard in a very lucid manner.
My next selection was John Brown's "Quiet Time" (Brown Boulevard Records), which is an excellent recording of jazz standards and pop music. This is where the SIT 2's similarities with a tube-based SET amplifier could be heard. The tonality/timbres of the brass instruments were rich and warm-bodied. The SIT 2 is not quite as "cozy/creamy" as a 300B SET amplifier because it has much more speed and quickness than transformer-coupled tube SET designs. However, the purity of how the SIT 2 renders tonality/timbres is very similar to what these great tube-based amplifiers produce; the SIT 2 adds a color density that makes many solid-state designs sound somewhat washed out. The SIT 2's production of the high frequencies of this jazz combo was extended and airy, and it had a tube-like "sweetness" overall.
My final selection was the Beatles album 1 (Apple), which features many of this group's most cherished songs. With the SIT 2, the vocals of John and Paul were breathtaking in their palpability and 3D imaging (at least on certain selections, depending on the quality of the recording). The amp helped to create the illusion that they were actually singing in a holographic space in front of me. In regards to its bass extension and overall dynamics, the SIT 2 came through with flying colors, as long as I did not attempt lease-breaking volume levels.
• The SIT 2 amplifier is a limited-edition piece, hand built by Nelson Pass, and one of the few amplifiers in the world based on Static Induction Transistors.
• The SIT 2 renders music with beautiful purity regarding tonality/timbres and creates a large, open, and realistic soundstage.
• Because the SIT 2 only uses one transistor per channel and has no apparent noise floor, it passes all the micro-details contained in the music with a reference-level lucidity and clarity.
• The SIT 2 comes very close to the sonic presentation of the greatest transformer-coupled tube SET amplifiers, but it offers more speed and quickness to the pace of the music compared with those tube designs.
• The SIT 2 only produces 10 watts per channel. Therefore, for it to function optimally, you can only use relatively high-efficiency speakers with reasonable, easy impedance loads. Otherwise, you will not get excellent results in your system.
• Because it is a Class A SET design, it runs very hot and cannot be placed in an enclosed rack.
• Because it has such a high level of clarity and transparency, you must drive it with a reference-level preamplifier. Otherwise, you will lose the beautiful purity of tone, colors, and timbres.
Comparison and Competition
Because of the SIT 2's unique design, it was rather challenging to come up with direct competitors. Based on its performance and not its price, the only amplifiers to which I could compare the SIT 2 would be either SET 300B designs like Audio Note SET amplifiers having a price range of $12,000 to $18,000 and the OTL amplifiers, like the Miyajima Labs 2010 OTL, which retails for $9,950. Based on my experience with many SET and OTL amplifiers, the SIT 2 delivers the beautiful tonal colors/timbres, transparency, and image density of these designs but with much greater speed and overall dynamics without the hassle of the upkeep and replacement of power tubes.
In his First Watt "laboratory" with the SIT 2, Nelson Pass has created a unique and special amplifier. It and the SIT 1 are the only amplifiers in the world that use (Silicon Carbide) Static Induction transistors in a SET solid-state design. What Nelson discovered during the development of the SIT amplifiers inspired him to bring many of the sonic virtues of the SIT designs to his most recent amplifiers in the Pass Labs .8 Series. These virtues are the beautiful purity of tone and color, remarkable transparency, and spatiality/holographic imaging found in the SIT 2 amplifier, along with the ultimate current/power and macro-dynamics of the large .8 series amplifiers. If you do not need or want a very high current/watt amplifier and have the right type of speakers that were discussed in the body of the review--and if you are a listener who values beauty of tone/color/timbres, along with a purity/transparency that allows all the details in the music to be heard--then the SIT 2 would be the perfect amplifier for you.