• We chose a simple circuit, where both channels of the input fed directly to each half of a 6SN7GT double triode operating in an unusually high current mode, the gain control potentiometer is placed AFTER this first gainstage, to allow the amplifier to be driven by any source with a minimum of noise introduced by this first stage.
   
• The 6SN7GT inut stage feeds a 12AX7 driver stage. The 12AX7 is a miniature double triode of high gain and in our circuit is configured is a SRPP (Shunt Regulated Push Pull), which gives a gain stage with a very wide dynamic swing, low impedence and outstanding drive capabilities.
   
• For the output stage we chose to use the popular and very rugged 6550 pentode. In our kit it is used within its limits and coupled to an oversized in-house designed and manufactured Audio Note output transformer with 4 ohm and 8 ohm taps.
   
• The power supply is highly evolved, starting with a 5U4G valve rectifier, then a pi-filter with a 10H choke, feeding the anodes of the 6550s. From here the supply is split a further 3 ways, proving further smoothing for the anodes of the 6SN7s, the 12AX7s and grid No.2 of the 6550s. Such a level of smoothing is achieved that there is no need for DC supplies for any of the heaters to keep the noise down. This amplifier runs as quiet as a mouse.
   
• The kit is built around two printed circuit boards, the power supply pcb and the input/driver stage pcb. Six components sit on a tag strip feeding the 6550s. Thus assisting ease of build. Have a look at part2 of the build instructions, see the "links" section at the bottom of the page.
   
• No real compromises have been made within the component choice in the audio circuit, each component being of the best quality and being operated most conservatively, ensuring reliability and long life. Despite the low price of the kit the chassis and printed circuit boards are of a high standard.
   

"It seems very capable of articulating the very smallest detail. It is as though I can hear things I have never heard before. Before, I probably heard it but only partially. With the kit 2 the music and all of its parts are completely integrated. The kit2 makes the music complete. And it thrives on complex and intricate pieces. "
Paul Hefer in USA

"My kit 2 came alive Friday May 27 at about 11:30 PM As stunning little amp that sounds as good as she looks.
I bought the kit2 as I needed to drive 88db Meadowlarks and the 300B kit offerings available were just not going to cut it. I favor the 'SET' sound as the normal push-pull unltralinear/tetrode amps have a transitory flavor that just doesn't float my boat. Brian convinced me to go for the 6550 SE (not SET mind) amp. The kit 2 runs single ended but in pentode mode.
When I fired her up I was amazed at the sound. The Kit2 is not a compromise, but seems to combine the best of a SET amp and a ultralinear/tetrode push pull. Strings, brass and vocals are amazingly detailed, lifelike and vibrant, yet the amp is extremely extended on both end and has a prostigeous bass. I was absolutely amazed when I heard the the bass -it really slams! My current reference is a (highly modified) 6C33 based SET from ASL and the kit2 was giving it a good run for it money, with std tubes and with no uprated parts. "