Audio Note Kit2
Integrated Single-Ended Triode Hi-Fi Amplifier - 12W per channel


Kit2 6550 Single Ended Amplifier 12-15W output with black transformer covers


Kit2 Power Supply Board


Power Supply and driver board positioned in Stainless Kit2 chassis

The Audio Note Kit Two 6550 stereo amplifier yields about 12 watts in pure unblemished Class A, single-ended operation. It uses a single 6550 pentode per channel, one of the most popular and reliable pentodes ever designed in a single-ended arrangement. Each stage of the amp is operated in class A.


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 12 AX7 is a miniature double triode of high gain and in our circuit is configured is a SRPP (Shunt Regulated PushPull), 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.

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 PC-boards are of a high standard.


What customers are saying about the Kit2

...Oh, the sound? It is a bit early but I can tell you that if you need a bit more than the 8 watts a 300B provides and 12 watts will drive your speakers, this may be the best 12 SE watts one can obtain. Even right off the bench, the Kit 2 has a beautiful, extended upper end and as a few others than came in and heard this amp commented, very impressive bass. The midrange is so real, you may feel obligated to offer the artist a glass of wine...

Bill Baker - Response Audio


AWESOME!!! What more can i say? I got it going just after we last talked,cause i was pretty confident everything was ok. And it was.It was dead quiet (until about half an hour later). This email is probably a couple of days late cause ive been too busy listening to music ive heard a thousand times before but NEVER like this before. Got to go cause Rush's Moving Pictures has just finished.

Brian in Perth Australia


It seems very capable of articulating the very smallest detail. It is as though I 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 articulated. I know understand what Arthur Salvatore means when he says music must be ‚?ocomplete‚?Ě. The kit2 makes the music complete. And it thrives on complex and intricate pieces, exactly the same as my new TT. Very nice match.

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 tetrode (or 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.


I wanted to build a parallel 300B amp but Brian convinced me to go with the kit2 instead. I must admit I am quite glad I went with the kit2.
I just love my kit2. I was a bit apprehensive at first as I wasn't so sure that 6550 would produce a nice sound Ė boy was I wrong. Since building the kit2 (about 3 month or so) I have spent many listening sessions that last till 3AM. I suspect the people at work think I am an alcoholic as I often arrive at work very bleary eyed and happy after an evening with the kit2.
My Kit2 is better then ever! I tried it on different loudspeakers and was impressed by the sound. I first tried it on horns I designd and built around a Fostex FE168Esigma, 95dB. That was fun, power was no problem! The sound was transparent with excellent imaging as you expect it from a single driver horn. Then I had to try the amp at home on my T+A, 89dB, and that was extremely impressing! Music was just flowing with an astonishing ease, without effort...! And power, WOW, nobody would guess it's just 12W! What impressed me most of all (on all loudspeakers I tried the Kit2 so far) was the feeling of ≥presence≤. I do not only mean the ability of filling a room which is common to most tube amps. Kit2 has a consistency, a way of making the sound more ≥solid≤ which is quite incredible.

Flo - Sweden


My kit 2 has been up and running for just over a week. I triple checked all my wiring and was confident that all was well. I have to say I'm shocked at how fantastic this amp sounds! I can't believe it. A good portion of my listing is done with my jaw on the floor. Thank you for all your help and patients. You were a big part of this very enjoyable experience. Now, lets talk speakers!
Every so often I pull out one of my other amps (tweaked 6C33 set and a tweaked EL34 triode push pull) and the kit2 never fails to humiliate them badly.The kit2 is the very best amp I have ever heard.
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