THE NOVEMBER SUN
I submitted my original article to Dave at the end of August, and now that it is November I have had almost three more months of acclimating to the Sun, and I am convinced that this is one of the most controversial amplifiers in America (like the Berning ZOTL SET)...and most will avoid it like the plague, because it will be too upsetting of their established notions of state of the art push/pull transformer coupled amplifiers. This the only push/pull amplifier I have ever encountered that is causing me serious doubts about the artistic primacy of single-ended circuits.
I noticed that in the Stereophile listing of recommended tube amplifiers the only push/pull 300B amplifier listed was the Manley Retro. This should indicate to all that this type of circuit, which exploits a transformer phase splitter, is completely unknown and undeveloped in America. (Remember, my job is to report from the edge)
This amplifier has given me the opportunity to know the suffering of young Martin Luther. Am I about to proclaim a heresy? I am not sure, because I am racked with single-ended doubt and it is because I have danced with the Devil...Riccardo Kron in the Sun.
Let me be more accurate, the combination of some very vintage 1950s NOS 6SN7s, the new KR 300BXL, and the VansEver Pandora tuneable line cords is creating an aural matrix that is as unique in its own way as the aural matrix created by Berning ZOTL SET 300B and ZH270, and by that I mean both bring me to the edge of my descriptive ability....but they are completely different. This is very confusing because I thought I had full measure of the Sun amps, and I was totally surprised by the transformation that occurred when I plugged in the matched set of the new KR 300BXL tubes. Did Kron put LSD on his tubes and then I put my fingers in my mouth?
And then when I took the extra five minutes of trouble and connected individual tube regulated power supplies to each Sun amp I was electro-shocked into a higher dimension of musical refinement. This is absolutely the clearest, most naturally dynamic, tonally creamy, subtle, airy, wide and deep transformer output amplifier I have ever experienced any where.
Has anyone in America other than me ever experienced a push/pull KR 300BXL amplifier of this refinement? (Did you like that dig?)
So let me lay upon you a gizmological insight: Both the Berning ZH-270 and the Sun amps are minimalist designs: both use only two tubes per channel. Over the decades of experimentation with amplifiers of all genres, including the Futterman and AtmaSpheres, I found that less tubes equaled greater clarity and harmonic whole-osity. Of course in my case power is not a consideration so I will always go for less is more in an output stage.
We the gifted listeners of America, the lunatic fringe of the thermionic revolution, have been rightly critical of the high price paid for big horsepower push/pull/pentode/high feedback amplifiers that make most audio reviewers drool with power, and it is safe to say that less than .01% Americans know that there is another way...and it is the Japanese way....which is an update of what America was into in the late 1930s.
Can I blame my favorite target once again? The reason that the American audio arts have stalled is because we can not yet get the right type of speakers...those which reveal the nascent subtle of our tube circuits....or to put it another way...speakers designers have fallen way behind thermionic techno-shamans.
Now lets have a slice of hot apple pie so I can be very pieous. If you come from the normal single-ended school and you hear a Berning ZOTL SET amplifier you immediately recognize that you have been missing the lowest and highest octaves. This is the price we pay for the midrange ecstasy of the directly heated single-ended triode with transformer output amplifiers. Yet, even the Berning SET ZOTL suffers in comparison to the Berning ZH-270 push/pull amplifier in lower octave dynamics...again the advantage will always go to push/pull circuits in this regard. The reason I mention this is if you are a single-ended addict like me, when you experience the Sun or ZH-270 you immediately realize that you have been missing something...the frequency extremes, and the dynamic coherence top to bottom that is only possible with refined push/pull amplifiers. And the other quality that is apparent and obvious is...yes...push/pull cancels a certain type of distortion and when going back to single-ended circuits...even my own custom jobs....you begin to wonder.......
Because I am so impressed by this amplifier I am going to do something that I rarely do....and I am doing this in the hope of stimulating your creativity. I am going to quickly analysis each aspect of this amplifier that may be contributing to is ORGANIC UNITY...but remember, it is the gourmet blending that creates the magic. I am repeating what I stated in my full article but it is worth repeating, so you can make a check list:
(1) 300B push/pull output stage: As far as I know only Cary Audio and VAC are making push/pull amplifiers with this tube, but Sun runs their tubes at only 320 Volts, and I believe they are run pure Class A, which yields only 20 watts; thereby sacrificing power to eliminate the NOT refinement of the more efficient AB1. (Emerging from the fog of my pre-Futterman push/pull days is my belief that my favorite pentode, the EL 34 sounded best running at 330 volts/Class A). I suspect that this is a very low distortion point for 300Bs and especially the KR tubes, but I cant be sure. I also need to point out that the filaments of 300Bs are run with AC, and a hum balance control, which, according to the purist, gives superior sonics over DC on the filaments. And most importantly I am experiencing the quality of the Tamura transformers.
Very few, because of the single-ended craze, have heard 300Bs in push/pull which reveals some extraordinary qualities that SET dont reveal. But again, the KR 300BXL is a triode of completely different nature than all other brands of 300Bs...even the Western Electric. The combination of dynamics, low distortion, full frequency dynamic wave front, and tonal refinement will be a unique thrill for directly heated triode fans. This makes we wonder what the Sun 2A3 push/pull amplifier would sound like with the new KR 2A3s which are very impressive.
In regards to the Western Electric 300Bs...when used in the Sun, they approach much more closely the midrange magic of single-ended circuits which have an intensity of musical cream in the midrange that totally dominates the aural matrix....so....if you want you Suns to sound more like a classic single-ended circuit use the Western Electric 300Bs.
Why Audio Research, Conrad Johnson, Sonic Frontier, and Golden Tube Audio dont create 300B push/pull amplifiers is beyond the beyond in terms of doing the right thing. And neither the Cary or VAC amps are an attempt at the edge of the art. Of course none of the tube manufacturers...neither Sovtek, Svetlana, Western Electric or KR are pushing this...so what can we expect when not even the worlds leading tube entrepreneurs have not yet explored push/pull directly heated triodes?
(2) Chokes: This ancient form of power supply filtration is so essential for optimal operation short of an active regulator. Nothing better indicates the general primitive state of American tube design than the almost total absence of choke filtered power supplies. Of course Sun uses a choke, and that matters a great deal.
(3) Power supply capacitors: Not normal aluminum electrolytics, but the more advanced form of Cerafine capacitor here. My experiments with oil capacitors in parallel with these indicated that there is an improvement, but they are so large, even for their small value, that external chassis would be needed. At New York Audio Labs we used to use very large polypropylene motor start capacitors in parallel with aluminum electrolytic used in all Moscode amplifiers and it made a big difference. The Futterman amplifier only used photo-flash capacitors in their power supplies which were very different that the aluminum types. Obviously Mr. Uchida knows what he is doing.
(4) Transformer phase splitter/no coupling capacitor: Of all of the elements of this amplifier this is the one that stands out, so let me get to the point: When I heard this amp, it was as different as my first experience of the Futterman OTL amplifier...compared to my 1979 reference amplifier. Something very unique and positive is present here, and Tamura has created a true work of art in this tiny little transformer phase splitter. Smart American tube amplifier designers will immediately order some and start experimenting with them....but that assume a degree of artistic maturity that is rare in America.
(5) Less is More Voltage amplifier: Using a medium mu dual triode 6SN7 with both sections in parallel does NOT yield much gain in this circuit, and others who use transformer phase splitter often use voltage amplifier circuits with higher gain, so my intuition is telling me that the aroma of this tube is important. Based on my experimentation with five or six different NOS 1950s brands I can confirm that there is an alchemy between the tone of this tube with the 300B family. I love the sound of RCA.
(6) Tube rectification: No solid state rectifiers to screw up the tone here. I cant wait until the new version of the Western Electric 274 and KR 274 is available because I believe that this will advance the sound of the stock amplifier. I can alter the tone of this amplifier by changing brands of rectifiers and this is very desirable. Change the brand of rectifier, shift the tone of the circuit.
(7) Tamura Iron: I am not going to repeat myself here other than to say...you owe to yourself to experience this level of transformer quality, but it is an exercise only for the ego secure because it will depress those who erroneously believe that American tube amplifiers are using the highest quality iron.
(8) Parts Quality: The simpler the circuit, and this is absolutely the simplest push/pull circuit, the more the quality of parts matter, and this amplifier maxes out on parts quality. Every time a friend comes to my house I take the bottom plate off this amplifier to show them the beauty of its construction. A Japanese artist soldered all of parts and did all of the hardwiring, and it is thrilling to gaze at this level of build quality...it is like gawking at a Ferrari motor....only better.
GETTING TO THE POINT: Contact Suns distributor Yong Kim and get the Sun and Tamura catalog, go to Sun Audio web site and check out what the Uchida family is into...it is very major.
When you check out the Sun catalog check out their phono preamp, which is a completely unique circuit, and I hope, I dream , that I can convince Mr. Uchida to send one to me so I may explore the other half of Suns genius.
Anyone who is interested in experiencing the highest level of single-ended bliss would be wise to explore the Sun single-ended circuits because evertyhing that I have said about their push/pull amplifiers must apply to their single-ended circuits. Those who are looking for absolutely the ultimate amplifier for their Lowthers should check out their 2A3 circuits, and make sure you use the KR 2A3 tubes.
Have I upset you? Good. That is how I know I am doing my job.
e-mail Dr. Harvey "Gizmo" Rosenberg: firstname.lastname@example.org
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