Show('n'tell)time. Without any speakers or cabling attached to insure that the big transmitter glass fired up without any sparks, I turned the right power knob sans white gloves. Too old for such fuss. I'd already meticulously polished the chassis to mirror magic. Virtually instantaneously the 211's signature intense white light came on followed by demure little specks of orange inside the 6SN7.
I seemingly was in business without any operational fuss or tubular testiness. All shined up, Neptune certainly cut an imposing figure. Time to wire up signal cables, check on self noise then run some get-to-know-ya tunes to regain my sea legs on the good ship Direct-Heated Triode. As might be clear from the next photo, the single lateral pin on the 211's fat metal base means there's only one way to insert it into Neptune's orange-anodized dress barrel with matching lateral slot. With the 6SN7 you'll use the equivalent orientation pin built into its black base nipple. It's easier than screwing in a light bulb. Without optional tube cage, the big emitter bottles must obviously be kept out of reach of small kids and heat-curious animals. They'd cause serious burns. It's the polar opposite of cool-running class D you don't even know is on like our Gold Note PA-10 Evo above, a pair of which powers the sub. Does Neptune's vintage solution of anachrophilia retain 21st-century relevance on sonic grounds? Early transistor sound had to equal or better prevailing tube sound before it gained acceptance amongst the cognoscenti. To this day some of them insist that tubes do things transistors cannot. Class D too had to prove its sonic mettle over against solid-stage class A and A/B. Likewise for USB then Ethernet then wireless streaming vis-à-vis CD which itself was judged against vinyl, open reel and cassette tape.
To know whether progress goes beyond the emperor's new clothes, we need ongoing premium examples of prior art. Without it streaming fanatics for example can go off claiming all sorts of nonsense until, one fine day, they get to hear a top-quality CD transport/DAC combo. Stern dismissal of nostalgia confronts actual assessment not just hearsay and gets humbled and finally honest. Time to admit that aside from cost and convenience, hifi progress often isn't all it's cracked up to be? In this context, how would I feel about my favourite 2.5MHz direct-coupled transistor amps on either side of Neptune? Now Attilio's wife Angela checked in: "The remote is only provisional as you'll see in the answers to your other questions Attilio will send soon. Also, a tube cover includes with all our amplifiers. We didn't send one to speed up shipping since we were late already and this was a review not sale."
From the listening seat, Neptune's self noise was a low-level hum through the dipole midrange and ported woofer. From prior SET ownership I'll call its magnitude quite low. My inner noise nazi of course who abhors any hum felt vehemently vindicated in his transistor truth. With raw voltage gain in massive surplus for this system, I heard no SPL reasons not to focus on Qualio's IQ over Cube's Nenuphar v2. Why pursue a specialty speaker when Neptune's design brief aims at more regular speakers and instantly showed itself fully capable? Would there be more to it than just sufficient voltage gain? To assuage complaints over my 100Hz transition to a big sub, one press on my active crossover's remote bypasses the filter to hear speakers in standard uncut mode and assess any amplifier's control down low. But remember that without the sub's cardioid radiation pattern, any speaker good to 30Hz rides my room's 35Hz and 70Hz modes for unavoidable boom. For proper linearity, it's either massive most unsightly bass traps; serious digital EQ; or the Ripole sub. My choice is the latter.
A mirror polish means exactly what it says. You see everything; including my beheaded reflection taking this shot.
Before we talk tubular turkey, I asked Thomas Mayer of Elrog on the high-voltage SET topic before I knew to expect more from Tektron: "I don't know whether you've the time or inclination but asking never hurts. Could you explain what the impedance step-down ratio of a single-ended 211 means relative to winding ratio, bandwidth, phase shift and parasitics for its output transformer? Also, are there any inherent advantages in a 1'200V plate voltage relative to the music signal voltage—another subject of ratios perhaps—versus power triodes that run on much lower voltages? Despite running very hot and requiring more complex output transformers, are there technical advantages to a properly designed 211 SET which exceed what an equally properly designed 300B SET can do if we disregard its lower output power by using speakers that are ably served by the 300B? Also, two paralleled single-ended 300B would make very similar power, even more if we used the high-power KR/EML/Vaic-type 300B variants."
"There's no simple answer to all this. If you ask three amp designers, you'll get three different opinions. I'm thinking about writing a blog post about this topic because a thorough answer is quite lengthy and then I prefer to use it myself as well. But if you plan to publish it as part of your 211 amp review, the designer of that amp might not like my views which are most likely contrary to his." That was a perfectly fair answer of course and readers curious in a 2nd opinion can look up Thomas' blog for his eventual formal take on the topic. From Attilio: "As previously mentioned, I decided on 211 because they're historic valves that have always been used for audio-frequency power amplifiers, mainly in single-ended configurations with excellent linearity. This intrinsic linearity also allows for low THD without feedback whilst delivering good power in a single stage with a direct-heated triode. As you know, it operates at around 1000 volts and due to its medium-high internal resistance of ~3'600Ω, it requires an output transformer with a primary impedance of 10kΩ with a 35:1 ratio. Our transformers are handcrafted in Italy using only high-quality ultra-permeable thin 0.23mm laminations. The coils are OFC copper and each layer is insulated with 0.05mm mylar. Furthermore, the windings are cemented in class H polyester resin on a autoclave mould with vacuum values close to zero. The Masterpiece range culminated after two years of collaborative R&D with industrial designer Alessandro Coletta and our mechanical engineer Jacopo Bartiromo who brilliantly implemented the mechanical aspects of Alessandro's design outline to recall the screw-less Italian minimalism of the 1960. One of Jacopo's key contributions is the internal intermediate base to which mount the most delicate components of transformers, capacitors and valves. This intermediate structure not only provides higher mechanical integrity but decisively cuts down vibrations. All steel laminations are thick, ensuring extreme strength and robustness. Finally the design team includes Antonio Panzetti who manufactures all of our transformers and Walter Gentilucci who provides technical assistance and performs all measurements."
