The avoidance of stock magnetics alone to get custom trafos made in Europe speaks volumes. Operating a small audio boutique in France which at this stage must still work to low volumes whilst insisting on bespoke parts can't help but take a toll on production costs. Designing with tubes whilst offering very high power to clamp crossover-less transducers to within centimeters¹ of our ear canals creates other challenges for engineering and execution. Pursuing the very lowest possible self noise should rely on extremist parts selection/rejection and matching. That's neither cheap nor quick either. Customization options create more workflow issues. Whilst I barely sketch, the emerging picture still explains why Amethyste is a costly little double decker. Pascal's CV doesn't help either. Working for decades with defence, aerospace and oceanographic institutions and their resources must have created a most uncompromising design ethos where only the best, most accurate and reliable will do. After all, nobody wants planes to fall out of the sky or torpedoes to misfire. Applying the same standards to audio might be extreme² but could be just what Kallyste are all on about. In which case, ready for take-off. Or should that be, arm the torpedoes and fire in the hole? On second thought, I much prefer the peaceful civilian image. As to what Pascal's domestic hifi press says about this machine, it seems that Vumetre's Sep/Oct 2023 issue has Vincent Guillemin's review award it "the highest praise". So Gallic difference doesn't stop at 'the big one' of Devialet. The country hosts many smaller brands which do things differently, be it Métronome or the Audioaero heirs at Vermeer, Neodio, Eera, B.audio, Ocellia, Aurai and Leehd's digital volume control as championed by Lumin, Soulution and Wattson. Just on paper, if I were to look for Amethyste competitors, I'd cross the border into Italy to head for either CanEver or Riviera.
¹ Of course Amethyste is also a preamp. Here it's telling that Pascal's FaceBook pages show one used in a system with 109dB sensitive Avantgarde horn speakers. No noise will have been the sternest of prerequisites there. In preamp mode the old-school approach of a motorized pot without noisy display means that unless we sit sufficiently close and/or well lit, the ridged knob's painted white marker might be hard to see. But its plain question is, "why would you need to see me when your ears can bloody well tell you how loud I sit?" It's funny how a bit of common sense can out many a modern creature feature as rather dumb and extraneous. Where a numerical volume display can matter is to precisely repeat settings. -27.5dB is -27.5dB and not some approximate guess. As a reviewer that's useful. Do Joe and Jill Civilian need it?
² On more 'extreme' this time on the user side, recent tests with top-end mechanical isolators by way of Carbide Audio Base Diamond and sound|kaos Vibra 68 footers were suggestive. It's not just the classic big direct-heated 45, 50, 2A3 and 300B which suffer microphonics to audibly clean up with engineered vibration attenuators. The 6922 in a Métronome AWQO 2 too appreciated their chassis floated. Whilst far more subliminal, their kind was microphonic as well. With a quad of Carbide's best in my tool box to combine viscoelastic decoupling with roller-ball isolators of zirconia spheres in diamond-coated ceramic raceways, I had an idea on how to best set up Amethyste. Yes it's decidedly extreme mollycoddling but spending €16K on a headphone amp warrants squeezing its performance for all its worth.
For my questions, Nathalie Fougues at Kallyste introduced herself to translate for Pascal who has no English. Apparently he's unfamiliar with Google Translator.
"I'm Pascal Curin's assistant and will be your contact for this shared adventure. Please feel free to ask any question. We'll do our best to give you significant explanations regardless of how many emails this might take. Pascal follows a very personal path which leads him to technical decisions which sometimes look atypical or even contrarious to other brands or current fashions. This includes his choice of tubes, absence of XLRs and more. We were impressed by your very serious well-documented preview and are happy that you elected to write for people who love to read."
My first round of questions asked about tube types and acceptable substitutes; recommended window of input voltages; number of gain stages; output transistor types; coupling approach between tubes and transistors; and output Ω in preamp mode.
230V transformer connections, 115V version in insert.
"One thing must be clarified upfront. The subject of tube rolling links to the fact that most consumer electronics use a few popular tube types, most of them triodes. Those allow for some sonic leeway which audiophiles enjoy playing with. It's like a game for tube collectors which we appreciate. If that's built into a design, why not?
"Pascal however works different. His genesis as a designer and his professional career always focused on fully optimized designs dedicated to maximum performance. That allows no random parameters so no random parts, either. To him the domain of fantasy belongs to the performers and composers. A hifi designer's function is to transmit their creation, not interpret it. That said, our power supply tubes are double-plate EZ81 rectifiers. They could be replaced by 6CA4 but wouldn't offer anything extra. These tubes sit in a very critical area. Replacing them requires removal of one of two boards to need a qualified technician. Our tubes are very high grade and designed for intense military use. Then we don't drive them hard so wear is very low.
"The preamp tubes are 5725³ pentodes from either Thomson or RTC. Existing substitutes would be 6AS6W or 6187. The circuit is most efficient when these tubes are properly matched and tested. The standard output voltage of digital sources is 2Vrms and Amethyste can handle up to 2.5V. Anything higher like from a DAC/preamp with volume control should be attenuated first. The circuit consists of two gain stages and the dual-differential transistor stage uses complementary bipolars. The tube stage couples via three top-quality capacitors. The output impedance of the preamp stage is appropriately low to be compatible with any power amps." I thought that sufficient information. Any potential buyer needing more is at liberty to do as I did and ask Nathalie. She's very responsive. "Personally I'm very happy that you will hear Kallyste quite apart from the business of reviews. That's because it's a part of Pascal's brain and character and we put our lives into what we do." This reflects in a 10-year warranty which the owner registers via the corresponding webpage. "Our remote is our own design and analog to avoid interference. We're still waiting on its aluminium delivery so will send you one as soon as possible." With overnight UPS delivery between France and Ireland, Amethyste certainly dispatched as speedily as possible.
Pascal Curin at the Munich HighEnd Show 2023.
³ The RadioMuseum.org describes this as identical to the CV4011 and 6AS6W and calls it a 7-pin miniature type with indirectly heated 6.3V filament. Meanwhile EZ81/6CA4 rectifiers remain in current production and are available from JJ of Slovakia. TAD aka Tube Amp Doctor have their own brand sourced from unnamed current suppliers. EZ81 show up in guitars amps from Marshall, Silvertone and various Hammond organ amps. As far as Pascal's love of small-signal pentodes goes, Shigeki Yamamoto of Japan's Yamamoto Sound Craft too is fond of using them as drivers for his low-power SET amps, be it Western Electric's 717A, the also American 1D5GP or the German Siemens C3m. Allen Wang of Melody Valve Hifi likewise embraces the Western Electric 429A pentode as driver for 845 and 212 output tubes. Javier Diaz of Copernic Audio too uses a D3a pentode to drive his 300B SET through an interstage transformer. None of them however combine a pentode with bipolar output transistors.
