Srajan Ebaen
Financial interests: click here
Sources: 27" iMac with 5K Retina display, 4GHz quad-core engine with 4.4GHz turbo boost, 3TB Fusion Drive, 16GB SDRAM, OSX Yosemite, PureMusic 3.01, Tidal & Qobuz lossless streaming, COS Engineering D1 & H1, AURALiC Vega, Aqua Hifi Formula, Fore Audio DAISy 1, Questyle QP1R, Soundaware Esther Pro & D100 Pro
Preamplifier: Nagra Jazz, Esoteric C-03, Vinnie Rossi LIO (AVC module), COS Engineering D1, Wyred4Sound STP-SE Stage 2
Power & integrated amplifiers: Pass Labs XA30.8; FirstWatt SIT1, F5, F6, F7; Crayon Audio CFA-1.2; Goldmund Job 225; Aura Note Premier; Wyred4Sound mINT; Nord Acoustics One SE UP NC500MB; Linnenberg Audio Allegro monos
Loudspeakers: Albedo Audio Aptica; EnigmAcoustics Mythology 1; Sounddeco Sigma 2; soundkaos Wave 40; Boenicke Audio W5se; Zu Audio Druid V & Submission; German Physiks HRS-120; Eversound Essence]
Cables: Complete loom of Zu Event; KingRex uArt, Zu and LightHarmonic LightSpeed double-header USB cables; Tombo Trøn S/PDIF; van den Hul AES/EBU; AudioQuest Diamond glass-fibre Toslink; Arkana Research XLR/RCA and speaker cables [on loan]; Sablon Audio Petit Corona power cords [on loan], Black Cat Cable redlevel Lupo
Power delivery: Vibex Granada/Alhambra on all components, 5m cords to amp/s + sub
Equipment rack: Artesania Audio Exoteryc double-wide 3-tier with optional glass shelves, Exoteryc Krion and glass amp stands [on loan]
Sundry accessories: Acoustic System resonators
Room: Rectangular 5.5 x 15m open floor plan with two-storey gabled ceiling, wood-sleeved steel trusses and stone-over-concrete flooring
Review component retail: £4,224

From our assistant's spelling
, we know ourselves to be on Germanic footing even though Audio Röhre turned to Audio Valve in the marque's name. The number 50 obviously refers to 8Ω power, placing it between the stablemate 30 and 100 Assistents. The Hessian designer Helmut Becker grew up around his parents' small electronics business at a time when televisions still did tubes. Post school this very naturally led to formal training as a TV technician. During his military service, this veered into radar with its magnetron, tyratron and klystron big bottles. Helmut capped off his education in telecom tech. Later he worked in the medical sector where he was awarded numerous patents for laboratory innovations in haematology coagulometers which measure blood clotting. Returning to his love of valves led to OTL amps, eventually the formation of Audio Valve in Kassel. This segues neatly back to the 5-input Assistent 50 with tape-out. Clearly it puts on quite a show, somewhere between Art Deco, opulence and Steampunk perhaps. Shazam.

Comparing these photos toggles between blue power-on mode above and red standby mode below. Copious clear acrylic lent itself to stealth lighting and being an open book on guts. For the full glory, unscrew the sun-dial lid to lay eyes on a rarely seen 9-pin* octet of QQE 03/12 double beam tetrodes good for 225MHz, with 7.5W plate dissipation and voltages from 200-300V. Configured for pure class A push/pull, these glow worms are swappable with RS1029 or CV2798. Also unique is the automated grid bias controller. During each power-up, it measures the quiescent current of every output tube, then applies corrections where needed before bypassing the muting relay. Should a tube be out of range to require replacement, the associated red LED will tell you. Easier than pie. The input/driver tubes are pairs of readily sourced double-triode ECC82 and ECC83. A full-function metal remote is included.

* The nine pins, respectively, are to the 1st control grid, cathode, 2nd control grid, 1st heater, 2nd heater, 1st anode, screen grids, 2nd anode and heater centre tap.

Input impedance is a bog-standard 47kΩ, THD below 0.3% for 20 watts. Weight is 18kg and dimensions are 42 x 15.5 x 32cm WxHxD. Now you know as much as I did when I accepted the assignment via Elite Audio UK. That's Mark Cargill's import house in Scotland. Due to proximity and a shared appreciation of certain brands, I've been granted access to their inventory for regular loaner purposes. Having never yet clapped eyes never mind ears on an Audio Valve piece which instead came recommended by Elite, it seemed good form to contact designer Helmut Becker and learn just a bit more about what makes his Assistent 50 tick. Off went an introductory email.