Reviewer: Srajan Ebaen
Financial interests: click here
Sources: Retina 5K 27" iMac (4GHz quad-core with Turbo boost, 32GB RAM, 3TB FusionDrive, OSX Yosemite. iTunes 14.4), PureMusic 3.02, Qobuz Hifi, Tidal Hifi, Fore Audio DAISy1, COS Engineering D1, Aqua Hifi Formula, AURALiC Vega
Preamplifier: Nagra Jazz, Wyred4Sound STP-SE Stage II, Vinnie Rossi LIO (AVT module)
Power & integrated amplifiers: Pass Labs XA30.8; FirstWatt SIT1 monos, F5, F6, F7; Crayon Audio CFA-1.2; Goldmund/Job 225; Linnenberg Allegro monos; Aura Note Premier; Wyred4Sound mINT; Nord Acoustics NC500 monos; LinnenberG Audio Allegro monos
Loudspeakers: Audio Physic Codex; Albedo Audio Aptica; EnigmAcoustics Mythology 1; 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; Black Cat Cable redlevel Lupo; Ocellia OCC Silver
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: 4 x 6m with high gabled beam ceiling opening into 4 x 8m kitchen and 5 x 8m living room, hence no wall behind the listening chairs
Review component retail: €16'000

With Æquo, Antipodes and Mola Mola at HighEnd Munich 2018

March 28th, 2018. Conversing with Ivo Linnenberg whilst prepping for my review of his Liszt mono amplifiers, I learnt of his forthcoming Widor stereo amp. "Sheer output power was not my design goal. In fact, Widor will have somewhat less power than Liszt. As you know, the lateral Mosfets of my Allegro/Liszt—or Bakoon, Goldmund, Kinki Studio, Nagra—sound so incredibly fine because they're so ridiculously fast and linear. Very low and particularly linear capacitance between drain, source and gate is the main reason. With most if not all other Mosfets, this capacitance which is unavoidable in any semiconductor is extremely voltage dependent. That introduces much unwanted distortion especially at high frequencies.

"Yet there's a drawback with these lateral versus vertical Mosfets and bipolars: their impedance is higher. That makes it difficult to build a brute-force amplifier with these otherwise very fine parts. To cut a long story short, I wanted to address this with Widor so I doubled up the output devices, used fully regulated supply rails even for the output stage, incorporated a beefier driver stage, used 240'000uF of storage per channel (twice that of Liszt, quadruple that of Allegro), employed a new fully discrete input stage as part of the so-called instrumentation amplifier and increased the quiescent bias current leading to larger heat sinks."

The reason I became privy to Widor early on was my expressed interest in trading up from our original Allegro to the Liszt. Ivo wanted me to have all the options and not learn of this forthcoming stereo amp after the fact should it match my needs even better. Never mind, I acquired the loaner pair of Liszt monos which I knew, shipped back the Allegro bricks and settled the difference by bank transfer. But what if...
from HifiKnight's show report

... you preferred one not two chassis and speakers which play at 2Ω for much of the time? Being bridged, the Liszt's two halves would see such loads as 1Ω to get stressed. With twice the number of output devices, the Widor would deliver similar yet unbridged power to snack on 2Ω all day long. With a single chassis and power transformer, it also wouldn't dig as deep into the wallet as two low-Ω happy mono versions. So Widor, whaddya say? Hit a 32-foot long pipe for 16 Hertz? That would be à propos seeing that namesake organist/composer Charles-Marie Jean Albert Widor (1844-1937) became most famous for his ten organ symphonies. With a pre-production casing at the May Munich show, I'd simply have to wait for full production to commence.

At the show.

July 13th was a Friday but Ivo's email was anything but hexed. "Two months have gone by since High End Munich. The Widor prototype has undergone extensive testing and runs faultlessly to my complete satisfaction. It turned out that no electronic parts will be changed compared to the prototype displayed at the show. Now it's high time to go into production. My estimation that two to three months would be a realistic time frame for me to get you a review sample may have been a bit too optimistic. For this reason I want to let you know that in about 6–7 weeks from today, you will get your Widor for review." I was in no rush but appreciated Ivo's professionalism at managing expectations and helping me lock down my schedule. When asked about a prelim render or sneak photo, "I haven’t got a picture or CAD render because a) production parts are not available yet and b) I do not work with 3D tools for mechanical engineering. Although very neat, these modeling tools are very time consuming to work with and not worth the effort compared to other CAD tools I use for electrical engineering. So a little explanation must do instead. Basically not much alteration. The dimensions stay the same. The heat sinks will be of much better quality and black anodized. The top plate will stay matte black, now having the logo engraved and some holes for venting. Although technically unnecessary, the holes brighten up the appearance. The front plate will be different in that it is made up of 10mm clear-anodized aluminum and stretches from one side to the other to better fit to existing gear and make it easier to design a companion preamp."

... to be continued in due time...

Linnenberg Audio website