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Reviewer: Srajan Ebaen
Source: Zanden Audio Model 2000P/5000S; Opera Audio Reference 2.2 Linear; Raysonic CD128 [on extended loan]
Preamp/Integrated: ModWright SWL 9.0SE; Music First Audio Passive Magnetic; Bel Canto Design PRe3; Wyetech Labs Jade; Supratek Cabernet Dual [on loan from owner]; Melody HiFi I2A3; Raysonic SA-30A [on review]; Eastern Electric M520; Yamamoto HA-02
EQ: Rane PEQ55 active merely below 40Hz
Amp: 2 x Audiosector Patek SE; Yamamoto A-08S; FirstWatt F3 & F1; Bel Canto e.One S300
Headphones: AKG K-1000 w. hardwired Stefan AudioArt harness; audio-technica W-1000
Speakers: Zu Cable Definition Pro in custom lacquer; Anthony Gallo Acoustics Ref 3.1; Mark & Daniel Ruby
Cables: Zanden Audio proprietary I²S cable, Zu Cable Varial, Gede, Libtech and Ibis; Stealth Audio Cable Indra, MetaCarbon & NanoFiber [on loan]; SilverFi interconnects; Crystal Cable Reference power cords; double cryo'd Acrolink with Furutech UK plug between wall and transformer
Stands: 1 x Grand Prix Audio Monaco Modular five-tier
Powerline conditioning: 2 x Walker Audio Velocitor S fed from custom AudioSector 1.5KV Plitron step-down transformer with balanced power output option
Sundry accessories: GPA Formula Carbon/Kevlar shelf for transport; GPA Apex footers underneath stand, DAC and amp; Walker Audio Extreme SST on all connections; Walker Audio Vivid CD cleaner; Walker Audio Reference HDLs; Furutech RD-2 CD demagnetizer
Room size: 16' w x 21' d x 9' h in short-wall setup, with openly adjoining 15' x 35' living room
Review Component Retail: € 6,500
The plot was thickening. It wasn't until I returned from the Audio Show Poland in Warsaw that I understood why Christian Feickert had greeted me in the RCM room. Online research on the RCM site led me to Christian's site. He's the German importer for RCM's Bonasus integrated. The very one that had played the big Duevels at the show with aplomb to merit a special one-out-of-four mention at the end of my report. Doctor Feickert is quickly emerging as a vinyl guru of repute in Germany. His table will be imported to the US by Globe Audio Marketing. Those folks also do Audio Aero and WLM speakers - another favorite room in Poland. And the Bonasus. In 2007. US pricing to be established. Vinyl and Bonasus. Strike one. Globe Audio Marketing and Bonasus. Strike two.
Then I learned that Warwick Freemantle from Down Under handles the Bonasus. Warwick also imports Yamamoto and Zu and Eastern Electric and Red Wine Audio and Melody. We've exchanged e-mails and Warwick gifted me with some hand-made Teflon inserts for the Yammy's binding posts. You can see where this is headed. It can't be helped. Any experienced audiophile with matured taste will, time and again, recognize his -- or her -- kind of sound in mere seconds. One eventually feels like a one-trick pony, spotting Alfalfa from miles away. By the same token, you sooner than later meet and identify members of your own tribe. You invariably feel drawn to the same rooms, the same equipment, the same designers. If you're consistent, disagreements will be few. Warwick and Bonasus. Strike three (and with the Continuum Labs Caliburn table, Warwick's into vinyl in a serious way as well).
Before today's review loaner from Poland even rolled into Cyprus, I felt pretty confident already. Whatever strange sympathetic recognition system clicks for us with one sound and not with another in a few short moments had once again honed in at the Polish event. Subsequent confirmation now presented itself from various directions. Tribal elders too had their eyes on the Bonasus. Or had done the deed a while back, quietly, as though testing whether I'd spot out the unit from amongst the crowds without help. And how long it'd take me, perhaps. Three strikes and you're out. Phew, I'd just made it.
The Bonasus is an all-Polish product, by an import house of 16-year tenure that presently brings Acoustic Signature, Amphion, Duevel, Feickert Analogue, Furutech, Isophon, Morch, SME and other brands into Poland. Heavily into vinyl, heavily into music, the RCM men's room at the show had also hosted a live Blues duo performance. "To remind people what the real thing sounds like." That's the spirit. As is what prompted RCM's expansion into manufacturing. Contrary to fast and furious pitches on the usual audio sales floors, the average audiophile taxes his amplifier to the tune of 1/10th to 6 watts while listening. That is RCM's observation at least. Accordingly and in their minds, the only audio device suitable for such small output voltages is thermionic. Valves. Their 44kg/97lb Bonasus became a 6-input valve amp, true dual mono right down the middle: two input transformers, two output transformers, two chokes. It was developed because as an import house, RCM couldn't find anything in this product category they were really happy with. Nose to the grind stone it was and the Bonasus launched two years ago, in one-up custom red to attract attention at trade shows.
This amp is push/pull single-ended as opposed to paralleled - ultra-linear Class A/B with just a pair of 6CA7/EL34/KT77 pentodes per side. It's zero feedback. It's tube rectified with two 5AR4s. It uses four 12BH7 drivers and phase splitters. It uses C-L-C choke filtering on the DC-coupled inputs and on the outputs. It uses AC heaters. Its input stage is direct-coupled to the phase splitter. It produces 16 watts though the circuit and tubes could readily produce 30. It pays special attention to enclosure construction, using advanced semi-elastic heat-conductive potting compounds to attenuate resonances and create an equalized thermal climate without hot-spotting in operation. No remote, yet. The superior conductive plastic Bourns part chosen for most transparent volume operation, longevity and perfect channel tracking isn't available as a motorized option. Remote will require additional work at RCM's Katowice headquarters. And it'll always be an option only. The non-remote unit under review will remain the core product.
|It's got a soft start feature to delay turning on the anode plate voltage. It's got left/right channel bias meters. Except for the input relays, it's done up point-to-point with hand-twisted low-gauge solid-core wire. Kiwame and Riken resistors, Mills, Audyn and Solen capacitors and the mentioned Bourns pot make up the parts list. The transformers are all Polish issue and custom manufactured for RCM, the chassis is partially built by military subcontractors. Transformer quality, as RCM's Roger will tell you, is paramount since he's deliberately avoided feedback as a corrective measure. (If you think about it, feedback invariably requires the generation of empty watts because it throws away gain. To generate the additional gain to be wasted with feedback in the first place often necessitates additional gain stages which complicate a circuit. And simpler circuits often sound better - if you can get them to perform in a linear fashion with real-world loads.)
|One amp builder at RCM takes about 10 days to put together a Bonasus by hand. As an EL34/6CA7 ultralinear amp, it enjoys a few rather famous precedents - Dynaco Stereo 70 and MkIV, Marantz 8B and 9, Mullard 520. That puts the Bonasus conceptually into good company without requiring any cheeky claims of reinventing the wheel. Or as Roger puts it, "proven principles executed at the highest level". That's certainly what it sounded like in Warsaw running 91dB 6-ohm Duevel Bella Luna Diamantes in a good-size room.|
|But for reviewers on the prowl of what to review next, show impressions are merely a starting point. What things sound like in the familiar home environment is where the real work begins and verifiable impressions get collected, sorted and processed.|
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