July 2006

Korato Anniversary Phono Stage

One of the things that has always intrigued me about high-end audio is how cosmopolitan it is. In my two systems, I have equipment made in seven different countries. That number might well be higher were there wider distribution of products from smaller companies around the globe. Not only is music the universal language, but it seems that the manufacture of gear to reproduce it is a pursuit that knows no national boundaries.

Some time ago I wandered into my friendly neighborhood audio shop where proprietor Jack Backerjian proudly showed me some cute little tube amps he was importing. I immediately thought that he had developed connections to the other side of the Pacific, but Jack pointed out that a Serbian company named Korato made the amps. Serbia evokes images of war and international economic sanctions over the last decade of the past century. Even now one wouldn’t think it the most stable place on the planet. As for exports, I can recall the ill-fated Yugo and a handful of NBA basketball players without having to resort to Google. Oh, and regarding audio, there is the Ei factory in the university town of Nis, from which come some very nice current-production audio tubes.

Korato was formed in Belgrade in 1987 by three mates, KOsta, RAdovan, and TOmke. Their goal was to provide the domestic market with quality audio electronics at more reasonable prices than imports. It seems they enjoyed some success, and word of their products spread beyond their borders into other parts of Europe. I can only speculate that the local events of the '90s dealt them a setback.

Despite this, Korato not only persisted, but the company marked the tenth year of its existence with production of the statement Anniversary series of electronics, which are built to higher standards and with higher-quality parts than Korato's regular line. The Anniversary series comprises a solid-state stereo amplifier, tube preamplifier, and the subject of this review, a tube phono preamplifier. This steadfast dedication to the cause of good audio would be less impressive if the outcome were so-so, but I will tell you right now that this Korato phono stage is not your mother’s Yugo.

Details

The Anniversary phono stage ($1950 USD) is a standard-sized (18 7/8"W x 2 7/8"H x 4 3/4"D) one-box unit that features brushed-metal inserts on the front face and oak side panels. It shares these cosmetics with its Anniversary-series brethren. My sample, which includes the optional moving-coil stage ($550), has two sets of RCA inputs labeled MC and MM and a pair of toggle switches for routing the signal through built-in step-up transformers. A pair of RCA outputs completes the connections. A rocker switch at the rear powers things up. The 13-pound chassis sits atop Spectra Dynamics anti-resonant feet. Feature-wise, then, this appears to be a no-frills unit that does not include less-often-used amenities such as a volume control or a mono switch.

Under the hood, true dual-mono construction is preserved from the power supplies on through. Each channel is powered through its own 50VA toroidal transformer. ECL82 and 85A2 tubes are used for voltage regulation of the power supplies. One 12AX7 and one 12AY7 (6072) per channel participate in two gain stages that use no overall feedback. RIAA equalization is done with a passive filter network that is said to be immune to the effects of tube aging. The unit is chock-full of goodies such as Solen and Hovland polypropylene caps, 1% metal-film resistors, and van den Hul premium wiring (MCS 300 and D502). Build quality appears superlative. Overall gain is 46dB, with a fixed input impedance of 47k ohms. The Anniversary can accommodate cartridges with an output of 0.6mV or greater.

The MC version includes a pair of Sowter step-up devices tucked neatly into the left-rear corner of the chassis. They are labeled as model 6469F, and the user’s manual says they provide an additional 16-20dB of gain with an input impedance of 10 to 20 ohms.

Review system

My vinyl setup has remained unchanged for quite some time. I use a Koetsu Rosewood Standard cartridge (0.6mV output, 5-ohm internal impedance) on an SME V tonearm mounted onto an Oracle Delphi Mk V turntable. Off the tonearm is an AudioQuest Amazon phono cable. Normally I run this into a vintage Audio Note Japan AN S4II step-up transformer, and from that unit's captive leads into the phono section of a Convergent Audio Technology Ultimate preamplifier. The signal subsequently passes through the CAT preamp's line stage before it is sent on to the amps. The CAT's phono section provides 47dB of gain, almost identical to that of the Korato; the preamp's line stage adds another 26dB.

I inserted the Korato Anniversary into a line-level input of the CAT with Purist Audio Designs Venustas interconnects, which is also what I used to the amplifiers. The rest of the system included Nagra VPA amplifiers, Purist Audio Venustas speaker cables, and Wilson WATT/Puppy 7 speakers. Everything was plugged into a Shunyata Research Hydra Model-8 -- the CAT preamp via an ESP The Essence power cord, the Korato via its generic stock cord.

Serbian sound

Through the Korato Anniversary’s moving-magnet inputs, noise was not appreciably above the low background level generated by my electronics alone. I obtained comfortable listening levels at 12:00 on the CAT preamp’s volume control, which is comparable to that used when I listen through the CAT phono stage without the Audio Note step-up. While the sound was more than acceptable overall, there did seem to be some thinness from the upper midrange on up. I suspect this was largely due to the Korato’s input impedance of 47k ohms, where the Koetsu cartridge is generally happiest loaded into 100 ohms or so. I should note, though, that I have had some success running moving-coil cartridges into 47k ohms and making compensatory VTA adjustments, which can result in nicely balanced sound as well as excellent dynamics. I didn’t bother with that here, because when I plugged my phono leads into the moving-coil inputs, I knew very quickly that this was how the rest of my listening would continue.

Through the transformers, the Korato Anniversary sounded absolutely captivating. It was captivating in a way that not only did I listen to some of my reference albums to try to dissect the sound, but I was also compelled to listen to a number of old favorites for the heck of it. I even managed to work through much of a small backlog of unwashed and unheard used records I’ve accumulated over the past few months.

"Captivating" is not exactly an audiophile descriptor, so what did I like so much about the Korato Anniversary? Well, this all-tube unit was dead quiet. Music arose from blacker backgrounds, and surface noise seemed to be pushed further back from consciousness. With the CAT preamp’s volume knob at 8:30, I obtained healthy sound levels. Dynamics were astounding, as exemplified by one of my recent finds, Astor Piazolla’s Tango: Zero Hour [Pangaea PAN-42138]. One might not think of Piazolla’s bandoleon as an instrument that would lend itself to wide dynamic contrasts, but together with the violin on "Tanguedia III," there was a huge "startle factor." Combine this with the underlying tango rhythm and a riveting listening experience results. At no time was there any audible distortion that might suggest overloading of the phono stage. In fact, it handled complex orchestral passages and crescendos with resolve and aplomb. The Korato Anniversary is specified to take a maximum input of 40mV, so the Koetsu’s output through the Sowter trannies (assuming a 1:10 or 1:12 step-up ratio) would surely fall well below this value.

Usually I listen to music to relax, but sometimes I listen to be stimulated and aroused. The Ray Bryant Trio’s Potpourri [Pablo 2310-860] definitely falls into the latter category. Here we have a piano-based trio playing straight-ahead jazz that is as good as it gets. Through the Anniversary, the bass lines were reproduced with thunderous solidity, and although the ride cymbal seems to be struck monotonously, this rhythm section generates a tremendous sense of pace and drive. Of course the piano work is the highlight here. Even on the only "slow" piece on this record, "My One and Only Love," the Korato Anniversary allowed me to appreciate Bryant’s complete control over his instrument. On the more up-tempo numbers, he appears to absolutely overpower the piano, a perception sometimes experienced when listening to a pianist up close and live but one rarely appreciated from a recording, and certainly not the stuff of wimpy phono stages.

The other aspect of this unit’s performance that captivated was the detail it rendered. Oscar Peterson’s mumbling as he plays, while remaining unintelligible, became more obvious. Although detail like this may or may not increase one’s appreciation of the performance, increased musical detail clearly does. Cacharpaya [Beggar’s Banquet BEGA 39] by the group Incantation is an old reference album of mine. This is Andean folk music such as the type you might hear played by street performers in a big city on a warm day. Unlike the street musicians who are likely to hail from South America, Incantation is an ensemble of accomplished musicians from Britain. Various flutes, panpipes (including some big, honking bass ones), guitars, and assorted percussion contribute to the wealth of musical information found on this album.

The Korato Anniversary reproduced individual instruments (and there are many of them) with amazing clarity and resolution as they drifted in and out of the music, their melodic and rhythmic lines easily followed throughout the songs. Leading-edge transients on the big bass pipes were crisp and full of impact, while guitar notes, for example, decayed in an extended, but not exaggerated, fashion. Soundstage depth and layering were impressive. Simply put, I could hear deeply into the music through the Anniversary phono stage.

The Korato Anniversary paints a rich, dense harmonic picture through its MC inputs. Koetsu cartridges are known for their midrange, and the Korato phono stage certainly doesn’t disappoint here. Horn solos on For Duke [M & K RealTime RT-101] were as fully fleshed out as I’ve ever heard, with wonderful depth of tone. Nicely recorded vocals, such as Maria Muldaur’s on Sweet and Slow [Stony Plain SPL 1074], were rendered with "you are there" presence that lends itself to lights-out listening. Other vocal favorites, such as Jennifer Warnes’ Shot Through the Heart [Arista AB 4217], were not given any added body or warmth, but were simply revealed for how they were produced. At times, however, the prominent midrange somewhat overshadowed the treble. I felt that there was almost a little too much energy in the mids, while some zip and sparkle seemed to be missing from the uppermost registers.

Comparisons

I briefly installed my now-discontinued Bel Canto PHONO1 from another system for comparison. At less than half the price of the Korato Anniversary, the PHONO1 ($900) is an excellent performer for the money and a former SoundStage! Reviewers' Choice. Compared to the Anniversary, however, the PHONO1 1 sounded dry and lacking some verve. The Korato phono stage simply played music more vividly and with more color.

How does the phono stage in the CAT Ultimate compare? I can’t separate out the performance of the CAT without that of the Audio Note step-up transformer, so they’ll have to be considered in toto as a much more expensive alternative. I have tweaked the CAT with selected tubes (1970s Tesla E88CCs and Telefunken 12AX7s) in both the line and phono sections to suit my tastes and system. I have an after-market power cord in use, and the preamp sits on Symposium Rollerblocks. The Korato Anniversary comes stock with Ei 12AX7s (as does the CAT) and IBM-labeled 12AY7s. I did not have the time or the inclination to tweak the Korato phono stage for this review, but I have little doubt that it would respond to judicious care and feeding.

My Audio Note step-up transformer also has multiple input- and output-impedance settings from which to choose. Rather than the actual values, the input settings are labeled with mostly obsolete cartridges. Here’s my dirty little secret: I’ve chosen the loading by ear rather than by the absolute values, which I’ve long forgotten. Setting the transformer for increased gain will have it sounding just as dynamic as the Korato Anniversary, but in my system I simply prefer the sound at the lower setting. I don’t remember which setting is optimal from an electrical standpoint, nor do I care. Lack of flexible loading is a shortfall of the Korato Anniversary, although its transformer’s input impedance of 10-20 ohms should be well suited to the internal impedance of many low-output moving-coil cartridges.

The Korato Anniversary betters the CAT/Audio Note combo in terms of retrieval of low-level detail and dynamics, and easily equals it in terms of harmonic richness. However, the CAT preamp's phono stage produces a slightly more relaxed sound that just seems more natural to me. Both the CAT/Audio Note combo and the Korato Anniversary are very energetic-sounding phono stages, but the Korato imbues the music with an additional sense of tension that might well appeal more to some listeners.

Digital to analog

Some CD players are lauded as sounding like analog. Present-day CD players that display harsh digital artifacts are now the exception rather than the rule. In contrast, I have heard more than one vinyl setup sound anemic and sterile in comparison to a modern CD player in the same system. No amount of fiddling with cartridge and tonearm geometry will correct this unless the phono stage is properly matched to the cartridge on one end and to the rest of the system on the other.

Let’s say you are getting back into vinyl after a protracted absence, or just starting out and want to test the waters with a mid-priced analog front-end. Would it make sense to spend the money to purchase the Korato Anniversary? Absolutely! The phono preamp is a critical link in the vinyl playback chain and, if skimped on, the potential of LP playback will not come close to being fully realized. A superior unit like the Korato Anniversary will also not bottleneck the inevitable upgrades that will follow.

On the other hand, let’s say you want to improve the performance of the top-shelf analog rig you already own. My impression from listening to various systems over the years suggests that the Korato Anniversary would suffer no embarrassment in the company of phono preamps costing twice as much.

Think outside your borders and give this beauty from Belgrade an audition!

...Ken Choi
kenc@soundstage.com

• The Vinyl Word Current Issue