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October / November 2009
Superior Audio Equipment Review

 

North American Premiere
Kuzma Stogi Reference 313 VTA Tonearm
Low arm noise-floor and dynamic VTA adjustment highlights this tonearm design.
Review By Dick Olsher

Click here to e-mail reviewer.

 

Kuzma Stogi Reference 313 VTA Tonearm Unit  For those of you who have followed my reviews closely this past decade, the fact that the Kuzma Stabi Reference turntable has been the cornerstone of my analog front end for over eight years should come as no surprise. If this sounds even remotely surprising, then as a prequel to this review, you should read my write-up of the Stabi Reference turntable (Kuzma review). For all these years, my faithful tonearm companion has been the Graham Engineering model 2.2. In early 2009 I was struck by an analog upgrade bug while having undertaken an analog vow for a full two months - totally avoiding digital sources. It occurred to me that it might be neat to finally explore an all-Kuzma table/arm combo. Both Franc Kuzma and Elite AV's Scot Markwell agreed, which set the review process in motion. This also set the stage for a serious shootout between these two arms. To be fair, it should be noted that the Graham Engineering 2.x series arms have been discontinued and I have no doubt that the Graham's latest, the Phantom II, is far superior to my 2.2. My objective here is simply to describe the chronology of events and its sonic impact on my analog system. In addition to the Stogi Reference 313 VTA arm, I also received a new power supply for the Stabi Reference which is definitely more user friendly than the older version.

All of the Kuzma arms share the same low-friction, zero-play, gimbals bearing design and cable. However, for the Stogi reference line, a conical arm tube is used and an azimuth adjustment is provided. The Ref 313 VTA is a 12-inch version of the Stogi Reference but fits a standard mounting hole for 9-inch arms. The 313 VTA's distinguishing difference is its VTA tower which enables cartridge VTA adjustments during playback. Raising or lowering of the arm pivot by a few millimeters is possible by simply rotating a dial. The dial is calibrated in steps of 0.1 mm, so that it is possible to lower or raise the arm in a repeatable and precise way. Even smaller increments can be judged visually between lines on the dial.

The conical arm tube is internally damped and subdivided into two compartments to further enhance its damping properties. Although the arm features the convenience of a detachable headshell, neither mechanical rigidity nor signal connection are compromised. That's because the wiring is continuous from the cartridge pins to the RCA output jacks and the headshell is held down snugly in the arm wand and fastened by means of a set screw. The main frame and most other parts are machined from solid aluminum stock. The bearings are housed in a heavily damped brass housing. A decoupled brass counterweight provides balance and controls vertical tracking force. Standard cable length is 1.5-meter consisting of Cardas Copper wire with Eichmann Copper Bullet plugs.

 

Technical Overview
The function of a tonearm (referred to by audio veterans as a pickup arm) was well known even half a century ago. R.E. Carlson writing in 1954 likened its function to that of a speaker cabinet. Both should be seen but not heard. Control and damping of vibrational energy is important in both cases. Naturally, first and foremost on his short list of factors impacting performance was arm resonances, both lateral and torsional. He did an exemplary job of elucidating the interplay between cartridge compliance and arm mass. He pointed out that the obvious solution of increasing arm mass in order to lower its fundamental resonant frequency is limited by a major practical consideration. As the equivalent mass at the stylus tip is increased, a proportionately greater tracking force is required to overcome groove acceleration or miss-tracking will occur. The dynamical performance of the arm/cartridge is governed by the moment of inertia of the entire moving system. It's not surprising therefore that some designers have argued for light-weight, low-inertia arm designs, although in practice things are not that simple.

Light-weight arms are more prone to vibration. And what about the mass increase due to lengthening the arm from 9 to 12 inches, as is the case with the VTA 313? The longer arm traces a more tangential path across the record thus reducing tracing distortion, and in my estimation the added mass is a small price to pay for increased harmonic purity. In addition, since most moving-coil cartridges are low compliance, they actually need some arm mass to keep the cartridge-arm resonance frequency in a safe zone. Thus, in practice a medium-weight arm is not necessarily a bad thing, and affords some significant benefits, especially if one is willing to up the ante when it comes to tracking force. The foregoing information should explain why I found it necessary with every cartridge I mounted on the VTA 313 to increase the tracking force to the upper limit recommended by the manufacturer.

Alan Woodard, then with Shure Brothers, wrote in the early 80s that in an ideal analog system the playback signal would be an exact replica of the electrical signal originally applied to the cutter head. Any deviation from this ideal represents distortion, a case in point being the vertical tracking error generated whenever the angles associated with cutting and playback do not match. Keep in mind that this is the angle between the stylus and a vertical line normal to the surface of the record. He undertook a survey to determine the range of angles found on commercial disks. Just how large a difference existed between vertical modulation angles (VMA) of cutter heads and stylus VTA? He found that cutter head VMA ranged between 15 and 23° while stylus VTA ranged from 22 to 35°. Given these results, Woodard concluded rather dramatically that a 20° mismatch between cartridge and recording is a possibility. Of course, that's a worst-case scenario. Nowadays most cartridges are designed for a VTA of 20° which could potentially result in only a small mismatch, especially for recordings cut with Neumann cutter heads whose VMAs are typically near 20°. Therefore, an adjustment range of about couple of degrees as afforded by devices such as the 313 VTA Tower are quite useful in dialing in a particular recording.

Arm setup was rather uneventful. My only quibble is quite minor and has to do with the counterweight markings. It is marked with red dots, such that the angular rotation between dots is approximately equal to 0.1 gram of tracking force. I would have preferred a numbered layout similar to a clock face, so that it would be easier to ascertain visually that the counterweight has not been bumped out of its correct setting. A paper cartridge alignment gauge is provided to facilitate adjustment of cartridge overhang and offset angle for a Baerwald geometry. I am happy to report that this gauge turned out to be quite accurate, at least as verified by the Dr. Feickert protractor.

 

Sonic Impressions
My first listen to the 313 VTA arm was with the Dynavector XV-1s moving coil cartridge, itself a superlative piece of engineering. Right out of the gate, image outlines were unbelievably solid with a robust 3-D soundstage. The Graham 2.2 arm was very good in these respects, but the Kuzma was nothing short of fantastic. The Kuzma appeared to dig deeper in the bass, and in general bass lines lines were tight and pitch perfect. Vocals soared without a hint of distortion. It also became clear about this time, that being a 12-inch arm, the Kuzma held an unfair advantage over all previous 9-inch arms I had experienced. It simply blew away those shorter arms in terms of reduced inner-groove tracing distortion. With the Kuzma there was far less difference in textural purity between the cartridge alignment's sweet spots and other positions on the record.

I found the VTA tower easy to use during play. Just remember to unlock the tower before making any adjustments. While unlocked, I didn't notice any slack in the tower and you might find it tempting therefore to simply leave it unlocked for the duration of play. However, I preferred the locked position as it produced a more cohesive sound. I think that this feature is really a big deal. A line-contact stylus' performance is particularly sensitive to VTA. I can't imagine being happy with an arm that failed to offer a dynamic VTA adjustment feature. Of course, your ear has to be in the loop during this process, that is after all the time-honored method of setting up an analog system.

It was a similar story with the Shelter Harmony MC. Performance was optimum when the tracking force was set at 2.0 gram. The Kuzma appeared to coax the Harmony's sonic potential to full bloom. This is a unique cartridge in that it doesn't emphasize any particular aspect of the music as many moving coils are prone to do. Its rich and vibrant presentation blends speed, detail, and palpable image outlines into one compelling organic whole. It's hard to argue with the Harmony's presentation, but at the same time I was convinced that the 313 VTA had a large role to play in the final outcome. Its low-noise bearings and non-resonant arm tube were in large part responsible for this cartridge's exceptional coherence and image stability.

Having partnered the Dynavector and Shelter cartridges in such an exemplary fashion, I was most curious to find out just how well the Kuzma would perform with my long-time workhorse, the Symphonic Line RG-8 Gold, a modified van den Hul Grasshopper MC. Again, tracking force had to be tweaked upward to 1.7 gram. This cartridge is hard to dial in and the VTA tower proved itself to be extremely helpful in optimizing the VTA setting. After years of being conditioned to this cartridge's sound in the context of the Graham 2.2 arm, the 313 VTA arm made for a mind blowing sonic leap. Bass reach improved and macrodynamics, the range from soft to loud, became explosive in character. This old cartridge turned out to have some new tricks in its bag! It was always a transparent and lively sounding cartridge, but its performance level just got kicked into a higher gear. Clarity, as defined by the ability to precisely follow the attack and decay of transients, was nothing short of sensational and serves as a strong indicator of the arm's low-noise floor.

 

Conclusion
The Kuzma did everything I could possibly ask of it, happily accommodating every MC cartridge in my collection. An extremely low arm noise-floor is an essential prerequisite for achieving optimal performance from any partnering cartridge. In a nutshell, control resonances, eliminate bearing chatter, facilitate dynamic VTA adjustment and you have the Kuzma 313 VTA arm. It sounds as superb as it is looks and easily earns my vote for best analog product of the year. Na zdravje, Mr. Kuzma, as I raise my glass to toast a superb analog product that decisively raises the performance bar in this arena.

 

 

Specifications
Type: Tonearm for turntable
Effective Mass: 13 gram
Effective Length: 313 mm
Pivot To Mounting Center Distance: 212 mm
Friction With Zero Play: less than 10 mg
Arm Mount: Linn compatible
Overall Mass: 1250 g
Price: $3800

 

Company Information
Kuzma Ltd.
Hotemaže 17/a 
SI-4205 Preddvor, 
Slovenija

Voice: :+386 4 253 54 50 
Fax: +386 4 253 54 54 
E-mail: kuzma@s5.net
Website: www.kuzma.si

 

United States Distributor
Elite Audio Video Distribution
P.O. Box 93896
Los Angeles, CA 90093

Voice: (323) 466-9694
E-mail: scot.markwell@eliteavdist.com
Website: www.eliteavdist.com

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

     
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