Spin Doctor #7: Korf Audio TA-SF9R tonearm, Zu Audio DL-103 Mk.II Rev B phono cartridge, Gates CB100 transcription turntable Page 2

Zu Audio DL-103 Mk.II Rev B phono cartridge
I can't think of another audio component that has been in continuous production for as long as the Denon DL-103, which was first produced in 1962 or 1964 depending on which source you believe. Sure, there have been a few revivals of vintage products over the years, and you can even buy a new pair of my beloved Quad ESL 57 loudspeakers, but the Denon has never gone away in 60 years. Originally developed for use by Japan's national broadcasting company NHK, the DL-103 found its way into US retailers around 1975 and saw its first of many appearances in these pages in September 1975, reviewed by J. Gordon Holt. Its first appearance in Audio magazine's annual directory was in 1977; it cost $135. Plug that figure into an inflation calculator, and you'll find that it's the equivalent of $715 in today's money, or more than double its $349 retail price. I guess there really is a production cost benefit when you've been making something more than a half-century, at least in this case.

Over the decades, an extensive aftermarket has grown up around the DL-103. These modifications range from a simple replacement of the lightweight plastic body to complete rebuilds with exotic new cantilevers and styli. Sometimes it can be tricky to spot original Denon parts. Some even try to hide their creation's humble origins with a new name and slick packaging that makes no mention of Denon.

Zu Audio's approach is straightforward and honest (footnote 4). They take the guts from a standard, off-the-shelf DL-103 and install it very precisely in their own hard-anodized aluminum body. Then they run an extensive series of tests to determine each cartridge's channel match accuracy and assign it one of four quality grades.

The Zu's Mk.II version made several changes over the previous generation. The body is machined from a new, tempered aluminum alloy. The housing shape was changed to address resonances. The epoxy used to bind the mechanism to the housing was changed. Zu calls the update "significant, both in performance and handling." Mk.II, though, has been out for a while. The new version is Mk.II Rev.B, and the changes here are more subtle: The generator was moved slightly further forward in the body, and a notch was added above the stylus position to make cueing easier. Zu says these latest changes don't affect the sound.

Prices start at $599 for the standard grade, which is still less than the inflation-adjusted price of the stock plastic version in 1977, making it a remarkable value. A Grade 1 Zu/DL-103 costs $791, Grade 2—the version I received for review—is $959, while the top version, Grade 2 Prime, costs $1319. All are delivered with the original Denon manual, test results, and packaging in addition to Zu's own extensive test results and detailed instructions.

In this issue's Gramophone Dreams column, Herb Reichert wrote about his experiences auditioning the DL-103 with a range of resistive loads but I had the advantage of being able to run the Zu/DL-103 through the CH Precision P1 phono stage's loading wizard, trying dozens of load values and getting a frequency-response plot for each. I learned just how insensitive to load the DL-103 really is. There is no sign of the expected steep high-frequency dropoff as the loading value approaches the cartridge's own 40 ohm internal impedance. Even at 40 ohms, the response remained pretty flat out to 18kHz, with a fairly gentle rolloff above that. (The main effect of increasing the load—of reducing the load impedance—is to reduce the output.) According to the P1, the most technically accurate response was with a 210 ohm load, but I expect IM distortion will play more of a role in the subjective performance, as Herb discusses in his column.

Another characteristic of the DL-103 seems to cause a lot of the DL-103 sound like a very low compliance cartridge, but it's not as low as it sounds. Most manufacturers specify compliance at 10Hz, not 100Hz, which leads to a dramatically different result because the stiffness of the elastomer increases linearly with frequency. A few years ago, Martin Colloms measured the DL-103 at 10Hz. He found that at that lower frequency, the compliance is closer to 13 (footnote 50). That's still low, but it's nothing like the buckboard-stiff, empty-bed-dually-pickup-truck-going-down-a-rutted-trail stiffness that 5cu would suggest. The upshot is that the Denon doesn't require the super-heavyweight iron girder arms that some suggest; it should work fine in any medium- or high-mass arm. Zu's aluminum body rebuild adds about 5.5gm over the stock plastic Denon, so most modern arms should work well—not just very high-mass arms.

I have installed dozens of Zu-modified DL-103s, so I am quite familiar with its sound. My main goal in getting one of the latest Revision B versions was to see how it matches up with the high-mass Korf tonearm. For the answer to that question, see above.

Stan Maxwell.

Stan Maxwell's Gates CB100 transcription turntable
As a fully paid-up member of audio hoarders anonymous, I confess that I have way too many turntable projects lying around. A while back, someone asked me how many turntables I own. I gave up counting at 30. Because I have such a backlog, I try to avoid adding more to the pile. But sometimes, something pops up that's too hard to resist.

A good example is a Gates CB100 transcription turntable I acquired recently from the family of its original owner. After serving with the US Navy intercepting German U-boat messages during WW2, Stan Maxwell founded a company called Academy Transcription Service, which provided wired music to businesses in Monmouth County, New Jersey. A few years later, he sold Academy to what would become the Muzak company and went to work at WJLK in Asbury Park, New Jersey, one of the nation's first FM stations. For 30 years, he was WJLK's chief cook and bottle washer—producer, engineer, and presenter—before retiring in 1981. I wish I'd had the opportunity to meet him. His daughter thinks we would have gotten along great.

The term "transcription turntable" is often misused—or maybe it would be more accurate to say that the meaning of the term has drifted. Historically, it refers to a turntable with a very large platter that's capable of playing the 16" transcription records used to distribute programming to radio stations in the 1930s and '40s. Transcription discs, which were recorded and played back at 33 1/3 as early as the 1930s, were widely used to record radio shows before and during the war. (Another difference is that transcription discs were often recorded vertically, not laterally, so they could not be played back by standard mono cartridges.) The introduction of high-quality tape recorders after the war and changing programming—specifically the trend toward human deejays playing music from short records and talking in between—slowly made transcription discs obsolete.

Michael Trei's Gates CB100 transcription turntable.

The Gates 100 was made by the Gates Radio Company of Quincy, Illinois. While it is hard to get a sense of scale from the photo, in the flesh the Gates is huge. A regular 12" LP looks lost on its 16" platter, and the main bearing shaft is about as thick as a broom handle. The synchronous motor looks like it was hijacked from a commercial washing machine; you wouldn't want to drop it on your foot. Coolest of all is the speed selector: Its ball-topped gated shifter looks like a miniature version of the gear selector in a 1962 Ferrari 250 GTO.

Stan Maxwell equipped his Gates with two tonearms that would cover just about any type of record he wanted to play. In the standard position on the right is a Gray Research "Micro-Balanced" 216 with a pivoting headshell that reminds me a bit of the crazy Transcriptors Vestigal arm from the early 1970s (another project I have on my back burner) and the more modern Dynavector DV 507. The Gray was one of the first arms designed to properly handle the new low-tracking-force, high-compliance cartridges that were becoming popular in the early 1960s. It is fully compatible with modern stereo cartridges.

Even more interesting is the second arm and cartridge setup mounted on the back, a package of components made by Western Electric called the 109A Reproducing Group. This includes the 9A moving coil reproducer (cartridge), the 5A reproducer arm, the KS-13386 equalizer, and the 171A repeating coil. I like to think of this system as being a bit like the Oppo universal disc player of its day because it can handle both laterally cut discs like standard 78s and vertical, hill-and-dale cuts like many of those big transcription records. A switch on the equalizer allows you to select between three lateral-cut and two vertical-cut settings, each with different EQ characteristics. The brochure says that the 9A pickup's "jewel stylus tip, together with the extremely light 35gm pressure of the generating element on the record assures long record life." Well okay then!

So far, I have only managed to haul the Gates into my apartment and clear out a spot where it can stay pending further attention, but the plan is to sort it out, tidy it up, and explore its capabilities in a further update. More to come.

Footnote 4: Zu Audio, 3350 S 1500 W, Ogden, Utah 84401 Tel: (801) 452-5578. Web: zuaudio.com

Footnote 5: For those new to turntable-tech nomenclature: Compliance measurements and calculations are presented in different units—10–6cm/dyne; µm/mN—which however are the same numerically. Consequently, "cu," short for "compliance unit," is often used in place of the specific units. Martin Colloms's DL-103 measurement appeared in the June 2015 Hi-Fi News & Record Review.


Arvo Palm-Leis's picture

There is an unopened, sealed copy of this album on ebay right now.