Analog Corner

Among the electrically connected, the phrase short circuit induces panic and horrific images of tripped breakers, blown fuses, acrid blue smoke, and melted circuit boards. Nonetheless, near short circuits are becoming popular among the analog set. Moving-coil cartridges of an inductance and impedance so low they're nearly short circuits are now more common, thanks to powerful neodymium magnets that help produce more and more electrical output from fewer and fewer turns of coil wire. Perhaps the most extreme example of this is the Haniwa HCTR01 Mk.II cartridge, which has an internal impedance of 0.4 ohm and an inductance of 0.3µH.

These new, high-efficiency circuits also permit the use of nonferrous formers that allow freedom from back-EMF, and thus wider dynamic range. Low-noise, high-gain phono preamplifiers, and those that use step-up transformers, are designed to deal with the typically low output voltages (eg, 0.2mV or 0.3mV) produced by these cartridges. While low-output MC cartridges are miserly producers of voltage, they deliver generous amounts of current. To take advantage of that, in the past few years some designers have produced phono preamps based on current amplification.

I first reviewed a current-amplification phono preamp in the July 2008 issue: the German company Aqvox's relatively inexpensive Phono 2Ci (then $1400). It was designed by Carlos Candeias, who further explored current amplification in his own B.M.C. Phono MCCI ($3890), which I reviewed in June 2013. The MCCI has since been updated; the newest version was in use this May at High End 2018, in Munich. In November 2014, on AnalogPlanet.com, I reviewed MR Labs' current-amplification–based VERA 20 MC ($4330 with its standalone power supply). Sadly, the owner of MR Labs, Maximillian Rotmann, a Swiss-born electronics engineer who lived in Florida, recently died. The company is now run by Rotmann's protégé, fellow engineer Nicholas L. Nagrodski. More recently, I bought CH Precision's P1 phono preamp with optional X1 outboard power supply ($48,000, footnote 1). The P1 has three inputs, two of them current based.

Like the cartridges of low internal impedance and inductance with which they're best partnered, current-amplification phono preamps are themselves close to being short circuits—at least, that's what the cartridge "sees." You just plug it in and play without having to worry about choosing a specific resistive loading for the cartridge. If your MC phono preamp isn't a current-amplification type, Hagerman Technology has provided a useful tutorial in how to load moving-magnet and MC cartridges, into which you can plug values to help determine the proper resistive loading (footnote 2).

Every amplification scheme, solid-state or tubed, has its pluses and minuses, but I have yet to figure out—or hear—any downside to current-amplification phono preamps. In fact, I'm a big fan of them—though I wouldn't be without the voltage-amplification Ypsilon VPS-100 and its associated outboard step-up transformers. That's another kind of magic.

van den Hul The Grail phono preamplifier
After using van den Hul's The Grail MM/MC phono preamplifier ($9350, footnote 3) for a few months, the only thing about it that didn't appeal to me was its name. I'm not into religious or mythological iconography. Otherwise, what's not to appreciate about this attractive, well-built, innovative, easy to use, sonically enticing phono preamp? Well, some think it's ugly. I disagree.

While the instruction manual doesn't specify that The Grail is a current-amplification phono preamplifier, it's described as having an "automatic adapting input stage . . . no matching resistors needed." For that reason, and owing to other of its design features, described below, I assume that it is one.

The Grail is a relatively compact, two-box design with a gracefully curved signal-processing unit housed in a thick metal case with a pebbly white finish and wooden side panels (very 1970s), and a somewhat less attractive black box of a power supply with a brushed-aluminum faceplate. They're connected by a generously long umbilical cord.

Both boxes are unusually heavy for their size, particularly the preamp itself. Perhaps that's because the RIAA deemphasis circuit uses an LCR network that includes inductors in series with the signal (and no resistors), plus capacitors and resistors in parallel—just as does my Ypsilon VPS-100 phono preamp. Inductors can be heavy, though the mass could be just the chassis and case. Other design features include: gold conducting paths on "special printed circuit board material," the specialness of which is not specified; feet of "selected wood" designed to dissipate energy; and an internal array of DIP switches for adjusting the level. If you need an MC gain different from The Grail's default setting of 56dB, remove the top panel, and set the appropriate combination of DIPs to achieve 64 or 73dB—enough gain for even the lowest-output MC.

On the rear panel are eight single-ended RCA jacks, one pair each for: MM input, MC input, output, and resistive or capacitive MM loading. The defaults for MM loading are 47k ohms resistive, 50pF capacitive; to change either, vdH advises soldering the desired resistors or capacitors into RCA plugs and plug these into the loading jacks—but, again, this would be for the MM input only.

van den Hul Colibri XGW Stradivarius Signature MC cartridge
Decades ago, Dutch physics professor A.J. van den Hul (footnote 4) used computer analysis to invent a new stylus profile, suggested as being uniquely good at digging details out of LP grooves. He's since sold more than a million of these van den Hul styli—installed in his own cartridges, through his retipping business, and in cartridges made by other companies.

Van den Hul's latest cartridge is a further refinement of his original Grasshopper, which was very popular in the 1990s. Like the Grasshopper, the Colibri, named for the tropical hummingbird, is a "nude" design: its cantilever is exposed, and there is no stylus guard, which make it somewhat impractical for anyone with cats, young children, and/or house cleaners—unless the turntable has a dustcover.

This latest Colibri is the XGW Stradivarius Signature ($11,995): The X indicates crosscoil, the G stands for the gold of its coil wires, and the W for wood (the cartridge's body is made of Koa wood). It features a new, more efficient magnet assembly that increases the previous Colibri's output of 0.38mV to a generous 0.7mV, though that specification doesn't yet appear on the cartridge's webpage. If vdH's The Grail is indeed a current amplifier, you really don't need such a high voltage output.

Van den Hul offers the Colibri in various iterations, including: coils wound with copper wire; high (0.38mV), medium (0.3mV), or low (0.22mV) output; and a body—more a support structure—of plastic or wood. Other specs include a recommended vertical tracking force (VTF) of 1.35–1.50gm, a load impedance of 50 ohms to 47k ohms (the latter absolutely not recommended by me), and loading of from 50 to 600 ohms (when loading is necessary). Van den Hul recommends using a tonearm with an effective mass of 10–16gm. The stylus is van den Hul's 1S (2µm × 85µm) mounted on a boron cantilever.

Van den Hul's website lists specs for the lower-output cartridges only, and I hesitate to repeat them here; the XGW Stradivarius Signature's output is nearly twice that of those cartridges, and must, at the very least, result in a different internal impedance—which, for some reason, was not specified on the review sample's box.

In any case, as long as it's relatively low, the cartridge's internal impedance won't matter. Nor will its loading—when plugged into The Grail or any current-based phono preamplifier.

Colibri: Setup and Sound
The Colibri XGW Stradivarius Signature's fully exposed motor made setup easy—I could see everything, and there were no surprises. I set a stylus rake angle (SRA) of 92°+ with the tonearm slightly above parallel to the record surface. I achieved maximum channel separation and minimum crosstalk in both directions when the cantilever, seen from the front, was almost perpendicular to the record surface. Measured with a digital oscilloscope, the separation was 30dB in one direction and 29dB in the other. No doubt, had I used the voltmeter-and-frequency-sweep method suggested by Soundsmith's Peter Ledermann, it would have been higher, but clearly, A.J. van den Hul, now nearly 80, can still build skillfully! At that age we should all have his energy and hand-eye coordination!

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Footnote 1: I reviewed the CH Precision P1 and X1 in my April 2017 column.

Footnote 2: See www.hagtech.com/loading.html.

Footnote 3: van den Hul, Oude Apeldoornseweg 69. 8171 LV Vaassen, The Netherlands. Tel: (31) (0)578-569-950. Web: www.vandenhul.com. US distributor: Finest Fidelity, 3 Sagebrook Drive, Bluffton, SC 29910. Tel: (386) 341-9103. Web: www.finestfidelity.net.

Footnote 4: John Atkinson interviewed A.J. van den Hul for Stereophile in December 1986, with a further interview by Thomas J. Norton in November 1994. Van den Hul's take on the Compact Disc was informed and prescient, and his discussion with JA about cartridges is illuminating. Both interviews can be found here.