Among the electrically related, the phrase brief circuit induces panic and horrific photos of tripped breakers, blown fuses, acrid blue smoke, and melted circuit boards. Nonetheless, close to brief circuits have gotten widespread among the many analog set. Moving-coil cartridges of an inductance and impedance so low they’re practically brief circuits are actually extra frequent, due to highly effective neodymium magnets that assist produce increasingly electrical output from fewer and fewer turns of coil wire. Perhaps essentially the most excessive instance of that is the Haniwa HCTR01 Mk.II cartridge, which has an inner impedance of 0.4 ohm and an inductance of 0.3µH.
These new, high-efficiency circuits additionally allow using nonferrous formers that permit freedom from back-EMF, and thus wider dynamic vary. Low-noise, high-gain phono preamplifiers, and people who use step-up transformers, are designed to take care of the usually low output voltages (eg, 0.2mV or 0.3mV) produced by these cartridges. While low-output MC cartridges are miserly producers of voltage, they ship beneficiant quantities of present. To benefit from that, previously few years some designers have produced phono preamps primarily based on present amplification.
I first reviewed a current-amplification phono preamp within the July 2008 subject: the German firm Aqvox’s comparatively cheap Phono 2Ci (then $1400). It was designed by Carlos Candeias, who additional explored present amplification in his personal B.M.C. Phono MCCI ($3890), which I reviewed in June 2013. The MCCI has since been up to date; the most recent model was in use this May at High End 2018, in Munich. In November 2014, on AnalogPlanet.com, I reviewed MR Labs’ current-amplificationprimarily based VERA 20 MC ($4330 with its standalone energy provide). Sadly, the proprietor of MR Labs, Maximillian Rotmann, a Swiss-born electronics engineer who lived in Florida, just lately died. The firm is now run by Rotmann’s protégé, fellow engineer Nicholas L. Nagrodski. More just lately, I purchased CH Precision’s P1 phono preamp with non-compulsory X1 outboard energy provide ($48,000, footnote 1). The P1 has three inputs, two of them present primarily based.
Like the cartridges of low inner impedance and inductance with which they’re finest partnered, current-amplification phono preamps are themselves near being brief circuitsno less than, that is what the cartridge “sees.” You simply plug it in and play with out having to fret about selecting a particular resistive loading for the cartridge. If your MC phono preamp is not a current-amplification sort, Hagerman Technology has offered a helpful tutorial in methods to load moving-magnet and MC cartridges, into which you’ll be able to plug values to assist decide the right resistive loading (footnote 2).
Every amplification scheme, solid-state or tubed, has its pluses and minuses, however I’ve but to determineor hearany draw back to current-amplification phono preamps. In truth, I’m a giant fan of themalthough I would not be with out the voltage-amplification Ypsilon VPS-100 and its related outboard step-up transformers. That’s one other sort of magic.
van den Hul The Grail phono preamplifier
After utilizing van den Hul’s The Grail MM/MC phono preamplifier ($9350, footnote 3) for just a few months, the one factor about it that did not attraction to me was its title. I’m not into non secular or mythological iconography. Otherwise, what’s to not recognize about this engaging, well-built, revolutionary, straightforward to make use of, sonically attractive phono preamp? Well, some suppose it is ugly. I disagree.
While the instruction handbook would not specify that The Grail is a current-amplification phono preamplifier, it is described as having an “computerized adapting enter stage . . . no matching resistors wanted.” For that cause, and owing to different of its design options, described under, I assume that it’s one.
The Grail is a comparatively compact, two-box design with a gracefully curved signal-processing unit housed in a thick metallic case with a pebbly white end and picket aspect panels (very Nineteen Seventies), and a considerably much less engaging black field of an influence provide with a brushed-aluminum faceplate. They’re related by a generously lengthy umbilical wire.
Both bins are unusually heavy for his or her dimension, notably the preamp itself. Perhaps that is as a result of the RIAA deemphasis circuit makes use of an LCR community that features inductors in sequence with the sign (and no resistors), plus capacitors and resistors in parallelsimply as does my Ypsilon VPS-100 phono preamp. Inductors will be heavy, although the mass could possibly be simply the chassis and case. Other design options embody: gold conducting paths on “particular printed circuit board materials,” the specialness of which isn’t specified; toes of “chosen wooden” designed to dissipate power; and an inner array of DIP switches for adjusting the extent. If you want an MC achieve totally different from The Grail’s default setting of 56dB, take away the highest panel, and set the suitable mixture of DIPs to attain 64 or 73dBsufficient achieve for even the lowest-output MC.
On the rear panel are eight single-ended RCA jacks, one pair every for: MM enter, MC enter, output, and resistive or capacitive MM loading. The defaults for MM loading are 47k ohms resistive, 50pF capacitive; to alter both, vdH advises soldering the specified resistors or capacitors into RCA plugs and plug these into the loading jackshowever, once more, this could be for the MM enter solely.
van den Hul Colibri XGW Stradivarius Signature MC cartridge
Decades in the past, Dutch physics professor A.J. van den Hul (footnote 4) used pc evaluation to invent a brand new stylus profile, prompt as being uniquely good at digging particulars out of LP grooves. He’s since offered greater than 1,000,000 of those van den Hul styliput in in his personal cartridges, by way of his retipping enterprise, and in cartridges made by different firms.
Van den Hul’s newest cartridge is an additional refinement of his unique Grasshopper, which was very fashionable within the Nineties. Like the Grasshopper, the Colibri, named for the tropical hummingbird, is a “nude” design: its cantilever is uncovered, and there’s no stylus guard, which make it considerably impractical for anybody with cats, younger kids, and/or home cleanersexcept the turntable has a dustcover.
This newest Colibri is the XGW Stradivarius Signature ($11,995): The X signifies crosscoil, the G stands for the gold of its coil wires, and the W for wooden (the cartridge’s physique is made from Koa wooden). It incorporates a new, extra environment friendly magnet meeting that will increase the earlier Colibri’s output of 0.38mV to a beneficiant 0.7mV, although that specification would not but seem on the cartridge’s webpage. If vdH’s The Grail is certainly a present amplifier, you actually do not want such a excessive voltage output.
Van den Hul gives the Colibri in varied iterations, together with: coils wound with copper wire; excessive (0.38mV), medium (0.3mV), or low (0.22mV) output; and a physiqueextra a assist constructionof plastic or wooden. Other specs embody a beneficial vertical monitoring drive (VTF) of 1.351.50gm, a load impedance of fifty ohms to 47k ohms (the latter completely not beneficial by me), and loading of from 50 to 600 ohms (when loading is important). Van den Hul recommends utilizing a tonearm with an efficient mass of 1016gm. The stylus is van den Hul’s 1S (2µm × 85µm) mounted on a boron cantilever.
Van den Hul’s web site lists specs for the lower-output cartridges solely, and I hesitate to repeat them right here; the XGW Stradivarius Signature’s output is almost twice that of these cartridges, and should, on the very least, end in a unique inner impedancewhich, for some cause, was not specified on the evaluation pattern’s field.
In any case, so long as it is comparatively low, the cartridge’s inner impedance will not matter. Nor will its loadingwhen plugged into The Grail or any current-based phono preamplifier.
Colibri: Setup and Sound
The Colibri XGW Stradivarius Signature’s totally uncovered motor made setup straightforwardI may see every part, and there have been no surprises. I set a stylus rake angle (SRA) of 92°+ with the tonearm barely above parallel to the report floor. I achieved most channel separation and minimal crosstalk in each instructions when the cantilever, seen from the entrance, was virtually perpendicular to the report floor. Measured with a digital oscilloscope, the separation was 30dB in a single path and 29dB within the different. No doubt, had I used the voltmeter-and-frequency-sweep methodology prompt by Soundsmith’s Peter Ledermann, it might have been larger, however clearly, A.J. van den Hul, now practically 80, can nonetheless construct skillfully! At that age we must always all have his power and hand-eye coordination!
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 an additional interview by Thomas J. Norton in November 1994. Van den Hul’s tackle the Compact Disc was knowledgeable and prescient, and his dialogue with JA about cartridges is illuminating. Both interviews will be discovered here.