MoFi Master Phono Preamplifier | REVIEW

Peter Madnick, longtime veteran audio engineer, has designed the new MoFi Master Phono (MSRP $5,995), a piece of gear that not only has a distinctive look, but also revives and improves upon a kind of circuit not much employed in today’s full galaxy of phono preamps. I have to confess, this specific aspect of phono design was something new to me, although it is an approach already familiar to many audio cognoscenti.

Words and Photos by Garrett Hongo

Known as a transimpedance circuit, it employs current drive amplification (as opposed to the more usual voltage drive) and is a method used by only a handful of established audio companies—a very expensive model designed by CH Precision, two mid-price ones made by Channel D, and fairly inexpensive to moderately priced ones from Sutherland Engineering. I have yet to hear any of these others, but the MoFi Master Phono certainly awakened me to the merits of this circuit by including it as one of its two options for amplification (the other uses voltage method). It was thrilling to hear when matched with the appropriate Koetsu, ZYX, and Miyajima MC cartridges in my collection.

MoFi Master Phono Design and Description

MoFi had already established their turntable design and manufacturing division about nine years ago with a plan to use notable engineering talents to create products that could bring out the superior qualities of their famed recordings. They approached Allen Perkins of Spiral Groove to help with designing a new line of turntables. For their speakers, they hired Andrew Jones, formerly of TAD Laboratories and ELAC. And, for their phono electronics, they went earlier to Tim de Paravicini (now lamentably deceased) of E.A.R., and, currently, to Peter Madnick himself.

Madnick has been involved in audio design for nearly fifty years. Most recently, he was the supervising presence who coordinated the creation of a superb line of high-end electronics for Constellation Audio. He once told me, years ago that, as a kid in Framingham, Massachusetts not yet in his teens, he’d taken household items like canned goods, pots and pans, an alarm clock, and his father’s plug-in radio and strung a long kite string between them as though linking components in an imaginary electronic circuit of his own devising. By high school, he was in retail audio sales, then, in college, he joined Dennesen Electrostatics to help sell bookshelf hybrid electrostatic speakers, finding his calling in product design. One of his first was the Soundtractor phono cartridge alignment device—still a most copied product in the industry. As for phono stages, there were his Dennesen Cetus head amp and the Sirius phono/line preamp.

Most significantly, around 1980, John Curl was hired to work with him on a preamp called the JC-80 and became his mentor, teaching him many of the design skills Madnick still uses today. Over the years, nearly five hundred other products followed, some under the Audio Alchemy brand, but perhaps the most notable are several phono preamps in the Constellation Audio line that he developed in collaboration with Curl. Yet the MoFi Master Phono is currently the piece he is most proud of.

The review unit I was sent is a hairline-finished black, dual-box affair, weighing 15 pounds and measuring 17” x 3.5” x 15.75” with black oak sides (walnut is an option). The warranty is for a fairly generous five years, parts and labor. Its look has the aura of pro audio gear, with an amber-lit, cutout window on the left of its faceplate to display its two meters and, on the right, two big selector dials. One has ten settings for cartridge loading (15, 30, 50, 75, 100 500, 1k, and 47k ohm and, for loading plugs, Option settings). The other has four settings for gain (ranging among 40db, 50db, 60db, and 70db).

In between the window and the knobs are a small selector switch for input (voltage or current), two tiny push-buttons for engaging mono function and subsonic filtering, and another button to control operation of the meters. The power On/Off switch is a square, backlit button at the lower left, under a patch of white, silk-screened MoFi labeling. But the most noticeable element of its overall look is the unique dual-box construction–the power supply unit at the front in a long, rectangular box and the control componentry in a bit wider box in back of it, both joined together with three evenly spaced, short lengths of gleaming copper pipe about an inch in circumference. In back are output connections for both XLR and RCA, XLR and RCA input pairs for current and voltage drive, two ground pins, and a pair of RCA inputs for external cartridge loading. An IEC, fuse holder, and standby/power switch are stacked on the far right. It sits on four compliant feet. And it comes with a sleek, all-metal, black remote that has a hairline finish toplate andan undercarriage of a trapezoidal profile that fits neatly in the hand with a pleasing weight and substance.Its twelve function buttons are for power, mute, current or voltage selection, gain, and MC loading as well as choice of filter, a dimly or brightly lit window panel, and mono operation.

The MoFi Master Phono has tons of features packed into it, ensuring a high quality of sound and providing capabilities absent in many other phono preamps at its price level. Critically, Madnick first segregated the power supply (a notoriously noisy element) and digital control electronics from the ultra-sensitive analog circuitry but dividing the unit into two boxes connected, not with an umbilical, but with copper piping running between them on the same plane, making for an uniquely elegant look. Then, he and the MoFi engineers settled on passive RIAA equalization without feedback and a high bandwidth. And only discrete circuitry got employed—having no interconnects and the shortest distances possible in the signal path were critical topological choices. To reduce noise coming from the wall AC mains, his team used a multiple series of voltage regulators. And, in order to take advantage of the contemporary range of low source-impedance MC Phono cartridges, Madnick designed an optimized current input option—the aforementioned transimpedance circuit—in addition to the more usual voltage input.

The MoFi Master Phono has mono capability, MC loading options switchable by dial or remote, and multiple inputs (balanced and single-ended). Finally, Madnick included meters in the design, taking the example from pro audio and incorporating the additional capabilities of electronically measured channel balancing and azimuth adjustment.

Via email, I asked Madnick to explain how the transimpedance circuit works and he gave me an engineer’s explanation, which I’ll try to capture in somewhat simpler terms.

The MoFi Master Phono provides two inputs, one voltage and one current. The voltage input circuit is how most other phono preamps function, taking the tiny voltage output from an MC cartridge, passing it across a loading resistor (perhaps dampening dynamics) and amplifying it via its internal gain stages and passing this signal along to a linestage. But the current input employs a circuit topology called “transimpedance,” which means that a cartridge with a very low internal impedance (under 10 ohms–the lower the better) will see a load of essentially zero ohms—in other words, a dead short in voltage terms. Into such a load (zero ohms), this low-impedance cartridge produces a high current. Then, the following circuitry in the MoFi Master Phono converts this current into a relatively large voltage (and more robust signal) fed through the rest of its circuits, RIAA, and output stages.

Madnick believes there are two other advantages to a current input—an effective suppression of RF interference (reducing overall noise) and the inherent magnetic damping of the zero ohm load (as opposed to resistor damping) which reduces resonance and ringing. Finally, rather than employing cheaper (and easier to implement) op-amps in his current-drive, Madnick elected to use choice bi-polar, JFET, and MOSFET components, further optimizing sound quality.

Installation and Operation

The MoFi Master Phono arrived in a double box, its outer one measuring 20” x 20” x 8” and weighing 17 pounds. The unit inside was floated neatly on a pair of Levi’s-colored Styrofoam cutout risers and I lifted it out easily, noting the 12-page setup pamphlet inside, which covered the basics of installation and operation. I placed the unit in my 5-tier Box Furniture rack, on the shelf below my TW-Acustic Raven AC turntable—where I usually have my Pass Labs XP-25 phono control unit. I transferred the HRS damping plate I use on the XP-25 to the Master Phono. For some reason, there was no power cord included with my review unit, but I normally use my own Audience frontRow MP powerChord anyway.

I used Audience frontRow balanced hookups to the preamp—at first my Zanden 3100, then a three-box Pass Labs X-32 linestage in for review. I don’t have balanced phono cables, so, using
Cardas XLR-to-RCA adapters to the Master’s single-ended current inputs, I ran an Audience frontRow phono cable hooked to an Ortofon RS-309D 12” tonearm and, to another pair of
Cardas adapters to its voltage ones, I ran my TW-Acustic Raven 10.5 arm’s captured cables (RCA terminated). On the Raven arm was first mounted a Kiseki Purpleheart N.S. (.48mV, 42ohm impedance), then a Koetsu Sky Blue MC cartridge (.4mV, 5ohm impedance). On the Ortofon arm I switched between a Miyajima Zero mono MC cart (.4mV, 6ohm impedance) and a ZYX Ultimate 4D cartridge (.24mV, 4ohm impedance). As three of these carts have the low internal impedances (below 10ohms) best suited to the current drive of the MoFi Master, I ended up trying each of these hooked up to its current drive inputs, switching among them for results I found profoundly interesting. Of course, I tried them via the voltage drive inputs as well. Yet I much preferred the sound via the current inputs.

It was fun going through the Master’s basic operations, selecting what load and gain settings I preferred for its voltage inputs (30ohm loading for Koetsu Sky Blue, 100ohm for ZYX Ultimate 4D, and 500ohm for Kiseki Purpleheart N.S.–all at 70dB), clicking through all the options via remote, switching my phono cables between voltage and current inputs, trying stereo, then mono, then back to stereo again. And then playing with the same functions via buttons on the faceplate. One note: selecting the current inputs automatically shuts off cartridge loading and their red engagement lights go off too. One function could be controlled only via the faceplate—this was the button for the meters.

There was no guidance in the user’s pamphlet that came with the unit, but there is a two-page guide downloadable from the MoFi Master Phono’s webpage on the net. This gave me very detailed, step-by-step instructions for optimizing each cartridge for use with it. In conjunction with playing test tone tracks from a test record, either The Ultimate Test LP from Analogue Productions or the HI-FI News Analogue Test LP (The Producer’s Cut), the meters show output levels between the left and right channels and also provide a means to measure azimuth. Balancing outputs between left and right channels, otherwise known as calibration, was a fairly straightforward process. But measuring and adjusting azimuth can be tedious, needing numerous repetitions of a cycle of measurements, adjustments, and re-adjustments. In the end, I could get channel balances pretty close for the ZYX and Kiseki, but spot-on for the Koetsu. Azimuth adjustment was non-existent with the Ortofon arm, but it measured fairly well regardless. Adjusting the Raven headshell involved loosening a set screw on the end of its arm tube, then making smaller and smaller twisting movements, turning the headshell one direction or another and re-tightening the set screw until I could not get things any better. I had to play the test track on my Ultimate Test LP several times, making very minute, fussy adjustments, and checking the somewhat jumpy movements of the meter while trying to gauge what was an average measurement of the signal tone versus what was measurement of extraneous noise.

Listening

The MoFi Master Phono proved not to be a great match with my Zanden 3100 linestage, but the Pass Labs XP-32 linestage (in for review) sounded wondrous with it, so my listening impressions that follow came with the XP-32 in the system.

With the Kiseki Purpleheart N.S. and through its voltage inputs, loading set at 500 ohms (400 recommended), my system produced consistently agile textures with jazz and other acoustic ensembles, renderings of male and female vocals that were airy and emotionally affecting. There often was a tactile presence in jazz recordings, fine spatial presentation to orchestral pieces, and a gut-punch to the kick drum in rock ‘n’ roll tracks. I especially liked the resolution and naturalistic resonances to instruments like violin, clarinet, and drums in Igor Stravinsky’s L’Histoire du Soldat (Columbia MS 6772). The Master demonstrated a fine ability to render the tonal characters of varied instruments with lifelike effect. The delicately reverberant sounds from the inner bodies of violin, clarinet, bassoon, and drum came through. For example, as a violin was bowed, I could hear a vibrantly etched attack across its strings. I sensed the sweet hollow of a clarinet’s body and the claxon-like effect of its piping timed together with quick notes from the violin so they rose, sustained, and faded in unison. There was a delicious choral effect of clarinet and bassoon with a trombone that, for a precious instant, lingered like ground fog in my listening room.

But, via its current drive, and with low internal impedance stereo cartridges like the Koetsu Sky Blue and ZYX Ultimate 4D, the MoFi Master Phono produced an unmistakably propulsive and wondrously articulate presentation partly achieved by having a much lowered noise floor compared to the sound via its voltage inputs. I had a lot of fun exploring a great range of music with my analog system set up this way, trying recordings from folk, rock, acoustic and electronic jazz, and classical genres.

I’ve loved Chilean folk ensembles ever since I heard Quilapayun perform in a live concert in Seattle back in 1975 when I was a graduate student. They had been on an international tour when the government of Salvador Allende was toppled in 1973 and so survived the murderous purge that followed. So survived the group Inti-Illimani, who were themselves touring abroad during the 1973 coup. Their music, incorporating indigenous instruments like the quena (an end-blown flute), panpipes, and charango (a kind of mandolin made from an armadillo’s back), often takes up messages of political resistance yet invariably creates a captivating collective sound out of its firmer roots in South American folk culture. On “Carnavalito de Quebrada de Humahuaca” from Canto de Pueblos Andinos 2 (DICAP/Plano G-P-0289), there was a thick drum and propulsive panpipes, high and audibly blown full of air, contributing to the insistent dance beat. A charango got frailed, flutteringly, producing both percussive and harplike notes, and a 12-string guitar was strummed tastefully along. There was a sparkling clarity to it all, instrumental images arising, particularly the quena, and fading marvelously within the broad soundstage. I was captivated.

Also gloriously rhythmic was Return to Forever’s “Spain” from Light as a Feather (Polydor PD 5525). From its languid intro, a cop from Rodrigo’s Concierto de Aranjuez, that then switched to an up-tempo dance beat, the track deftly changes between melodic and rhythmic emphases, blending Flora Purim’s airy contralto voice with Joe Farrell’s flute, at times creating an eerie cloudlike chorus sounding like the Bachianas Brazilieras of Heitor Villa Lobos. There was frequently an exciting sonic weave of timbres—Farrell’s flute, Chick Corea’s electric piano, Stanley Clark’s bass (both acoustic and electric, the former occasionally bowed), and the clean trapwork of drummer Lenny White. I heard temple blocks in a passage or two, improvised applause during a Flamenco break, castanets, and other exotic percussion instruments. Farrell’s flute solo, with its emphatic high notes deftly overblown and a rich, piping midrange, demonstrated the Master’s ease with dynamic shadings and inner performance. And, through the speed and fluidity of Corea’s piano solo with its cascades of notes coming rapidly syncopated, the MoFi Master phono was undaunted, even while the solo was punctuated by Corea’s lush chordings and waterfall-like metallic splashes from Lenny White hitting his cymbals. I caught every brilliant flourish of sound, felt the dithering bebop line underlying each solo whether from flute, piano, or Al diMeola’s electric guitar.

As far as voices go, I couldn’t think of better challenges than jazz chanteuse Samara Joy’s or Texican cantor’s Raul Malo’s. On Erroll Garner’s jazz classic “Misty” from Linger Awhile (Verve V6-8613), Joy demonstrates tremendous control, her cooing sending shivers in the intro, her voice having a shimmering but permeable top like a foamless slick at the crest of a lolling wave, lilting exquisitely. Rich in tone, with elegant portamento, it ranged through her lower and midrange registers with silkiness and breathy flatting, her vocal graceful rising to a pianissimo topnote performed with a delicate vibrato. Malo sang like a Tex-Mex tenor virtuoso on “When the Next Teardrop Falls” from the Mavericks’ Play This (Mono Mundo Recordings MMR-005-LP). With a guitar accompaniment that sounded like a Guadalajaran harp at times, Malo’s voice was exceptionally powerful, flowing into an even higher register as he sang a verse in Spanish, an accordion taking mournful fills behind him. His tenor was penetrating yet pliant, heroic with gorgeously rendered vocal ornaments, easeful with the slow waltz rhythms of the tune, and I enjoyed being able to discern fine, emotional shifts of timbre.

I loved the wide and deep soundstage the MoFi Master Phono was able to present on Khatia Buniatishvili’s performance of Sergei Rachmaninoff’s Piano Concerto Nos. 2 & 3 with the Czech Philharmonic Orchestra conducted by Paavo Järvi (Sony MOVCL034). It stretched three feet past the outer edges of my speakers and seemed at least five feet deep for most stretches. On the Moderato-Più vivo-Allegro-Maestoso (Alla marcia)-Moderato of the First Movement of No. 2, I heard liquidinous runs from Buniatshvili’s piano, ringing bursts of high notes, and an orchestral that played with a sense of elegiac mystery. Notes from bassoons and horns were sombre, understated in their richness coming from depth in the soundstage, and there was a well-maintained balance between the orchestra and piano with no congestion or opacity in crescendos. Violins were an elegant and stately timbral contrast to the piano’s dynamic shadings that ranged from warmly luscious to brisk and startling. Spatial presentation was, dare I say, realistic within the soundstage–piano very much up front and centered, the orchestra spread out behind with woodwinds and horns from center right rear, violins center rear to left forward.

Given MoFi’s stated ambition of creating electronics that could better render the quality of its famed analog recordings, I had to try spinning some. After sampling many in my collection, I settled on Linda Ronstadt’s Heart Like a Wheel (MFSL 1-472) for my rock ‘n’ roll test track. “You’re No Good” is a number with big images, solid instrumental tones, and room-filling sound that produced a wall-to-wall soundstage as well. Ronstadt’s voice starts in her lower, breathy register–dulcet, seductive, and pulsing in the first verse–then quickly ramps to her powerful, rocker’s scream during the chorus—I’m gonna say it again! The soundstage seemed to bulge into the open space of the room with those lines, her screams and wails curling like a shredder carving into the face of a wave. But the track also exhibited layers of registers and textures, Andrew Gold’s guitars (he played three) making double-octave breaks, then a duet bridge to a thrilling slide, electric, and acoustic guitar trio. Ronstadt’s voice rode over the female backup singers, and the gut-punch of drums locked to the electric bassline with the boom-chuck of Eddie Black’s dampened rhythm guitar strumming insistently over them. There was a clattering high-hat, a chiming electric guitar at times, and an undulating rhythm figure from an electric piano underlying these, creating a complex, rock ‘n’ roll tapestry of sound. I’d say MoFi earned its analog diploma and electronics bonafides with this one.

Even Cream’s Wheels of Fire double album (ATCO SD2-700), a notoriously poor live recording, sounded great to me, rocking hard on “White Room.” Eric Clapton’s electric guitar intro was like a distorted orchestra–whammy bar chords in the right channel, bluesy whines in the left. Ginger Baker’s heavy kick, crunchy high hat and thumping toms then came on, shoving the song into its operatic vocal by bassist Jack Bruce. Whenever I feel sorry for myself, it’s a tune that can lift me out of melancholy and into a nostalgic reverie for the psychedelic rock of my youth. The MoFi Master Phono was headbanging good.

The mono function on the MoFi Master Phono was a nice plus that made an interesting difference with a number of recordings that I played using the Miyajima Zero Mono MC. Switching between stereo and mono functions revealed that the sound was more solid, weightier via the mono setting of the Master. Moreover, using the current inputs added more vivacity, impact, and propulsiveness as well.

Bill Evans at Town Hall (Verve V-8683), released in 1966, has long been one of my favorite recordings of any kind, a staple of my collection since I was in college during the 70s. I’ve played it on numerous iterations of my system from an old Zenith turntable/amplifier combo with “Circle of Sound” speakers hooked together with lampcord all the way to my current reference rig of mostly Zanden Modern line electronics with Ascendo System M speakers and mainly Audience frontRow cabling. On “Make Someone Happy,” Evans’ chordings were rich in upper harmonics that produced a kind of mellow chime in the air. There were forceful notes that broke through the soundfield, extending into my listening room, and his playing moved through lovely dynamic shifts as he worked the pedals, producing prolonged legato at times. The sound centered between my speakers in a tall oval.

Come Fly with Me (Capitol W 920) by Frank Sinatra with Billy May and His Orchestra is another longtime favorite that never sounded better than via the MoFi Master Phono and its current inputs. On the title track, Sinatra sings a strong, bravura vocal, rich in tone with fine expressiveness in his famous phrasings, but with the added virtue of more nuance in his dynamic shadings than when I’d played the record before. May’s orchestra is a bit washed out, much as it had always sounded before, with a bumptious horn chorus and cocktail splashes of brass fanfares in interludes and punctuating the lyrics.

Django Reinhardt’s lazy guitar intro “St. Louis Blues” from The Django Reinhardt Anthology (Not Now Music NOT2LP198) gave way to forte plucking and forceful, expressive strumming. The Roma musician cleverly bent notes close to the guitar’s bridge, creating a percussive, yet dampened effect, the sustains cutting out quickly, before he switched to a furious scramble of pluckings on the higher strings near the petite bouche, or sound hole. Feathered strummings followed, then the habanera bridge with bluesy notes, all emerging out of a silent background. My descriptive vocabulary gets exhausted after that, suffice to say the plethora of virtuosic stylings justifiably earns the term le hot jazz Reinhardt was famous for all over Paris of the Thirties.

MoFi Master Phono Conclusions

I thoroughly enjoyed my time with the MoFi Master Phono. I found capabilities in my MC pickups that I hadn’t realized were there, once I employed the Master’s current drive inputs. The ZYX Ultimate 4D, for instance, was a cartridge I’d previously thought of as predominantly refined and sensitive in its characteristics, well-suited to orchestral and operatic music and not especially great with rock ‘n’ roll. But it had all the slam and swagger I wanted on tracks from Cream’s live Wheels of Fire double album. Not only that, the Master Phono seemed to widen the versatility of both the ZYX and Koetsu Sky Blue cartridges, as I played all genres of music with both of them to great satisfaction and enjoyment. The breadth of their capabilities, via the Master’s transimpedance circuit, covered the full range of all the music I play from folk, traditional jazz, jazz fusion, big band and Tex-Mex vocal, classical, and rock. The meters and mono features further stretch the unit’s versatility and value. If you’re in the market for a reasonably affordable piece of analog electronics, I encourage you to start with this phono stage aptly named the Master. At its price point, I just can’t think of a better buy than the MoFi Master Phono.

Garrett Hongo

MoFi Electronics Master Phono Stage
$5,995.00
Specifications:
Inputs: Current mode and voltage mode, balanced and unbalanced
Gain: 40db, 50db, 60db, 70db (selectable)
Loading: 15 ohms, 30 ohms, 50 ohms, 75 ohms, 100 ohms, 500 ohms, 1k ohms, 10k ohms,
47k ohms, 150pF, and “Custom”
Output Impedance: 230 ohms (balanced); 115 ohms (unbalanced)
RIAA accuracy: ±0.05dB
Frequency response: 10Hz–50kHz ±0.2dB
S/N ratio 85dB, 93dB (balanced mm); 81dB, 85dB (balanced mc); 75dB, 83dB (unbalanced
mm); 69dB, 75dB (unbalanced mc)
Dimensions: 17.5″ x 3.5″ x 15.75″
Weight: 15 lbs.
mofielectronics.com
1811 Bryn Mawr Ave.
Chicago, Ill. 60660
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