Fosgate Signature Phono Stage
by Ken Choi | July 10, 2010
Like peanut butter and jelly, vinyl and tubes just seem to complement each other, especially for listening to acoustic music. The way the musics flow and textural richness are captured is what makes the collective sound of tubes and vinyl so appealing, and the simplest and most effective path to this sonic bliss is to utilize tube gain at the point closest to the source -- in the phono stage.
I must not be alone in my fondness of these archaic technologies, as there has been huge regrowth in the analog sector of the audiophile market. Certainly there are many more turntables and phono stages to choose from now as compared to 40 years ago, when I started my record collection and when vinyl was really the only meaningful music-storage medium. Back then (and perhaps now as well) the name Fosgate was most associated with car audio, but much of Jim Fosgates career has been devoted to multichannel audio circuitry, as evidenced by his development of Dolby Pro Logic II. Fosgate also shares a strong personal affinity for vinyl and tubes. Fortunately for us anachrophiles, in his downtime Fosgate applies his considerable noodle to conceiving circuitry and building prototypes. The Fosgate Signature phono stage represents several decades of his thinking and experimenting.
The Signature utilizes three tube-based gain stages. Each uses triode pairs (6922s, 12AX7s and 12AT7s) operating in a shunt-regulated, push-pull fashion. Here the triode pairs work one on top of the other, with the bottom tube taking the input signal and driving the top tube, which provides the output. Each of the gain stages is powered by separate oversized storage capacitors essentially acting as batteries, and the power supply is subject to tube rectification via a single 6X4. There are no solid-state devices in the signal path and no step-up transformers to potentially degrade the signal.
The Signature offers either 42dB or 60.5dB of gain selectable by toggle switches at the top of the unit. Cartridge loading from 100 ohms to 100k ohms -- with stops at 300, 500, 1k and 47k ohms in between -- is selected with a knob at the rear. The only other switch is the one to power the whole thing up. About 20 seconds after toggling this, a subtle blue light illuminates the front fascia, and the front three tube sockets become bathed in a blue-lit glow, indicating that the unit is good to go.
I do not use an outboard phono stage at present. I listen through the built-in phono stages of Nagra PL-P and Audion Quattro Premier preamps. Like the Fosgate, the Audion phono stage relies completely on tubes for gain, while the Nagra adds in-house-designed step-up transformers to the tubes. The Fosgate Signature compares very favorably to both of my existing phono stages, but I may not have concluded this had I only used the cartridges I own -- ZYX Universe S and Denon DL-103R, which both have 0.3mV output. The line stages of my two preamps are not typical, in that they offer the Fosgate very little help in the way of gain -- virtually none for the Audion and a paltry 6dB for the Nagra. The Audion preamp is essentially a high-gain phono stage that has three line-level inputs, these being cathode followers with no gain.
I normally use the Denon cartridge in a system with Sonus Faber speakers and Nagra electronics. The Fosgate phono stage gave a very nice accounting of itself when it was part of this system. While the Denon and ZYX cartridges sound wonderful through the Audion preamp in my main system, which includes an Audio Research 100.2 amp and Tidal Piano Diacera speakers, running them through the Fosgate Signature first resulted in a somewhat uninteresting, flat, two-dimensional sound -- hallmarks of insufficient gain. Interestingly, the Denon-Fosgate-Nagra combination also fared sub-optimally in this system, leading me to conclude that the overall gain (which includes the contribution of the Audio Research amplifier and the sensitivity of the Tidal speakers) was borderline.
Sensing this issue, Garth Leerer of Musical Surroundings, manufacturer and worldwide distributor of the Fosgate Signature, suggested I also audition a Clearaudio daVinci cartridge, which has 0.8mV output, with the Signature. Indeed, it was this combo into the Nagra preamp that put the Signature in the best light, and it was used for much of the listening.
These experiences illustrate once again the close tolerances that need to be considered when introducing a phono stage and cartridge into an audio system. My cartridges did not fare particularly well through the Fosgate Signature, especially when it was used with the Audion preamp. Depending on the rest of the system, its performance may be tenuous with cartridges that output less than 0.6 mV @5cm/second. However, with a different line stage that provides considerably more gain, like one from VTL or Convergent Audio Technology, this issue would be a nonissue. Higher-gain amplifiers and more sensitive speakers would also help the cause.
In sonic terms, the Fosgate Signature was right at home in either of my systems, sounding tonally much more like the Nagra and Audion phono stages than not. They all share traits produced by good tube phono stages, including an expansive soundstage and deeply saturated tonal colors accompanied by a certain degree of bloom -- the ability of the music to swell throughout the soundstage. The Fosgate falls between the Nagra (most) and Audion (least) in terms of bloom. The relative differences were minor, however, and the bloom itself was subtle, not of the old-fashioned variety that can give way to bloat, smearing or oversized sonic images. Rather, all three phono stages produced well-balanced sound, adding body to the presentation while lacking varying degrees of the agility and quickness of the best solid-state units.
There was very little that was old-fashioned about the Fosgate Signature's sound. It conveyed transient speed and dynamics particularly well, and clearly bettered the other two units here, at least when the systems were fronted by the Clearaudio daVinci cartridge. Through the Signature, the piercing and projectile quality of Earl Hines keyboard work on "Old Fashioned Love" from Fatha [M&K RealTime RT105] provided compelling evidence that the piano is indeed a percussion instrument. Each note positively launched from the speakers, as it should with this purist recording. The Signature was also particularly extended at the frequency extremes -- again, significantly more so than the other two units. Bass was deep, articulate and untube-like in its tightness. Considerable high-frequency energy was produced, which partly explained the previously unheard details that were revealed time and again. The other part of the explanation may relate to the amazing resolution of my Tidal speakers, yet substitution of my other phono stages confirmed the Fosgates proficiency and superiority at retrieving low-level detail.
A listen to an old audiophile chestnut, Malcolm Arnolds English, Scottish and Cornish Dances [Lyrita SRCS 109], through the Signature enabled me to finally understand why there is such a fuss about this album. Thundering tympani, crashing cymbals, and the lilting rhythms of the "Eight English Dances" were presented in a very energetic and engaging manner. Previously unappreciated orchestral and ambient details abounded, the soundstage appearing orchestrally big in all dimensions. Truth be told, I listen to this kind of music much less often than I do to smaller-scale works, such as the "Mozart Quintette" on The Heifetz-Piatigorsky Concerts [RCA Victor LSC-2738]. Here, the Fosgate Signature rendered the strings with dense tonality and appropriate bite, underscoring their inherent realism. The tension and interplay between the individual players was nicely brought out in this superb performance.
With smaller-scale music, however, I value the more obtuse qualities of liquidity and flow over dynamics and bandwidth. This is where the Audion Quattro Premier phono stage shines. Music through it sounds less exciting and perhaps a little less detailed than through the Fosgate Signature, but it's more relaxed and natural. The Audion phono stage is very noisy, however. I suspect that most listeners, especially those accustomed to the low noise of digital playback, would find this unacceptable. In contrast, the Fosgate Signature and Nagra PL-P are quiet, with only mild ear-to-speaker hiss apparent -- all the more impressive in the case of the Fosgate, because it is not transformer coupled. For me, noise isn't much of an issue, because once the music begins the background noise is obscured. Many of my favorite albums, such as the Heifetz-Piatigorsky "shaded dog," are very noisy to begin with.
I regret that I did not have a solid-state line stage to use with the Fosgate Signature, as I suspect this pairing would work particularly well, revealing the music in a straightforward, quick-paced, uncolored way. However, I suspect the Fosgate Signature would acquit itself well in any system with a cartridge of suitable output, and it would be an ideal choice for the audiophile who wishes to start with or revisit vinyl without worrying about the phono stage as a limiting factor.
The Fosgate Signature sounds much as it looks. It is thoroughly modern in its quiet, detailed and punchy character, while imbuing the music with body and texture that are the unmistakable provenance of tubes. By not hiding its valves in a box, its appearance proudly states what it is. Its fit, finish, and industrial design are clearly contemporary and even elegant. It represents a huge sonic step up for those analog lovers who are using phono stages in the crowded $1000 price range, and it will be an end-of-the-road piece for many sensible vinylphiles.
Warranty: Two years parts and labor.
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Oakland, CA 94609
Analog: Brinkmann LaGrange turntable with tube power supply, Breuer Dynamic Type 8 tonearm, ZYX Universe S cartridge, and Silver Audio Silver Breeze phono cable; Linn LP-12 Valhalla turntable, Linn Ittok LVII tonearm, and Denon DL-103R cartridge.
Digital: EMM Labs CDSD transport and DCC2 digital-to-analog converter, Audio Aero Prima CD player.
Tuner: Magnum Dynalab Etude.
Preamplifiers: Audion Premier Quattro, Nagra PL-P.
Power amplifiers: Audio Research 100.2 stereo amp, Nagra VPA monoblocks.
Speakers: Sonus Faber Guarneri Homage, Tidal Audio Piano Diacera.
Subwoofer: Rel Strata III.
Interconnects: Cardas Hexlink 5, Purist Audio Venustas.
Speaker cables: Nordost Red Dawn, Purist Audio Venustas.
Power conditioners: Shunyata Research Hydra Model-8.
Power cords: Purist Audio Venustas, Essential Sound Products The Essence, some stock power cords.
Equipment rack and platforms: Atacama Equinox equipment rack with custom walnut shelves, Atacama Equinox XL Pro equipment rack, Symposium shelves, Harmonic Resolution Systems MX3 platform.