AOM Logo November 1998

The Sonic Frontiers Phono 1 Phono Stage
All Quiet on the Analogue Front

Blair Roger

In just ten years, Sonic Frontiers Inc. has become a major player in the high-end audio industry with a steady record of improvement in product quality. Their primary design goal is to provide the specialty electronics consumer with the highest performance product combined with outstanding perceived value. They do this through a blend of conservative design: short, simple signal paths, use of the finest quality parts available and attractive, classic chassis design. They seem to have a canny understanding of who their potential customers are and what will appeal to them. For example, Sonic Frontiers is nearly synonymous with tubes and almost every one of their designs uses them. It seems that the typical SFI customer wants tubes, a big chassis, and a large, unstressed power supply. The new Phono 1 fits the template perfectly, and is an appealing adjunct to the company's lineup of remote-controlled preamplifiers.

Sonic Frontiers Phono 1 Phono Stage

Technical Description
The Phono 1 is a single-box phono stage measuring 19" x 14.25" x 4.5" (WxDxH) and weighing in at a hefty 21.5 lbs. Power is supplied via an IEC detachable power cord. The chassis is constructed from 14 awg plated steel in order to reject RFI and reduce the effects of EMI. The front panel is thick, bright metal, rather plain looking but tasteful. It is overlaid by a central trim panel featuring power and mute switches to the right, and a central green LED indicating operational status. The trim panel is discreetly silk-screened and available in brushed charcoal or gold finishes. The slightly reticent appearance is clearly compatible with the Line 1, 2, and 3 preamplifiers.

Three pre-defined gain settings, 44, 54, and 62 dB, are provided, designed to suit moving-magnet, high-output and low-output moving-coil cartridges respectively. The unit I auditioned was set for 62 dB, mating quite successfully with the 0.4 mV Lyra Lydian cartridge. The first input gain stage is non phase-inverting and uses a pair of single, close tolerance JFET devices encapsulated for thermal stability and noise reduction. Two pairs of low noise Sovtek 6922 tubes are used in a non-inverting configuration for the two following gain stages. This topology results in a low output impedance suitable for driving preamplifiers with at least 10K of input impedance. It is interesting to note that the Line 1, 2, and 3 preamplifiers all feature input impedances of 21 kOhms, which would presumably be optimum for the Phono 1. The manufacturer indicates that RIAA equalization is accomplished through frequency dependent feedback and, as the compensation network is fed from a relatively low impedance, slew limiting and associated distortion at high frequencies is said to be avoided.

Typical of Sonic Frontiers' best efforts, the Phono 1 uses MultiCap and Solen capacitors, Roderstein, Vishay and Mills resistors and Kimber silver and solid-core wire at the inputs and outputs. Circuit boards are mil-spec: 3/32" thick to resist cracking, and plated with 3.5 ounce copper traces, equivalent to 18 awg wire. The main printed circuit board is decoupled through the use of elastomer mount suspension points, similar to those used in the top-o'-the-heap Line 3 preamplifier, thereby reducing tube microphonics to vanishingly low levels. The fitting of EAR sorbothane isolation feet reduces external vibrations transmitted to the underside of the chassis.

The Phono 1 makes use of a potted and encapsulated custom toroidal power transformer, magnetically shielded in silicone steel and specially designed for low noise and hum. Additionally, this transformer is mounted, along with the raw power supply, on a separate circuit board to further isolate the sensitive phono amplifier from noise and hum pick-up. The designer of this unit, Mike Kerster, informed me that he could not have achieved better noise isolation, even if he had resorted to an outboard power supply. He is particularly proud of the signal to noise figures for the Phono 1 (typically -83 dB below a 1.0mV 1kHz input signal at 62 dB gain). My test unit, selected from stock at random, 'scoped out on Mr. Kerster's test bench at slightly better than specified.

The most interesting feature of the Phono 1 is the provision for user-selectable cartridge loading from two banks of ten DIP switches on the unit's back panel. The standard load is 47 kOhms/10 pF but this can be altered easily to suit personal taste or the requirements of a particular phono cartridge. Loads of 10, 100, 1K and 10K Ohms resistance and capacitance values of 47 and 100 pFare available at the flick of a DIP switch. Two solder posts are provided inside the unit, allowing one to mount other values or exotic brands of resistors. There was a time when vinyl hounds had to purchase a phono stage from the likes of Levinson, Rowland or FM Acoustics to be provided with this level of flexibility. Such flexibility sets the Phono 1 apart from much of the competition at or near its price point.

The fit and finish of the Phono 1 is superb, contributing greatly to its perceived value. Packing and instructions are among the best I have encountered - nothing has been overlooked. This includes the high quality Philips-head screwdriver provided to open the case during tube installation, and the cotton gloves for handling the tubes without depositing oily fingerprints.

The Sound
It should be evident from the preceding commentary that the Phono 1 has the technical wherewithal to qualify for a position at the forefront of analog reproduction. After several months of auditioning, I can say that this is, for the most part, true. In a few words, the Phono 1 sounds neutral and transparent, possessing a refined and detailed treble, articulate and satisfying midrange, and firm, solid deep bass. It embodies, as one would expect from a hybrid unit, the better qualities of both solid state and tubes, and, thankfully, avoids the negatives of either.

The salient characteristic of the Phono 1 is indeed neutrality. The tonal balance is uncoloured by tube-related aberrations. Anyone hoping that the 6922/6DJ8 tube lineup will bring extra warmth or a darker tonality to their audio system will be disappointed. Experimenting with vintage (1960) Tesla 6922s only proved that they had little effect on the character of the Phono 1. The Phono 1's overall tonality is rather like that of a solid-state device, and I mean that in the best sense of the term: the unit possesses a clarity that penetrates the most obscure recordings with a pure, white light, free of glare, harshness or artificial warmth. I might be tempted to speculate, until I hear something better, that the combination of JFET and tubes provides an ideal balance between the two schools of audio design: the ruthlessly revealing and soft romanticism.

Allied with an overall neutrality is the extremely low noise of this design, which allows subtle details and instrumental effects to be revealed. In fact, it is just this low noise that first struck me about the Phono 1, and remains my abiding impression of it. Not only is this ghostly silence evident in gross terms, such as a lack of hiss even with the volume control open fully, but also in the more subtle way that the midrange and treble exude a liquidity and grainless texture. These appealing characteristics are a natural outcome of the way in which electronic noise has been drained from the unit, resulting in exceedingly low distortion and sound of the highest purity. One is allowed to hear what is really in the vinyl grooves and to appreciate the differences in recorded acoustic and microphones employed from one record to another.

The latter is aptly exemplified by two versions of the Dvorák Symphony No. 9, From the New World, one by Giulini and the Philharmonia [EMI SXLP 30163], the other by von Karajan and the Berlin Philharmonic [EMI Columbia SAX 2275]. The Phono 1 allows one to hear immediately the difference in the recordings' perspective. The Giulini is upfront and rather shallow, with the musicians tightly focused across the soundstage. Switching to the von Karajan recording, the soundstage is cavernous, deep, and wide so that one has the feeling of sitting in the highest reaches of the balcony. And when the woodwinds take their solos in the opening movement, one can hear the column of air that expands and contracts around each, as the keys open and close.

The Phono 1 exposed Rhapsodies [LSC-2471, 6s/8s pressing] by Stokowski and the RCA Victor Symphony to be the odd recording it is. Yes, this is schlock, but played by a crack pick-up band it's enjoyable nevertheless. Stokowski had a reputation as an incorrigible knob-twiddler, and it seems they couldn't keep the maestro out of the control room this time either. The upper midrange, just where the strings and brass bite, possesses an undeniable edge. The soundstage is wide with a touch of artificial reverb adding to the spaciousness and depth. Soloists are clearly defined and pop up all over the place - woodwinds high in the centre back to celli low and to the right - the effect is entertaining and that's the point, isn't it? Listening to the Enéscu Roumainian Rhapsody No. 1, I was swept away by the dazzling counterpoint of the faintly Asian melodies.

The Phono 1 is not only neutral and revealing, but transparent and dynamic too. The Analogue Productions pressing of Ben Webster At The Renaissance [APJ 011] is a moment frozen in time in the club-date life of jazz musicians. The vinyl is dead quiet and the ambiance of The Renaissance club has been captured vividly. Dropping the stylus into the groove causes an acoustic bubble to suddenly appear in the listening room. The drum kit is spread absurdly wide across from right to left, the piano, deep to the right is out of tune, and Ben Webster wanders around while improvising. The shock of rim shots echo across the soundstage and, during bass solos, one can hear someone humming at the back of the stage. The opening of the second side is particularly vivid as Ben sets the tempo with finger snaps and banter. The astounding thing about this record is the way the dimensions of the acoustic space have been defined even with such an unsophisticated mike setup. This is typical of the fascinating detail that the Phono 1 can reveal, one record after another.

Regarding the variable loading feature: I listened to the Lyra Lydian for about two weeks loaded at 100 Ohms instead of the standard 47K recommended by the importer. The sound was dramatically different. Instrumental focus was tighter, but dynamics were less freewheeling and frequency response at both ends of the spectrum was reigned-in. Some moving-coil cartridges with high-frequency resonance peaks might benefit from a 100 Ohm loading, but the Lydian, to my ears, has no such problems and was not improved by using such a resistive value. Although the Lydian exhibited maximum dynamics, air and frequency response when used in conjunction with the 47K setting, other cartridges may benefit from the Phono 1's flexible loading scheme.

Another well-known hybrid preamplifier comes to mind at once, and that is the Audio Research SP9 Mk. II. The Phono 1 is altogether harmonically richer and more spacious than the ARC's phono stage, and completely outdoes it in the areas of transparency and depth-of-field. Keep in mind, however, that the SP9 Mk. II, a truly superb preamplifier in all of its incarnations, sold for less than the price of the Phono 1, and included a line stage and all the switching capabilities of a full-function preamplifier.

Having just come off of my recent review of the US$895.00, all-tube EAR 834P phono stage, a comparison with the Phono 1 was unavoidable. Considering the differences in both price and apparent sophistication of the two products, the 834P stood up well on all counts. After listening to the EAR phono stage, with its warmer and slightly darker presentation, one might come to the conclusion that the Phono 1 was a bit lean through the treble. The differing presentations of these units makes it rather apparent that both were designed by different people with different conceptions of musicality, and hence different sonic priorities flowing from that as a logical consequence. Given the excellent low-level resolution of the Phono 1, I was rather surprised to find that the EAR 834P revealed a greater degree of the room ambiance captured on Ben Webster At The Renaissance. Perhaps this was only an illusion caused by valve microphonics in the all-tube EAR phono stage, but it was engaging nonetheless.

I'm very much in favour of putting together a minimalist system using only the components that are relevant to maximizing the extraction of musical signal. In my own case, I've been listening to the Phono 1 connected directly to the passive volume control of the Jadis Orchestra integrated amplifier. One would be hard pressed to construct an analogue signal path that was much shorter or simpler. Nonetheless, I have experienced no dynamic or volume limitations with the Orchestra driving the Quad ESL-63 Monitors, and although I am curious about what sort of improvement an active line stage would bring to the setup, I'm quite sure that the extra componentry in the signal path would likely outweigh any advantage. I can assure you that the Phono 1, with 62 dB of gain, generates plenty of signal with no audible noise, and is fully capable of generating realistic playback levels without the need for an active line stage.

In summary, Sonic Frontiers has produced a superbly finished, reliable and refined unit in the Phono 1. If neutrality, dynamics, and liquid retrieval of detail appeal to you in vinyl playback, then the Sonic Frontiers Phono 1 phono stage must come with a high recommendation.

Phono 1 Phono Stage
Manufactured by Sonic Frontiers International
2790 Brighton Road, Oakville, Ontario, Canada, L6H 5T4
phone: (905) 829-3838, fax: (905) 829-3033
web:, e-mail:
Price: US$1995
Source of review sample: Manufacturer Loan
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