SONIC FRONTIERS Phono-1 Phono Stage (Gold)

Original MSRP: $2199.95

Asking Price: $1399.95

NOTE: Special Edition Plus Mods and NOS Tube Upgrades available - inquire for details

The Phono 1 is Sonic Frontiers' newest addition to the Sonic line replacing the now discontinued SFP-1 and SFP-1 Signature products.

The Phono 1 phono stage embodies the newest thinking of Sonic Frontiers dedicated and enthusiastic technical design staff. The unit has 54dB of gain, and, just as importantly, the new Phono 1 boasts an extremely low noise level, so in practical use, the 54dB gain is usable in systems with low overall sensitivity.

The new Phono 1 uses J-Fets as the input device, because the decrease in noise directly correlates to increased sonic performance with low output moving coil cartridges down to .2 mV. The Phono 1has no gain selection as it was felt that the sonic compromise and added circuit complexity would be unacceptable. The Phono 1 uses (2) 6922 dual triodes per channel in a non-inverting circuit configuration. In addition to high circuit performance, the Phono 1 has several unique features and innovative design details.

User selectable loading of phono cartridges (resistance and capacitance) via DIP switches on the rear of the unit, plus two user positions that allow the technically competent consumer or technician to install special resistors or capacitors, providing complete flexibility for various phono cartridges which may perform better at settings other than the default 47K ohm value.

Another feature that is new (perhaps to the industry) is the cue/mute function, adjacent to the power switch. This feature allow the user to "cue up" a track on a LP without potentially damaging the system loudspeakers. This works by reducing the gain by 9 dB when the switch is depressed. This allows records to be "cued up" or changed without muting the system. This switch can also be internally configured as a mute switch, if so desired.

In addition to these user-friendly features, the Phono 1 has some very special design details. To maximize performance, we have chosen to use a custom-made internally-shielded toroidal power transformer, specially designed for low noise and hum. This transformer is mounted, as well as the unit's raw power supply, on a separate circuit board. This assists in isolating the sensitive phono amplifier from noise and hum pick-up. To further protect the signal integrity the phono amplifier board is itself mounted on four isolated chassis mounts, as used on our top preamplifier, the Line 3. In addition, Soundcoat chassis damping material is intelligently applied to the chassis and the top cover. This damping material, as well as the isolated chassis mounts, and the 3/32" thick printed circuit boards reduce microphonics to inaudible levels.

Phono 3/4Sonically, all of these design details culminate to present the listener with a complete musical picture. Precise instrument focus, holographic soundstaging and pinpoint imaging are the hallmarks of this product. Moreover, the very low noise floor of thePhono 1 ensures that the smallest amount of musical detail and ambience are revealed with astonishing clarity.

The new Phono 1 phono stage embodies all of the Sonic Frontiers strengths - innovative, high performance circuitry, immaculate design execution, lasting value and impeccable sonic quality.

Technical Overview

The Sonic Frontiers Phono 1 is a single chassis phono stage with an equalized gain of 62dB at 1kHz. The circuit topology is non-inverting, and uses a single high quality J-Fet for the input amplifier, and a special series amplifier for the second amplifying stage. In order to provide a low output impedance, a cathode follower is used after the second stage, transforming the high output impedance from the second stage to a lower output impedance suitable for driving any preamplifier with a reasonable input impedance. The input amplifier is a common source amplifier with a high drain load. This provides a gain that is (almost) the drain load divided by the source load, in this case 100X. The second stage uses one section of a 6922 as an active load element, and this minimizes the distortion in this stage regardless of tube variations. The equalization is accomplished by the use of frequency dependent feedback . Only one compensation network is used, and this is fed from a relatively low impedance, thereby avoiding slew limiting at high frequencies, and its attendant distortions.

Despite the high technical performance achieved by this innovative approach, it was realized that noise would be the final barrier to the finished products performance. Great strides were made in reducing noise from both the circuit and the power supply. Circuit noise reduction techniques such as careful component selection and ground planes as well as advanced power supply noise reduction techniques has helped achieve excellent noise specifications, on par with many of the best solid-state units.

TECHNICAL SPECIFICATIONS

• Frequency Response: +/- .1dB, 20Hz to 20kHz, RIAA equalized.
• NOISE: 0.07uV equivalent input noise, -83 dB below a 1mV 1kHz input. IHF - A-weighted, shorted input.
• GAIN: 54dB at 1kHz (1200X) - recommended for cartridges with >1.7mV or less output. (optional versions available from the factory: 62dB, suitable for cartridges below .6mV output level, and 44dB, suitable for cartridges below 5mV output level)
• POWER REQUIREMENTS: 100V - 135VAC 50/60 Hz. (200 - 270VAC 50/60Hz), 60 VA maximum. Line fuse 0.75A SLO BLO (0.375A 240V)
• INPUT IMPEDANCE: 47K ohms / 10pf standard and 10, 100, 1K, 10K ohms resistance and 47, 47, 100, and 100pf capacitance available by user selected DIP switches on rear of unit. Two positions available per channel for user selected components via solder posts.
• Output Impedance: 175 ohms at 1kHz.
• MAXIMUM INPUT: 50mV at 1kHz and 280mV at 20kHz.
• Dimensions: 19" Wide x 14.25" Deep x 4.5" High (48cm x 36cm x 11.5cm)
• Weight: 21.5lbs. (9.75kg) - Unpacked

Special PCX-Certified Program

Owning Pre-Owned Audio Gear manufactured by Sonic Frontiers (under any of it's three "original" brand names - made between 1990 thru 2001) is a wise investment.

• all units are thoroughly cleaned and fully detailed (faceplates, displays, chassis, internal chassis compartments, etc.)
• any missing accessory items (cords, manuals, tools, remotes, etc.) are replaced, if available
• any missing or worn chassis hardware is replaced
• all electrical connections are "specially" cleaned and contact enhanced, as necessary
• the units go through a full battery of electrical tests, as comprehensive (if not more) than original production testing and problems found are fully rectified
• any internal electronic parts which have failed (including those that are too aged, worn-out or burned out) are replaced, with parts which meet or exceed, original factory specifications
• all tubes are checked, and the units are sold with a tube set which has passed all acceptable noise, gain,transconductance, and microphonics standards
• any and all calibration adjustments are made, to ensure each unit meets or exceeds, original factory standards
• finally, all units are burned in for a full 24 hours, before a final 2nd test is done...after which, they are re-packed for sale.

Finally, these PCX-Certified units are offered with a full 1 Year Parts & Labour warranty (90 days on the tubes).