Pro-Ject - Phono Box S2 Ultra Silver

The S2 with a discrete output stage and a steeper subsonic filter — and a published distortion figure of 0.00052%, which is twenty times lower than the standard S2 and lower than several Pro-Ject stages that cost considerably more.

The Phono Box S2 Ultra takes the S2’s adjustment set and rebuilds the output stage. The gain ladder is unchanged at 40, 43, 60 and 63dB, and the impedance options are unchanged at 10Ω, 100Ω, 1kΩ and 47kΩ. What changes is the measured performance: signal-to-noise goes from 85dB to 89dB, and total harmonic distortion drops to a published 0.00052%.

That distortion figure deserves a sentence of context because it is unusual. It is roughly twenty times lower than the standard S2’s 0.01%, and lower than the figure Pro-Ject publishes for boxes a full tier above it. Pro-Ject gives the same number on both their web page and their PDF datasheet, so it is at least a consistent manufacturer claim rather than a transcription error. We are reporting it as published.

The subsonic filter is also improved, going from 12dB per octave on the S2 to 18dB per octave here, so warp energy is dealt with more decisively for a given amount of intrusion into the audible bass.

One real difference to know about before you assume the Ultra is the S2 in every respect but better: the capacitance options are narrower. The standard S2 offers four values (100, 200, 320 and 420pF); the Ultra offers two (100 and 220pF). For the overwhelming majority of moving-magnet cartridges, whose makers specify somewhere between 100 and 300pF including the cable, that is enough. For a cartridge that specifically wants 400pF or more, the standard S2 is the better tool. This is a published difference, not an error.

Features

• Discrete output stage
• Published total harmonic distortion of 0.00052%
• 89dB signal-to-noise ratio
• Four gain settings: 40, 43, 60 and 63dB
• Four input impedance settings: 10Ω, 100Ω, 1kΩ and 47kΩ
• Switchable subsonic filter at 20Hz, 18dB per octave
• DIP switches on the underside for every setting
• Available in silver or black

Specifications

• Type: Moving-magnet and moving-coil phono preamplifier with a discrete output stage
• Cartridge support: MM and MC, switchable
• Gain: 40 / 43 / 60 / 63dB
• Input impedance: 10Ω / 100Ω / 1kΩ / 47kΩ
• Input capacitance: 100 / 220pF. Note that this is a narrower set than the standard S2’s four values — a real published difference between the two models
• How the settings are made: DIP switches on the underside of the unit
• Signal-to-noise ratio: 89dB (moving-magnet). No separate moving-coil figure is published
• THD: 0.00052%
• RIAA accuracy: Less than 0.4dB, 20Hz–20kHz
• Subsonic filter: Switchable, −18dB at 20Hz
• Alternate EQ curves: None. RIAA only
• Channel separation: Not published. Pro-Ject publishes no channel separation or crosstalk figure for any product in the Phono Box or Tube Box range.
• Inputs: 1 pair RCA
• Outputs: 1 pair RCA
• Power supply: External, 18V DC / 500mA. The unit draws 80mA
• Dimensions: 103 x 37 x 119 mm (W x H x D)
• Weight: 570g without the power supply
• Finishes: Silver or black
• Country of manufacture: Not published for this model
• Warranty: Two years from date of purchase, extendable to three years by registering the product with Pro-Ject and subscribing to their newsletter. Pro-Ject states that warranty is administered by the local distributor and that terms can vary by region; no separate United States term is published. Coverage requires purchase from an authorised dealer — The ’In Groove is one.