The Pro-Ject Connect it SI RCA is the silver-conductor flagship of Pro-Ject's Connect it phono cable range, designed specifically for the critical signal path between a turntable and a phono stage. This is the 1.23m pair, the most popular working length for connecting a deck on the top shelf of a rack to a separates phono preamplifier.
Unlike the copper-based Connect it E, S, DS and RS variants in the wider Connect it family, the SI uses pure silver throughout the signal conductor. Pro-Ject markets the SI as a low-colouration, low-capacitance, fully-shielded interconnect that has been voiced through extensive listening tests, with materials chosen to suit the very small signal levels coming out of a moving-magnet or moving-coil cartridge.
Pure Silver Signal Conductors
Phono-level signals are several orders of magnitude smaller than line-level signals, so any loss or distortion in the cable is exaggerated by the gain of the phono stage that follows. Silver has the highest electrical conductivity of any metal and does not attenuate high frequencies in the way that less pure copper can. In the SI, this translates to a more open top end and better retrieval of fine detail from the cartridge, with less of the soft, rolled-off character that some copper phono leads exhibit.
Low Capacitance for Cartridge Matching
Cable capacitance is far more critical on a phono interconnect than on a line-level cable, because it sits in parallel with the cartridge inductance and directly affects the resonant peak of a moving-magnet cartridge. The Connect it SI is rated at 58 pF per metre, so a 1.23m pair adds roughly 71 pF per channel. Combined with the typical 100-200 pF input loading of a modern phono stage, this stays well within the manufacturer-recommended total capacitance range for the majority of MM cartridges, helping preserve a flat treble response and the correct cartridge resonance.
Electrical Shielding with Separate Ground Lead
The cable is fully electrically shielded against external interference, which is particularly important on the phono path because of how easily turntable wiring picks up mains hum and RF. A separate ground lead is included so the turntable's chassis or tonearm earth can be connected directly to the phono stage's ground post, completing the safety and signal-grounding path independently of the audio shield.
Locking RCA Plugs
The SI is terminated with Pro-Ject's locking RCA plugs. A collar on each plug screws down onto the RCA socket of the phono stage or turntable, guaranteeing a tight, low-resistance contact that cannot work itself loose with cable movement or vibration. This is especially useful at the turntable end, where a slight pull on the cable can otherwise unseat a standard RCA plug enough to introduce noise.
Handmade in Europe
Like the rest of the Connect it range, the SI is hand-assembled in Europe. The conductors, dielectric and connectors were specified by Pro-Ject following internal listening trials rather than purely on measurement, and each cable is directional - one end is marked as the source end - so the shield is grounded only at the receiving component, the standard arrangement for keeping ground loops out of the signal path.