Bob’s Devices SKY Step-Up Transformer

A hand-crafted, MC SUT with gold-plated hardware.

Designed to match the inductance of a wide range of cartridges, Bob’s Devices SKY SUT sits between a low-output moving coil cart and your phonostage. The SKY uses proprietary 80% nickel mu-metal laminations in the transformer windings which are processed for optimal performance at very low signal levels. The result is giant crystal structures within the material, and when the laminations are stacked into the coils great care is taken not to induce any strain. Due to this, bandwidth has been extended in both directions than in previous versions.

The new  CineMag SKY (Blue Version) transformers are matched by gold-plated hardware in a hand-polished black powder-coated cast-aluminum enclosure. All lettering is laser etched. The two C&K Silver front panel switches control gain (high, low) and ground (on/lift).

SKY Models

The models offer the following switchable gain options.

SKY 10: 1:5 (14 dB), 1:10 (20 dB)

SKY 20: 1:10 (20 dB), 1:20 (26 dB)

SKY 30: 1:15 (24 dB), 1:30 (30 dB)

SKY 40: 1:20 (26 dB), 1:40 (32 dB). Also available as fixed 1:40 (32 dB), eliminating the toggle switch in the signal path.

Construction Techniques

All connections are resistance soldered using the American Beauty system which avoids heat damage to the delicate insulation on the hair-like wires of the transformers. A grounding post lets you connect your turntable ground and your preamplifier ground. It also includes a ground “lift” switch.

In all modes, the transformer cases and internal Faraday shields are connected to the ground screw. In the Ground mode, the phono negatives are connected to the grounding lug. This configuration works well for those systems where the turntable ground is connected to the negative leads coming from the phono cartridge or where the negative inputs to the preamp are internally connected to ground.

In the Lift mode, none of the conductors in the RCA jacks are connected to the case, ground, or shield and there is no electrical connection between channels. This design allows you much flexibility to mitigate ground loops regardless of the configuration of your other equipment.