Bob's Devices SKY 30-S Step-Up Transformer

Switchable 1:15 / 1:30 MC step-up with longer core and improved winding. Handcrafted in the USA

Bob's Devices SUTs are hand-made, one at a time, using point-to-point wiring and are individually tested. No circuit boards are used. The 30-S runs passively, adding no noise, and is designed for highly resolving analog systems.

The SKY 30-S is an upgrade from the SKY 30. It is heavier and has better sound. Says Bob's Devices, "It was hard to upgrade the SKY 30. We tried many combinations and found that by increasing the length of the core, we could change the winding scheme just a bit. You will 'hear the magic."

The SKY 30-S has the same ratios as the original: 1:15 in low and 1:30 in high. You will hear improved bandwidth and dynamics, and enjoy the same black powder-coated cast-aluminum enclosure with laser-etched lettering.

SUT with MM Phono Vs. MC Phono

Most moving-coil phono preamps add an extra gain stage to boost the tiny MC signal up to moving-magnet level, but that almost always raises noise and compromises sound. That's a lot of gain needed on a very delicate signal.

A Bob’s Devices step-up transformer (SUT) avoids those trade-offs: it’s passive, silent, and purpose-built to match your specific MC cartridge to any MM phono input.

Instead of dealing with switches, jumpers, and noise level inside an all-in-one preamp, you get the cleanest signal path, better cartridge matching, and a lower noise floor.

If you want your MC cartridge to deliver everything it’s capable of—clarity, dynamics, and a quieter background—you’ll get it with a dedicated Bob’s Devices SUT.

Specifications

Transformers

Lamination/Core: 80% nickel mu-metal laminations, processed for low-level performance

Electrical

Step-Up Ratios (Low, High): 1:15, 1:30

Connectivity

Inputs/Outputs: Choose from RCA and XLR

Grounding: Ground post with Ground/Lift toggle

Switching Hardware: Premium silver-contact toggles for Gain and Ground

Construction

Enclosure: Hand-polished black powder-coated cast-aluminum; laser-etched labeling

Wiring: Point-to-point; no PCBs

Manufacture: Hand-built in the USA