Pro-Ject MC Step-Up Box DS3 B Step-Up Transformer

Passive dual-mono SUT for low-output moving coil cartridges, with XLR and RCA inputs

Low output MC cartridges send an output that’s about a tenth the output of MM cartridges. This means they require a specialty phonostage with more gain and different electrical parameters… unless you add a step-up transformer to prep the signal for your MM phono stage!

The MC Step-Up Box DS3 B works very differently from a phono preamplifier. The windings ratio of the transformer determines the gain factor. As it’s a passive device that doesn’t require a power supply, no additional power can be produced. The increase in voltage is achieved through a corresponding decrease in current.

As there is no amplification, the MC Step-Up Box DS3 B is remarkably low in noise and distortion with a lively, dynamic and natural sonic signature. It offers both balanced and single-ended inputs and outputs and uses high-quality Lundahl LL 1678 audio transformers to preserve every detail.

Why Use a Step-Up Transformer?

Once upon a time, step-up transformers were all but required for the optimal handling of a low-output MC cartridge’s signal. Active amplification technology was simply too noisy back then (defeating the purpose of the low-output design). A step-up transformer removes active amplification from the equation and passively boosts the signal the old-fashioned way. Operating entirely apart from mains power, it’s an opportunity to silently add 21 or 24 dB, an output level that’s comparable to MM cartridges.

Needless to say, modern active amplification has improved by leaps and bounds. MC phono preamps can apply all the necessary gain without inducing excessive noise levels; yet there remains a niche population of critical listeners who continue to swear by the performance of the step-up transformer. It’s just a different approach that, pending your low-output cartridge and MM preamp, may be just what you’re after.

Designed & Handmade in Europe

The Step-Up Box DS3 B is carefully designed and handmade in Europe. Our goal is to develop a technically flawless device in a housing that is only as big as necessary. Due to the timeless design and rigid aluminum chassis, the MC Step Up Box DS3 B is built to last. With high-quality materials and components and a well-thought-out design, Pro-Ject brings the concept of MC step-up transformers back into the conversation.