A New/Old Way to Upgrade Your MC

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

The MC Step-Up Box S3 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 S3 is remarkably low in noise & distortion with a lively, dynamic & natural sonic signature.

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 & passively boosts the signal the old-fashioned way. Operating entirely apart from mains power, it’s an opportunity to silently add 21 or 24dB, which amounts to an output that’s comparable to MM cartridges (this is why a step-up transformer’s output is connected to an MM phono preamp input). Needless to say, modern active amplification has improved by leaps & 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 S3 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 & rigid aluminum chassis, the MC Step Up Box S3 is built to last an eternity. With high-quality materials & components and a well-thought-out design, Pro-Ject brings the concept of MC step-up transformers back into the conversation.

Additional information
Weight 0.93 kg
Dimensions 16.4 × 20.6 × 5.5 cm



  • Sonic upgrade for MC cartridges
  • Fully passive transformer (no power supply!)
  • Superior sound quality
  • 1:16 transformer ratio
  • Mu-metal transformer shielding
  • Input impedance matching (10 or 100 ohms)
  • Dual-mono design principle
  • High channel separation
  • Gold-plated RCA terminals
  • Solid aluminum chassis shields RF/EMI
  • Available in silver or black
  • Made in Europe


  • Frequency response: 10Hz – 55kHz (+/- 1dB)
  • Gain at 10-40 ohms: 21dB at 1kHz
  • Gain at 40-150 ohms: 24dB at 1kHz
  • Recommended load: 47k ohms / 100pF
  • Input: 1x pair RCA phono sockets
  • Output: 1x pair RCA phono sockets
  • Dimensions (WxHxD): 206 x 65 x 164mm
  • Dimensions (standard): 8.11 x 2.56 x 6.46″
  • Mass (weight): 940g (2.07 lbs)