Speed Box S

  • Improved power supply for older turntables
  • Automatic switching between 33 and 45RPM
  • Makes some turntables 78RPM compatible

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The Speed Box S offers a functional and convenient upgrade for many Pro-Ject turntables with a 16V AC motor that do not already have built-in speed control.

The Speed Box S acts as an AC generator for the turntable, replacing the fluctuant supply from a normal 16V power supply and regulating it. The result is a clean power signal that allows the motor to perform optimally. The added convenience is that the Speed Box S can shift frequency, for easy changing between 33 and 45RPM at the push of a button.

Inside, the Speed Box S makes use of high-quality materials in the quartz-controlled oscillator and filter circuits. Externally it is stylish, compact and minimal - matching any other Box Design S Line component. 

Connection is simple, as the Speed Box S is supplied with a link cable that plugs into your turntable instead of the normal power supply. There is also a wide range of compatibility (see below), and in some cases the Speed Box S can even add 78RPM compatibility, when partnered with a special Speed Box Pulley.

Key Features:

  • Electronic speed change between 33 and 45RPM (see below)
  • 78RPM also possible after fitting accessory pulley (see below)
  • Replaces the existing 16V turntable power supply
  • Quartz-generated high precision electronic speed regulation 
  • Creates a cleaner AC mains signal for your turntable
  • Allows the motor to run more efficiently and with less resonance

For a full compatibility list, read our FAQ

Technical Data

Input Power: 18V DC (Supplied PSU)
Output Power: 16V AC / 190mA (3W max.)
Nominal Speeds: 33 / 45 RPM
78 RPM with Optional Pulley
Speed Stability: ± 0.001%
Power Cable Length: Approx. 400mm
(Turntable to Speedbox)
Dimensions: 103 x 36 x 104mm
103 x 36 x 115mm (Incl. Sockets)
Weight: 560g


Will the Speed Box S work with my turntable?

The Speed Box S will only work with certain Pro-Ject turntable models that have a detachable mains socket and a 16V AC power supply. It will not work with items that have a captive mains lead, or a DC power supply. To make your compliant turntable turn at 78RPM, you will need to purchase the additional 78RPM Pulley and a 78RPM stylus.

Below is a list of compliant turntables...

Works with Speed Box S (and turns at 78RPM with additional pulley):

  • Debut II (later versions with 16V power supply)
  • Debut III
  • Debut S/E3
  • 1.2 (later versions with 16V power supply)
  • 1 Xpression
  • 1 Xpression II
  • 1-Xpression III
  • RPM 4 (later versions with 16V power supply)
  • RPM 5  

Works with Speed Box S (33 and 45RPM only):

  • Essential
  • 2.9 (later versions with 16V power supply)
  • 2 Xperience (non-DC versions)
  • 2 Xperience Classic (non-DC versions)
  • 6 Perspex (non-DC versions)
  • RPM 1.3 (Genie 3)
  • RPM 9
  • RPM 9.1X
  • RPM 9.2
  • RPM 10
  • RPM 10.1

The Speed Box S will not work with any turntable that has a captive mains cable.
The Speed Box S will not work with any turntable that has a DC power supply.
The Speed Box S will not work with any turntable that has speed control or a USB phono stage built-in.

If your turntable is not in the list above, or if you are unsure, please Contact Us for confirmation of compatibility.

For more help and advice visit our Tech Support section

Note: We’re constantly updating our website to ensure all our listings are as accurate as possible. However, the images and text on this page can be subject to change without notice, and errors and omissions are excepted.

If you have any questions, please contact us.