SPL Gemini Mastering M/S Processor

SPL Gemini Mastering M/S Processor


Available in black or red.

Gemini is the first M/S Mastering Processor in 120V technology.

With Gemini, M/S processing enters the SPL Mastering series. Gemini is an M/S Encoder and Decoder. Mid signals (voice, snare, bass …) can clearly be separated from side signals (guitar, spatial sounds, cymbals …) and can individually be processed. When working on the sum signal, M/S coding often is the best way to specifically get access to individual elements within a mix. 

Gemini also provides the possibility to work on the stereo panorama. With the Balance control, you can position the mid signal within the stereo panorama. With the Trim control, you can adjust the level of the mid signal in relation to the side signal. In connection with the Stereo Width control, the mixing ratio of both channels can be adjusted. 

An Elliptical Filter, which can cut low-frequency ratios of the sideband is also provided.

M/S with Gemini & Hermes

Hermes and Gemini operate in their complete range of functions as stand-alone devices. A pairing of Hermes and Gemini enables lots of further possibilities.


If the M/S Encoder and Decoder stages of Gemini are each paired with an insert of Hermes, it is possible to freely choose a position for the M/S Encoder and Decoder within the processing chain. This way, it is possible (see image below) to place the M/S Encoder on the third position, an equalizer on the fourth to use it for separate processing of the mid and side signal and then use the M/S Decoder stage of the Gemini on the fifth position to generate an L/R stereo signal.

If you now like to additionally use a compressor, as a further device for M/S processing, you can place it on position 5 and the M/S Decoder stage would thus move to position 6.



  • Max. Input Level: +32,5 dBu
  • Input Impedance: 20 kOhms (bal.)


  • Max. Output Level: +32,5 dBu
  • Output Impedance: ‹ 100 Ohms (bal.)
  • Noise (A-weighted, Insert, Balance & Trim, Filter & Width = active): -98,2 dBu
  • THD & N (at +20dBu): › -110 dB
  • Common-Mode-Rejection (at 0 dBu): -79 dB
  • Transmission Bandwidth: 10 Hz-150 kHz

Power Consumption:

  • 0,11 Amp, 230V/50Hz, 24 Watt, 32 VA
  • 0,22 Amp, 115V/60Hz, 24 Watt, 32 VA


  • 230V/50Hz: 0,5 Amp
  • 115V/60Hz: 1 Amp


  • Standard EIA 19 Inch Housing/1U: 482 x 44 x 300 mm / ca. 19″ x 1.73″ x 11.8″ (front panel excl.)
  • Weight: 5kg / 11 lb


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