Gema

Open Source Kit: Not available as full kit, read below for details.

Gema is a large 3-way speaker paying homage to the classic speaker of the 1970’s. Generous enclosure proportions fitted with large bass drivers were the bee’s knees at the time. And for good reason! The Gema is our take on a retro-styled speaker, and the much loved 12″ SB34NRXL75-8 lays the foundation of a deep, well controlled and tuneful bassline.

The dedicated midrange is covered from 680Hz and all the way up to 3kHz by the 4″ paper cone SB12MNRX2-25-4 which is characterized by good efficiency, low moving mass and great linearity resulting in excellent midrange clarity.

To perfectly match the articulate and open midrange the top end is handed over to the 1 inch soft dome SB26STAC-c000-4 equipped with die-cast aluminium faceplate, optimised rear chamber and full copper cap.

The well braced cabinet is designed with a large slot port tuned to 28 Hz opening to the front of the speaker and a generous sealed enclosure for the dedicated midrange. We highly recommend building the speakers from high quality 18mm plywood.

A good starting point for the placement of the Gema would be a spacing of 2.5-3 meters between the speakers with generous clearance to any side and rear walls and ideally on a stand or plinth elevating the speaker about 25cm from the floor and tilted back at about 6 degrees and a slight toe in. The tweeter and midrange are intended to be on the outside, but this will depend on the room – as usual, we encourage you to experiment with speaker placement to suit your taste and listening space.

 

Open Source Kit

Gema is an open source kit meaning the speaker is fully developed and documented by SB Acoustics and you are free to use the plans.

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Specs

  • Frequency Range: 36 – 24000 Hz
  • Sensitivity ( 2.83V / 1m ): 87 dB
  • Nominal Impedance: 6Ω
  • Max SPL: 108 dB
  • Recommended Amplifier: 50 – 200 W
  • Crossover Frequency: 680/ 3000 Hz
  • Enclosure Type: Bass reflex
  • Port tuning Frequency: 28 Hz
  • Drive Units: SB26STAC-C000-4, 4″ SB12MNRX25-4 & 12″ SB34NRXL75-8