Bellatrix   Shelf speaker as in K+T 6/2018

Technical data
  • impedance: 4 Ohm
  • sensivity (2,83V/1m): 90 dB
  • size (HxWxD): 600 x 200 x 300 mm
  • frequency range (-8dB): 45 - 25000 Hz
  • crossover frequency(s): 2900 Hz
  • speaker type: bass reflex

Bellatrix is a two way compact speaker with air motion transformer and two high end bass loudspeakers.

Bellatrix is a bass-reflex cabinet loudspeaker with drivers of Audaphon and Wavecor.

The kit is delivered with the following drivers:
- a Audaphon AMT 2i air motion transformer (ribbon-tweeter)
- two Wavecor WF152CU14 midrange / bass drivers

The loudspeaker has been developed by Dennis Frank and Daniel Gattig.

The crossover consists of:
- a 3rd order high-pass filter (18 dB per octave slope) for the tweeter.
- a 3rd order low-pass filter (18 dB per octave slope) for the woofer.

The frequency response of this speaker is nearly linear.

The decay spectrum as shown in the waterfall diagram is exemplary, free of any disturbing resonance.

At low volume, i.e. 85 dB at 1 m, the nonlinear distortions are below 1% above 200 Hz and doesn't exceed 1,1% at 95 dB at 1 m between 300 and 15000 Hz.

Our kit consists of

  • Audaphon AMT-2i
  • 2x WF152CU14, Wavecor Mid/Woofer, 8 Ohm, paper cone, BD, phase plug
  • 2x Bass reflex tube HP50, 50x145 mm, black
  • 2x Damping fleece MT Bondum 800 (30 x 50 x 2 cm)
  • 0,5x PE sealing tape, 5x2 mm, 7.5 m
  • Damping Sonofil 100 x 35 cm for 20 litres
  • Binding Post PK28 I, gold plated (one pair, red and black)
  • 3m Speaker cable 2x1.5 mm2, transparent
  • Allen wood screws IS 4x16mm, black (MZF-8614), 8 pcs
  • Plan for DIY kit

the crossover components (right),
to be mounted on a small wooden board.

  • Audaphon MKP CAP Superior 5.6 uF / 400 Vdc
  • Audaphon MKP CAP Superior 8.2 uF / 400 Vdc
  • Audaphon MKP CAP Superior 12 uF / 400 Vdc
  • Mundorf air core coil L140, 0.27 mH/0.13 Ohm
  • 1.3 mm air core coil, 0.82 mH/0.275 Ohm
  • 0.7 mm air core coil, 0.22 mH/0.39 Ohm

Kit without cabinet, price per speaker   EUR 719,00 excl. VAT: € 604.20 / $ 688.79

Kit with high-end crossover

The high-end kit is delivered with copper foil coils or baked varnish air core coils on important parts of the crossover for minimizing microphonic effects. - The current flow through the coil creates a magnetic field which sets the reel of wire in motion. This motion induces a voltage in the coil which adds itself to the signal. The stiffer the reel of wire is, the less the signal will be altered. The capacitors for the tweeter are of type polypropylen (MKP) Clarity-Cap ESA 250.

Kit with high-end-crossover without cabinet, price per speaker   EUR 758,00 excl. VAT: € 636.97 / $ 726.15

Biwiring Terminal plates

The kit is delivered with binding posts of high quality. If you prefer a terminal plate with four binding posts for bi-wiring (tweeter and woofer are connected to the amplifier separately) please tell.

Impedance correction

If you want to use a valve amplifier with this speaker an impedance correction should be employed. In this case the component quality is less important; therefore, we offer only one kit (upon request higher quality components are available).


Price per impedance correction for one speaker, to be mounted on a small wooden board.     EUR 14,50 excl. VAT: € 12.18 / $ 13.89

universal PCB

If you prefer to mount the crossover components on a universal PCB instead on wood
PCB 150x115 mm, tin plated, price per unit:   EUR 4,70 excl. VAT: € 3.95 / $ 4.50
We recommend two boards per kit (4 boards per speaker pair)


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