CT 286   Shelf speaker as in K+T 4/2016

Technical data
  • impedance: 4 Ohm
  • sensivity (2,83V/1m): 81 dB
  • size (HxWxD): 492 x 132 x 222 mm
  • frequency range (-8dB): 38 - 21000 Hz
  • crossover frequency(s): 1000 Hz
  • speaker type: bass reflex

CT 286 is a slim floorstanding speaker for usage on the desk next to the monitor. The high of the speaker is similar to modern TFT monitors with sizes of 27 inch.

CT286 is developed by Holger Barske and Thomas Schmidt.

The crossover consists of a second order high-pass filter (12 dB per octave slope) for the full range loudspeaker. A trap filter in series to the fullrrange loudspeaker smoothens the frequency response. The woofer is connected to a 2nd order low-pass filter.

The frequency response is under 30 degrees flat. The decay spectrum is good with exception of some resonances at about 500 Hz. At low volume, i.e. 85 dB at 1 m, the nonlinear distortions are not higher than 1% above 500 Hz and does not exceed 4% at 95 dB at 1 m.

Our kit consists of

  • Visaton FR 58, 8 Ohm
  • Visaton KT 100 V, 4 Ohm
  • Bass reflex tube HP35, 35x125 mm, black
  • 0,5x PE sealing tape, 5x2 mm, 7.5 m
  • Damping Sonofil 100 x 35 cm for 20 litres
  • Binding Post PK31, gold plated (one pair, red and black)
  • 1,5m Speaker cable 2x1.5 mm2, transparent
  • Pan screws 3.5x17 black, cross recess, 8 pieces
  • Plan for DIY kit

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

  • Audaphon MKT CAP 2.2 μF / 160 Vdc
  • Audaphon MKT CAP 4.7 μF / 160 Vdc
  • Audaphon MKT CAP 10 μF / 160 Vdc
  • electrolytic capacitor, unetched, 68uF / 50 Vdc
  • 1.0 mm air core coil, 1.2 mH/0.54 Ohm
  • 0.7 mm air core coil, 0.47 mH/0.50 Ohm
  • Mundorf H core coil H50, 5.6 mH/1.11 0hm
  • Metal-oxide resistor, 10W 10 Ohm (brown-black-black)

Kit without cabinet, price per speaker   EUR 102,00 excl. VAT: € 85.71 / $ 92.57

Kit with high-end crossover

The high-end kit is delivered with baked varnish air core coils 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. All capacitors are foil capacitors and in series to the fullrange driver high quality polypropylen capacitors (MKP) are used.

Kit with high-end-crossover without cabinet, price per speaker   EUR 151,00 excl. VAT: € 126.89 / $ 137.04

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 8,70 excl. VAT: € 7.31 / $ 7.90

universal PCBs

If you prefer to mount the crossover components on a 140 x 102 mm universal PCB instead on wood:
Universal PCB RA140, order no.. str-RA140, price per unit:   EUR 4,20 excl. VAT: € 3.53 / $ 3.81
We recommend one board per kit (two boards for a speaker pair)

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