CT 288   Shelf speaker as in K+T 6/2016

Technical data
  • impedance: 8 Ohm
  • sensivity (2,83V/1m): 80 dB
  • size (HxWxD): 310 x 200 x 285 mm
  • frequency range (-8dB): 48 - 26000 Hz
  • crossover frequency(s): Hz
  • speaker type:

CT 288 is an compact speaker with drivers from Fountek, SEAS and Mission. The kit is delivered with a SEAS 22 TAF/G tweeter, a Fountek FW146 Woofer, and a Mission CP 168 as passive radiator.

The Mission CP 162 must be tuned for the job as a passive radiator. With a angle grinder, the magnet must be cut from the basket. A round wooden part must be glued in the voice coil former to screw on weights. The spider must be partially cutted for a lower resonance frequency.

CT 288 has been developed by Oliver Martin and Frank Zeppelin.

The crossover consists of a 2nd order high-pass filter (12 dB per octave slope) for the tweeter. The woofer are connected to a 3rd order low pass filter (18 dB per octave slope). An RCL circuit in parallel to the woofer is smoothing the frequency response.

The frequency response of this speaker is linear. The decay spectrum is nearly perfect. At low volume, i.e. 85 dB at 1 m, the nonlinear distortions are lower than 0,5% above 200 Hz and doesn't exceed 1% at 95 dB at 1 m .

Our kit consists of

  • Seas 22TAF/G (H1283-06)
  • Fountek FW 146
  • Mission CP-168
  • 2x Damping fleece MT Bondum 800 (30 x 50 x 2 cm)
  • Bi-wiring Terminal T122 Au with brass, gold plated
  • 1,5m Speaker cable 2x1.5 mm2, transparent
  • 2x 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 MKP CAP Superior 3.3 μF / 400 Vdc
  • Audaphon MKT CAP 2.2 μF / 160 Vdc
  • Audaphon MKT CAP 3.3 μF / 160 Vdc
  • 1.0 mm air core coil, 0.82 mH/0.44 Ohm
  • 1.0 mm air core coil, 2.2 mH/0.89 Ohm
  • 0.7 mm air core coil, 0.10 mH/0.27 Ohm
  • 0.7 mm air core coil, 0.82 mH/0.89 Ohm
  • Metal-oxide resistor, 10W 1.5 Ohm (brown-green-gold)
  • 2x Metal-oxide resistor, 10W 8.2 Ohm (grey-red-gold)

Instead of Basotect damping material we deliver Bondum 800.

Kit without cabinet, price per speaker   - not available

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 of type polypropylen (MKP) and in series to the tweeter a Clarity-Cap ESA 250 V is employed.

Kit with high-end-crossover without cabinet, price per speaker   - not available

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 13,30 excl. VAT: € 11.18 / $ 12.07

universal PCBs

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 / $ 4.27
We recommend one board per kit (2 boards per speaker pair)

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