CT 313   Shelf speaker as in K+T 1/2021

Technical data
  • impedance: 4 Ohm
  • sensivity (2,83V/1m): 85 dB
  • size (HxWxD): 317 x 192 x 200 mm
  • frequency range (-8dB): 90 - 21000 Hz
  • crossover frequency(s): 3100 Hz
  • speaker type: closed box

CT 313 is a two way compact speaker.

CT 313 is a closed-cabinet loudspeaker with drivers of Tang Band .

The kit is delivered with the following drivers:
- a Tang Band 25-1719 tweeter
- a Tang Band W4-655 midrange / bass driver

The loudspeaker has been developed by Michael Rochow and Thomas Schmidt.

The crossover consists of:
- a 2nd order high-pass filter (12 dB per octave slope) for the tweeter.
- a 2nd order low-pass filter (12 dB per octave slope) for the mids-woofer.

The frequency response of this speaker is perfectly linear.

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

At low volume, i.e. 80 dB at 1 m, the nonlinear distortions are below 0,7% above 300 Hz and doesn't exceed 2,2% at 90 dB at 1 m between 300 and 15000 Hz.

Our kit consists of

  • Tang Band 25-1719 ceramic tweeter
  • Tang Band W4-655 C, unshielded
  • 0,5x PE sealing tape, 5x2 mm, 7.5 m
  • 0,25x Damping Sonofil 100 x 35 cm for 20 litres
  • 0,25x Foam N25, 97,5x49x4 cm, black
  • 2x Binding Post PK31, gold plated (one pair, red and black)
  • 1,5m Speaker cable 2x1.5 mm2, transparent
  • Pan screws 3.5x17 black, torx, 8 pieces
  • Plan for DIY kit

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

  • Audaphon MKP CAP Superior 4.7 μF; / 400 Vdc
  • Audaphon MKT CAP 6.8 μF; / 160 Vdc
  • 1.0 mm air core coil, 1.5 mH/0.63 Ohm
  • 0.7 mm air core coil, 0.15 mH/0.28 Ohm
  • Metal-oxide resistor, 10W 2.7 Ohm (red-purple-gold)

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 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 Tang Band 25-1719 are of type polypropylen (MKP) Clarity-Cap ESA 250 V.

  • ClarityCap ESA capacitor 4.7 μF; / 250 Vdc
  • Audaphon MKP CAP Superior 6.8 μF; / 400 Vdc
  • Mundorf baked varnish air core coil BL71, 0.15 mH/0.28 Ohm
  • Mundorf baked varnish air core coil BL100, 1.5 mH/0.62 Ohm
  • Metal-oxide resistor, 10W 2.7 Ohm (red-purple-gold)

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).

  • Mundorf, electrolytic capacitor, etched, 56 μF;/100 Vdc
  • 0.7 mm air core coil, 0.12 mH/0.29 Ohm
  • ceramic resistor 4.7 Ohm/20 Watt

Price per impedance correction for one speaker, to be mounted on a small wooden board.     EUR 9,12 excl. VAT: € 7.66 / $ 8.20

universal PCB

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 / $ 3.78
We recommend one board per kit (two boards for a speaker pair)

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