CT251, Floorstanding   as in K+T 6/2010

The CT 251 is a large but not particularly high floorstanding bass reflex loudspeaker.

The speaker is equipped with a Dayton dome tweeter DC-28F-8, a dome midrange DC50F-8 and a 20 cm Dayton woofer SD215-88. According to the building instruction the dome midrange may be improved on by adding additional foam.

The drivers are controlled by three-way crossover. The crossover is 18 dB /octave for mids and tops and 12 dB/octave for bass.

The CT 251 was designed by Thomas Schmidt and Holger Barske. By using only rectangular boards the cabinet is easy to build.

The bass reflex tube is on the rear side and consists of a bent drainage pipe (a straight 20 cm part and a bent part of 90 degrees) that may be bought at a builder's merchant.

An excerpt from the Klang+Ton review

... "That's definitely audible: like almost no other loudspeaker the CT251 really gets cracking and immediately one is tempted to increase the volume even further as if the speaker would lack dynamics. The usual reverberation and resonance is simply not there. After a short while getting used to the extremely clean reproduction - (the drivers also have to find some common ground) you learn to appreciate this inexpensive loudspeaker.

One wouldn't describe the performance as cheap showmanship but rather as dignified. Even the extremely low bass doesn't show off: the solid foundation is simply there and reproduces every low note with nonchalance. The two dome drivers perform with an unobtrusive airiness and nonchalance especially accommodating lighter music styles - there is speed and sparkle that is fully integrated into the overall reproduction. A really good loudspeaker for both, low and high volumes."

Our kit consists of

Please note: our standard kit already comprises MKP instead of MKT capacitors in the path to the tweeter and for mid frequencies a non-etched E-Cap is used instead of an etched one.

Kit without cabinet, price per speaker - not available

If you prefer to mount the crossover components on a 240 x 165 mm universal PCB instead on wood:
Universal PCB RA240, order no.. str-RA240, price per unit: EUR 8,60 excl. VAT: € 7.23 / $ 7.81
We recommend one board per kit (two boards for a speaker pair)

Kit with high-end crossover

In our high-end version no etched capacitors are used. In parallel to the woofer there are unetched capacitors. Elsewhere in the crossover only MKP capacitors are used (foil capacitors with very small losses). All coils are without core to reduce distortion.

• electrolytic capacitor, unetched, 47uF / 50 Vdc
• electrolytic capacitor, unetched, 100uF / 50 Vdc
• MKP-Kondensator 18 μF (15 μF + 3.3 μF in parallel)
• MKP-Kondensator 3.3 μF / 400 Vdc
• 2 ocs MKP-Kondensator 15 μF / 400 Vdc
• MKP-Kondensator 66 μF (3x 22 μF in parallel)
• 1.0 mm air core coil, 1.5 mH/0.62 Ohm
• Mundorf baked varnish air core coil BL71, 0.18 mH/0.34 Ohm
• Mundorf baked varnish air core coil BL71, 0.39 mH/0.51 Ohm
• Mundorf baked varnish air core coil BL71, 0.56 mH/0.64 Ohm
• I-core coil, small 2.2 mH/0.40 Ohm
• MOX10 resistor 1.0 Ohm/10Watt (brown-black-gold)
• MOX10 resistor 3.3 Ohm/10Watt (orange-orange-gold)
• MOX10 resistor 4.7 Ohm/10Watt (yellow-purple-gold)

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

If you prefer to mount the crossover components on a 240 x 165 mm universal PCB instead on wood:
Universal PCB RA240, order no.. str-RA240, price per unit: EUR 8,60 excl. VAT: € 7.23 / $ 7.81
We recommend one board per kit (two boards for a speaker pair)